tag:theconversation.com,2011:/au/topics/microbes-5025/articlesMicrobes – The Conversation2024-03-25T12:39:22Ztag:theconversation.com,2011:article/2241522024-03-25T12:39:22Z2024-03-25T12:39:22ZWhat is dirt? There’s a whole wriggling world alive in the ground beneath our feet, as a soil scientist explains<figure><img src="https://images.theconversation.com/files/582688/original/file-20240318-24-77z9su.jpg?ixlib=rb-1.1.0&rect=0%2C9%2C3110%2C2057&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Dig into soil and you'll find rock dust but also thousands of living species.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/little-childs-hands-digging-in-the-mud-royalty-free-image/619539728">ChristinLola/iStock/Getty Images Plus</a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em><a href="https://theconversation.com/us/topics/curious-kids-us-74795">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">curiouskidsus@theconversation.com</a>.</em></p>
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<blockquote>
<p><strong>What is dirt? – Belle and Ryatt, ages 7 and 5, Keystone, South Dakota</strong></p>
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<p>When you think about dirt, you’re probably picturing soil. There’s so much more going on under our feet than the rock dust, or “dirt,” that gets on your pants.</p>
<p>When <a href="https://arts-sciences.und.edu/academics/biology/brian-darby/index.html">I began studying soil</a>, I was amazed at how much of it is actually alive. Soil is teeming with life, and not just the earthworms that you see on rainy days.</p>
<p>Keeping this vibrant world healthy is <a href="https://www.youtube.com/watch?v=Qas9tPQKd8w">crucial for food, forests and flowers to grow</a> and for the animals that live in the ground to thrive. Here’s a closer look at what’s down there and how it all works together.</p>
<figure class="align-center ">
<img alt="Cupped hands holds soil against a dark background with a tendril of plant root dangling through the fingers." src="https://images.theconversation.com/files/582689/original/file-20240318-20-8yglsj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/582689/original/file-20240318-20-8yglsj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/582689/original/file-20240318-20-8yglsj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/582689/original/file-20240318-20-8yglsj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/582689/original/file-20240318-20-8yglsj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/582689/original/file-20240318-20-8yglsj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/582689/original/file-20240318-20-8yglsj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Soil is a vibrant ecosystem.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/bokeh-photography-of-person-carrying-soil-jin4W1HqgL4">Gabriel Jimenez via Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>The rocky part of soils</h2>
<p>If you scoop up a handful of dry soil, the basic dirt that you feel in your hand is actually very small pieces of <a href="https://passel2.unl.edu/view/lesson/c62dc027ae56/1">weathered rock</a>. These tiny bits eroded from larger rocks over millions of years.</p>
<p>The <a href="https://www.soils4teachers.org/physical-properties/">balance of these particles</a> is important for how well soil can hold water and nutrients that plants need to thrive. </p>
<p>For example, <a href="https://www.masterclass.com/articles/sandy-soil-guide">sandy soil</a> has larger rock grains, so it will be loose and can easily wash away. It won’t hold very much water. <a href="https://www.thespruce.com/understanding-and-improving-clay-soil-2539857">Soil with mostly clay</a> is finer and more compact, making it difficult for plants to access its moisture. In between the two in size is <a href="https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/what-is-silt.htm">silt, a mix of rock dust and minerals</a> often found in fertile flood plains.</p>
<p>Some of the most productive soils have a good balance of sand, clay and silt. <a href="https://www.masterclass.com/articles/how-to-create-loam-soil-for-your-garden">That combination</a>, along with the remnants of plants and animals that have died, helps the soil to retain water, allows plants to access that water and minimizes erosion from wind or rain.</p>
<figure class="align-center ">
<img alt="Three tipped over pots spill different types of soil – sandy is heavier grain, clay is finer grain and thicker, and loamy is darker." src="https://images.theconversation.com/files/581414/original/file-20240312-16-meqnvu.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/581414/original/file-20240312-16-meqnvu.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=371&fit=crop&dpr=1 600w, https://images.theconversation.com/files/581414/original/file-20240312-16-meqnvu.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=371&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/581414/original/file-20240312-16-meqnvu.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=371&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/581414/original/file-20240312-16-meqnvu.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=467&fit=crop&dpr=1 754w, https://images.theconversation.com/files/581414/original/file-20240312-16-meqnvu.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=467&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/581414/original/file-20240312-16-meqnvu.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=467&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Loamy soil, ideal for gardens, is a mix of sand, clay and silt.</span>
<span class="attribution"><a class="source" href="https://www.nesdis.noaa.gov/learn-about-soil-types">NOAA</a></span>
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</figure>
<h2>The wriggling, munching parts of soil</h2>
<p>Among all those rock particles is a <a href="https://doi.org/10.3390/app10113717">whole world of living things</a>, each busy doing its job.</p>
<p>To get a sense of just how many creatures are there, picture this: The zoo in Omaha, Nebraska, boasts <a href="https://www.omahazoo.com/">over 1,000 animal species</a>. But if you scooped up a small spoonful of soil in your backyard, it would likely contain <a href="https://www.ceh.ac.uk/our-science/case-studies/case-study-why-do-soil-microbes-matter">at least 10,000 species</a> and around a billion living microscopic cells.</p>
<p>Most of those species are <a href="https://www.westernsydney.edu.au/newscentre/news_centre/story_archive/2018/first_soil_atlas">still largely a mystery</a>. Scientists don’t know much about them or what they do in soil. In fact, most species in soil don’t even have a formal scientific name. But each plays some kind of role in the vast soil ecosystem, including generating the <a href="https://www.aces.edu/blog/topics/farming/essential-plant-elements/">nutrients that plants need to grow</a>.</p>
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<a href="https://images.theconversation.com/files/581410/original/file-20240312-20-vn3j2x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two centipede-like creatures caught on camera immediately after a rock is lifted." src="https://images.theconversation.com/files/581410/original/file-20240312-20-vn3j2x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/581410/original/file-20240312-20-vn3j2x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=439&fit=crop&dpr=1 600w, https://images.theconversation.com/files/581410/original/file-20240312-20-vn3j2x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=439&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/581410/original/file-20240312-20-vn3j2x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=439&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/581410/original/file-20240312-20-vn3j2x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=552&fit=crop&dpr=1 754w, https://images.theconversation.com/files/581410/original/file-20240312-20-vn3j2x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=552&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/581410/original/file-20240312-20-vn3j2x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=552&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Lifting a rock reveals a symphylan, or garden centipede, left, and a poduromorph, or plump springtail, munching through the soil.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Symphylan_%26_poduromorph_springtail_(3406419924).jpg">Marshal Hedin via Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Imagine a leaf falling from a tree in late autumn.</p>
<p>Inside that leaf are a lot of nutrients that plants need, such as nitrogen, potassium and phosphorus. There is also a lot of <a href="https://scied.ucar.edu/learning-zone/earth-system/biogeochemical-cycles">carbon in that leaf</a>, which holds energy that can be used by other organisms such as bacteria and fungi.</p>
<p>The leaf itself is too large for a plant to take up through its roots, of course. But that leaf can be broken down into smaller and smaller pieces. This process of breaking down plant and animal tissue is <a href="https://youtu.be/IBvKKMzXYtY?feature=shared">known as decomposition</a>.</p>
<p>When the leaf first falls to the ground, <a href="https://doi.org/10.3390%2Finsects11010054">arthropods</a> – such as insects, mites and <a href="https://www.chaosofdelight.org/collembola-springtails">collembolans</a> – break the leaf down into smaller chunks by shredding the tissue. Then, an <a href="https://youtu.be/n3wsUYg3XV0?feature=shared">earthworm might come along</a> and eat one of the smaller chunks and break it down even more in <a href="https://www.pbs.org/video/how-do-worms-turn-garbage-into-compost-jwj6cm/">its digestive tract</a>.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/2Pa1FwmKZcQ?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">PBS explores how earthworms help turn dead plants into fertile soil.</span></figcaption>
</figure>
<p>Now the broken-up leaf is small enough for microbes to come in. <a href="https://ohioline.osu.edu/factsheet/anr-36">Bacteria</a> and <a href="https://ohioline.osu.edu/factsheet/anr-37">fungi secrete enzymes</a> into the soil that further break down organic material into even smaller pieces. If enough microbes are active, eventually this organic material will be broken down enough that it can dissolve in water and be taken up by plants that need it.</p>
<p>To aid in this process, there are many small animals, such as <a href="https://www.canr.msu.edu/news/are_soil_nematodes_beneficial_or_harmful">nematodes</a> and <a href="https://www.livingsoil.net/protozoa">amoebae</a>, that consume bacteria and fungi. There are also predatory nematodes that feed on other nematodes to make sure they don’t become too abundant, so everything remains in balance as much as possible. </p>
<p>It’s quite a complicated food web of interacting species in a delicate balance.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/IBvKKMzXYtY?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A time-lapse video filmed about 4 inches underground shows a leaf decomposing over 21 days in July. At the end, radish roots make their way down into the soil. Video by Josh Williams.</span></figcaption>
</figure>
<p>While some fungi and bacteria <a href="https://www.growingagreenerworld.com/bacteria-fungus-and-viruses-an-overview/">can harm plants</a>, there are many species that are considered beneficial. In fact, they <a href="https://www.nrcs.usda.gov/conservation-basics/natural-resource-concerns/soils/soil-health">may be the key</a> to figuring out how to grow enough crops to feed everyone without degrading and overburdening the soil.</p>
<h2>Figuring out your soil type</h2>
<p>Scientists have named <a href="https://www.nrcs.usda.gov/resources/education-and-teaching-materials/soil-facts">over 20,000 different types</a> of unique soils. If you’re curious about the <a href="https://www.nesdis.noaa.gov/learn-about-soil-types">soil and dirt in your area</a>, the University of California, Davis has a <a href="https://casoilresource.lawr.ucdavis.edu/gmap/">website where you can learn</a> more about local soils and their chemical and physical attributes.</p>
<p><a href="https://www.farmers.gov/conservation/soil-health">Caring for soil</a> to promote its living creatures’ benefits and minimize their harm takes work, but it’s essential for keeping the land healthy and growing food for the future.</p>
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<p><em>Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to <a href="mailto:curiouskidsus@theconversation.com">CuriousKidsUS@theconversation.com</a>. Please tell us your name, age and the city where you live.</em></p>
<p><em>And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.</em></p><img src="https://counter.theconversation.com/content/224152/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Brian Darby receives funding from the United States Department of Agriculture. </span></em></p>Rock dust is only part of the story of soil. Living creatures, many of them too tiny to see, keep that soil healthy for growing everything from food to forests.Brian Darby, Associate Professor of Biology, University of North DakotaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2202802024-03-01T00:15:33Z2024-03-01T00:15:33ZWhy and how often do I need to wash makeup brushes and sponges?<figure><img src="https://images.theconversation.com/files/576120/original/file-20240216-24-9aako6.jpg?ixlib=rb-1.1.0&rect=0%2C7%2C4928%2C3268&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://unsplash.com/@anniespratt?utm_content=creditCopyText&utm_medium=referral&utm_source=unsplash">Annie Spratt</a> on <a href="https://unsplash.com/photos/selective-focus-photography-of-woman-applying-blush-on-on-her-face-xOEmZX6YSu8">Annie Spratt/Unsplash</a></span></figcaption></figure><p>From the bristles of brushes to the porous surfaces of sponges, your makeup kit can harbour a host of bacteria and fungi.</p>
<p>These potentially hazardous contaminants can originate not only from the cosmetics themselves, but also from the very surface of our skin. </p>
<p>So, how can we keep things hygienic and avoid microbial growth on makeup brushes and sponges? Here’s what you need to know.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-is-micellar-water-and-how-does-it-work-219492">What is micellar water and how does it work?</a>
</strong>
</em>
</p>
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<h2>How do germs and fungi get in my brushes and sponges?</h2>
<p>Germs and fungi can make their way into your makeup kit in lots of ways. </p>
<p>Ever flushed a toilet with the lid open with your makeup brushes nearby? There’s a good chance <a href="https://theconversation.com/mobile-phones-are-covered-in-germs-disinfecting-them-daily-could-help-stop-diseases-spreading-135318">faecal particles</a> have landed on them. </p>
<p>Perhaps a family member or housemate has used your eyeshadow brush when you weren’t looking, and transferred some microbes across in the process. </p>
<p>Bacteria that trigger a pimple outbreak can be easily transferred from the surface of your skin to a makeup brush or sponge. </p>
<p>And tiny little mites called Demodex mites, which have been linked to certain rashes and acne, live on your skin, as well, and so may end up in your sponge or brushes.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/579069/original/file-20240229-16-csz1bk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A young Asian man applies makeup at a cluttered vanity." src="https://images.theconversation.com/files/579069/original/file-20240229-16-csz1bk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/579069/original/file-20240229-16-csz1bk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=316&fit=crop&dpr=1 600w, https://images.theconversation.com/files/579069/original/file-20240229-16-csz1bk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=316&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/579069/original/file-20240229-16-csz1bk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=316&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/579069/original/file-20240229-16-csz1bk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=397&fit=crop&dpr=1 754w, https://images.theconversation.com/files/579069/original/file-20240229-16-csz1bk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=397&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/579069/original/file-20240229-16-csz1bk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=397&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Germs and fungi can make their way into your makeup in lots of ways.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/gay-queer-man-nonbinary-beauty-blogger-2361479535">Chay_Tee/Shutterstock</a></span>
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<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/invisible-skin-mites-called-demodex-almost-certainly-live-on-your-face-but-what-about-your-mascara-195451">Invisible skin mites called Demodex almost certainly live on your face – but what about your mascara?</a>
</strong>
</em>
</p>
<hr>
<p>Bacterial contamination of <a href="https://pubmed.ncbi.nlm.nih.gov/38020232/">lip cosmetics</a>, in particular, can pose a risk of skin and eye infections (so keep that in mind if you use lip brushes). Lipsticks are frequently contaminated with bacteria such as <em>Staphylococcus aureus</em>, <em>E. coli</em>, and <em>Streptococcus pneumoniae</em>.</p>
<p>Low-quality cosmetics are more likely to have higher and more diverse microbial growth compared to <a href="https://www.sciencedirect.com/science/article/pii/S1319562X23002978?pes=vor">high-quality cosmetics</a>.</p>
<p>Brushes exposed to sensitive areas like the eyes, mouth and nose are particularly susceptible to being potential sources of infection. </p>
<p>The range of conditions caused by these microorganisms includes:</p>
<ul>
<li><p>abscesses</p></li>
<li><p>skin and soft tissue infections</p></li>
<li><p>skin lesions</p></li>
<li><p>rashes</p></li>
<li><p>and dermatitis.</p></li>
</ul>
<p>In severe cases, infections can lead to invasion of the bloodstream or deep tissues. </p>
<p>Commercially available cosmetics contain varying amounts and types of preservatives aimed at inhibiting the growth of fungi and bacteria.</p>
<p>But when you apply makeup, different cosmetics with unique formulations of preservatives can become mixed. When a preservative meant for one product mixes with others, it might not work as well because they have different water amounts or pH levels.</p>
<p>So preservatives are not foolproof. We also need to observe good hygiene practices when it comes to brushes and other cosmetics applicators. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/576113/original/file-20240216-16-qqim5d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A woman washes a makeup brush in a sink." src="https://images.theconversation.com/files/576113/original/file-20240216-16-qqim5d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/576113/original/file-20240216-16-qqim5d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/576113/original/file-20240216-16-qqim5d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/576113/original/file-20240216-16-qqim5d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/576113/original/file-20240216-16-qqim5d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/576113/original/file-20240216-16-qqim5d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/576113/original/file-20240216-16-qqim5d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">You don’t need to use micellar water to clean your brushes.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/woman-washing-makeup-brush-under-water-2020030193">Pixel-Shot/Shutterstock</a></span>
</figcaption>
</figure>
<h2>Keeping brushes clean</h2>
<p>Start with the basics: never <a href="https://www.semanticscholar.org/paper/Isolation-of-Pathogenic-Microbes-from-Beauty-Salons-Hassan-Hamad/0199635290628fe326fcd04a2b8a2422884a8240">share makeup brushes or sponges</a>. Everyone carries different microbes on their skin, so sharing brushes and sponges means you are also sharing germs and fungi.</p>
<p>If you need to share makeup, use something disposable to apply it, or make sure any shared brushes are washed and sterilised before the next person uses it.</p>
<p>Clean makeup brushes by washing with hot soapy water and rinsing thoroughly.</p>
<p>How often? Stick to a cleaning routine you can repeat with consistency (as opposed to a deep clean that is done annually). <a href="https://www.aad.org/public/everyday-care/skin-care-secrets/routine/clean-your-makeup-brushes#:%7E:text=To%20protect%20your%20skin%20and,every%207%20to%2010%20days.">Once a week</a> might be a good goal for some, while others may need to wash more regularly if they are heavy users of makeup. </p>
<p>Definitely wash straight away if someone else has used your brushes or sponges. And if you’ve had an eye infection such as conjunctivitis, ensure you clean applicators thoroughly after the infection has resolved. </p>
<p>You can use bactericidal soap, 70% ethanol or chlorhexidine solutions to wash. Just make sure you wash very thoroughly with hot water after, as some of these things can irritate your skin. (While some people online say alcohol can degrade brushes and sponges, opinion seems to be mixed; in general, most disinfectants are unlikely to cause significant corrosion.)</p>
<p>For some brushes, heating or steaming them and letting them dry may also be an effective sterilisation method once they are washed with detergent. Microwaving sponges isn’t a good idea because while the heat generated by a domestic microwave would kill microbes, it would need temperatures approaching 100°C for a decent period of time (at least several minutes). The heat could melt some parts of the sponge and hot materials could be a scalding hazard.</p>
<p>Once clean, ensure brushes and sponges are stored in a dry place away from water sources (and not near an open toilet).</p>
<p>If you’re having makeup applied professionally, brushes and applicators should be sterilised or changed from person to person. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/576114/original/file-20240216-30-c04ns7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A bunch of makeup brushes are set out to dry on a towel." src="https://images.theconversation.com/files/576114/original/file-20240216-30-c04ns7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/576114/original/file-20240216-30-c04ns7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/576114/original/file-20240216-30-c04ns7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/576114/original/file-20240216-30-c04ns7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/576114/original/file-20240216-30-c04ns7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/576114/original/file-20240216-30-c04ns7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/576114/original/file-20240216-30-c04ns7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Dry brushes thoroughly after washing.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/after-cleaning-makeup-brushes-finish-will-653637367">prachyaloyfar/Shutterstock</a></span>
</figcaption>
</figure>
<h2>Should I wash them with micellar water?</h2>
<p>No. </p>
<p>Not only is this expensive, it’s unnecessary. The same benefits can be achieved with cheaper detergents or alcohol (just rinse brushes carefully afterwards).</p>
<p>Disinfection methods such as using bactericidal soap, 70% ethanol, or chlorhexidine are all very good at reducing the amount of microbes on your brushes and sponges.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-is-micellar-water-and-how-does-it-work-219492">What is micellar water and how does it work?</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/220280/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rosalie Hocking is currently the recipient of an Australian government Future Fellowship.
</span></em></p><p class="fine-print"><em><span>Enzo Palombo does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Yes, you need to wash them but no, you don’t need to use micellar water to do it.Enzo Palombo, Professor of Microbiology, Swinburne University of TechnologyRosalie Hocking, Swinburne University of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2202832024-02-22T13:42:50Z2024-02-22T13:42:50ZBacteria can develop resistance to drugs they haven’t encountered before − scientists figured this out decades ago in a classic experiment<figure><img src="https://images.theconversation.com/files/575458/original/file-20240213-24-7w1h4o.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2048%2C1480&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Bacteria are evolutionarily primed to outpace drug developers.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/nihgov/28881401596/in/photolist-U4kMcq-c57xDd-L19JtW-c9uWe5-dYBMYW-a5tw3L-2joPCWz-2jfgs7P-9VPmA4-fuUV2g-fvxv6D-ot5Jyg-fvacBd-vughy5-7NapMs-7N7qSL-yrSV6f-7N5dpc-Mj3KFR-7Na6i5-ysPK3x-7Na5Wq-ftHb6n-ftXtfs-ftH7Vt-7Na6P5-tCCMPo-xvLN1S-ybiGai-yqtCoy-982F9z-ftHaAP-7N3qKg-7N674D-fvxufn-fvMDps-x2Btgv-ftHapZ-7Na6sy-7NaoHs-fuUUt8-fuUQjz-fvxptp-fuUXN2-7U2mNs-7N66b2-fvaabC-xtGans">National Institute of Allergy and Infectious Diseases, National Institutes of Health/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>Do bacteria mutate randomly, or do they mutate for a purpose? Researchers have been <a href="https://doi.org/10.1017/S0022172400017125">puzzling over this conundrum for over a century</a>.</p>
<p>In 1943, microbiologist Salvador Luria and physicist turned biologist Max Delbrück <a href="https://doi.org/10.1080/09332480.2010.10739800">invented an experiment</a> to argue that bacteria mutated aimlessly. Using their test, other scientists showed that bacteria could acquire resistance to antibiotics they hadn’t encountered before.</p>
<p>The <a href="https://doi.org/10.1080/09332480.2010.10739800">Luria–Delbrück experiment</a> has had a significant effect on science. The findings helped Luria and Delbruck win the <a href="https://www.nobelprize.org/prizes/medicine/1969/summary/">Nobel Prize in physiology or medicine in 1969</a>, and students today learn this experiment in <a href="https://doi.org/10.1128/jmbe.00161-23">biology classrooms</a>. I have been studying this experiment in my work as a biostatistician for <a href="https://doi.org/10.1016/S0025-5564(99)00045-0">over 20 years</a>.</p>
<hr>
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<p><em>You can listen to more articles from The Conversation, <a href="https://theconversation.com/us/topics/audio-narrated-99682">narrated by Noa</a>.</em></p>
<hr>
<p>Decades later, this experiment offers lessons still relevant today, because it implies that bacteria can develop resistance to antibiotics that haven’t been developed yet.</p>
<h2>Slot machines and a eureka moment</h2>
<p>Imagine a test tube containing bacteria living in nutrient broth. The broth is cloudy due to the high concentration of bacteria within it. Adding a virus that infects bacteria, <a href="https://theconversation.com/viruses-are-both-the-villains-and-heroes-of-life-as-we-know-it-169131">also known as a phage</a>, into the tube kills most of the bacteria and makes the broth clear.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/426550/original/file-20211014-27-n6jugx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Illustration of bacteriophage structure." src="https://images.theconversation.com/files/426550/original/file-20211014-27-n6jugx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/426550/original/file-20211014-27-n6jugx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1014&fit=crop&dpr=1 600w, https://images.theconversation.com/files/426550/original/file-20211014-27-n6jugx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1014&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/426550/original/file-20211014-27-n6jugx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1014&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/426550/original/file-20211014-27-n6jugx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1274&fit=crop&dpr=1 754w, https://images.theconversation.com/files/426550/original/file-20211014-27-n6jugx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1274&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/426550/original/file-20211014-27-n6jugx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1274&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Bacteriophages are viruses that specifically infect bacteria.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/flat-illustration-of-bacteriophage-royalty-free-illustration/1285360925">Kristina Dukart/iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<p>However, keeping the test tube under conditions favorable for bacterial growth will turn the broth cloudy again over time. This indicates that the bacteria developed resistance against the phages and were able to proliferate.</p>
<p>What role did the phages play in this change?</p>
<p>Some scientists thought the phages incited the bacteria to mutate for survival. Others suggested that bacteria routinely mutate randomly, and the development of phage-resistant variants was simply <a href="https://doi.org/10.1128/jb.28.6.619-639.1934">a lucky outcome</a>. Luria and Delbrück had been working together for months to solve this conundrum, but none of their experiments had been successful. </p>
<p>On the night of Jan. 16, 1943, Luria got a hint about how to crack the mystery while watching a colleague hit the jackpot at a slot machine. The next morning, he hurried to his lab.</p>
<p>Luria’s experiment consisted of a few tubes and dishes. Each tube contained nutrient broth that would help the bacteria <em>E. coli</em> multiply, while each dish contained material coated with phages. A few bacteria were placed into each tube and given two opportunities to generate phage-resistant variants. They could either mutate in the tubes in the absence of phages, or they could mutate in the dishes in the presence of phages.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/575442/original/file-20240213-28-9m0ay7.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Illustration of six test tubes and and six petri dishes, a few of the dishes containing red dots" src="https://images.theconversation.com/files/575442/original/file-20240213-28-9m0ay7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/575442/original/file-20240213-28-9m0ay7.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=277&fit=crop&dpr=1 600w, https://images.theconversation.com/files/575442/original/file-20240213-28-9m0ay7.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=277&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/575442/original/file-20240213-28-9m0ay7.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=277&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/575442/original/file-20240213-28-9m0ay7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=348&fit=crop&dpr=1 754w, https://images.theconversation.com/files/575442/original/file-20240213-28-9m0ay7.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=348&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/575442/original/file-20240213-28-9m0ay7.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=348&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This diagram of the Luria-Delbrück experiment depicts colonies of phage-resistant variants of <em>E. coli</em> (red) developing in petri dishes.</span>
<span class="attribution"><span class="source">Qi Zheng</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>The next day, Luria transferred the bacteria in each tube into a dish filled with phages. The day after that, he counted the number of resistant bacterial colonies in each dish. </p>
<p>If bacteria develop resistance against phages by interacting with them, none of the bacteria in the tubes should have mutations. On the other hand, only a few of the bacteria – say, 1 out of 10 million bacteria – should spawn resistant variants when they are transferred into a dish containing phages. Each phage-resistant variant would grow into a colony, but the remaining bacteria would die from infection.</p>
<p>If bacteria develop resistance independently of interacting with phages, some of the bacteria in the tubes will have mutations. This is because each time a bacterium divides in a tube, it has a small probability of spawning a resistant variant. If the starting generation of bacteria is the first to mutate, at least half of the bacteria will be resistant in later generations. If a bacterium in the second generation is the first to mutate, at least an eighth of the bacteria will be resistant in later generations.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/575444/original/file-20240213-30-vbeqfp.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Four tree diagrams of green and red circles, with subsequent branches from red dots turning red" src="https://images.theconversation.com/files/575444/original/file-20240213-30-vbeqfp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/575444/original/file-20240213-30-vbeqfp.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=340&fit=crop&dpr=1 600w, https://images.theconversation.com/files/575444/original/file-20240213-30-vbeqfp.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=340&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/575444/original/file-20240213-30-vbeqfp.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=340&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/575444/original/file-20240213-30-vbeqfp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=427&fit=crop&dpr=1 754w, https://images.theconversation.com/files/575444/original/file-20240213-30-vbeqfp.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=427&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/575444/original/file-20240213-30-vbeqfp.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=427&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Mutations that confer resistance against phages (red) early on will spawn a large number of phage-resistant variants, while mutations that occur later on will spawn only a few resistant variants.</span>
<span class="attribution"><span class="source">Qi Zheng</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Like small-prize cash-outs in slot machines, late-generation mutations occur more often but give fewer resistant variants. Like jackpots, early-generation mutations occur rarely but give large numbers of variants. Early-generation mutations are rare because early on there are only a small number of bacteria available to mutate.</p>
<p>For example, in a 20-generation experiment, a mutation occurring at the 10th generation of bacteria would give 1,024 phage-resistant variants. A mutation occurring at the 17th generation would give only four phage-resistant variants. </p>
<p>The number of resistant colonies in Luria’s experiments showed a similar pattern to that of slot machine cash-outs. Most dishes contained no or small numbers of mutant colonies, but several contained a large number of mutant colonies that Luria considered jackpots. This meant that the bacteria developed resistant variants before they interacted with the phages in the dishes.</p>
<h2>An experiment’s legacy</h2>
<p>Luria sent a note to Delbrück after his experiment was completed, asking him to check his work. The two scientists then worked together to write <a href="https://doi.org/10.1093/genetics/28.6.491">a classic paper</a> describing the experimental protocol and a theoretical framework to measure bacterial mutation rates.</p>
<p>Other scientists conducted similar experiments by replacing phages <a href="https://doi.org/10.1073/pnas.31.1.16">with penicillin</a> and with <a href="https://doi.org/10.1128/am.20.5.810-814.1970">tuberculosis drugs</a>. Similarly, they found that bacteria did not need to encounter an antibiotic to acquire resistance to it.</p>
<p>Bacteria have relied on random mutations to cope with harsh, constantly changing environments <a href="https://theconversation.com/antibiotic-resistance-is-not-new-it-existed-long-before-people-used-drugs-to-kill-bacteria-115836">for millions of years</a>. Their incessant, random mutations will lead them to inevitably develop variants that are resistant to the antibiotics of the future. </p>
<p>Drug resistance is a reality of life we will have to accept and continue to fight against.</p><img src="https://counter.theconversation.com/content/220283/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Qi Zheng does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The Nobel Prize-winning Luria−Delbrück experiment showed that random mutations in bacteria can allow them to develop resistance by chance.Qi Zheng, Professor of Biostatistics, Texas A&M UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2232242024-02-21T13:04:38Z2024-02-21T13:04:38ZGut bacteria may explain why grey squirrels outcompete reds – new research<p>Across large parts of the UK, the native red squirrel has been replaced by the grey squirrel, a North American species. As well as endangering reds, grey squirrels pose a threat to our woodlands because of the damage they cause to trees. </p>
<p><a href="https://www.microbiologyresearch.org/content/journal/jmm/10.1099/jmm.0.001793">New research</a> from my colleagues and I compared the gut bacteria of red and grey squirrels. We found that differences between the two may explain their competition and red squirrel decline, as well as why grey squirrels are so destructive to woodland.</p>
<p>Grey squirrels were introduced to the UK between 1876 and 1929 and have displaced reds in most areas of the UK. Greys carry a virus called “squirrelpox”, which doesn’t affect them but leads to sickness and often death in red squirrels.</p>
<p>Grey squirrels are bigger than red squirrels and compete with them <a href="https://www.frontiersin.org/articles/10.3389/fevo.2023.1083008/full">for food and habitat</a>.
Acorns, a widespread food source, contain tannins, which are hard for red squirrels to digest. But greys can digest acorns easily, giving them an extra edge in competing for resources. </p>
<p>Grey squirrels frequently strip the bark from deciduous trees. In commercial plantations, the damage can lead to fungal infection and result in the tree producing low quality timber. The annual cost is an <a href="https://rfs.org.uk/insights-publications/rfs-reports/report-overview-the-cost-of-grey-squirrel-damage-to-woodland-in-england-and-wales/">estimated £37 million.</a> with sycamore, oak, birch and beech frequently targeted. </p>
<p>The grey squirrels select the strongest growing trees as these have bark containing the largest volume of sap. Intriguingly, grey squirrels do not select trees with the <a href="https://www.researchgate.net/publication/230344319_Bark-stripping_by_Grey_squirrels_Sciurus_carolinensis">highest sugar content</a>. This observation has led scientists to posit that the squirrels consume bark to obtain <a href="https://www.sciencedirect.com/science/article/pii/S0378112716300421?via%3Dihub">certain micro-nutrients</a>. </p>
<h2>Gut bacteria</h2>
<p>All mammals have microorganisms living in their intestines. For example, the typical human colon is host to at least <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5847071/">160 bacterial species</a>, while in birds, research has found thousands of different bacterial species in <a href="https://pubmed.ncbi.nlm.nih.gov/33868800/">chicken intestines.</a></p>
<p>The bacteria break down foods and help synthesise vitamins, complementing the enzymes secreted by the body. The diversity of these microorganisms, known as the “microbiota”, can reflect the level of health and also the diet of an individual. But we don’t know enough about the microbiota living in squirrel intestines. </p>
<p>The types of microbes present vary between species, yet the extent to which they differ between grey and red squirrels is unclear. We explored this and investigated the potential for any differences to affect competition between the two squirrel species. We also examined whether gut bacteria might be playing a role in bark stripping behaviour.</p>
<p>We sampled bacterial DNA from red and grey squirrel intestinal contents and performed gene sequencing to identify the range of bacteria present in the samples. The results were analysed to compare any important differences between the two.</p>
<figure class="align-center ">
<img alt="A cute red squirrels with a large bushy tail stands on the branch of a tree." src="https://images.theconversation.com/files/576545/original/file-20240219-20-ivfdqj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/576545/original/file-20240219-20-ivfdqj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=430&fit=crop&dpr=1 600w, https://images.theconversation.com/files/576545/original/file-20240219-20-ivfdqj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=430&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/576545/original/file-20240219-20-ivfdqj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=430&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/576545/original/file-20240219-20-ivfdqj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=541&fit=crop&dpr=1 754w, https://images.theconversation.com/files/576545/original/file-20240219-20-ivfdqj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=541&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/576545/original/file-20240219-20-ivfdqj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=541&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Ynys Môn off the north Wales coast is one of the few places in the UK where greys have been eradicated in favour of red squirrels.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/red-squirrel-views-around-north-wales-2232607907">Gail Johnson/Shutterstock</a></span>
</figcaption>
</figure>
<h2>Calcium</h2>
<p>Calcium is an important nutrient in the body and is required for healthy bones, muscles and nerves. It is especially needed by lactating animals and ones that are young and growing.</p>
<p>We found that grey squirrels may have the capacity to obtain the calcium that exists in tree bark thanks to the presence of a bacteria called “oxalobacter” in their gut. The calcium in tree bark comes in an insoluble form and is hard for an animal to digest. But oxalobacter would be able to change this into a form that could be more digestible. </p>
<p>Calcium levels <a href="https://www.sciencedirect.com/science/article/pii/S0378112716300421?via%3Dihub">increase in trees</a> as active growth resumes after winter dormancy. This happens immediately before the main squirrel bark-stripping season of May to July. Our research may therefore help to explain the destructive behaviour of grey squirrels and why red squirrels appear to strip bark much less frequently.</p>
<p>Our research also identified a significantly higher diversity of bacteria in the intestines of grey squirrels compared to red squirrels. This could hold the key to further understanding why grey squirrels outcompete red squirrels in the UK. </p>
<p>A more diverse range of bacteria being sustained in the gut means that grey squirrels potentially may be able to access a broader range of resources than red squirrels in addition to acorns.</p>
<h2>Adenovirus</h2>
<p>The grey squirrel harbours not just the squirrelpox virus, but also another potential threat – adenovirus. While this virus causes severe intestinal lesions in some red squirrels, curiously, grey squirrels never exhibit the same symptoms.</p>
<p>This discrepancy underscores the fascinating and complex potential role of gut microbiota. Research increasingly reveals their influence on everything from digestion to immune response, and even susceptibility to disease.</p>
<p>In the context of red squirrels, understanding how variations in their gut bacteria might predispose them to adenovirus becomes crucial. This is especially pertinent for captive breeding programs, where adenovirus infections pose a hurdle to successful reintroductions of red squirrels into the wild.</p>
<p>Given we only sampled red and grey squirrels from north Wales, we hope that future studies will map the gut microbiota of other European populations too. Such future research will continue to improve our knowledge of the competition between red and grey squirrels.</p><img src="https://counter.theconversation.com/content/223224/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Craig Shuttleworth does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>New research suggests the gut bacteria of red and grey squirrels differ significantly, potentially explaining the decline of the native red and the success of its grey counterpart.Craig Shuttleworth, Honorary Visiting Research Fellow, Bangor UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2153112024-02-09T16:50:23Z2024-02-09T16:50:23ZYour unique smell can provide clues about how healthy you are<figure><img src="https://images.theconversation.com/files/574043/original/file-20240207-19-o4ehc8.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5291%2C3516&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/happy-calm-teen-girl-enjoying-good-1325627765">fizkes/Shutterstock</a></span></figcaption></figure><p>Hundreds of chemicals stream from our bodies into the air every second. These chemicals release into the air easily as they have high vapour pressures, meaning they boil and turn into gases at room temperature. They give clues about who we are, and how healthy we are. </p>
<p>Since ancient Greek times, we’ve known that we smell differently when we are unwell. While we rely on blood analysis today, ancient Greek physicians used smell to diagnose maladies. If they took a whiff of your breath and described it as <em>fetor hepaticus</em> (meaning bad liver), it meant you could be headed for liver failure.</p>
<p>If a person’s whiff was sweet or fruity, physicians thought this meant that sugars in the digestive system were not being broken down, and that person had probably diabetes. Science has since shown the ancient Greeks were right – liver failure and <a href="https://tisserandinstitute.org/human-volatilome/">diabetes</a> and many <a href="https://link.springer.com/article/10.1007/s00216-023-04986-z">other diseases</a> including infectious diseases give your breath a distinctive smell.</p>
<p>In 1971, <a href="https://www.nobelprize.org/prizes/peace/1962/pauling/facts/">Nobel Laureate chemist Linus Pauling</a> <a href="https://edu.rsc.org/feature/breath-analysis/2020106.article#:%7E:text=The%20'modern%20era'%20of%20breath,in%20an%20average%20breath%20sample.">counted 250 different</a> gaseous chemicals in breath. These gaseous chemicals are called volatile organic compounds or VOCs. </p>
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<p>Since Pauling’s discovery, other scientists have <a href="https://link.springer.com/article/10.1007/s40291-023-00640-7">discovered hundreds more VOCs</a> in our breath. We have learned that many of these VOCs have distinctive odours, but some have no odour that our noses can perceive. </p>
<p>Scientists believe that whether a VOC <a href="https://tisserandinstitute.org/human-volatilome/">has an odour</a> that our noses can detect or not, they can reveal information about how healthy someone is.</p>
<p>A Scottish man’s Parkinson’s disease onset was <a href="https://www.bbc.co.uk/news/uk-scotland-47627179">identified by his wife</a>, retired nurse Joy Milner, after she was convinced the way he smelled had changed, years before he was diagnosed in 2005. This discovery has <a href="https://www.manchester.ac.uk/discover/news/smell-of-skin-could-lead-to-early-diagnosis-for-parkinsons/">led to research programmes</a> involving Joy Milner to identify <a href="https://www.scientificamerican.com/article/a-supersmeller-can-detect-the-scent-of-parkinsons-leading-to-an-experimental-test-for-the-illness/">the precise smell</a> of this disease. </p>
<p>Dogs can <a href="https://www.nature.com/articles/d41586-022-01629-8">sniff out more diseases</a> than humans because of their more <a href="https://www.understandinganimalresearch.org.uk/news/the-science-of-sniffs-disease-smelling-dogs%20-%20I%20think%20the%20previous%20nature%20link%20has%20more%20credibility%20for%20here%20also">sophisticated olfactory talents</a>. But technological techniques, like <a href="https://www.britannica.com/science/mass-spectrometry">analytical tool mass spectrometry</a>, picks up even more subtle changes in VOC profiles that are being linked to <a href="https://www.thelancet.com/journals/ebiom/article/PIIS2352-3964(20)30100-6/fulltext">gut</a>, <a href="https://www-sciencedirect-com.dcu.idm.oclc.org/science/article/pii/S0165993618305168">skin</a> and <a href="https://err.ersjournals.com/content/28/152/190011">respiratory</a> diseases as well as neurological diseases like Parkinson’s. Researchers believe that one day some diseases will be diagnosed simply by breathing into a device. </p>
<figure>
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</figure>
<h2>Where do VOCs come from?</h2>
<p>Breath is not the only source of VOCs in the body. They are also emitted from skin, urine and faeces. </p>
<p>VOCs from skin are the result of millions of skin glands removing metabolic waste from the body, as well as waste generated by bacteria and other microbes that live on our skin. Sweating produces extra nutrients for these bacteria to metabolise which can result in particularly odorous VOCs. Odour from sweat only makes up a fraction of the scents from VOCs though.</p>
<p><a href="https://www.nature.com/articles/nrmicro.2017.157">Our skin</a> and also our gut microbiomes are made up from a delicate balance of these microbes. Scientists think <a href="https://journals.lww.com/co-gastroenterology/abstract/2015/01000/the_gut_microbiome_in_health_and_in_disease.12.aspx">they influence our health</a>, but we don’t yet understand a lot about how this relationship works. </p>
<p>Unlike the gut, the skin is relatively easy to study – you can collect skin samples from living humans without having to go deep into the body. <a href="https://www-sciencedirect-com.dcu.idm.oclc.org/science/article/pii/S1471492221002087">Scientists think</a> skin VOCs can offer insights into how the microbiome’s bacteria and the human body work together to maintain our health and protect us from disease.</p>
<p>In my team’s laboratory, <a href="https://iopscience.iop.org/article/10.1088/1752-7163/abf20a">we are investigating</a> whether the skin VOC signature can reveal different attributes of the person it belongs to. These signals in skin VOC signatures are probably how dogs distinguish between people by smell. </p>
<p>We are at a relatively early stage in this research area but we have shown that you can tell males from females based on how acidic the VOCs from skin are. We use mass spectrometry to see this as the average human nose is not sophisticated enough to detect these VOCs. </p>
<p>We can also predict a person’s age with reasonable accuracy to within a few years from their skin VOC profile. This is not surprising considering that oxidative stress in our bodies increases as we age.</p>
<p><a href="https://www.metabolismjournal.com/article/S0026-0495(00)80077-3/pdf">Oxidative stress</a> happens when your antioxidant levels are low and causes irreversible damage to our cells and organs. <a href="https://pubs.acs.org/doi/10.1021/jasms.3c00315">Our recent research</a> found by-products of this oxidative damage in skin VOC profiles. </p>
<p>Not only are these VOCs responsible for personal scent – they are used by plants, insects and animals as a communication channel. Plants are in a <a href="https://www.nature.com/articles/s41598-017-10975-x">constant VOC dialogue</a> with other organisms including pollinators, herbivores, other plants and their natural enemies such as harmful bacteria and insects. VOCs used for this back and forth dialogue are known as pheromones. </p>
<h2>What has science shown about love pheromones?</h2>
<p>In the animal kingdom, there is good evidence VOCs can act as aphrodisiacs. Mice for example have microbes which contribute to a particularly <a href="https://www.sciencedirect.com/science/article/pii/S0960982212012687">smelly compound called trimethylamine</a>, which allows mice to verify the species of a potential mate. <a href="https://www.sciencedirect.com/science/article/abs/pii/S0093691X21003083">Pigs</a> and <a href="https://www.nature.com/articles/4381097a">elephants</a> have sex pheromones too. </p>
<p>It is possible that humans also produce VOCs for attracting the perfect mate. Scientists have yet to fully decode skin – or other VOCs that are released from our bodies. But evidence for human love pheromones so far is <a href="https://www.science.org/content/article/do-human-pheromones-actually-exist">controversial at best</a>. <a href="https://www.newscientist.com/article/dn3835-colour-vision-ended-human-pheromone-use/">One theory suggests</a> that they were lost about 23 million years ago when primates developed full colour vision and started relying on their enhanced vision to choose a mate.</p>
<p>However, we believe that whether human pheromones exist or not, skin VOCs can reveal who and how we are, in terms of things like ageing, nutrition and fitness, fertility and even stress levels. This signature probably contains markers we can use to monitor our health and diagnose disease.</p><img src="https://counter.theconversation.com/content/215311/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Aoife Morrin receives funding from Science Foundation Ireland.</span></em></p>The science of smell is an exciting area of research.Aoife Morrin, Associate Professor of Analytical Chemistry, Dublin City UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2208502024-01-31T19:07:41Z2024-01-31T19:07:41ZHow the weird and wonderful microbes in wastewater can make our cities more sustainable<figure><img src="https://images.theconversation.com/files/571375/original/file-20240125-23-39o9n9.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4638%2C3086&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/sludge-digestion-installation-on-waste-water-89462866">hans engbers/Shutterstock</a></span></figcaption></figure><p>COVID-19 showed us how useful <a href="https://theconversation.com/wastewater-monitoring-took-off-during-the-covid-19-pandemic-and-heres-how-it-could-help-head-off-future-outbreaks-180775">monitoring wastewater</a> can be. But the genetic material in our wastewater, namely DNA and RNA, is a treasure trove of other useful information. It reveals the presence of thousands of different types of weird and wonderful wastewater microbes. </p>
<p>The diversity of these microbes can “talk” to us and tell us how to get more renewable energy out of our wastes. If only we could listen to them. Soon we can. </p>
<p>How will that work? It all starts with our poo. These types of microbes have been used <a href="https://extension.psu.edu/a-short-history-of-anaerobic-digestion">since the 19th century</a> to treat and reduce the ever-increasing volumes of sewage sludge arriving at our wastewater treatment plants, especially in urban areas. <a href="https://unhabitat.org/wcr/">Two-thirds of the world’s people</a> are expected to live in urban areas by 2050, hence sewage treatment <a href="https://www.nature.com/articles/s44284-023-00021-5">will be in high demand</a>. </p>
<p>Yet most people today have little idea how vital microbes are for sustainable growth of cities. We need them to treat our waste.</p>
<p>We also need sources of renewable energy. Thanks to naturally occurring microbes, our water utilities can produce renewable biogas from human waste. By reducing our reliance on fossil fuels, their <a href="https://www.iea.org/reports/outlook-for-biogas-and-biomethane-prospects-for-organic-growth/an-introduction-to-biogas-and-biomethane">poo biogas</a> can help to mitigate climate change.</p>
<p>So we need to learn more about these microbes to ensure they are doing the best possible job of processing our waste. One way of doing that is by monitoring DNA in human waste sludge.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1119277007571841024"}"></div></p>
<h2>A living sludge mass</h2>
<p>First of all, this promising waste-to-energy technology, which fully relies on microbes, is called <a href="https://www.epa.gov/agstar/how-does-anaerobic-digestion-work">anaerobic digestion</a>. </p>
<p>Operating anaerobic digesters is expensive. It requires intense monitoring strategies and frequent interventions. That is because microbes can be unpredictable. </p>
<p>On the face of it, the process is really simple. Wastewater sludge is pumped into large vessels without oxygen, where microbes are left alone for a few days to practically eat the sludge and breathe out biogas. Sludge goes in, treated sludge plus gas goes out. </p>
<p>The process reduces overall sludge mass and the number of pathogens. This ultimately makes it a safer material, while also generating renewable energy. Brilliant, right? </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/QdprryhhFbI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Using anaerobic digesters to treat human waste has multiple benefits, but depends on keeping a community of microbes healthy.</span></figcaption>
</figure>
<p>But there is a catch. This process is only effective if these living, breathing treatment vessels behave. Unfortunately, sometimes they get out of control without warning, making them difficult to manage. </p>
<p>These sludge microbes are similar to those in our gut. Once we know this, we might intuitively understand how sensitive they can be, given our experience of <a href="https://www.bmj.com/content/361/bmj.k2179.full">gastrointestinal disorders linked to our gut microbes</a>. </p>
<p>So microbial happiness is not only important for our own health, it is crucial for the health of the large digester vessels managed by wastewater treatment plants. To make it cheaper to run these facilities, we urgently need to learn more about life in our sludge.</p>
<figure class="align-center ">
<img alt="Sludge pours into a large open tank at a waste treatment plant" src="https://images.theconversation.com/files/571376/original/file-20240125-19-vgrp27.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/571376/original/file-20240125-19-vgrp27.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/571376/original/file-20240125-19-vgrp27.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/571376/original/file-20240125-19-vgrp27.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/571376/original/file-20240125-19-vgrp27.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/571376/original/file-20240125-19-vgrp27.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/571376/original/file-20240125-19-vgrp27.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The huge amounts of human waste we create support an extraordinarily rich variety of microbial life.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/part-sewage-treatment-plant-scene-230751835">Geermy/Shutterstock</a></span>
</figcaption>
</figure>
<h2>DNA, a window on an invisible world</h2>
<p>At the <a href="https://www.transformingbiosolids.org.au">ARC Biosolids Training Centre</a> we want to make anaerobic digestion easier for water utilities by developing routine DNA-based monitoring tools. Essentially, we are looking for a way to predict the process to manage it better. </p>
<p>DNA tells the story of thousands of different types of microbes that work together to treat our sludge. To optimise the wastewater treatment process we need to identify them, the troublemakers and the do-gooders. </p>
<p>But sludge life is complex. Before it can tell us its story, we require empirical studies. We have to be able to relate microbial DNA to the process. </p>
<p>To show how that works we produced a <a href="https://www.frontiersin.org/articles/10.3389/fmicb.2022.1079136/full">review</a> of the role of microbes for monitoring anaerobic digestion. This includes some of the diversity metrics that ecologists use to assess the health of the whole system based on the composition of microbes.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/572320/original/file-20240131-23-dw2h6m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Compound microscope images of microbes in waste sludge" src="https://images.theconversation.com/files/572320/original/file-20240131-23-dw2h6m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/572320/original/file-20240131-23-dw2h6m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/572320/original/file-20240131-23-dw2h6m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/572320/original/file-20240131-23-dw2h6m.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/572320/original/file-20240131-23-dw2h6m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=603&fit=crop&dpr=1 754w, https://images.theconversation.com/files/572320/original/file-20240131-23-dw2h6m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=603&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/572320/original/file-20240131-23-dw2h6m.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=603&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Compound microscope images of just a few of the thousands of different types of microbes in wastewater sludge.</span>
<span class="attribution"><span class="source">Helen Stratton and Melody Christie, Stratton Microbial Ecology Lab at Griffith University</span></span>
</figcaption>
</figure>
<h2>The weird and the wonderful</h2>
<p>The microbes that are used to treat sludge consist of a diverse range of ancient, weird, at times alien-like bacteria and <a href="https://www.britannica.com/science/archaea">archaea</a> (another form of single-celled organisms). They can metabolise materials that no other lifeform can. </p>
<p>Amazingly, some of them <a href="https://news.mit.edu/2018/mit-researchers-determine-timing-of-methanogen-evolution-0404">existed 3.5 billion years ago</a> – the Earth formed 4.5 billion years ago. There is even <a href="https://www.nature.com/articles/s41550-022-01786-w">a chance some have existed on Mars</a>. </p>
<p>And sludge life is a very active community of microbes: some are bullies, some collaborators. Through their DNA, we count them to learn how many different types of microbes there are and how often they appear. This counted diversity can then tell us if a system is healthy or not. </p>
<p>For a healthy, productive system, <a href="https://theconversation.com/diverse-gut-microbiomes-give-better-protection-against-harmful-bugs-now-we-know-why-219734">we need diversity</a> – as many different microbes as possible – to provide stability. If a particular organism somehow starts to grow faster or slower, it means something is getting out of control.</p>
<p>We can exploit that knowledge to develop risk scores for the operators of treatment facilities. And that is what we try to do. </p>
<p>We will keep working so that someday we can properly listen to our sludge-eating microbes and get more value out of our poo.</p><img src="https://counter.theconversation.com/content/220850/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christian Krohn's reseach receives funding from an Australian Research Council Industrial Transformation Training Centre Grant (IC190100033). </span></em></p>Much like our gut microbes, the community of microbes used to process human waste must be healthy to do the job well. Monitoring the DNA in waste sludge can help us ensure the system stays healthy.Christian Krohn, Postoctoral Researcher, School of Science, RMIT UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2163552024-01-16T19:15:14Z2024-01-16T19:15:14ZSpace travel taxes astronauts’ brains. But microbes on the menu could help in unexpected ways<figure><img src="https://images.theconversation.com/files/565638/original/file-20231213-27-4xr8mj.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5991%2C3000&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/smiling-man-astronaut-presents-shawarma-kebab-1128088580">studiostoks/Shutterstock</a></span></figcaption></figure><p>Feeding astronauts on a long mission to Mars goes well beyond ensuring they have enough nutrients and calories to survive their multi-year journey.</p>
<p>Providing astronauts with the right diet is also paramount in supporting their <a href="https://www.frontiersin.org/articles/10.3389/fncir.2023.1170395/full?trk=public_post_comment-text">mental and cognitive health</a>, in a way unlike previous missions.</p>
<p>So we need to radically rethink how we feed astronauts not only on a challenging mission to Mars, which could be on the cards in the late 2030s or early 2040s, but to prepare for possible settlement on the red planet. </p>
<p>That includes acknowledging the role of microbes in mental health and wellbeing, and providing astronauts with the right foods and conditions for a variety of these beneficial microbes to grow. Our research aims to do just that.</p>
<p>Here’s why a healthy balance of microbes is important under such challenging conditions, and how we could put microbes on the menu.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/was-going-to-space-a-good-idea-218235">Was going to space a good idea?</a>
</strong>
</em>
</p>
<hr>
<h2>Why are missions to Mars so challenging?</h2>
<p>Deep space missions will expose humans to immense physical and psychological challenges. These include prolonged isolation from loved ones, extreme space and resource constraints, and the difficulties of microgravity. </p>
<p>Disruption to astronauts’ circadian rhythms, prolonged radiation exposure and dietary changes can also lower their cognitive performance and wellbeing. </p>
<p>The hazardous conditions, combined with the psychological toll of potential spacecraft failures, can all contribute to mental health problems.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-to-live-in-space-what-weve-learned-from-20-years-of-the-international-space-station-144851">How to live in space: what we've learned from 20 years of the International Space Station</a>
</strong>
</em>
</p>
<hr>
<h2>Why is diet important for mental health?</h2>
<p>We already know the quality of people’s diet not only influences their physical health, but also their mental and brain health. </p>
<p>Diet quality is <a href="https://www.nature.com/articles/s41380-018-0237-8">consistently and independently linked</a> to the risk of depression or anxiety. Clinical trials <a href="https://pubmed.ncbi.nlm.nih.gov/35441666/">show</a> improving diet quality <a href="https://www.ncbi.nlm.nih.gov/pubmed/30720698">can lead to</a> profound improvements in depression and anxiety symptoms. </p>
<p>Diet also affects the size and function of a specific brain region – the hippocampus – that is crucial to learning and memory, as well as for maintaining <a href="https://bmcmedicine.biomedcentral.com/articles/10.1186/s12916-015-0461-x?report=reader">mental health</a>. When even young healthy adults eat “junk” foods, aspects of cognition linked to the hippocampus quickly <a href="https://royalsocietypublishing.org/doi/abs/10.1098/rsos.191338">decline</a>.</p>
<p>On the other hand, research shows a diet containing more and varied plant foods and seafood (which are rich in components called long-chain omega-3 fatty acids and flavonoids) leads to <a href="https://www.nature.com/articles/s41598-022-21927-5">better cognitive performance</a>. This study was conducted in a closed chamber for 45 days, designed to mimic conditions in space.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/565649/original/file-20231213-23-owo81l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Plate of salmon on bed of green salad, with lemon slices, on blue wood table" src="https://images.theconversation.com/files/565649/original/file-20231213-23-owo81l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/565649/original/file-20231213-23-owo81l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/565649/original/file-20231213-23-owo81l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/565649/original/file-20231213-23-owo81l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/565649/original/file-20231213-23-owo81l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/565649/original/file-20231213-23-owo81l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/565649/original/file-20231213-23-owo81l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A diet rich in plant food and seafood might help your brain, but how do you turn that into space food that will go the distance?</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/grilled-salmon-vegetables-366852431">Jacek Chabraszewski/Shutterstock</a></span>
</figcaption>
</figure>
<p>Diet can have such consequences by <a href="https://www.ncbi.nlm.nih.gov/pubmed/33144709">altering</a>:</p>
<ul>
<li>immune function</li>
<li>the size and functioning of the hippocampus </li>
<li>chemical messenger (neurotransmitter) systems</li>
<li>how our bodies respond to stress.</li>
</ul>
<p>Diet can also influence the many ways microbes in the gut affect the brain, a link known as the <a href="https://journals.physiology.org/doi/full/10.1152/physrev.00018.2018?rfr_dat=cr_pub">microbiota gut-brain axis</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/essays-on-health-microbes-arent-the-enemy-theyre-a-big-part-of-who-we-are-79116">Essays on health: microbes aren't the enemy, they're a big part of who we are</a>
</strong>
</em>
</p>
<hr>
<h2>Not all foods make the grade</h2>
<p>Space foods need to appeal to a diverse crew and stay nutritious for an extremely long time (likely a three- to five-year mission). They also need to be lightweight and compact enough to fit on the spacecraft.</p>
<p>Once on Mars, challenges include growing fresh food and culturing protein sources. Beyond providing nutrients, we also need to consider providing more recently identified factors including phytonutrients (such as polyphenols), fermentation products and microbes. These will likely be crucial to sustain health and, indeed, life on deep space missions.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/humans-are-going-back-to-the-moon-and-beyond-but-how-will-we-feed-them-189794">Humans are going back to the Moon, and beyond – but how will we feed them?</a>
</strong>
</em>
</p>
<hr>
<h2>Why are microbes so important?</h2>
<p>If you’ve seen the film <a href="https://theconversation.com/the-martian-review-science-fiction-that-respects-science-fact-48373">The Martian</a>, you’ll know microbes are a crucial aspect of growing food, and are essential for keeping humans alive and functioning. </p>
<p>We have co-evolved with, and are hosts to, trillions of different microbes that live on our skin and in all our niches and cavities. This includes our mouths, nose, vagina, lungs and – crucially – our gut.</p>
<p>Most of these microbes are bacteria. The largest number are in the gut, where they influence our digestion, metabolism, and immune, endocrine (hormone) and nervous systems.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/YB-8JEo_0bI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">What is the human microbiome?</span></figcaption>
</figure>
<p>The relationship between gut microbes and <a href="https://journals.physiology.org/doi/full/10.1152/physrev.00018.2018?rfr_dat=cr_pub">mental health and behaviour</a> goes both ways. Gut microbes influence our mental health and behaviour, and these, in turn, influence our gut microbes. </p>
<p>Other components of our microbiomes – viruses, fungi and even parasites – and the oral and lung microbiome are also linked to mental and <a href="https://journals.physiology.org/doi/full/10.1152/physrev.00018.2018?rfr_dat=cr_pub">brain health</a>. </p>
<p>Importantly, we <a href="https://www.nature.com/articles/s41586-022-05620-1">share microbes</a> with others, including via the exchange of air, which is highly relevant in closed-environment systems such as inside spacecrafts.</p>
<p>So ensuring all astronauts have the healthiest and most diverse of microbes for the whole of the mission is vital.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-why-do-some-farts-smell-and-some-dont-and-why-do-some-farts-feel-hot-215064">Curious Kids: why do some farts smell and some don’t? And why do some farts feel hot?</a>
</strong>
</em>
</p>
<hr>
<h2>How could we encourage healthy microbes?</h2>
<p>It’s not just the food itself we have to think about. We also need to think about how we grow the food if we are to support healthy microbiomes. </p>
<p>Indeed, microbes play an essential role in the nutrient and phytochemical content of plants, and the microbes in soil, plants and humans are interconnected. Research published in 2023 confirms bacteria on vegetables and other plant foods find a home in the <a href="https://www.tandfonline.com/doi/abs/10.1080/19490976.2023.2258565">human gut</a>, enhancing microbe diversity. </p>
<p>But current ways of growing foods on spacecraft don’t use natural soil. Standard “vertical farming” methods grow plants in an alternative growth medium – imagine a next-generation hydroponics system. So we may need to add an optimised microbial cocktail to these systems to enhance the health properties of the foods astronauts grow and eat.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/565654/original/file-20231213-19-kwbbo1.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Growing tending plants in a vertical farm" src="https://images.theconversation.com/files/565654/original/file-20231213-19-kwbbo1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/565654/original/file-20231213-19-kwbbo1.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=421&fit=crop&dpr=1 600w, https://images.theconversation.com/files/565654/original/file-20231213-19-kwbbo1.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=421&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/565654/original/file-20231213-19-kwbbo1.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=421&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/565654/original/file-20231213-19-kwbbo1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=529&fit=crop&dpr=1 754w, https://images.theconversation.com/files/565654/original/file-20231213-19-kwbbo1.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=529&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/565654/original/file-20231213-19-kwbbo1.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=529&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This closed chamber mimics how astronauts will grow fresh crops in space.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/technology/tech-transfer-spinoffs/nasa-research-launches-a-new-generation-of-indoor-farming/">NASA</a></span>
</figcaption>
</figure>
<p><a href="https://www.cell.com/cell/fulltext/S0092-8674(22)01515-X?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS009286742201515X%3Fshowall%3Dtrue">Fermented protein</a> from microbes can be quickly produced in a bioreactor on board the spacecraft, even from food waste. Some types have a meat-like flavour and texture, and can provide all the amino acids humans need as well as useful byproducts from the microbes themselves. </p>
<p>Fermentation itself creates thousands of different bioactive molecules, including some vitamins, that have diverse <a href="https://www.tandfonline.com/doi/abs/10.1080/1028415X.2018.1544332">beneficial effects on health</a>, including possible benefits to mental health.</p>
<p>While we don’t yet know what types of fermented foods are possible in space, we could include fermented foods, such as kimchi and sauerkraut, in astronauts’ diets on Earth.</p>
<p>Probiotics and prebiotics as supplements may also be essential. Probiotics are live microbes that have demonstrated health benefits and prebiotics are food for these healthy microbes.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-is-kombucha-and-how-do-the-health-claims-stack-up-87180">What is kombucha and how do the health claims stack up?</a>
</strong>
</em>
</p>
<hr>
<h2>Benefits on Earth too</h2>
<p>We’re only at the start of learning how to optimise microbes to keep space crews healthy, which is crucial for long space flights and for possible settlement on other planets. </p>
<p>However, this research could have many other applications. We can use what we learn to help create self-sustaining and <a href="https://www.nasa.gov/technology/tech-transfer-spinoffs/nasa-research-launches-a-new-generation-of-indoor-farming/">sustainable food systems</a> on Earth to improve the environment and human health.</p><img src="https://counter.theconversation.com/content/216355/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Felice N Jacka is supported by a National Health and Medical Research Council investigator grant (#1194982). She has received: (1) competitive grant/research support from the Brain and Behaviour Research Institute, the National Health and Medical Research Council, Australian Rotary Health, the Geelong Medical Research Foundation, the Ian Potter Foundation, The University of Melbourne; (2) industry support for research from Meat and Livestock Australia, Woolworths Limited, the A2 Milk Company, Be Fit Foods, Bega Cheese; (3) philanthropic support from the Fernwood Foundation, Wilson Foundation, the JTM Foundation, the Serp Hills Foundation, the Roberts Family Foundation, the Waterloo Foundation and; (4) travel support and speakers honoraria from Sanofi-Synthelabo, Janssen Cilag, Servier, Pfizer, Network Nutrition, Angelini Farmaceutica, Eli Lilly, Metagenics, and The Beauty Chef. She is on the Scientific Advisory Board of the Dauten Family Centre for Bipolar Treatment Innovation and Zoe Limited. Felice Jacka has written two books for commercial publication.</span></em></p><p class="fine-print"><em><span>Dorit Donoviel is Executive Director, NASA-Funded Translational (moving products from lab-bench to practice) Research Institute for Space Health at Baylor College of Medicine. Dorit receives funding from NASA through Cooperative Agreement NNX16AO69A and disburses this funding to research groups and companies performing work to safeguard the health of humans in deep space.</span></em></p>Here’s why a healthy balance of microbes is important for astronauts when they travel to Mars and beyond.Felice Jacka, Alfred Deakin Professor, Deakin UniversityDorit Donoviel, Executive Director/Associate Professor, Baylor College of Medicine Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2146882023-12-19T18:13:36Z2023-12-19T18:13:36ZShipwrecks teem with underwater life, from microbes to sharks<figure><img src="https://images.theconversation.com/files/555600/original/file-20231024-25-xo8h4f.jpg?ixlib=rb-1.1.0&rect=30%2C15%2C5061%2C3534&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A school of grunts on a sunken World War II German submarine in the Atlantic Ocean off North Carolina.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/diver-and-schooling-tomtates-on-wwii-u-352-german-royalty-free-image/153943111">Karen Doody/Stocktrek Images via Getty Images</a></span></figcaption></figure><p>Humans have sailed the world’s oceans for thousands of years, but they haven’t all reached port. Researchers estimate that there are <a href="https://unesdoc.unesco.org/ark:/48223/pf0000152883">some three million shipwrecks</a> worldwide, resting in shallow rivers and bays, coastal waters and the deep ocean. Many sank during catastrophes – some during storms or after running aground, others in battle or collisions with other vessels.</p>
<p>Shipwrecks like <a href="https://www.britannica.com/topic/Titanic">the RMS Titanic</a>, <a href="https://www.britannica.com/topic/Lusitania-British-ship">RMS Lusitania</a> and <a href="https://www.britannica.com/technology/monitor-ship-type#ref51448">USS Monitor</a> conjure tales of human courage and sacrifice, sunken treasure and unsolved mysteries. But there’s another angle to their stories that doesn’t feature humans. </p>
<p>I have <a href="https://scholar.google.com/citations?user=wZ-kv2AAAAAJ&hl=en">studied the biology of shipwrecks</a> in the United States and internationally for 14 years. From this work, I have learned that shipwrecks are not only cultural icons but can also be biological treasures that create habitat for diverse communities of underwater life. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/FTYyzAxt3JI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The USS Monitor, which sank off Cape Hatteras, North Carolina, in a storm on Dec. 31, 1862, is now a center for sea life.</span></figcaption>
</figure>
<p>Recently, I led an international team of biologists and archaeologists in disentangling the mysteries of how this transformation happens. Drawing on scientific advances from our team and international colleagues, our <a href="https://academic.oup.com/bioscience/article-lookup/doi/10.1093/biosci/biad084">new study</a> describes how wrecked vessels can have second lives as seabed habitats.</p>
<h2>A new home for underwater life</h2>
<p>Ships are typically made of metal or wood. When a vessel sinks, it adds foreign, artificial structure to the seafloor. </p>
<p>For example, the World War II tanker <a href="https://monitor.noaa.gov/shipwrecks/clark.html">E.M. Clark</a> sank on a relatively flat, sandy seabed in 1942 when it was torpedoed by a German submarine. To this day, the intact metal wreck looms over the North Carolina seafloor like an underwater skyscraper, creating an island oasis in the sand. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Bx_uzNvNU1s?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">In this video narrated by NOAA research scientist Avery Paxton, sand tiger sharks hover above the wreck of the E.M. Clark off North Carolina, with vermilion snapper schooling nearby. Jacks and an invasive lionfish also appear.</span></figcaption>
</figure>
<p>The creatures that reside on and around sunken ships are so diverse and abundant that scientists often colloquially call these sites “<a href="https://3d-shipwreck-data-viewer-noaa.hub.arcgis.com/">living shipwrecks</a>.” Marine life ranging from microscopic critters to some of the largest animals in the sea use shipwrecks as homes. Brilliantly colored corals and sponges blanket the wrecks’ surfaces. Silvery schools of baitfish dart and shimmer around the structures, chased by sleek, fast-moving predators. Sharks sometimes cruise around wrecks, likely resting or looking for prey. </p>
<h2>The origin of a second life</h2>
<p>A ship’s transformation from an in-service vessel into a thriving metropolis for marine life can seem like a fairy tale. It has a once-upon-a-time origin story – the wrecking event – and a sequence of life arriving on the sunken structure and beginning to blossom.</p>
<p>Tiny microbes invisible to the naked human eye initially settle on the wreck’s surface, forming a carpet of cells, called a <a href="https://www.britannica.com/science/biofilm">biofilm</a>. This coating helps to <a href="https://doi.org/10.3389/fmars.2019.00048">make the wreck structure suitable</a> for larval animals like sponges and corals to settle and grow there.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/555611/original/file-20231024-23-oqeoj2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Shellfish, deepwater coral and anemones cling to the surface of a sunken wreck." src="https://images.theconversation.com/files/555611/original/file-20231024-23-oqeoj2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/555611/original/file-20231024-23-oqeoj2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/555611/original/file-20231024-23-oqeoj2.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/555611/original/file-20231024-23-oqeoj2.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/555611/original/file-20231024-23-oqeoj2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/555611/original/file-20231024-23-oqeoj2.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/555611/original/file-20231024-23-oqeoj2.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Diverse sea creatures living on the 19th-century, wooden-hulled Ewing Bank wreck, which lies 2,000 feet (610 meters) deep in the Gulf of Mexico.</span>
<span class="attribution"><a class="source" href="https://oceanexplorer.noaa.gov/explorations/19microbial-stowaways/background/archaeology/media/img2-hires.jpg">NOAA</a></span>
</figcaption>
</figure>
<p>Larger animals like fish sometimes appear within minutes after a ship sinks. <a href="https://coastalscience.noaa.gov/news/artificial-reefs-may-help-tropical-fish-expand-geographic-range-video/">Small fish</a> hide in the structure’s cracks and crevices, while <a href="https://doi.org/10.1016/j.fooweb.2020.e00147">large sharks</a> glide around it. <a href="https://doi.org/10.1016/j.marenvres.2020.104916">Sea turtles</a> and marine mammals such as <a href="https://doi.org/10.1371/journal.pone.0130581">fur seals</a> have also been spotted on wrecks.</p>
<h2>Hot spots for biodiversity</h2>
<p>Shipwrecks host quantities and varieties of marine life that can make them hot spots for biodiversity. The microbes that transform the wreck structure into habitat also enrich the surrounding sand. Evidence from deep Gulf of Mexico wrecks shows that a <a href="https://doi.org/10.1038/s41396-021-00978-y">halo of increased microbial diversity</a> radiates outward anywhere from 650 to 1,000 feet (200-300 meters) from the wreck. In the Atlantic Ocean, <a href="https://doi.org/10.1111/faf.12548">thousands of grouper</a>, a type of reef fish highly valued by fishers, congregate around and inside shipwrecks.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/555613/original/file-20231024-29-aaqe3w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Fish hover above a wrecked ship's surface." src="https://images.theconversation.com/files/555613/original/file-20231024-29-aaqe3w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/555613/original/file-20231024-29-aaqe3w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/555613/original/file-20231024-29-aaqe3w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/555613/original/file-20231024-29-aaqe3w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/555613/original/file-20231024-29-aaqe3w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/555613/original/file-20231024-29-aaqe3w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/555613/original/file-20231024-29-aaqe3w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Groupers and a conger eel, bottom center, on the wreck of the German submarine U-576 off the coast of North Carolina.</span>
<span class="attribution"><a class="source" href="https://oceanexplorer.noaa.gov/explorations/16battlefield/logs/sept7/sept7.html">NOAA</a></span>
</figcaption>
</figure>
<p>Shipwrecks can also serve as stepping stones across the ocean floor that animals use as temporary homes while moving from one location to another. This has been documented in areas of the world with dense concentrations of shipwrecks, such as off North Carolina, where storms and war have sunk hundreds of ships.</p>
<p>In this part of the ocean, popularly known as the “<a href="https://www.ncpedia.org/graveyard-atlantic">Graveyard of the Atlantic</a>,” reef fish likely <a href="https://doi.org/10.1038/s42003-019-0398-2">use the islandlike shipwrecks as corridors</a> when moving north or south away from the equator to find favorable water temperatures as climate change <a href="https://theconversation.com/ocean-heat-is-at-record-levels-with-major-consequences-174760">warms the oceans</a>. Scientists have also observed <a href="https://doi.org/10.1002/ecy.2687">sand tiger sharks</a> traveling from one wreck to another, possibly using the shipwrecks like rest stops during migration.</p>
<p>In the deep sea, life growing on shipwrecks can even generate energy. Tube worms that grow on organic shipwreck materials such as paper, cotton and wood host symbiotic bacteria that produce chemical energy. Such tube worm colonies have been documented in the Gulf of Mexico on the steel <a href="https://www.boem.gov/sites/default/files/boem-newsroom/Library/Ocean-Science/Ocean-Science-Jul-Aug-Sep-2014.pdf">luxury yacht Anona</a>. </p>
<h2>Biological mysteries abound</h2>
<p>Despite their biological value, shipwrecks can also threaten underwater life by altering or destroying natural habitats, causing pollution and spreading invasive species.</p>
<p>When a ship sinks, it can damage existing seafloor habitats. In a well-documented case in the Line Islands of the central Pacific, an <a href="https://doi.org/10.1038/ismej.2011.114">iron shipwreck</a> sank on a healthy coral reef. The iron infusion substantially decreased coral cover, and the reef was overcome by algae.</p>
<p>Ships may carry pollutants as fuel or cargo. As shipwrecks deteriorate in seawater, there is a risk that these pollutants may be released. The <a href="https://doi.org/10.1016/j.marpolbul.2021.112087">level of risk</a> depends on how much of the pollutant the ship was carrying and how intact the wreck is. One recent investigation revealed that effects from shipwreck pollutants can be detected in microbes up to <a href="https://doi.org/10.3389/fmars.2022.1017136">80 years after the wreck</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/JTq4b9c3Z00?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Ships and planes wrecked in wartime can leak toxic materials for decades after they come to rest in the ocean.</span></figcaption>
</figure>
<p>Shipwrecks may also inadvertently assist the spread of invasive plants and animals that wreak biological havoc. Wrecks are new structures that invasive species can settle on, grow and use as a hub to expand to other habitats. <a href="https://doi.org/10.1016/j.marpolbul.2020.111394">Invasive cup coral</a> has spread on World War II shipwrecks off Brazil. In Palmyra Atoll in the Pacific, a type of anemone called a corallimorph <a href="https://doi.org/10.1371/journal.pone.0002989">rapidly invaded</a> a shipwreck and now <a href="https://doi.org/10.1007/s10530-018-1696-1">threatens healthy coral reefs</a>.</p>
<h2>The future of shipwreck exploration</h2>
<p>Shipwrecks create millions of study sites that scientists can use to ask questions about marine life and habitats. One of the greatest challenges is that many wrecks are undiscovered or in remote locations. Advances in technology can help researchers see into the most inaccessible areas of the ocean, not only to find shipwrecks but to better understand their biology. </p>
<p>Maximizing discovery will require biologists, archaeologists and engineers to work together to explore these special habitats. Ultimately, the more we learn, the more effectively we can conserve these historical and biological gems.</p><img src="https://counter.theconversation.com/content/214688/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Avery Paxton is affiliated with NOAA National Centers for Coastal Ocean Science. </span></em></p>When ships sink, they add artificial structures to the seafloor that can quickly become diverse, ecologically important underwater communities.Avery Paxton, Research Marine Biologist, National Oceanic and Atmospheric AdministrationLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2140482023-09-28T12:28:11Z2023-09-28T12:28:11ZYour microbes live on after you die − a microbiologist explains how your necrobiome recycles your body to nourish new life<figure><img src="https://images.theconversation.com/files/550423/original/file-20230926-27-qpnpj4.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1794%2C1668&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">After you die, bacteria harvest your body for the nutrients that help push daisies.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/embroidery-skull-and-roses-grapes-humming-royalty-free-illustration/931298520">Matriyoshka/iStock via Getty Images Plus</a></span></figcaption></figure><p>Each human body contains a <a href="https://www.hmpdacc.org/overview/">complex community of trillions of microorganisms</a> that are important for your health while you’re alive. These <a href="https://open.oregonstate.education/generalmicrobiology/chapter/microbial-symbioses/">microbial symbionts</a> help you digest food, produce essential vitamins, protect you from infection and serve many other critical functions. In turn, the microbes, which are mostly concentrated in your gut, get to live in a relatively stable, warm environment with a steady supply of food.</p>
<p>But what happens to these symbiotic allies after you die? </p>
<p>As an <a href="https://scholar.google.com/citations?user=U_xOnjEAAAAJ&hl=en">environmental microbiologist</a> who studies <a href="https://doi.org/10.1093/femsec/fiad006">the necrobiome</a> – the microbes that live in, on and around a decomposing body – I’ve been curious about our postmortem microbial legacy. You might assume that your microbes die with you – once your body breaks down and your microbes are flushed into the environment, they won’t survive out in the real world. </p>
<p>In our September 2023 study, my research team and I share evidence that not only do your microbes continue to live on after you die, they actually play an important role in <a href="https://doi.org/10.1186/s13717-023-00451-y">recycling your body</a> so that new life can flourish.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/c_ZRZkU-FEw?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Your microbes accompany you from cradle to grave.</span></figcaption>
</figure>
<h2>Microbial life after death</h2>
<p>When you die, your heart stops circulating the blood that has carried oxygen throughout your body. Cells deprived of oxygen start digesting themselves in a <a href="https://en.wikipedia.org/wiki/Autolysis_(biology)">process called autolysis</a>. Enzymes in those cells – which normally digest carbohydrates, proteins and fats for energy or growth in a controlled way – start to work on the membranes, proteins, DNA and other components that make up the cells. </p>
<p>The products of this cellular breakdown make excellent food for your symbiotic bacteria, and without your immune system to keep them in check and a steady supply of food from your digestive system, they turn to this new source of nutrition. </p>
<p><a href="https://doi.org/10.7717/peerj.3437">Gut bacteria</a>, especially a class of microbes called <a href="https://doi.org/10.3389/fmicb.2017.02096"><em>Clostridia</em></a>, <a href="https://doi.org/10.1016/j.forsciint.2016.03.019">spread through your organs</a> and digest you from the inside out in a process called <a href="https://www.ncbi.nlm.nih.gov/books/NBK539741/">putrefaction</a>. Without oxygen inside the body, your anaerobic bacteria rely on energy-producing processes that don’t require oxygen, such as fermentation. These create the distinctly odorous-gases signature to decomposition.</p>
<p>From an <a href="https://doi.org/10.1016/j.meegid.2017.09.006">evolutionary standpoint</a>, it makes sense that your microbes would have evolved ways to adapt to a dying body. Like rats on a sinking ship, your bacteria will soon have to abandon their host and survive out in the world long enough to find a new host to colonize. Taking advantage of the carbon and nutrients of your body allows them to increase their numbers. A bigger population means a higher probability that at least a few will survive out in the harsher environment and successfully find a new body.</p>
<h2>A microbial invasion</h2>
<p>If you’re buried in the ground, your microbes are flushed into the soil along with a soup of decomposition fluids as your body breaks down. They’re entering an entirely new environment and encountering a whole new microbial community in the soil.</p>
<p>The <a href="https://doi.org/10.1016/j.tree.2015.06.004">mixing or coalescence</a> of two distinct microbial communities happens frequently in nature. Coalescence happens when the roots of two plants grow together, when wastewater is emptied into a river or even when two people kiss.</p>
<p>The outcome of mixing – which community dominates and which microbes are active – depends on several factors, such as how much environmental change the microbes experience and who was there first. Your microbes are adapted to the stable, warm environment inside your body where they receive a steady supply of food. In contrast, soil is a particularly <a href="https://doi.org/10.1016/B978-0-12-820202-9.00002-2">harsh place to live</a> – it’s a highly variable environment with steep chemical and physical gradients and big swings in temperature, moisture and nutrients. Furthermore, soil already hosts an exceptionally diverse microbial community full of decomposers that are well adapted to that environment and would presumably outcompete any newcomers. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/550417/original/file-20230926-19-r1tn2a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Microscopy image of Clostridium septicum" src="https://images.theconversation.com/files/550417/original/file-20230926-19-r1tn2a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/550417/original/file-20230926-19-r1tn2a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=501&fit=crop&dpr=1 600w, https://images.theconversation.com/files/550417/original/file-20230926-19-r1tn2a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=501&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/550417/original/file-20230926-19-r1tn2a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=501&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/550417/original/file-20230926-19-r1tn2a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=629&fit=crop&dpr=1 754w, https://images.theconversation.com/files/550417/original/file-20230926-19-r1tn2a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=629&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/550417/original/file-20230926-19-r1tn2a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=629&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"><em>Clostridium septicum</em> is one species of bacteria involved in putrefaction.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/2n1hVng">Joseph E. Rubin/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>It’s easy to assume that your microbes will die off once they are outside your body. However, my research team’s previous studies have shown that the DNA signatures of host-associated microbes can be detected in the soil below a decomposing body, <a href="https://doi.org/10.1371/journal.pone.0130201">on the soil surface</a> and <a href="https://doi.org/10.1371/journal.pone.0208845">in graves</a> for months or years after the soft tissues of the body have decomposed. This raised the question of whether these microbes are still alive and active or if they are merely in a dormant state waiting for the next host.</p>
<p>Our newest study suggests that your microbes are not only living in the soil but also <a href="https://doi.org/10.1186/s13717-023-00451-y">cooperating with native soil microbes</a> to help decompose your body. In the lab, we showed that mixing soil and decomposition fluids filled with host-associated microbes increased decomposition rates beyond that of the soil communities alone.</p>
<p>We also found that host-associated microbes <a href="https://doi.org/10.1186/s13717-023-00451-y">enhanced nitrogen cycling</a>. Nitrogen is an essential nutrient for life, but most of the nitrogen on Earth is tied up as atmospheric gas that organisms can’t use. Decomposers play a critical role recycling organic forms of nitrogen such as proteins <a href="https://doi.org/10.1016/j.soilbio.2018.03.005">into inorganic forms</a> such as ammonium and nitrate that microbes and plants can use. </p>
<p>Our new findings suggest that our microbes are likely <a href="https://doi.org/10.1186/s13717-023-00451-y">playing a part</a> in this recycling process by converting large nitrogen-containing molecules like proteins and nucleic acids into ammonium. Nitrifying microbes in the soil can then convert the ammonium into nitrate. </p>
<h2>Next generation of life</h2>
<p>The recycling of nutrients from detritus, or nonliving organic matter, is a <a href="https://doi.org/10.2307/1930126">core process in all ecosystems</a>. In terrestrial ecosystems, decomposition of dead animals, or carrion, <a href="https://doi.org/10.1007/s00442-012-2460-3">fuels biodiversity</a> and is an important <a href="https://doi.org/10.1002/ece3.7542">link in food webs</a>.</p>
<p>Living animals are a bottleneck for the carbon and nutrient cycles of an ecosystem. They slowly accumulate nutrients and carbon from large areas of the landscape throughout their lives then deposit it all at once in a small, localized spot when they die. One dead animal can support a whole pop-up food web of <a href="https://doi.org/10.1093/femsec/fiad006">microbes</a>, <a href="https://doi.org/10.1371/journal.pone.0241777">soil fauna</a> and <a href="https://doi.org/10.1007/978-3-642-88448-1_6">arthropods</a> that make their living off carcasses. </p>
<p><a href="https://theconversation.com/life-after-death-how-insects-rise-from-the-dead-and-transform-corpses-into-skeletons-148847">Insect</a> and <a href="https://doi.org/10.1890/09-0292.1">animal scavengers</a> help further redistribute nutrients in the ecosystem. Decomposer microbes convert the concentrated pools of nutrient-rich organic molecules from our bodies into <a href="https://doi.org/10.1371/journal.pone.0287094">smaller, more bioavailable forms</a> that other organisms can use to support new life. It’s not uncommon to see <a href="https://doi.org/10.1002/ecs2.1537">plant life flourishing near a decomposing animal</a>, visible evidence that nutrients in bodies are being recycled back into the ecosystem.</p>
<p>That our own microbes play an important role in this cycle is one microscopic way we live on after death.</p><img src="https://counter.theconversation.com/content/214048/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jennifer DeBruyn receives funding from the United States Department of Agriculture, National Science Foundation, Department of Justice, and Defense Advanced Research Projects Agency.</span></em></p>With the help of the microbes that once played an essential role in keeping you alive, the building blocks of your body go on to become a part of other living things.Jennifer DeBruyn, Professor of Environmental Microbiology, University of TennesseeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2041642023-09-10T13:04:13Z2023-09-10T13:04:13ZThe nose knows: How microbiomes and the smells they produce help shape behaviour in bugs, birds, beasts and humans<figure><img src="https://images.theconversation.com/files/547261/original/file-20230908-27-yeuep5.jpg?ixlib=rb-1.1.0&rect=612%2C68%2C4958%2C3759&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The microbiome functions as an 'invisible organ' but it often makes its presence known by emitting sounds and smells.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/the-nose-knows-how-microbiomes-and-the-smells-they-produce-help-shape-behaviour-in-bugs-birds-beasts-and-humans" width="100%" height="400"></iframe>
<p>Microbes are an integral part of most, if not all multi-cellular organisms. In fact, these organisms are the way they are because of the tiny partners they house within and on them. These microbes constitute the microbiome: an “invisible organ” weighing approximately <a href="https://doi.org/10.1007/978-981-10-7684-8">2.5 to three kilograms</a> in an adult human and much more in larger animals.</p>
<p>This unique body part was made visible with the advent of modern molecular imaging technologies. In my book <em><a href="https://www.routledge.com/Microbiomes-and-Their-Functions-Why-Organisms-Need-Microbes/Appanna/p/book/9780367749897">Microbiomes and their Functions</a></em>, I explore how it works in partnership with other visible organs and engages in a variety of physiological functions essential for the development and survival of the hosts. </p>
<p>Microbiomes have been part of all these organisms from the beginning, and have evolved in tandem with them, just as their visible organs have.</p>
<p>The digestive tract, with all its components, is a good example of how organs can be shaped by their microbial inhabitants. The digestive tract has markedly disparate features in a carnivore, an omnivore or a herbivore. Herbivores have the longest digestive tracts and <a href="https://opentextbc.ca/biology/chapter/15-1-digestive-systems/">carnivores have the shortest</a>.</p>
<h2>The microbiome</h2>
<p>The bulk of microbiome is found in the <a href="https://doi.org/10.1007/978-981-10-7684-8_2">digestive tract</a>, where it helps extract nutrients from our diet. The diverse microbes constituting the microbiome not only contribute to optimal digestion, but also help prime our immune system, and produce hormones and neurotransmitters (or their precursors) that have profound influence on our behaviours.</p>
<p>The information-laden molecules generated by the microbiome play a crucial role in the body’s <a href="https://doi.org/10.3389/fimmu.2020.00700">non-verbal communication</a>. These <a href="https://doi.org/10.1038/s41467-020-18871-1">microbiome-derived signals</a> can elicit a range of responses including hunger, satiety (feeling full), mood changes and social behaviour.</p>
<figure class="align-right ">
<img alt="Human silhouette showing the gut-brain connection" src="https://images.theconversation.com/files/547017/original/file-20230907-29-lkr7n3.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/547017/original/file-20230907-29-lkr7n3.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=796&fit=crop&dpr=1 600w, https://images.theconversation.com/files/547017/original/file-20230907-29-lkr7n3.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=796&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/547017/original/file-20230907-29-lkr7n3.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=796&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/547017/original/file-20230907-29-lkr7n3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1000&fit=crop&dpr=1 754w, https://images.theconversation.com/files/547017/original/file-20230907-29-lkr7n3.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1000&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/547017/original/file-20230907-29-lkr7n3.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1000&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The information network between the gut microbiome and the brain is aided by the vagus nerve that connects these two organs.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>The information network between the gut microbiome and the brain is aided by the vagus nerve that <a href="https://routledge.pub/Microbiomes-and-Their-Functions">connects these two organs</a>.</p>
<p>Microbes like Lactobacillus and Bifidobacterium residing in the gut secrete neurotransmitters known to influence human behaviour <a href="https://doi.org/10.3390/cimb44040096">such as GABA</a> (gamma-aminobutyric acid), acetylcholine, norepinephrine, oxytocin and indole metabolites. Indole derivatives are obtained when gut microbes metabolize the essential amino-acid, tryptophan.</p>
<p>For instance, the <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4449495">neurotransmitter dopamine</a> is considered a “feel good” hormone and is often associated with positive emotions. However, low levels of this molecule may contribute to anxiety. On the other hand, indoles are linked to satiety, resulting in a tendency to eat less, and are associated with weight loss.</p>
<h2>Smelly signals</h2>
<p>Despite its invisible nature, the microbiome often makes its presence known by emitting sounds and smells. The latter can be powerful signals that can influence behaviour.</p>
<p>These smelly signals can, at a distance or at a close range, prompt happiness, enthusiasm, anxiety, attraction, fear or <a href="https://doi.org/10.1007/978-981-10-7684-8">aggression</a>. The microbially-concocted odours are a very important tool in the communication arsenal that most organisms — including humans — rely on to send or receive non-verbal messages.</p>
<p>The human skin is home to a diverse range of microorganisms known to contribute to different odours. Bacteria like Staphylococcus and Corynebacterium lodge in the warm and moist underarm region of the skin where the apocrine glands, a source of chemicals, abound. The resident bacteria use these chemical nutrients to shape <a href="https://asm.org/Articles/2021/December/Microbial-Origins-of-Body-Odor">body odour</a>.</p>
<p>These apocrine glands generally produce odourless compounds. It is microbes that fashion those compounds into smell signatures characteristic of an individual. These odoriferous signals can serve to attract or repel people and modify social behaviours. For instance, the presence of select bacteria is known to process non-smelly steroids into compounds with a characteristic urine odour, not conducive to making friends. </p>
<h2>Chemical signals in animals, birds, plants, fungi</h2>
<p>In other mammals, odoriferous compounds like trimethylamine or pentanoic acid entice mates, while in animals endowed with a scent pouch, they lure prey, defend or mark territories. Some of the <a href="https://doi.org/10.3389/fevo.2017.00143">pungent chemicals</a> are notoriously reputed to keep <a href="https://www.washingtonpost.com/lifestyle/kidspost/whats-that-smell-for-some-animals-their-stink-helps-keep-them-alive/2018/08/13/9058fc62-9678-11e8-810c-5fa705927d54_story.html">predators at bay</a>. </p>
<p>Birds have a special gland that hosts a diverse microbial population, which generates scent-releasing chemicals. These easily transmittable signals are aimed at repelling predators, attracting mates, recognizing kin, promoting parental care and <a href="https://www.nytimes.com/2019/11/10/science/birds-smell-bacteria.html">identifying proprietary nests</a>.</p>
<figure class="align-center ">
<img alt="A man's hand holding a small shovel with a truffle on it, patting his truffle-hunting dog with his other hand" src="https://images.theconversation.com/files/547027/original/file-20230907-19-ya50zw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/547027/original/file-20230907-19-ya50zw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/547027/original/file-20230907-19-ya50zw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/547027/original/file-20230907-19-ya50zw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/547027/original/file-20230907-19-ya50zw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/547027/original/file-20230907-19-ya50zw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/547027/original/file-20230907-19-ya50zw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Truffles — the highly sought-after edible fungus — recruit select microbes to generate aromatic alcohols that lure small mammals to dig them up, which promotes the dispersal of the truffle’s spores.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>These smelly marks are also key to maintaining the social order of numerous insects. <a href="https://doi.org/10.1186/s40168-018-0588-z">These scents</a> can not only help camouflage the hosts, but can also convert loners to crowd-lovers. For instance, it is a scent that cajoles the solitary <a href="https://doi.org/10.3390/insects11100655">locust</a> into a gregarious lifestyle during the feeding season and triggers an insatiable appetite for vegetation.</p>
<p>Some fungi are known to enlist the fragrance of vapour-like chemicals to assemble their microbiome, which in turn helps the host perform a variety of essential physiological functions.</p>
<p>Truffles — the highly sought-after edible fungus — are renowned for their distinctive smell, but they may be dependent on the microbiome to produce this sweet fragrance. In fact, <a href="https://doi.org/10.1128/aem.01098-15">truffles recruit select microbes</a> to generate aromatic alcohols that lure small mammals to dig them up, which promotes the dispersal of the truffle’s spores.</p>
<p>Plants and algae are also dependent on microbe-derived odour prompts to assist them to survive, and even die and be scavenged. Plants depend on these smell signatures to communicate dangers lurking in their environment and even to fend off insects, birds or <a href="https://doi.org/10.3389/fmicb.2021.772420">other predators</a>.</p>
<p>When some algae bloom beyond control due to environmental conditions, they plot their own demise with the <a href="https://doi.org/10.1201/9781003166481">assistance of microbes</a>. Some of these microbes not only help the algae die, but are also responsible for producing distinctive odours that are detected and decoded as food by birds and fish. The result is a clean-up of the dead algae by feasting birds and fish.</p>
<p>The microbiome and its signature smells are crucial for most organisms, whether human, insect or plant. The silent signals sent by the microbiome are essential communications that influence behaviour, and have evolved to help the host survive and thrive.</p><img src="https://counter.theconversation.com/content/204164/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Vasu Appanna receives / has received funding from NATO, NSERC, NOHFC and FEDNOR</span></em></p>The microbiome and its signature smells are crucial for most organisms, whether human, insect or plant. The silent signals sent by the microbiome are essential communications that influence behaviour.Vasu Appanna, Professor, Biochemistry, Laurentian UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2118612023-08-23T12:25:48Z2023-08-23T12:25:48ZAcne bacteria trigger cells to produce fats, oils and other lipids essential to skin health – new research<figure><img src="https://images.theconversation.com/files/543536/original/file-20230818-27-a54vaz.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2094%2C1416&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">There's more to the bacterium _Cutibacterium acnes_ than meets the eye.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/cropped-shot-of-the-face-of-a-young-woman-with-royalty-free-image/1581451668">Youngoldman/iStock via Getty Images Plus</a></span></figcaption></figure><p>The skin is the <a href="https://theconversation.com/the-skin-is-a-very-important-and-our-largest-organ-what-does-it-do-91515">largest organ of the body</a>, and it plays a crucial role as the first line of defense against pathogens and insults from the external environment. It provides important functions like temperature regulation and moisture retention. And despite the misconception that lipids harm your skin by causing oiliness and acne, they actually <a href="https://doi.org/10.1126/sciadv.adg6262">play a vital role</a> in maintaining the skin barrier.</p>
<p>Lipids – organic compounds that include <a href="https://www.khanacademy.org/science/biology/macromolecules/lipids/a/lipids">fats, oils, waxes and other types of molecules</a> – are essential components of the outermost layer of skin. Changes to the skin’s lipid composition can disrupt its ability to function as a protective barrier, leading to a <a href="https://doi.org/10.1046/j.0022-202x.2001.01455.x">range of skin diseases</a>, including eczema and psoriasis.</p>
<p>Human skin is colonized by <a href="https://doi.org/10.1038/nrmicro.2017.157">thousands of species of bacteria</a>. One of the most common microbes on the skin, <a href="https://doi.org/10.3390/microorganisms9030628"><em>Cutibacterium acnes</em>, or <em>C. acnes</em></a>, is well known for its potential involvement in causing acne, but its broader effects on skin health are less understood.</p>
<p>I am a <a href="https://profiles.ucsd.edu/samia.l.almoughrabie">researcher in dermatology</a> working in the <a href="https://dermatology.ucsd.edu/research/basic-science/gallo-lab/index.html">Gallo Lab</a> at the University of California, San Diego. My colleagues and I study how the skin defends the body against infections and the environment, with a particular focus on the skin microbiome, or the microbes living on the skin. In our recently published research conducted in collaboration with SILAB, a company developing active ingredients for skincare products, we found that <em>C. acnes</em> triggers certain skin cells to <a href="https://doi.org/10.1126/sciadv.adg6262">significantly increase production of lipids</a> that are important to maintaining the skin barrier.</p>
<h2>Skin bacteria and lipid synthesis</h2>
<p>To determine the role that bacteria play in lipid production, we exposed keratinocytes, the cells that <a href="https://www.britannica.com/science/human-skin/The-epidermis#">make up the epidermis</a>, to different bacteria naturally present on the skin and analyzed changes in lipid composition. </p>
<p>Of the common skin bacteria we tested, only <em>C. acnes</em> triggered an <a href="https://doi.org/10.1126/sciadv.adg6262">increase in lipid production</a> within these cells. More specifically, we found a threefold increase in total lipids, including ceramides, cholesterol, free fatty acids and especially triglycerides. Each of these lipid types are essential to maintaining the skin barrier, locking in moisture and protecting against damage. These findings suggest that <em>C. acnes</em> plays a distinctive role in the lipid skin regulation. </p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/MWE3U3FItlc?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The skin microbiome contains bacteria and other microbes that help protect your body.</span></figcaption>
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<p>We found that <em>C. acnes</em> induced this increase in lipid production by producing a type of short-chain fatty acid called <a href="https://doi.org/10.1126/sciadv.adg6262">propionic acid</a>. Propionic acid creates an acidic skin environment that provides a number of benefits, including limiting pathogen growth, reducing staph infections and contributing to anti-inflammatory effects in the gut. </p>
<p>We also identified the <a href="https://doi.org/10.1126/sciadv.adg6262">specific gene and receptor</a> that regulate lipid synthesis through <em>C. acnes</em>. Blocking these components also blocked <em>C. acnes</em>-induced lipid synthesis.</p>
<p>In all, our findings highlight the substantial role that a common skin bacterium and its chemical byproducts play in shaping the composition of skin lipids.</p>
<h2>Reinforcing the skin barrier</h2>
<p>Our research suggests that propionic acid from <em>C. acnes</em> has <a href="https://doi.org/10.1126/sciadv.adg6262">multiple advantageous effects</a> on the skin barrier. For example, by increasing the lipid content in skin cells, propionic acid reduced water loss through the skin.</p>
<p>We also found that the lipids skin cells produce after exposure to <em>C. acnes</em> or propionic acid have antimicrobial effects against <em>C. acnes</em>. This suggests that the lipids <em>C. acnes</em> helps produce have a dual role: They not only control the presence of <em>C. acnes</em> on the skin but also contribute to the overall balance of the skin microbiome so one species of microbe doesn’t dominate the rest.</p>
<p>In the complex interplay between the skin and its microbial inhabitants, the ubiquitous <em>C. acnes</em> is emerging as an important player. Further research to better understand the skin microbiome may help lead to new treatments for skin conditions.</p><img src="https://counter.theconversation.com/content/211861/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Samia Almoughrabie does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Bacteria and lipids get a bad rap for causing breakouts and oily skin. But both play an essential role in helping your skin barrier stay strong against pathogens and insults from the environment.Samia Almoughrabie, Postdoctoral Researcher in Dermatology, University of California, San DiegoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2114552023-08-16T14:52:16Z2023-08-16T14:52:16ZMore than half of life on Earth is found in soil – here’s why that’s important<figure><img src="https://images.theconversation.com/files/542806/original/file-20230815-17-8wyoa2.jpeg?ixlib=rb-1.1.0&rect=93%2C67%2C1501%2C831&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Springtails (Fasciosminthurus quinquefasciatus) are found in any damp soil.</span> <span class="attribution"><a class="source" href="https://www.chaosofdelight.org/gallery/5kispkk47gfjazdxskbw7m04mgvga3">Andy Murray/chaosofdelight.org</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>A <a href="https://www.pnas.org/doi/abs/10.1073/pnas.2304663120">recent study</a> has found that soil is home to 59% of all life on Earth, from an insect feeding on the soil surface to a tiny microbe nestled in a soil pore. This discovery crowns soil as the most biodiverse habitat on the planet.</p>
<p>The paper estimates that around 2 million species of <a href="https://www.britannica.com/animal/arthropod">arthropod</a> (think insects and spiders) inhabit the soil – some 30% of all known arthropod species. There are far fewer species of soil specialists such as <a href="https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/enchytraeidae"><em>enchytraeidae</em></a> (resembling mini earthworms) and <a href="https://www.britannica.com/animal/oligochaete"><em>oligochaeta</em></a> (worms), with only 770 and 6,000 species respectively. That might not seem like a lot, but it still represents around 98% and 63% of these animal groups.</p>
<p>The variety of mammals living in soil is, by comparison, quite limited. Only 3.8% of mammal species are associated with this habitat. On the other hand, 85% of plants have their roots buried in the soil and around 43% of <a href="https://www.britannica.com/animal/nematode"><em>nematode</em></a> (tiny worms) species call soil their home, or reside within the plants and animals that inhabit it.</p>
<p>However, the number of animal and plant species that live in soil are dwarfed by microscopic organisms. The researchers estimate that a mind-blowing 430 million species (or more than 50%) of bacteria and 5.6 million species (or 90%) of fungi have made soil their home.</p>
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<em>
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Read more:
<a href="https://theconversation.com/the-melting-arctic-is-a-crime-scene-the-microbes-i-study-have-long-warned-us-of-this-catastrophe-but-they-are-also-driving-it-207785">The melting Arctic is a crime scene. The microbes I study have long warned us of this catastrophe – but they are also driving it</a>
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<p>But perhaps more important than the raw numbers are the functions that this biodiversity performs. The life within the soil not only helps to produce the food we eat, it also plays a crucial role in holding the soil together and even gives us potential sources for new antibiotics and medicines.</p>
<h2>Helping plants grow</h2>
<p>Small animals, including <a href="https://www.britannica.com/animal/earthworm">earthworms</a> and <a href="https://www.britannica.com/animal/springtail">springtails</a>, break down plant material and other forms of organic matter, such as dead insects, and incorporate them into the soil. This process releases the nutrients that most plants rely on to grow. But it’s not the only way that soil organisms <a href="https://theconversation.com/tapping-the-plant-microbiome-to-improve-farming-and-plant-health-36288">help plants gain more nutrition</a>. </p>
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<iframe src="https://player.vimeo.com/video/222168889" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
<figcaption><span class="caption">How soil organisms break down plant remains and create soil pores.</span></figcaption>
</figure>
<p><a href="https://www.rhs.org.uk/biodiversity/mycorrhizal-fungi"><em>Mycorrhizal</em> fungi</a> (a species of fungi that grow in association with plant roots), for instance, embed themselves in the roots of plants where they extract energy-rich compounds. In return, the fungi help plants expand their reach in the soil, allowing them to access a greater amount of nutrients.</p>
<p>Other species that are vital for food production include <a href="https://www.britannica.com/science/nitrogen-fixing-bacteria">nitrogen-fixing bacteria</a>. They are commonly associated with legumes such as beans and clover. These bacteria convert nitrogen gas from the atmosphere into compounds that the plants can use – an undertaking that can otherwise only be done synthetically, using vast amounts of energy.</p>
<h2>Holding soil together</h2>
<p>As organisms penetrate the soil, whether by burrowing, creating nests or as a means of anchoring themselves, they engineer pathways through the soil and contribute to its structure. Notable examples include <a href="https://www.britannica.com/animal/termite">termites</a> rearranging the soil to create channels for air and water to filter through, as well as <a href="https://doi.org/10.1093/aob/mcab029">roots and root hairs enmeshing soil</a>.</p>
<p>The incorporation of decomposed plant material into the soil serves a similarly crucial purpose. It helps to hold the soil together and creates pores that protect the soil from erosion and increase its capacity to store water.</p>
<p>Some of this organic material is also locked away with soil minerals, leading to the <a href="https://theconversation.com/france-has-a-great-plan-for-its-soil-and-its-not-just-about-wine-47335">storage of carbon</a>. In fact, <a href="https://www.ipcc.ch/site/assets/uploads/2018/03/WGI_TAR_full_report.pdf">soils hold</a> three times as much carbon as vegetation and twice as much as the atmosphere. </p>
<figure class="align-center ">
<img alt="A termite mound on the Savanna." src="https://images.theconversation.com/files/542774/original/file-20230815-19-a37hww.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/542774/original/file-20230815-19-a37hww.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=434&fit=crop&dpr=1 600w, https://images.theconversation.com/files/542774/original/file-20230815-19-a37hww.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=434&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/542774/original/file-20230815-19-a37hww.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=434&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/542774/original/file-20230815-19-a37hww.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=546&fit=crop&dpr=1 754w, https://images.theconversation.com/files/542774/original/file-20230815-19-a37hww.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=546&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/542774/original/file-20230815-19-a37hww.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=546&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Termites create structures above and below ground for air and water to move through.</span>
<span class="attribution"><span class="source">John Quinton</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>Biodiversity increases resilience</h2>
<p>In many cases, these functions involve a variety of species. Having multiple species perform the same function offers a safety net if conditions change, such as during a drought or a flood. </p>
<p>Some species are more resilient to these events than others. When conditions change, unaffected organisms within the soil can step in to fulfil the same functions as those that might have suffered – a process ecologists call “functional redundancy”. This improves the ability of an ecosystem, such as soil, to withstand and recover from environmental shocks. </p>
<p>Soil biodiversity is also a key reservoir for new drugs. Soil bacteria have produced <a href="https://doi.org/10.1016/j.cub.2009.04.001">most of our antibiotics</a>, including streptomycin, chloramphenicol and tetracycline. Unfortunately, the rise of antibiotic resistance has rendered many early antibiotics ineffective. However, searching through different soils is <a href="https://www.nature.com/articles/d41586-018-01931-4">yielding promising new antibiotics</a> with the potential to kill “superbugs” that are resistant to existing drugs.</p>
<figure class="align-center ">
<img alt="A soil animal eating mould." src="https://images.theconversation.com/files/542612/original/file-20230814-25671-a5b8tl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/542612/original/file-20230814-25671-a5b8tl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/542612/original/file-20230814-25671-a5b8tl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/542612/original/file-20230814-25671-a5b8tl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/542612/original/file-20230814-25671-a5b8tl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/542612/original/file-20230814-25671-a5b8tl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/542612/original/file-20230814-25671-a5b8tl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A peeudachorutes species eating a slime mould.</span>
<span class="attribution"><a class="source" href="https://www.chaosofdelight.org/gallery/m5bftdf81d97p7ib5tgiais5dymfb8">Andy Murray/ChaosofDelight.org</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Soil biodiversity plays an important role in producing the food we eat, sustaining soil health and helping to deliver a range of other services, from sourcing medicines to reducing the impact of floods and droughts. The importance of protecting our soils for future generations becomes ever clearer.</p>
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<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><strong><em>Don’t have time to read about climate change as much as you’d like?</em></strong>
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<p class="fine-print"><em><span>John Quinton receives research funding from the Natural Environment Research Council, The Engineering and Physical Sciences Research Council and the European Commission</span></em></p>With more than one species for every person on the planet, soils are the most diverse habitat on Earth.John Quinton, Professor of Soil Science, Lancaster UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2010822023-07-27T02:08:56Z2023-07-27T02:08:56ZWhat is dandruff? How do I get rid of it? Why does it keep coming back?<figure><img src="https://images.theconversation.com/files/536006/original/file-20230706-25-n7njvh.jpg?ixlib=rb-1.1.0&rect=2%2C0%2C995%2C667&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/dander-that-causes-itching-scalp-373934782">Shutterstock</a></span></figcaption></figure><p>Dandruff can be dry, like snowflakes, or greasy, with yellow clumps. <a href="https://www.ncbi.nlm.nih.gov/books/NBK551707/">Up to half</a> of all adults have had this scalp condition at one point, so you’ll no doubt know about these skin flakes and the itchiness. </p>
<p>Dandruff can be <a href="https://onlinelibrary.wiley.com/doi/10.1111/j.1439-0507.2008.01624.x">embarrassing</a>. It can affect many aspects of people’s lives, such as how they socialise, how they style their hair, and what clothes they wear.</p>
<p>Dandruff is not a modern problem. In fact, it has been around for millennia and was <a href="https://pubmed.ncbi.nlm.nih.gov/2181905/">described</a> by Greek physicians. We don’t know for sure whether our ancestors were as bothered by it as much as we are today. But they were interested in what causes it.</p>
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Read more:
<a href="https://theconversation.com/big-hair-bald-how-much-difference-your-hair-really-makes-to-keep-you-cool-or-warm-201380">Big hair? Bald? How much difference your hair really makes to keep you cool or warm</a>
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</em>
</p>
<hr>
<h2>What causes dandruff?</h2>
<p>Dandruff is mainly caused by the yeast <em><a href="https://www.cell.com/cell-host-microbe/pdf/S1931-3128(19)30106-4.pdf">Malassezia</a></em>. The yeast lives on most people’s skin, either on the surface or in the opening of the hair follicle, the structure that surrounds a hair’s root and strand.</p>
<p>The yeast feeds on sebum, the natural moisturiser secreted by your sebaceous glands to stop your skin drying out. These glands are attached to every hair follicle and the hair provides a dark, sheltered micro-environment ideal for the yeast to flourish.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/536003/original/file-20230706-22-6t0yr8.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Diagram of skin cross-section showing hair follicle and other skin structures" src="https://images.theconversation.com/files/536003/original/file-20230706-22-6t0yr8.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/536003/original/file-20230706-22-6t0yr8.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=520&fit=crop&dpr=1 600w, https://images.theconversation.com/files/536003/original/file-20230706-22-6t0yr8.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=520&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/536003/original/file-20230706-22-6t0yr8.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=520&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/536003/original/file-20230706-22-6t0yr8.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=653&fit=crop&dpr=1 754w, https://images.theconversation.com/files/536003/original/file-20230706-22-6t0yr8.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=653&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/536003/original/file-20230706-22-6t0yr8.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=653&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The yeast that causes dandruff lives on the skin surface and in the opening of the hair follicle.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/medical-education-chart-biology-hair-diagram-645657787">Shutterstock</a></span>
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</figure>
<p>As the yeast grows, it releases molecules that irritate the skin and disrupts how the skin normally renews itself. This causes the cells to cluster together, appearing as white flakes. When there is excess sebum, this can mix with the cells and cause the dandruff to appear <a href="https://www.headandshoulders.co.in/en-in/healthy-hair-and-scalp/dandruff/yellow-dandruff">yellow</a>.</p>
<p>The link between dandruff and yeast was made nearly 150 years ago. The person who first identified and described this yeast <a href="https://www.cell.com/cell-host-microbe/pdf/S1931-3128(19)30106-4.pdf">in 1874</a> was Louis-Charles Malassez (the yeast’s namesake).</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/invisible-skin-mites-called-demodex-almost-certainly-live-on-your-face-but-what-about-your-mascara-195451">Invisible skin mites called Demodex almost certainly live on your face – but what about your mascara?</a>
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</em>
</p>
<hr>
<h2>Why do I have dandruff?</h2>
<p>As <em>Malassezia</em> is found on most people, why do some people get dandruff and others don’t? This depends on a range of factors.</p>
<p>These include the quality of your skin barrier. This may mean yeast can penetrate deeper if the skin is damaged in some way, for example, if it’s sunburnt. Other factors include your immunity, and external factors, such as which hair-care products you use.</p>
<p>How <em>Malassezia</em> grows also depends on the <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4864613/">balance</a> of other microorganisms that live on your skin, such as bacteria.</p>
<h2>How do I get rid of dandruff?</h2>
<p>Dandruff is mostly treated with <a href="https://www.sciencedirect.com/science/article/abs/pii/S0939641123000292?via%3Dihub">anti-fungal</a> shampoos and scalp treatments to dampen down growth of <em>Malassezia</em>. The shampoos most commonly contain the anti-fungal agent <a href="https://pubmed.ncbi.nlm.nih.gov/34575891/">zinc pyrithione</a> (ZnPT for short). Other common anti-fungals in shampoos include selenium sulfide, ketoconazole and coal tar. </p>
<p>You can also treat dandruff with scalp masks and scrubs that help restore the scalp barrier, by reducing inflammation and irritation. But as these may not have any anti-fungal action, your dandruff is likely to return.</p>
<p>Home remedies <a href="https://www.healthline.com/nutrition/ways-to-treat-dandruff#7.-Omega-3s">include</a> tea tree oil, coconut or other oils, and honey. There is some evidence to support their use, mostly from <a href="https://pubmed.ncbi.nlm.nih.gov/35642120/">studies</a> that show extracts from botanical ingredients can reduce growth of the yeast in the lab. But there is great variation in the quality and composition of these ingredients.</p>
<p>There is also the risk of making the problem worse by providing more oils that the yeast will enjoy, causing more imbalance to the scalp micro-organisms and leading to more irritation.</p>
<p>So it’s best to stick with commercial products.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/does-the-price-of-your-shampoo-affect-how-clean-your-hair-is-heres-the-science-71597">Does the price of your shampoo affect how clean your hair is? Here's the science</a>
</strong>
</em>
</p>
<hr>
<h2>Why does my dandruff come back?</h2>
<p>Your dandruff is likely to return unless the active ingredients in your shampoo can reach the right spot, at the right concentration, for the right amount of time needed to kill the yeast. </p>
<p>Our <a href="https://pubmed.ncbi.nlm.nih.gov/36842718/">research</a> focussing on zinc pyrithione-based products showed these shampoos reached the skin surface. But they less-reliably ended up in the harder-to-reach hair follicles.</p>
<p>We found the zinc pythione seemed <a href="https://pubmed.ncbi.nlm.nih.gov/35631659/">to target</a> the top of the follicles rather than deep into the follicles. </p>
<p>So this may explain why dandruff keeps on coming back. Your shampoo’s active ingredient may not reach the yeast that causes your dandruff.</p>
<p>We don’t yet know how we can encourage existing formulations to penetrate deeper into the follicles.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-is-toe-jam-from-harmless-gunk-to-a-feast-for-bugs-177454">What is toe jam? From harmless gunk to a feast for bugs</a>
</strong>
</em>
</p>
<hr>
<h2>What about future treatments?</h2>
<p>We’ll likely see new formulations of dandruff shampoos and scalp treatments that better deliver the active ingredient to where it’s needed – deeper into the hair follicles.</p>
<p>We can also expect new active ingredients, such as <a href="https://pubmed.ncbi.nlm.nih.gov/28766952/">carbonic anhydrase</a> enzymes. These might target how the yeast grows in a different way to current active ingredients.</p>
<p>We are also beginning to see the development of creams and lotions that aim to boost the health balance of flora of the skin, much like we see with similar products for the gut. These include pre-biotics (supplements or food for skin flora) or pro-biotics (products that contain skin flora). However we have <a href="https://www.mdpi.com/2079-9284/8/3/90/htm">much to learn</a> about these types of formulations.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/your-bed-probably-isnt-as-clean-as-you-think-a-microbiologist-explains-163513">Your bed probably isn’t as clean as you think – a microbiologist explains</a>
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</em>
</p>
<hr>
<h2>In a nutshell</h2>
<p>Dandruff is annoying, treatment helps, but you may need to repeat it. Hopefully, we can develop improved shampoos that better deliver the active ingredient to where it’s needed.</p>
<p>But we need to strike a balance. We don’t want to eliminate all micro-organisms from our skin.</p>
<p>These are important for our immunity, including preventing more disease-causing microbes (pathogens) from moving in. They also help the skin produce antimicrobial peptides (short proteins) that protect us from pathogens.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/essays-on-health-microbes-arent-the-enemy-theyre-a-big-part-of-who-we-are-79116">Essays on health: microbes aren't the enemy, they're a big part of who we are</a>
</strong>
</em>
</p>
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<img src="https://counter.theconversation.com/content/201082/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sean Mangion is also a medical student at The University of Sydney. </span></em></p><p class="fine-print"><em><span>Lorraine Mackenzie does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>We’ve known about dandruff for thousands of years. Here’s how to get rid of yours.Lorraine Mackenzie, Associate Professor, Clinical and Health Sciences, University of South AustraliaSean Mangion, PhD Candidate, University of South AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2060452023-07-05T12:23:01Z2023-07-05T12:23:01Z‘E. coli’ is one of the most widely studied organisms – and that may be a problem for both science and medicine<figure><img src="https://images.theconversation.com/files/534368/original/file-20230627-19-w2lrsx.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2133%2C1404&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">_E. coli_ as a model organism helped researchers better understand how DNA works.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/researcher-with-e-coli-bacteria-royalty-free-image/521677434">Ed Horowitz Photography/The Image Bank via Getty Images</a></span></figcaption></figure><p>In 1857, a young pediatrician named <a href="https://doi.org/10.1038/nrmicro1810">Theodor Escherich</a> discovered what may very well be the most well-studied organism today. The rod-shaped bacterium named <em>Escherichia coli</em>, better known as <em>E. coli</em>, is a very common microbe residing in your gut. It’s also the workhorse of early molecular biology.</p>
<p>Luck likely played a role in its rise in popularity among scientists. Even under 19th-century lab conditions, where sterilization techniques were not perfect and little was known about what food bacteria need to survive, this microbe was easy to cultivate and grow quickly. It can <a href="https://doi.org/10.1098/rspb.2018.0789">replicate in under 20 minutes</a> and can use a variety of <a href="https://doi.org/10.1186/s12918-014-0133-z">carbon sources for energy</a>. </p>
<p>As the first species to have its <a href="https://doi.org/10.1128/jb.29.2.205-213.1935">physiology thoroughly explored</a>, <em>E. coli</em> has contributed fundamental knowledge to the fields of microbiology, molecular genetics and biochemistry, including how DNA replicates, how genes create proteins and how bacteria share genetic material among themselves – a huge <a href="https://theconversation.com/antibiotic-resistance-is-at-a-crisis-point-government-support-for-academia-and-big-pharma-to-find-new-drugs-could-help-defeat-superbugs-169443">cause of antibiotic resistance</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/534417/original/file-20230627-17-qy37yx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Diagram of E. coli structure" src="https://images.theconversation.com/files/534417/original/file-20230627-17-qy37yx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/534417/original/file-20230627-17-qy37yx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=365&fit=crop&dpr=1 600w, https://images.theconversation.com/files/534417/original/file-20230627-17-qy37yx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=365&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/534417/original/file-20230627-17-qy37yx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=365&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/534417/original/file-20230627-17-qy37yx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=458&fit=crop&dpr=1 754w, https://images.theconversation.com/files/534417/original/file-20230627-17-qy37yx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=458&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/534417/original/file-20230627-17-qy37yx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=458&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"><em>E. coli</em> is a rod-shaped bacterium with flagella that help it move.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/coli-bacteria-micro-biological-vector-royalty-free-illustration/957344970">VectorMine/iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<p>However, the favored use of <em>E. coli</em> in the lab has also <a href="https://doi.org/10.1529/biophysj.107.104398">led to oversimplifications</a> in the world of microbiology, distracting researchers from the thousands of other bacterial species that <a href="https://doi.org/10.1073/pnas.1707009114">remain understudied</a>. </p>
<p>As <a href="https://doerr.wicmb.cornell.edu/current-lab-members/">microbiologists</a> <a href="https://scholar.google.com/citations?user=yYroRg8AAAAJ&hl=en">studying the</a> inner mechanisms of <a href="https://theconversation.com/looming-behind-antibiotic-resistance-is-another-bacterial-threat-antibiotic-tolerance-200226">antibiotic tolerance</a>, we and colleagues in <a href="https://doerr.wicmb.cornell.edu/">our lab</a> examine bacterial species that physiologically differ from <em>E. coli</em> in hopes of expanding the existing pool of knowledge within microbiology. For instance, drugs like penicillin fall into a class of antibiotics that target the outer defenses of the bacteria. We found that while <em>E. coli</em> succumbs to this attack, species like <em>Vibrio</em> or <em>Klebsiella</em> can <a href="https://theconversation.com/looming-behind-antibiotic-resistance-is-another-bacterial-threat-antibiotic-tolerance-200226">tolerate it and survive</a>. </p>
<p>A one-size-fits-all approach may have worked in the past, but embracing the true diversity of microbes could help scientists better fight the rise of antibiotic resistance.</p>
<h2>Scientific good of <em>E. coli</em></h2>
<p>Researchers worked out the very foundations of life using <em>E. coli</em>. The significance of this bacterium for the field of biology is probably best captured by the biochemist <a href="https://www.nobelprize.org/prizes/medicine/1965/monod/facts/">Jacques Monod</a>, who famously said, “What is true for <em>E. coli</em> is true for the elephant.” </p>
<p>Because researchers were able to watch regions of <a href="https://doi.org/10.1038/158558a0"><em>E. coli</em>‘s DNA become mobile</a>, allowing bacteria to transfer DNA among one another in a process called conjugation, scientists learned to manipulate this process to genetically alter organisms and study the effects of different genes. </p>
<p><em>E. coli</em> helped reveal that <a href="https://doi.org/10.1101/SQB.1963.028.01.011">bacterial chromosomes are circular</a> and that <a href="https://doi.org/10.1016/S0022-2836(59)80045-0">manipulating a specific enzyme</a> can allow scientists to easily clone parts of the bacterial genome. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/534393/original/file-20230627-27-wdxgtr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Microscopy image of E. coli, colored orange" src="https://images.theconversation.com/files/534393/original/file-20230627-27-wdxgtr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/534393/original/file-20230627-27-wdxgtr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=516&fit=crop&dpr=1 600w, https://images.theconversation.com/files/534393/original/file-20230627-27-wdxgtr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=516&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/534393/original/file-20230627-27-wdxgtr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=516&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/534393/original/file-20230627-27-wdxgtr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=648&fit=crop&dpr=1 754w, https://images.theconversation.com/files/534393/original/file-20230627-27-wdxgtr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=648&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/534393/original/file-20230627-27-wdxgtr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=648&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">While <em>E. coli</em> are common residents in your gut, certain strains can cause serious infections.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/coli-sem-royalty-free-image/1414386430">Steve Gschmeissner/Science Photo Library via Getty Images</a></span>
</figcaption>
</figure>
<p><em>E. coli</em> also opened doors to using a type of <a href="https://theconversation.com/viruses-are-both-the-villains-and-heroes-of-life-as-we-know-it-169131">bacterial viruses called phages</a> as an <a href="https://doi.org/10.1085/jgp.22.3.365">alternative to antibiotics</a>. </p>
<p>Widely available knowledge about and methods to study <em>E. coli</em> led to its prominence in academic and commercial research and drug production. In 2015, <a href="https://doi.org/10.4014/jmb.1412.12079">nearly 30% of proteins used as treatments</a> for a wide range of diseases like hepatitis C and multiple sclerosis were derived from <em>E. coli</em>.</p>
<h2>Model organism drawbacks</h2>
<p><em>E. coli</em>’s track record has solidified its place in the lab as a <a href="https://doi.org/10.1007/978-1-4419-9863-7_76">model organism</a>. Model organisms are nonhuman species researchers use to study biology, with the expectation that the findings can be applied to other species like humans. Species are often chosen for their ease of maintenance, quick life cycles and overall cost-effectiveness. </p>
<p>However, model organisms have their drawbacks. Some researchers have argued that drawing parallels across species can <a href="https://theconversation.com/expanding-alzheimers-research-with-primates-could-overcome-the-problem-with-treatments-that-show-promise-in-mice-but-dont-help-humans-188207">sometimes fall short</a>, leading to assumptions about more complex species that may not be true.</p>
<p>Additionally, study findings using nonmodel organisms are often less visible in the broader scientific community, since many researchers focus on organisms with known and defined traits. This bias results in a shadow space where progress is not immediately incorporated into broader scientific knowledge, which can slow down research that actually covers a range from bacteria to elephants.</p>
<h2>ESKAPE pathogens don’t include <em>E. coli</em></h2>
<p>Model organisms are not perfect, and <em>E. coli</em> may not be an effective species to use to study many human bacterial infections. Focusing research on this microbe limits the exploration of how other bacteria infiltrate and infect human hosts. While some <a href="https://doi.org/10.1038/nrmicro818">strains of <em>E. coli</em> can be deadly</a>, they are not the only worrisome pathogens today. </p>
<p><a href="https://doi.org/10.1128/cmr.00181-19">ESKAPE pathogens</a>, a group of bacteria that are highly resistant to antibiotics, pose a massive global health threat because they can quickly evolve traits that allow them to evade immune systems and available treatments. Species within ESKAPE, such as <em>Klebsiella pneumoniae</em> and <em>E. cloacae</em>, are able to resist multiple drugs and <a href="https://doi.org/10.1128/aac.00756-19">exhibit physical characteristics</a> that <em>E. coli</em> does not, such as the ability to remove their cell wall and evade certain drugs.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/EkyAuG9RSSU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Antibiotic-resistant bacteria are a major global health threat.</span></figcaption>
</figure>
<p>Our lab is studying the unique traits that allow ESKAPE pathogens to survive antibiotics – traits we would not have known about if we used only <em>E. coli</em> as a model organism in our research.</p>
<p>With the many basics of fundamental bacterial cell and molecular biology covered thanks to <em>E. coli</em>, it may be time for researchers to turn toward the new pathogens wreaking havoc on society. Model organisms are wondrous tools, but they have limited power to allow findings to be extrapolated to other organisms. Better understanding the underpinnings of bacterial infections and antibiotics for a given disease requires studying the specific organism.</p><img src="https://counter.theconversation.com/content/206045/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Megan Keller receives funding from National Science Foundation. </span></em></p><p class="fine-print"><em><span>Tobias Dörr receives funding from National Institutes of Health. </span></em></p>Researchers uncovered the foundations of biology by using E. coli as a model organism. But over-reliance on this microbe can lead to knowledge blind spots with implications for antibiotic resistance.Megan Keller, Ph.D. Candidate in Microbiology, Cornell UniversityTobias Dörr, Associate Professor of Microbiology, Cornell UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2077372023-06-26T20:05:49Z2023-06-26T20:05:49ZWhat do the different colours of mould mean in my house?<figure><img src="https://images.theconversation.com/files/533888/original/file-20230626-29-3zt1z7.jpg?ixlib=rb-1.1.0&rect=23%2C62%2C4656%2C3205&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/jDRd_WHGFAI">Sandy Millar/Unsplash</a></span></figcaption></figure><p>You may be interested (or possibly horrified) to discover you ingest and inhale thousands of tiny life forms on a daily basis.</p>
<p>The air and surfaces around you are home to multitudes of <a href="https://www.sciencedirect.com/science/article/abs/pii/B978012394805200004X">bacteria, fungi, viruses</a>, mites, algae and <a href="https://www.sciencedirect.com/science/article/abs/pii/S0043135400004206">protozoa</a>. Your skin isn’t much better, with a complex ecosystem of organisms called commensals which aren’t necessarily good or bad, but will shift in their composition depending on <a href="https://www.nature.com/articles/nature11053">where you live</a>, <a href="https://www.mdpi.com/2079-9284/6/1/2">the products you use</a> and <a href="https://elifesciences.org/articles/458">the pets you have</a>. </p>
<p>Most of these creatures are generally undetectable due to their microscopic size and low concentrations. But when they find a niche they can exploit, you might notice them by their smell, or the appearance of unwanted staining and colour changes. A lot of this fungal growth is what we call mould.</p>
<p>We’ve all been disappointed in ourselves at one time or another, lifting a neglected orange out of the fruit bowl to discover the bottom half is covered in a velvety blue-green growth.</p>
<p>But what do the myriad colours that appear on our stuff tell us about the world we try not to think about?</p>
<h2>Black</h2>
<p>Often black staining is quite a disturbing occurrence. The concept of toxic black mould is one many people have become aware of due to <a href="https://theconversation.com/fungi-after-the-floods-how-to-get-rid-of-mould-to-protect-your-health-111341">flood impacts</a>.</p>
<p>A quick online search will likely terrify you, but not all black discolouration is due to the same organisms, and almost none of it will outright cause you harm.</p>
<p><em>Stachybotrys</em> is the one known as toxic black mould. It often turns up on <a href="https://ehp.niehs.nih.gov/doi/pdf/10.1289/ehp.99107s3505">building materials that have been wet for a long time</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/533907/original/file-20230626-67275-zxd3ah.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A severely mouldy wall covered in grey and black blotches" src="https://images.theconversation.com/files/533907/original/file-20230626-67275-zxd3ah.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/533907/original/file-20230626-67275-zxd3ah.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=384&fit=crop&dpr=1 600w, https://images.theconversation.com/files/533907/original/file-20230626-67275-zxd3ah.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=384&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/533907/original/file-20230626-67275-zxd3ah.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=384&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/533907/original/file-20230626-67275-zxd3ah.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=483&fit=crop&dpr=1 754w, https://images.theconversation.com/files/533907/original/file-20230626-67275-zxd3ah.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=483&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/533907/original/file-20230626-67275-zxd3ah.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=483&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Toxic black mould can develop in the home due to a flood or chronic damp conditions.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/water-damage-causing-mold-growth-on-547425403">Shutterstock</a></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/health-check-how-does-household-mould-affect-your-health-48341">Health Check: how does household mould affect your health?</a>
</strong>
</em>
</p>
<hr>
<p>When the grout in your shower turns black though, that’s a different fungus called <em><a href="https://www.ajol.info/index.php/ajb/article/view/130453">Aureobasidium</a></em>. It’s slimy, sticky and somewhere between a filamentous mould, which grows threadlike roots through whatever it’s eating, and a yeast, which prefer a free-floating, single-celled style of life. </p>
<p>Bleaching will often kill <em>Aureobasidium</em>, but the dark pigmentation will likely hang around – harmlessly, but stubbornly.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/533894/original/file-20230626-19-68wsem.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A close-up of white grout between grey tiles with black spots on it" src="https://images.theconversation.com/files/533894/original/file-20230626-19-68wsem.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/533894/original/file-20230626-19-68wsem.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/533894/original/file-20230626-19-68wsem.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/533894/original/file-20230626-19-68wsem.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/533894/original/file-20230626-19-68wsem.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=425&fit=crop&dpr=1 754w, https://images.theconversation.com/files/533894/original/file-20230626-19-68wsem.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=425&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/533894/original/file-20230626-19-68wsem.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=425&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The mould colonising the grout in your shower is unlikely to be toxic. In fact, you can kill it with bleach, but the harmless pigment may linger behind.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/black-green-mold-growing-on-shower-1999288574">Shutterstock</a></span>
</figcaption>
</figure>
<h2>Blue</h2>
<p>That blue orange I mentioned before, you can thank <em>Penicillium</em> for that. The organism that <a href="https://www.sciencedirect.com/science/article/abs/pii/S0168160512000852">gives us blue cheese</a> and the antibiotic penicillin is also responsible for producing a dense growth of mould that almost looks like smoke when disturbed, spreading millions of spores onto the rest of your fruit bowl.</p>
<p><em>Penicillium</em> is a big group with <a href="https://www.sciencedirect.com/science/article/pii/S0166061620300129">hundreds of species</a>, ranging from recognised pathogens to species yet to be named. However, the ones that turn up in our homes are generally the same “weed” species that simply cause food spoilage or grow in soil. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/533895/original/file-20230626-107392-7jinnz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Close-up of a bright orange with a fuzzy blue mould spot on it" src="https://images.theconversation.com/files/533895/original/file-20230626-107392-7jinnz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/533895/original/file-20230626-107392-7jinnz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/533895/original/file-20230626-107392-7jinnz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/533895/original/file-20230626-107392-7jinnz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/533895/original/file-20230626-107392-7jinnz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/533895/original/file-20230626-107392-7jinnz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/533895/original/file-20230626-107392-7jinnz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Mould growing in your fruit bowl is related to the one that gave us penicillin. The dusty appearance are spores waiting to be disturbed and spread all over your other fruit.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/moldy-orange-fruit-close-rotten-concept-2131666769">Shutterstock</a></span>
</figcaption>
</figure>
<h2>Yellow and orange</h2>
<p>We often think of fungi as organisms that thrive in the dark, but that’s not always true. In fact, some need exposure to light – and ultraviolet (UV) light in particular – to complete their life cycle.</p>
<p>Many plant pathogens use UV light exposure as a trigger to produce their spores, and then protect their DNA by <a href="https://link.springer.com/article/10.1134/S0003683814020094">hiding it behind melanin-containing shells</a>.</p>
<p><em>Stemphylium</em> and <em>Epicoccum</em> turn up in our homes from time to time, often hitching a ride on natural fibres such as jute, hemp and hessian. They produce a spectrum of staining that can often turn damp items yellow, brown or orange. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/533948/original/file-20230626-15121-eh3869.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A piece of wood laminate with yellow patches on it" src="https://images.theconversation.com/files/533948/original/file-20230626-15121-eh3869.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/533948/original/file-20230626-15121-eh3869.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/533948/original/file-20230626-15121-eh3869.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/533948/original/file-20230626-15121-eh3869.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/533948/original/file-20230626-15121-eh3869.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/533948/original/file-20230626-15121-eh3869.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/533948/original/file-20230626-15121-eh3869.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Yellow moulds can leave a stain behind even once the spores are gone.</span>
<span class="attribution"><span class="source">Michael Taylor</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Green</h2>
<p>We’re all fairly familiar with the green spots that turn up on mouldy bread, cake and other food items. Often we try to convince ourselves if we just cut off the bad bit, we can still salvage lunch.</p>
<p>Sadly that’s not the case, as the roots of the fungi – collectively called mycelium – spread through the food, digesting and collecting sufficient nutrients to pop out a series of tiny fruiting bodies which produce the coloured spores you see.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/health-check-is-it-safe-to-cut-mould-off-food-21382">Health Check: is it safe to cut mould off food?</a>
</strong>
</em>
</p>
<hr>
<p>The green tuft is often from a group of fungi called <em>Aspergillus</em>. Under the microscope they look rather like the puffy top of a dandelion gone to seed.</p>
<p>Like <em>Penicillium</em>, <em>Aspergillus</em> is another big fungal group with lots of species that turn up virtually in every environment. Some are <a href="https://academic.oup.com/mmy/article/43/Supplement_1/S87/1748298">heat tolerant</a>, some <a href="https://www.tandfonline.com/doi/full/10.1080/21553769.2015.1033653">love acid</a> and some will happily produce spores that <a href="https://www.sciencedirect.com/science/article/abs/pii/S1749461311000406">stay airborne for days to months at a time</a>.</p>
<p>In the green gang is also a fungus called <em>Trichoderma</em>, which is Latin for “hairy skin”. <em>Trichoderma</em> produces masses of forest-green, spherical spores which tend to grow on wet cardboard or dirty carpet. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/533897/original/file-20230626-160496-7cuh4q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A pile of green grains on a small round tray" src="https://images.theconversation.com/files/533897/original/file-20230626-160496-7cuh4q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/533897/original/file-20230626-160496-7cuh4q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/533897/original/file-20230626-160496-7cuh4q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/533897/original/file-20230626-160496-7cuh4q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/533897/original/file-20230626-160496-7cuh4q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/533897/original/file-20230626-160496-7cuh4q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/533897/original/file-20230626-160496-7cuh4q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Trichoderma is present in all soils, and will grow fast if the conditions are right.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/trichoderma-biocontrol-agent-plant-disease-control-670125520">Shutterstock</a></span>
</figcaption>
</figure>
<h2>Pink, purple and red</h2>
<p>There are plenty to speak of in this category. And there is also a common bacterium that makes the list.</p>
<p><em>Neurospora</em>, also known as the red bread mould, is one of the most studied fungi in scientific literature. It’s another common, non-hazardous one that has been used as <a href="https://bsapubs.onlinelibrary.wiley.com/doi/full/10.3732/ajb.1400377">a model organism</a> to observe fungal genetics, evolution and growth.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/533913/original/file-20230626-24-eh3869.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A block of orange mouldy substance sitting on a banana leaf" src="https://images.theconversation.com/files/533913/original/file-20230626-24-eh3869.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/533913/original/file-20230626-24-eh3869.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/533913/original/file-20230626-24-eh3869.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/533913/original/file-20230626-24-eh3869.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/533913/original/file-20230626-24-eh3869.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/533913/original/file-20230626-24-eh3869.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/533913/original/file-20230626-24-eh3869.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Red oncom, a traditional staple food in West Java, Indonesia, is made with <em>Neurospora</em>.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/fresh-raw-red-oncom-vegetarian-food-396059380">Shutterstock</a></span>
</figcaption>
</figure>
<p><em>Fusarium</em> is less common indoors, being <a href="https://www.sciencedirect.com/science/article/pii/S0261219416302794">an important crop pathogen</a>, but will sometimes turn spoiled rice purple. It also occasionally turns up on wet cement sheet, causing splotchy violet patches. <em>Fusarium</em> makes large, sticky, moon-shaped spores that have evolved to spread by rain splashes and hang onto plants. However, it is fairly bad at getting airborne and so doesn’t tend to spread very far from where it’s growing. </p>
<p>Finally in this category, that pink scum that turns up around bathroom taps or in the shower? It’s actually a bacterium called <em>Serratia</em>. It will happily chew up the soap scum residue left over in bathrooms, and has been shown to <a href="https://journals.asm.org/doi/full/10.1128/AEM.02632-10">survive in liquid soaps and handwash</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/533900/original/file-20230626-98733-ggql6s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Close-up of white tile grout covered in a pink translucent film" src="https://images.theconversation.com/files/533900/original/file-20230626-98733-ggql6s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/533900/original/file-20230626-98733-ggql6s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/533900/original/file-20230626-98733-ggql6s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/533900/original/file-20230626-98733-ggql6s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/533900/original/file-20230626-98733-ggql6s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/533900/original/file-20230626-98733-ggql6s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/533900/original/file-20230626-98733-ggql6s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Some of the pink stuff in your bathroom isn’t even mould – it’s bacteria.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/red-bacteria-serratia-marcescens-growing-on-1694681443">Shutterstock</a></span>
</figcaption>
</figure>
<h2>White</h2>
<p>When fungi were first being classified and were eventually given their own phylogenetic kingdom, there were lots of wonderful and not strictly categorical ways we tried to split them up. One of these was hyaline and non-hyaline, essentially referring to transparent and coloured, respectively.</p>
<p>One of the interesting non-pigmented moulds you may well catch sight of is a thing called <em>Isaria farinosa</em> (“farinosa” being Latin for “floury”). This fungus is a parasite of some moths and cicadas and is visible as brilliant white, <a href="https://www.tandfonline.com/doi/abs/10.1080/09583150802471812">tree-shaped growths on their unfortunate hosts</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/533911/original/file-20230626-72187-xubf6k.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A dead bug on a green forest floor with white and yellow growths sticking out of it" src="https://images.theconversation.com/files/533911/original/file-20230626-72187-xubf6k.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/533911/original/file-20230626-72187-xubf6k.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/533911/original/file-20230626-72187-xubf6k.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/533911/original/file-20230626-72187-xubf6k.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/533911/original/file-20230626-72187-xubf6k.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/533911/original/file-20230626-72187-xubf6k.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/533911/original/file-20230626-72187-xubf6k.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A example of <em>Isaria farinosa</em> growing out of its host.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Isaria_farinosa_%28Holmsk.%29_Fr_448940.jpg">Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>So when you notice the world around you changing colour, you can marvel with your newfound knowledge at the microscopic wonders that live complex lives alongside yours. Then maybe clean it up, and give the fruit bowl a wash. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/hidden-housemates-meet-the-moulds-growing-in-your-home-54743">Hidden housemates: meet the moulds growing in your home</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/207737/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Taylor consults for WSP Australia in the area of occupational hygiene, indoor environmental quality and hazardous materials. He has previously received grant funding from SafeWork SA to study fungi in indoor environments. </span></em></p>Usually, mould spores are invisible – but give them a niche to exploit and you’ll get all kinds of colours on the things in your home.Michael Taylor, Adjunct academic, Flinders UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1990742023-06-26T12:21:11Z2023-06-26T12:21:11ZDo you crush microbes when you step on them?<figure><img src="https://images.theconversation.com/files/528637/original/file-20230526-23155-iczgi5.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2122%2C1410&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">You don't need to watch where you step when it comes to bacteria.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/woman-walking-in-park-on-sunny-day-royalty-free-image/1326118536">Westend61/Getty Images</a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em><a href="https://theconversation.com/us/topics/curious-kids-us-74795">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">curiouskidsus@theconversation.com</a>.</em></p>
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<p><strong>Do viruses, bacteria and other small things get crushed like an ant when stepped on? – Ryan L., age 12, Chapel Hill, North Carolina</strong></p>
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<p>When you step on some things, like a banana, they squish and flatten to the ground. But when you step on other things, like a rock, they maintain their shape and aren’t affected. So what happens when you step on bacteria? Are they squishy?</p>
<p>While we work with microorganisms and other cells as chemical and biological engineers, neither of us has actually tried squishing them in the lab. One of us has a background in physics and <a href="https://scholar.google.co.in/citations?user=-LTVKKkAAAAJ&hl=en">studies mechanical forces in biology</a>, while one of us <a href="https://scholar.google.com/citations?user=9M8gP1YAAAAJ&hl=en">genetically engineers microorganisms</a> and cultivates them to make biofuels and other chemicals. </p>
<p>Between the two of us, we thought we could figure out the answer.</p>
<h2>Forces and pressures</h2>
<p>Let’s think about what happens when you step on something. Any time you push or pull on an object, you <a href="https://eng.libretexts.org/Bookshelves/Mechanical_Engineering/Mechanics_Map_(Moore_et_al.)/01%3A_Basics_of_Newtonian_Mechanics/1.02%3A_Forces">exert a force</a> on it. What happens after that depends on how much force you’re exerting and the properties of the object. </p>
<p>The force your footstep exerts comes mainly from your body weight. Also important is the <a href="https://eng.libretexts.org/Bookshelves/Mechanical_Engineering/Mechanics_Map_(Moore_et_al.)/04%3A_Statically_Equivalent_Systems/4.04%3A_Distributed_Forces#">area over which that force is distributed</a> on your foot, which creates pressure. That part about the area is important – it’s why you can walk on snow with snowshoes, but you’d sink with regular shoes.</p>
<p>You can calculate pressure by dividing the weight of an object by its area. If your foot is approximately a rectangle of 7 inches (about 18 centimeters) in length and 4 inches (10 cm) in width, it has a surface area of 28 square inches (180 square cm). And if your weight is 110 pounds (50 kilograms), the force you exert per square inch is roughly 3.9 pounds per square inch. </p>
<p>For comparison, the pressure of the air, or <a href="https://www.britannica.com/science/atmospheric-pressure">atmospheric pressure</a>, on your body at sea level is 14.7 pounds per square inch. The atmosphere exerts significantly more pressure on you than your footstep does on the ground – you just don’t feel it because it is balanced by the internal pressure of the air inside your body.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/528641/original/file-20230526-23-tn4j5p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Microscopy image of Salmonella Typhimurium invading a human epithelial cell" src="https://images.theconversation.com/files/528641/original/file-20230526-23-tn4j5p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/528641/original/file-20230526-23-tn4j5p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=435&fit=crop&dpr=1 600w, https://images.theconversation.com/files/528641/original/file-20230526-23-tn4j5p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=435&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/528641/original/file-20230526-23-tn4j5p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=435&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/528641/original/file-20230526-23-tn4j5p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=547&fit=crop&dpr=1 754w, https://images.theconversation.com/files/528641/original/file-20230526-23-tn4j5p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=547&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/528641/original/file-20230526-23-tn4j5p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=547&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">It takes a little more than a stomp to kill bacteria like <em>Salmonella</em>.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/2mbGDKv">NIAID/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<h2>Stepping on a microbe</h2>
<p>Now what happens to a bacterial cell when you apply the force of your footstep on it? </p>
<p>Bacteria <a href="https://microbiologysociety.org/why-microbiology-matters/what-is-microbiology/bacteria.html">have different shapes</a>, ranging from spheres to rods and spirals. Bacterial cells have walls that protect their gel-like insides from the environment. How strong is a bacterial cell wall, and can it withstand the force of your footstep?</p>
<p>Scientists have studied the strength of bacterial cell walls for several reasons, including to find out whether <a href="https://bio.libretexts.org/Bookshelves/Microbiology/Microbiology_(Boundless)/06%3A_Culturing_Microorganisms/6.14%3A_Physical_Antimicrobial_Control/6.14D%3A_High_Pressure">high pressure can kill bacteria</a>. People in the <a href="https://education.seattlepi.com/pressure-kill-bacteria-6032.html">food industry use high pressure</a> to make food such as milk safe for us to consume.</p>
<p>To determine the toughness of bacterial cell walls, researchers use a variety of tools to measure their <a href="https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Polymer_Chemistry_(Schaller)/04%3A_Polymer_Properties/4.07%3A_Stress-Strain_Relationships">ultimate tensile strength</a>, which is the maximum pressure an object can withstand before breaking. This can be done, for example, by putting them in a sealed container and rapidly lowering the pressure until they explode. A 1985 study found that it would take <a href="https://doi.org/10.1104/pp.79.2.485">nearly 1,500 pounds per square inch</a> to make the bacterium <em>Salmonella</em> explode, and later experiments showed it would take <a href="https://doi.org/10.1128/jb.173.1.197-203.1991">about 1,900 pounds per square inch</a> for the common soil bacterium <em>Bacillus subtilis</em> to explode. That’s 400 to 500 times more pressure than your sneaker is going to have on the sidewalk and any microbes lying about.</p>
<p>To understand these numbers in a different way, imagine a bacterium large enough for a person to stand on top of it. If it had the same cell wall strength as <em>Salmonella</em>, it could support over 350 people of 110 pounds each standing on it at the same time. While high pressures can kill bacteria in some applications such as <a href="https://doi.org/10.1007/s00253-011-3854-6">food processing</a>, one person standing on them won’t work.</p>
<h2>Slipping through the cracks</h2>
<p>It’s clear that bacterial cell walls are very strong. But there’s an added complication that makes it even harder to squish bacteria: They’re incredibly small. The average bacterium is only about <a href="http://book.bionumbers.org/how-big-is-an-e-coli-cell-and-what-is-its-mass/">1 to 5 microns or millionths of a meter</a> (smaller than ten-thousandth of an inch) in size. In comparison, the tip of a common pin is about 130 microns in diameter.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/528647/original/file-20230526-19-5psnd0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Close-up of skin wrinkles" src="https://images.theconversation.com/files/528647/original/file-20230526-19-5psnd0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/528647/original/file-20230526-19-5psnd0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/528647/original/file-20230526-19-5psnd0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/528647/original/file-20230526-19-5psnd0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/528647/original/file-20230526-19-5psnd0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/528647/original/file-20230526-19-5psnd0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/528647/original/file-20230526-19-5psnd0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Your skin, like the soles of your shoes, contains grooves that bacteria can slide into to take off the pressure of getting stepped on.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/human-skin-royalty-free-image/177771717">deyangeorgiev/iStock via Getty Images Plus</a></span>
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<p>The surface of your skin has fine grooves called <a href="https://doi.org/10.1007/s10043-013-0014-5">sulci cutis</a> that are, on average, tens of microns deep. The soles of your shoes also have grooves that are much deeper than the ones in your skin. As a result, whether you are stepping on bacteria with your bare feet or while wearing shoes, most of the cells will slide into one of those grooves and escape from the full pressure you exert on the ground. </p>
<h2>Standing on a pin</h2>
<p>How could you increase the pressure your feet exert on a bacteria cell to squish it? </p>
<p>One theoretical way would be to change the bottoms of your shoes from flat to very pointy, with the bottom of the point having a diameter as wide as the tip of a pin. While walking on these shoes would be impossible, a 110-pound person would exert a pressure of 5.6 million pounds per square inch. That is enough to smash any known bacteria. </p>
<p>While people can’t actually do this, it turns out that some insects can. Cicada wings have <a href="https://doi.org/10.1002/smll.201200528">tiny molecular structures</a> that look like needles. These needle-like structures are only nanometers in size, a thousand times smaller than most bacteria, and are called nanorods. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/vTX2PHMLI9I?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Cicada wings are covered with cone-shaped nanopillars that can puncture bacteria.</span></figcaption>
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<p>When a bacterium lands on the surface of the cicada wing, it makes special chemicals that help it stick to the surface. When the bacteria divides, it produces tiny forces that allow the new cells to separate from each other. These small forces are magnified into enormous pressures when they push against the nanorods on the cicada wing, puncturing the bacteria and killing it.</p>
<p>Cicadas, dragonflies and many other flying insects have similar wing surfaces that are naturally bactericidal, meaning bacteria killing. Bioengineers are taking inspiration from nature and trying to make surfaces with needle-like structures that <a href="https://doi.org/10.1038/srep16817">kill bacteria in a similar way</a>.</p>
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<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>You can squash small bugs by stepping on them, but can you crush even tinier microorganisms like viruses and bacteria? It turns out that you’d need to apply a lot of pressure.Ashok Prasad, Associate Professor of Chemical and Biological Engineering, Colorado State UniversityKenneth F. Reardon, Professor of Chemical and Biological Engineering, Colorado State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2077852023-06-23T15:51:06Z2023-06-23T15:51:06ZThe melting Arctic is a crime scene. The microbes I study have long warned us of this catastrophe – but they are also driving it<p>The Arctic’s climate is warming at least four times faster than the global average, causing irrevocable changes to this vast <a href="https://news.sky.com/story/dramatic-changes-to-polar-ice-caps-revealed-on-new-map-of-arctic-and-antarctica-12898550">landscape</a> and precarious <a href="https://www.nwf.org/Educational-Resources/Wildlife-Guide/Wild-Places/Arctic#:%7E:text=The%20Arctic%20is%20a%20unique,in%20the%20summer%20to%20breed.">ecosystem</a> – from the anticipated <a href="https://earth.org/polar-bears-to-become-extinct-by-2100/">extinction of polar bears</a> to the <a href="https://www.scientificamerican.com/article/as-arctic-sea-ice-melts-killer-whales-are-moving-in/#:%7E:text=Killer%20whales%20often%20feed%20on,navigate%20through%20the%20icy%20waters.">appearance of killer whales</a> in ever-greater numbers. A new <a href="https://www.nature.com/articles/s41467-023-38511-8">study</a> suggests the Arctic Ocean could be ice-free in summer <a href="https://theconversation.com/arctic-ocean-could-be-ice-free-in-summer-by-2030s-say-scientists-this-would-have-global-damaging-and-dangerous-consequences-206974">as soon as the 2030s</a> – around a decade earlier than previously predicted.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/532508/original/file-20230618-17-lemk5e.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map of Arctic sea ice changes" src="https://images.theconversation.com/files/532508/original/file-20230618-17-lemk5e.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/532508/original/file-20230618-17-lemk5e.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=700&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532508/original/file-20230618-17-lemk5e.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=700&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532508/original/file-20230618-17-lemk5e.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=700&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532508/original/file-20230618-17-lemk5e.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=879&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532508/original/file-20230618-17-lemk5e.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=879&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532508/original/file-20230618-17-lemk5e.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=879&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">A new Arctic sea ice map compares the 30-year average with recent ten-year averages.</span>
<span class="attribution"><a class="source" href="https://www.bas.ac.uk/media-post/new-map-of-polar-regions-updated-to-reflect-ice-loss-name-changes-and-new-data/">British Antarctic Survey</a></span>
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<p>But to properly understand the pace and force of what’s to come, we should instead focus on organisms too small to be seen with the naked eye. These single-celled microbes are both the watchkeepers and arch-agitators of the Arctic’s demise.</p>
<p>Scientists like me who study them have become forensic pathologists, processing crime scenes in our Arctic field sites. We don the same white anti-contamination suits, photograph each sampling site, and bag our samples for DNA analysis. In some areas, red-coloured microbes even create an effect known as “blood snow”.</p>
<p>In this complex criminal investigation, however, the invisible witnesses are also responsible for the damage being done. Microbes testify to the vulnerability of their Arctic habitats to the changes that humans have caused. But they also create powerful climate feedback loops that are doing ever-more damage both to the Arctic, and the planet as a whole.</p>
<h2>Zipping headlong into icy oblivion</h2>
<p>My first visit to the Arctic was also nearly my last. As a PhD student in my early 20s in 2006, I had set out with colleagues to sample microbes growing on a glacier in the Norwegian archipelago of <a href="https://www.theguardian.com/environment/2023/may/13/svalbard-the-arctic-islands-where-we-can-see-the-future-of-global-heating">Svalbard</a> – the planet’s northernmost year-round settlement, about 760 miles from the North Pole.</p>
<p>Our treacherous commute took us high above the glacier, traversing an icy scree slope to approach its flank before crossing a river at the ice’s margin. It was a route we had navigated recently – yet this day I mis-stepped. Time slowed as I slid towards the stream swollen with ice melt, my axe bouncing uselessly off the glassy ice. I was zipping headlong into icy oblivion.</p>
<p>In that near-death calm, two things bothered me. The water would carry me deep into the glacier, so it would be decades before my remains were returned to my family. And the ear-worm of that field season meant I would die to the theme tune to Indiana Jones.</p>
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<img alt="" src="https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><strong><em>This article is part of Conversation Insights</em></strong>
<br><em>The Insights team generates <a href="https://theconversation.com/uk/topics/insights-series-71218">long-form journalism</a> derived from interdisciplinary research. The team is working with academics from different backgrounds who have been engaged in projects aimed at tackling societal and scientific challenges.</em></p>
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<p>Thankfully, the scree slowed my slide – I lived and learned, quickly, that dead scientists don’t get to write up their papers. And I’m still learning about the tiny organisms that populate every habitat there: from seawater in the Arctic Ocean to ice crystals buried deep in the <a href="https://en.wikipedia.org/wiki/Greenland_ice_sheet">Greenland ice sheet</a>.</p>
<p>These micro-managers of all manner of planetary processes are acutely sensitive to the temperatures of their habitats. The slightest change above freezing can transform an Arctic landscape from a frozen waste devoid of liquid water to one where microbes get busy reproducing in nutrient-rich water, transforming themselves in ways that <a href="https://www.nature.com/articles/ismej2010108">further amplify</a> the effects of climate warming.</p>
<p>The Svalbard region is now warming seven times faster than the global average. While much of the world continues its efforts to limit global warming to 1.5°C above pre-industrial levels, in the Arctic, that battle was lost long ago.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/0VOGGdeB8eI?wmode=transparent&start=17" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Joseph Cook’s film on the microbes that inhabit the Greenland ice sheet.</span></figcaption>
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<h2>Decades ahead of us all</h2>
<p>It’s 2011, and <a href="http://www.earth.s.chiba-u.ac.jp/english/education/education02/staff16.html">Nozomu Takeuchi</a> is visiting Svalbard from Japan. It has been a difficult year back home, following the earthquake, tsunami and Fukushima nuclear incident, but Nozomu – a glacier ecologist and professor at Chiba University – is unrelenting in his quest to measure the effects of climate change. </p>
<p>Just hours after he stepped off a plane in the August midnight sun at Longyearbyen airport, we are marching up the nearest glacier. Above us, snow-capped mountain sides loom out of the swirling mist.</p>
<p>Since the 1990s, Nozomu has been collecting samples and measurements from glaciers all over the world. When we reach our goal near the snowline, he opens his rucksack to reveal a bento box full of sampling kit – stainless steel scoops, test tubes, sample bags, all arranged for efficiency. As he scurries around with practised efficiency, I think of offering help but fear I would only slow him down.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/532612/original/file-20230619-27-w8e0xr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Scientist takes a reading in snowy Arctic landscape" src="https://images.theconversation.com/files/532612/original/file-20230619-27-w8e0xr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532612/original/file-20230619-27-w8e0xr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532612/original/file-20230619-27-w8e0xr.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532612/original/file-20230619-27-w8e0xr.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532612/original/file-20230619-27-w8e0xr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532612/original/file-20230619-27-w8e0xr.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532612/original/file-20230619-27-w8e0xr.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=533&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Nozomu Takeuchi measuring the biological darkening of a Svalbard glacier in 2011.</span>
<span class="attribution"><span class="source">Arwyn Edwards</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>In truth, Nozomu is decades ahead of us all. Years ago, he made the link between the future of life and the death of ice, and these melting Svalbard glaciers are adding yet more points to his graphs.</p>
<p>Just as we apply oodles of factor 50 to protect ourselves from the Sun, so the billions of microbes sandwiched between the sky and surface of the glacier protect themselves by accumulating sunscreen-like pigments. And if enough of these pigments rest in one place under the Sun, this area of “biological darkening” absorbs the heat of the Sun much more effectively than reflective white snow and ice – so it melts faster.</p>
<p>Nozomu scoops up some of the so-called blood snow, heavily laden with algae. Under the microscope, their cells are indeed reminiscent of red blood cells. But rather than haemoglobin, these cells are laden with carotenoids – pigments also found in vegetables that <a href="https://academic.oup.com/femsec/article/94/3/fiy007/4810544?login=false">protect the algae from overheating</a>. Other patches of the glacier are verdant green, rich in algae that are busy photosynthesising light into chemical energy in this 24-hour daylight world.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/532611/original/file-20230619-29-l44kho.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Man in icy landscape holding scientific sample" src="https://images.theconversation.com/files/532611/original/file-20230619-29-l44kho.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/532611/original/file-20230619-29-l44kho.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532611/original/file-20230619-29-l44kho.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532611/original/file-20230619-29-l44kho.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532611/original/file-20230619-29-l44kho.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532611/original/file-20230619-29-l44kho.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532611/original/file-20230619-29-l44kho.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The author with a sample of ‘blood snow’, collected from a glacier surface.</span>
<span class="attribution"><span class="source">Arwyn Edwards</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Further down the glacier, the professor crushes some “dirty” ice into a bag. A different kind of algae lives here that, depending on your point-of-view, is either black, brown or purple (perhaps it depends on the tint of your sunglasses). The <a href="https://www.researchgate.net/figure/Chemical-structure-of-compound-3-purpurogallin-carboxylic-acid-6-O-b-d-glucopyranoside_fig2_51806131#:%7E:text=A%20gallotannin%20derivative%20(galloylglucopyranose%2C%20i.e.,et%20al.%2C%202012b)%20.">pigment</a> created is like the compounds that colour tea, and the algae keep it in layers like parasols above the photosynthetic factories within their cells – ensuring they have just enough sunlight to photosynthesise, but not enough to burn.</p>
<p>Open Google Earth and as you zoom in on the Arctic, you may spot the large dark stripe that scars the western margin of the <a href="https://en.wikipedia.org/wiki/Greenland_ice_sheet">Greenland ice sheet</a>. This is the “dark zone”, but it’s not caused by dark <a href="https://www.nature.com/articles/s41467-020-20627-w">dust</a> or soot. It’s alive, <a href="https://www.nature.com/articles/ismej2012107">laden with algae</a> – and it has been darkening, and growing, as Greenland warms.</p>
<p>Between 2000 and 2014, the <a href="https://www.frontiersin.org/articles/10.3389/feart.2016.00043/full">dark zone’s area grew by 14%</a>. At 279,075 km² in 2012, it was already more than twice the <a href="https://www.britannica.com/summary/England#:%7E:text=Area%3A%2050%2C301%20sq%20mi%20(130%2C278,even%20with%20the%20entire%20kingdom.).%20This%20had%20a%20powerful%20impact%20on%20the%20rate%20of%20ice%20melt%20--%20areas%20blooming%20with%20algae%20%5Bmelt%20nearly%202cm%20more%20each%20day%5D(https://www.pnas.org/doi/abs/10.1073/pnas.1918412117">size of England</a> than bare ice.</p>
<p>Next morning, I am woken by the smell of chemicals, having slept beneath a coffee table. Nozomu is busy processing his samples: bags of melting ice pinned to a clothesline by bulldog clips. They resemble bunting around the crowded room, but this is no time for celebration. The tint of each bag adds a measurement which quantifies the link between these algae, their pigments, and the death of their icy home.</p>
<h2>The case becomes urgent</h2>
<p>By the summer of 2014, glaciologists all over the world have started to listen to the warnings of pioneering ecologists such as Nozomu. The glaciers are dying even as life blossoms on their darkening surfaces. The case has become urgent.</p>
<p>I am in a helicopter, flying with colleagues to a camp in the dark zone on the Greenland ice sheet – the largest mass of glacial ice in the northern hemisphere. Covering 1.7 million km², its ice holds the equivalent of the water required to raise global sea levels by 7.7 metres.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/532620/original/file-20230619-23-shc4a3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A landscape of dark ice intertwined with blue rivers of meltwater." src="https://images.theconversation.com/files/532620/original/file-20230619-23-shc4a3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532620/original/file-20230619-23-shc4a3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532620/original/file-20230619-23-shc4a3.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532620/original/file-20230619-23-shc4a3.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532620/original/file-20230619-23-shc4a3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532620/original/file-20230619-23-shc4a3.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532620/original/file-20230619-23-shc4a3.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A highly darkened surface of the Greenland ice sheet, rich in algae and incised with rivers of meltwater.</span>
<span class="attribution"><span class="source">Arwyn Edwards</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>As we warm our climate, the rate of water flowing from this reservoir increases, with each degree Celsius added to global temperatures opening the drainage valve even wider. Feedback processes such as biological darkening have the potential to multiply the number of drainage valves that are open, hastening dramatically the rate at which sea levels rise.</p>
<p>To monitor this effect, every day <a href="https://www.gla.ac.uk/schools/ges/staff/karencameron/">Karen Cameron</a>, the leader of our camp this summer, walks to undisturbed patches of ice carrying a £100,000 backpack which contains a spectrometer to measure the darkness of the ice, capturing how it absorbs the solar energy that causes melting. The glaciologists are desperate for ground truth, and their models need data.</p>
<p>Up to this point, none of their predictions of how the Greenland ice sheet would respond to our warming climate have included biological darkening. Even if the effect were modest, it could still topple the ice sheet from a predictable, straightline response to climate warming.</p>
<p>All the time we are in Greenland, the only lifeforms we encounter are the flies that hatch from the fresh fruit and peppers in our food rations. These and the few types of glacier algae and several hundred kinds of bacteria that are biologically darkening the ice: a living scum scarring the surface of the ice sheet.</p>
<p>My work focuses on how these tiny organisms adapt to their icy habitat, but the implications of their behaviour are now of global concern. A <a href="https://screenworks.org.uk/archive/baftss-practice-research-award-2017/timeline">filmmaker</a> at the camp is weaving a thread between the ice melt in Greenland and its consequences for people living in coastal communities all over the world – from villages near my home on the <a href="https://www.theguardian.com/environment/2019/may/18/this-is-a-wake-up-call-the-villagers-who-could-be-britains-first-climate-refugees">west coast of Wales</a>, to huge metropolises like Manhattan, Amsterdam and Mumbai, and even entire low-lying island nations in the Pacific.</p>
<p>As smaller glaciers fade, and the larger ice sheets of Greenland and Antarctica start to respond with full force to our warming climate, it is these communities, capitals and countries that will bear the brunt of the flooding, inundation and erosion that comes with rising sea levels.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/532622/original/file-20230619-28-oh4l8z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two scientists inspecting an ice corer device dripping with meltwater." src="https://images.theconversation.com/files/532622/original/file-20230619-28-oh4l8z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532622/original/file-20230619-28-oh4l8z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532622/original/file-20230619-28-oh4l8z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532622/original/file-20230619-28-oh4l8z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532622/original/file-20230619-28-oh4l8z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532622/original/file-20230619-28-oh4l8z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532622/original/file-20230619-28-oh4l8z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The author (left) and Joseph Cook high on the Greenland ice sheet, meltwater dripping from their ice corer.</span>
<span class="attribution"><span class="source">Sara Penrhyn Jones</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Before heading home, our helicopter takes us on a detour, high over the ice sheet. We fly over the brown-black-purple algae to brighter, higher elevations where the palette shrinks to the blue and white of water and ice, then snow and sky. Greenland makes its own weather and, in these higher elevations, we expect the ice to be frozen all year round. When we land and begin to collect snow samples and a small ice core, however, we find we are digging into slush. The ice has started to melt up here, too. </p>
<p>We heave up our ice corer, and meltwater dribbles out from its bottom. In periods of extreme warming, much of the surface of the ice sheet can experience melting episodes, <a href="https://www.frontiersin.org/articles/10.3389/fmicb.2015.00225/full">disturbing the slumbering microbes</a> stored within the otherwise permanently frozen surface. It’s a sobering moment for us all.</p>
<p>Flying back to camp, I watch the streams become rivers and lakes as we head back over the dark zone, where melt and microbes dominate the icescape. I contemplate how much water, once locked in the ice, will become free to flow into the sea and into millions of homes by the end of the century.</p>
<h2>Popping a pingo</h2>
<p>The frozen lands of eight nations encircle the Arctic. Their soils store vast quantities of carbon: a third of the planet’s entire quantity of soil carbon resides in this frozen ground.</p>
<p>The carbon is a legacy of soils formed in past climates and preserved for millennia. However, human-induced climate change is reheating this leftover carbon, providing a luxuriant food source for microbes resident within the <a href="https://earthobservatory.nasa.gov/biome/biotundra.php">tundra</a>, which then emit it as greenhouse gases.</p>
<p>This is known as the <a href="https://en.wikipedia.org/wiki/Permafrost_carbon_cycle#:%7E:text=Carbon%20emissions%20from%20permafrost%20thaw,which%20increases%20permafrost%20thaw%20depths.">permafrost carbon</a> feedback loop. When even modest quantities of this vast carbon store reach the atmosphere, warming accelerates – resulting in faster thawing of the tundra and the release of yet more greenhouse gases.</p>
<p>Furthermore, not all greenhouse gases are equal in their impact. While carbon dioxide is relatively abundant and stable for centuries in the atmosphere, methane is less abundant and shorter-lived, but remarkably powerful as a greenhouse gas – nearly 30 times more damaging to the climate than carbon dioxide, for the same volume.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/532615/original/file-20230619-1823-ekek0j.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Scientist crouched on ice taking water samples." src="https://images.theconversation.com/files/532615/original/file-20230619-1823-ekek0j.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532615/original/file-20230619-1823-ekek0j.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=307&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532615/original/file-20230619-1823-ekek0j.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=307&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532615/original/file-20230619-1823-ekek0j.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=307&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532615/original/file-20230619-1823-ekek0j.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=386&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532615/original/file-20230619-1823-ekek0j.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=386&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532615/original/file-20230619-1823-ekek0j.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=386&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Andy Hodson sampling methane from a freshly ‘popped’ pingo.</span>
<span class="attribution"><span class="source">Arwyn Edwards</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>For more than three decades, <a href="https://www.unis.no/staff/andy-hodson/">Andy Hodson</a> has worked at the frontier where microbes, carbon and the Arctic landscape meet. In 2018, we join him on a brisk spring day in Svalbard. It’s -26°C but the snowmobile commute is thankfully brief – then we work quickly against the cold.</p>
<p>Hodson’s plan is to “pop” one of the many <a href="https://en.wikipedia.org/wiki/Pingo">pingos</a> that populate the floor of this wide open valley. Think of pingos as the acne of the Arctic: they form as permafrost compresses unfrozen wet sediments, erupting as small hills blistering the skin of the tundra.</p>
<p>The story of these microbes’ lives is complicated. They only live beyond the reach of oxygen – where oxygen is more prevalent, methane-consuming microbes thrive instead, quenching the belches of methane from below. Similarly, should mineral sources of iron or sulphide be nearby, then microbes that use them outcompete the methanogens.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/532614/original/file-20230619-15-6i78fv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A small fountain of water in an opening in the ice, amid a snowy landscape." src="https://images.theconversation.com/files/532614/original/file-20230619-15-6i78fv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/532614/original/file-20230619-15-6i78fv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532614/original/file-20230619-15-6i78fv.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532614/original/file-20230619-15-6i78fv.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532614/original/file-20230619-15-6i78fv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532614/original/file-20230619-15-6i78fv.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532614/original/file-20230619-15-6i78fv.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A popped pingo discharging supercooled water rich in methane.</span>
<span class="attribution"><span class="source">Arwyn Edwards</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>It all adds up to one of the greatest uncertainties for our civilisation: the extent and composition of greenhouse gases escaping from Arctic lands. <a href="https://www.cam.ac.uk/research/news/emissions-from-melting-permafrost-could-cost-43-trillion#:%7E:text=Increased%20greenhouse%20gas%20emissions%20from,and%20the%20University%20of%20Colorado.">Estimates of the economic impacts</a> from this permafrost carbon feedback tally in the tens of trillions of dollars to the global economy. We know it is bad news, but exactly how bad depends on the microbes in their microscopic mosaic.</p>
<p>Hodson’s field work shows that, during the Arctic winter, this pingo is probably the only source of methane in the immediate area, its chimney enabling the gas to escape from the depths of the ice before methane-consuming microbes can catch it. Annually, tens of kilograms of methane and more than a ton of carbon dioxide will escape from this pingo alone - one of <a href="https://doi.org/10.1016/j.geomorph.2023.108694">more than 10,000</a> scattered across the Arctic, in addition to its other methane-producing hotspots.</p>
<h2>A near-perfect ecosystem</h2>
<p>Arctic lands are a patchwork of permafrost carbon feedbacks, and our future depends on the uncertain fate of the microbes within. </p>
<p>While the ice melt enhances the growth of microbes in the short term, if it continues to the point of erasing habitats then the microbes will be lost with them. We recognise this danger for polar bears and walruses, but not the invisible biodiversity of the Arctic. Small does not mean insignificant though.</p>
<p>To appreciate this, we can head back to the dark zone on Greenland’s ice sheet and join <a href="https://www.rolex.org/rolex-awards/exploration/joseph-cook">Joseph Cook</a> during our summer 2014 field season. He’s lying on a mat improvised from a bath towel and a binbag wrapped in duct tape, peering into a dark, pothole-like depression in the ice. It’s a cryoconite hole, and millions of them are dotted over the edges of the ice sheet. Where pingos contribute to climate warming by emitting methane, cryoconite is a good sink of greenhouse gases, but this creates its own problems. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/532618/original/file-20230619-27-4a5amn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Crouching scientist takes samples in the Arctic snow." src="https://images.theconversation.com/files/532618/original/file-20230619-27-4a5amn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532618/original/file-20230619-27-4a5amn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532618/original/file-20230619-27-4a5amn.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532618/original/file-20230619-27-4a5amn.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532618/original/file-20230619-27-4a5amn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532618/original/file-20230619-27-4a5amn.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532618/original/file-20230619-27-4a5amn.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Joseph Cook measuring the carbon cycling activities of Greenland’s cryoconite holes.</span>
<span class="attribution"><span class="source">Arwyn Edwards</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2486.2008.01758.x">earliest estimate</a> of its ability to store carbon dioxide from the air on the ice surface of the world’s glaciers exceeded Finland’s total carbon emissions in the same year. Every cryoconite hole is a near-perfect ecosystem – with a singular flaw. Its inhabitants must melt ice to live. But the very act of melting the ice hastens the demise of their glacier habitat. </p>
<p>Despite being found in some of the harshest locations on Earth, cryoconite is home for thousands of different types of bacteria (including the all-important photosynthetic cyanobacteria), fungi, and <a href="https://microbiologysociety.org/why-microbiology-matters/what-is-microbiology/protozoa.html">protozoa</a>. Even <a href="https://www.theguardian.com/environment/2020/oct/17/tardigrade-ice-hole-arctic-greenland">tardigrades</a> thrive in cryoconite.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/532623/original/file-20230619-21-7v4otj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Microscope image of a single cryoconite granule." src="https://images.theconversation.com/files/532623/original/file-20230619-21-7v4otj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/532623/original/file-20230619-21-7v4otj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532623/original/file-20230619-21-7v4otj.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532623/original/file-20230619-21-7v4otj.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532623/original/file-20230619-21-7v4otj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532623/original/file-20230619-21-7v4otj.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532623/original/file-20230619-21-7v4otj.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Microscope image of a cryoconite granule, showing biological darkening and cyanobacteria growing through it.</span>
<span class="attribution"><span class="source">Arwyn Edwards</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Cook is professionally besotted with the perfection of this near-frozen “microscopic rainforest”. Its inhabitants are shielded and nourished at just the right depth and in the right shape for a busy ecosystem to be engineered by the interaction of sunlight with cyanobacteria, dust and ice to the benefit of all its inhabitants. The cyanobacteria use sunshine to capture carbon dioxide from the air and convert it into the slimy cement that builds each granule of cryoconite</p>
<p>However, with vast numbers of cryoconite holes dotted across the ice surface, “swarms” of these holes help <a href="https://www.frontiersin.org/articles/10.3389/feart.2015.00078/full">shape and darken the ice surface</a>. This in turn influences the melting rate, as the surface is sculpted under the sun of 24-hour daylight.</p>
<p>Writing in the scientific journal <a href="https://www.nature.com/articles/029039a0">Nature in 1883</a>, Swedish polar explorer Adolf Erik Nordenskjöld, who discovered cryoconite, thanked the organisms within cryoconite for melting away the ancient ice that once covered Norway and Sweden:</p>
<blockquote>
<p>In spite of their insignificance, [they] play a very important part in nature’s economy, from the fact that their dark colour far more readily absorbs the Sun’s heat than the bluish-white ice, and thereby they contribute to the destruction of the ice sheet, and prevent its extension. Undoubtedly we have, in no small degree, to thank these organisms for the melting away of the layer of ice which once covered the Scandinavian peninsula.</p>
</blockquote>
<h2>Taking DNA analysis to strange new places</h2>
<p>We return to Greenland in winter 2018 to explore cryoconite’s singular flaw. Cook and I are joined by Melanie Hay, then a PhD student in Arctic bioinformatics.</p>
<p>Hay and I are taking DNA analysis to strange new places to learn more about the evolution and biology of cryoconite. Powerful advances in genomics are changing our view of the microbial world, but large DNA-sequencing instruments fare best in sophisticated labs.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/532619/original/file-20230619-17-uv14gu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Scientist sitting outside her tent with backpack, looking out at icy landscape." src="https://images.theconversation.com/files/532619/original/file-20230619-17-uv14gu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532619/original/file-20230619-17-uv14gu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=442&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532619/original/file-20230619-17-uv14gu.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=442&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532619/original/file-20230619-17-uv14gu.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=442&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532619/original/file-20230619-17-uv14gu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=555&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532619/original/file-20230619-17-uv14gu.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=555&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532619/original/file-20230619-17-uv14gu.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=555&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Melanie Hay camping and sampling on the Greenland ice sheet.</span>
<span class="attribution"><span class="source">Arwyn Edwards</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Instead, we are using a stapler-sized nanopore sequencer hooked up to the USB port of a winterised laptop. Outside the tent, it is –20°C – but the DNA sequencer must run at body temperature. The only sustainable source of warmth is body heat, so I have snuggled up with the sequencer in my sleeping bag every night and in my clothes all day.</p>
<p>That evening, we are caught in a storm of hurricane force. Becoming disorientated while moving between tents would be lethal, so we crawl in a human chain through the whiteout to our sleeping tents. Hay reaches her tent but Cook’s is lost, so we squeeze into my one-person tent. Somehow I sleep soundly, while Cook is exposed to the full force of the night’s terror.</p>
<p>In the morning, we excavate Hay, whose snow-laden tent had collapsed in the night. The sequencing is complete, but storm damage to our generator means the camp is losing power, so she must work quickly. She identifies the cyanobacteria building the cryoconite – it’s a short list dominated by one species: <em>Phormidesmis priestleyi</em>.</p>
<p>This species, found in cryoconite throughout the Arctic, seems to be the ecosystem engineer of cryoconite – a microscopic beaver building a dam of dust. But the flaw is the darkness of the near-perfect cryoconite ecosystems it creates. Like the neighbouring glacier algae we met earlier, <em>Phormidesmis priestleyi</em> is biologically darkening Arctic ice, and eventually hastening the demise of the thousands of different types of organism contained in cryoconite holes.</p>
<p>And so, this work shows us ever more clearly that the <a href="https://www.nature.com/articles/s41559-020-1163-0">loss of the planet’s glaciers</a> is as much a component of the global biodiversity crisis as it is a headline impact of climate change.</p>
<h2>Last line of defence against antibiotic resistance</h2>
<p>The loss of the Arctic’s microbial biodiversity matters in other ways too. Hay and Aliyah Debbonaire are both reformed biomedical scientists seeking cures from the Arctic in the form of new antibiotics. In the summer of 2018, we are in Svalbard looking for clues.</p>
<p>The world is running out of effective antibiotics, and the Arctic’s frontiers may be our last line of defence in this antibiotic resistance crisis. Countless species of microbes have evolved to live within its harsh habitats using all the tricks in the book, including making antibiotics as chemical weapons to kill off competitors. This means they may be sources of new antibiotics.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/532631/original/file-20230619-1900-kr9gwx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Scientists (one kneeling) taking samples in the snowy Arctic landscape." src="https://images.theconversation.com/files/532631/original/file-20230619-1900-kr9gwx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532631/original/file-20230619-1900-kr9gwx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=413&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532631/original/file-20230619-1900-kr9gwx.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=413&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532631/original/file-20230619-1900-kr9gwx.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=413&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532631/original/file-20230619-1900-kr9gwx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=519&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532631/original/file-20230619-1900-kr9gwx.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=519&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532631/original/file-20230619-1900-kr9gwx.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=519&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Aliyah Debbonaire (left) and Melanie Hay sampling a cryoconite hole.</span>
<span class="attribution"><span class="source">Arwyn Edwards</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>And this is not their only application. From cheeses to eco-friendly biological washing powders, entire shopping aisles of products have been derived from cold-adapted microbes. As climate warming threatens to disrupt entire Arctic habitats, our opportunity to use, learn from, and protect this biodiversity may be lost forever.</p>
<p>As our tiny plane returns to the nearest town, Longyearbyen, we fly low over the <a href="https://theconversation.com/after-svalbard-why-safety-of-world-seed-vaults-is-crucial-to-future-food-security-79586">Svalbard Global Seed Vault</a>, which contains the fruits of more than 12,000 years of agriculture in the form of seeds from a million different varieties of crop. Nearby, a similar facility inside a disused coal mine stores essential computer programmes on microfilm – the ultimate backup for our data-addicted world.</p>
<p>Within a snowy kilometre, you can walk between the the alpha and omega of human innovation in civilisation. Both facilities have chosen the fastest-warming town on the planet as the safest place to store these treasures of humanity. Yet no such facility is dedicated to the microbial biodiversity of the Arctic, despite its critical importance to the future of the world’s biotech and medical sectors.</p>
<p>Instead, it falls to microbiologists such as Debbonaire, racing against time to identify, nurture and screen the microbes of the melting Arctic. Her painstaking work accumulates towers of Petri dishes, each a temporary refuge for a different Arctic microbe.</p>
<p>Eventually, they will be stored in <a href="https://www.dellamarca.it/en/how-does-an-ultra-low-freezer-work/">ultra-freezers</a> in laboratories scattered across the world. Such work is unglamorous to funders, so it is done piecemeal on the edges of other projects. Yet it represents our only attempt to save the microbes of the Arctic.</p>
<h2>The battle is lost</h2>
<p>Most of all, the Arctic matters because it is the fastest-warming part of the planet, and its microbes are responding first. What happens there carries implications for everyone. It is the harbinger of change for everywhere.</p>
<p>Another Arctic microbiologist could strike plangent notes regarding permafrost or sea ice, but as an ecologist of glaciers I am drawn to glacial ice.</p>
<p>Over the first fifth of this century, Earth’s glaciers have discharged some ten quadrillion (ten to the power 25) tablespoons of melt a year – and within each tablespoon, the <a href="https://www.nature.com/articles/s43247-022-00609-0">tens of thousands of bacteria and viruses</a> that were once stored within that ice.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/meltwater-is-infiltrating-greenlands-ice-sheet-through-millions-of-hairline-cracks-destabilizing-its-structure-207468">Meltwater is infiltrating Greenland’s ice sheet through millions of hairline cracks – destabilizing its structure</a>
</strong>
</em>
</p>
<hr>
<p>What’s to come is sadly predictable. Even the most modest warming scenario of 1.5°C above the pre-industrial era will lead to the extinction of at least <a href="https://www.science.org/doi/10.1126/science.abo1324">half the Earth’s 200,000 glaciers</a> by the end of the century.</p>
<p>Depending on the urgency and effectiveness of our actions as a civilisation, this century could also represent the “peak melt” in our history. Yet the battle to save many of these precious icy habitats is already lost. Instead, for scientists like me, our field work is now largely a question of documenting these “crime scenes” – so at least the knowledge of life within ice can be preserved, before it melts away forever.</p>
<hr>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=112&fit=crop&dpr=1 600w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=112&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=112&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=140&fit=crop&dpr=1 754w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=140&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=140&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
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<ul>
<li><p><em><a href="https://theconversation.com/prehistoric-communities-off-the-coast-of-britain-embraced-rising-seas-what-this-means-for-todays-island-nations-147879?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=InsightsUK">Prehistoric communities off the coast of Britain embraced rising seas – what this means for today’s island nations
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<p><em>To hear about new Insights articles, join the hundreds of thousands of people who value The Conversation’s evidence-based news. <a href="https://theconversation.com/uk/newsletters/the-daily-newsletter-2?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=InsightsUK"><strong>Subscribe to our newsletter</strong></a>.</em></p><img src="https://counter.theconversation.com/content/207785/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Arwyn Edwards receives funding from UK Research & Innovation - Natural Environment Research Council, as well as the Research Council of Norway, the Leverhulme Trust, and the Royal Geographical Society. </span></em></p>To fully understand the extent of climate-related dangers the Arctic – and our planet – is facing, we must focus on organisms too small to be seen with the naked eye.Arwyn Edwards, Reader in Biology, Department of Life Sciences, Aberystwyth UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2069322023-06-04T11:19:08Z2023-06-04T11:19:08ZRemoving antimicrobial resistance from the WHO’s ‘pandemic treaty’ will leave humanity extremely vulnerable to future pandemics<figure><img src="https://images.theconversation.com/files/529846/original/file-20230602-27-nnu80l.png?ixlib=rb-1.1.0&rect=17%2C80%2C1680%2C1219&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Antimicrobial resistance is now a leading cause of death worldwide due to drug-resistant infections, including drug-resistant strains of tuberculosis, pneumonia and Staph infections like the methicillin-resistant Staphylococcus aureus shown here.</span> <span class="attribution"><span class="source">(NIAID, cropped from original)</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/removing-antimicrobial-resistance-from-the-who-s--pandemic-treaty--will-leave-humanity-extremely-vulnerable-to-future-pandemics" width="100%" height="400"></iframe>
<p>In late May, the latest version of the draft Pandemic Instrument, also referred to as the “pandemic treaty,” was shared with Member States at the <a href="https://www.who.int/about/governance/world-health-assembly">World Health Assembly</a>. The text was made available online via <a href="https://healthpolicy-watch.news/wp-content/uploads/2023/05/DRAFT_INB_Bureau-text_22-May.pdf">Health Policy Watch</a> and it quickly became apparent that all mentions of addressing antimicrobial resistance in the Pandemic Instrument were at risk of removal.</p>
<p>Work on the Pandemic Instrument began in December 2021 after the World Health Assembly agreed to a global process to draft and negotiate an international instrument — under the Constitution of the World Health Organization (WHO) — to protect nations and communities from future pandemic emergencies.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/drug-resistant-superbugs-a-global-threat-intensified-by-the-fight-against-coronavirus-135790">Drug-resistant superbugs: A global threat intensified by the fight against coronavirus</a>
</strong>
</em>
</p>
<hr>
<p>Since the beginning of negotiations on the Pandemic Instrument, there have been calls from civil society and leading experts, including the <a href="https://www.amrleaders.org/docs/librariesprovider20/default-document-library/amr-as-substantive-element-of-the-international-instument-of-pandemic-prevention-preparedness-and-response.pdf?sfvrsn=300292c8_5&download=true">Global Leaders Group on Antimicrobial Resistance</a>, to include the so-called “silent” pandemic of antimicrobial resistance in the instrument.</p>
<p>Just three years after the onset of a global pandemic, it is understandable why Member States negotiating the Pandemic Instrument have focused on preventing pandemics that resemble COVID-19. But not all pandemics in the past have been caused by viruses and not all pandemics in the future will be caused by viruses. Devastating past pandemics of bacterial diseases have included <a href="https://www.who.int/news-room/fact-sheets/detail/plague">plague</a> and <a href="https://www.who.int/news-room/fact-sheets/detail/cholera">cholera</a>. The next pandemic could be caused by bacteria or other microbes.</p>
<h2>Antimicrobial resistance</h2>
<figure class="align-right ">
<img alt="Yellow particles on purple spikes" src="https://images.theconversation.com/files/529862/original/file-20230602-19-rvxpbm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/529862/original/file-20230602-19-rvxpbm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/529862/original/file-20230602-19-rvxpbm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/529862/original/file-20230602-19-rvxpbm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/529862/original/file-20230602-19-rvxpbm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/529862/original/file-20230602-19-rvxpbm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/529862/original/file-20230602-19-rvxpbm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Microscopic view of Yersinia pestis, the bacteria that cause bubonic plague, on a flea. Plague is an example of previous devastating pandemics of bacterial disease.</span>
<span class="attribution"><span class="source">(NIAID)</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Antimicrobial resistance (AMR) is the process by which infections caused by microbes become resistant to the medicines developed to treat them. Microbes include bacteria, fungi, viruses and parasites. Bacterial infections alone cause <a href="https://www.tropicalmedicine.ox.ac.uk/gram/news/bacterial-infections-linked-to-one-in-eight-global-deaths-according-to-gram-study">one in eight deaths</a> globally.</p>
<p>AMR is fueling the rise of drug-resistant infections, including <a href="https://www.cdc.gov/tb/publications/factsheets/drtb/xdrtb.htm">drug-resistant tuberculosis</a>, <a href="https://www.cdc.gov/drugresistance/pdf/threats-report/strep-pneumoniae-508.pdf">drug-resistant pneumonia</a> and drug-resistant Staph infections such as <a href="https://www.cdc.gov/mrsa/index.html">methicillin-resistant Staphylococcus aureus</a> (MRSA). These infections are killing and debilitating millions of people annually, and <a href="https://doi.org/10.1016/S0140-6736(21)02724-0">AMR is now a leading cause of death worldwide</a>. </p>
<p>Without knowing what the next pandemic will be, the “pandemic treaty” must plan, prepare and develop effective tools to respond to a wider range of pandemic threats, not solely viruses.</p>
<p>Even if the world faces another viral pandemic, <a href="https://theconversation.com/when-covid-19-or-flu-viruses-kill-they-often-have-an-accomplice-bacterial-infections-187056">secondary bacterial infections</a> will be a serious issue. During the COVID-19 pandemic for instance, large percentages of those hospitalized with COVID-19 required treatment for secondary bacterial infections. </p>
<p>New research from Northwestern University suggests that many of the deaths among hospitalized COVID-19 patients <a href="https://news.feinberg.northwestern.edu/2023/05/05/secondary-bacterial-pneumonia-drove-many-covid-19-deaths/">were associated with pneumonia — a secondary bacterial infection that must be treated with antibiotics</a>. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/529852/original/file-20230602-29-ejrjyi.gif?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An illustrative diagram that shows the difference between a drug resistant bacteria and a non-resistant bacteria." src="https://images.theconversation.com/files/529852/original/file-20230602-29-ejrjyi.gif?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/529852/original/file-20230602-29-ejrjyi.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=558&fit=crop&dpr=1 600w, https://images.theconversation.com/files/529852/original/file-20230602-29-ejrjyi.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=558&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/529852/original/file-20230602-29-ejrjyi.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=558&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/529852/original/file-20230602-29-ejrjyi.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=701&fit=crop&dpr=1 754w, https://images.theconversation.com/files/529852/original/file-20230602-29-ejrjyi.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=701&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/529852/original/file-20230602-29-ejrjyi.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=701&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Antimicrobial resistance means infections that were once treatable are much more difficult to treat.</span>
<span class="attribution"><span class="source">(NIAID)</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Treating these bacterial infections requires effective antibiotics, and with AMR increasing, <a href="https://www.who.int/news-room/fact-sheets/detail/antimicrobial-resistance">effective antibiotics are becoming a scarce resource</a>. Essentially, safeguarding the remaining effective antibiotics we have is critical to responding to any pandemic.</p>
<p>That’s why the potential removal of measures that would help mitigate AMR and better safeguard antimicrobial effectiveness is so concerning. Sections of the text which may be removed include measures to prevent infections (caused by bacteria, viruses and other microbes), such as:</p>
<ul>
<li> better access to safe water, sanitation and hygiene; </li>
<li> higher standards of infection prevention and control; </li>
<li> integrated surveillance of infectious disease threats from human, animals and the environment; and </li>
<li> strengthening <a href="https://www.cdc.gov/antibiotic-use/core-elements/index.html">antimicrobial stewardship</a> efforts to optimize how antimicrobial drugs are used and prevent the development of AMR.</li>
</ul>
<p>The exclusion of these measures would hinder efforts to protect people from future pandemics, and appears to be part of a <a href="https://www.nature.com/articles/d41586-023-01805-4">broader shift to water-down the language in the Pandemic Instrument</a>, making it easier for countries to opt-out of taking recommended actions to prevent future pandemics. </p>
<h2>Making the ‘pandemic treaty’ more robust</h2>
<p>Measures to address AMR could be easily included and addressed in the “pandemic treaty.”</p>
<p>In September 2022, I was part of a group of civil society and research organizations that specialize in mitigating AMR who were invited the WHO’s <a href="https://inb.who.int/">Intergovernmental Negotiating Body</a> (INB) to provide an <a href="https://amrpolicy.org/resources/recommendations-to-the-intergovernmental-negotiating-body-inb-concerning-amr-the-pandemic-instrument/">analysis on how AMR should be addressed</a>, within the then-draft text. </p>
<p>They outlined that including bacterial pathogens in the definition of “pandemics” was critical. They also identified specific provisions that should be tweaked to track and address both viral and bacterial threats. These included AMR and recommended harmonizing national AMR stewardship rules.</p>
<p>In March 2023, I joined other leading academic researchers and experts from various fields in publishing a special edition of the <a href="https://www.cambridge.org/core/journals/journal-of-law-medicine-and-ethics/issue/DC40B54126C7B273BD62EBEED9641D2A"><em>Journal of Medicine, Law and Ethics</em>,</a> outlining why the Pandemic Instrument must address AMR. </p>
<p>The researchers of this special issue argued that the Pandemic Instrument was overly focused on viral threats and ignored AMR and bacterial threats, including the need to manage antibiotics as a common-pool resource and revitalize research and development of novel antimicrobial drugs. </p>
<h2>Next steps</h2>
<p>While <a href="https://apps.who.int/gb/inb/pdf_files/inb4/A_INB4_3-en.pdf">earlier drafts of the Pandemic Instrument</a> drew on guidance from AMR policy researchers and civil society organizations, after the first round of closed-door negotiations by Member States, all of these insertions, are now at risk for removal.</p>
<p>The Pandemic Instrument is the best option to mitigate AMR and safeguard lifesaving antimicrobials to treat secondary infections in pandemics. AMR exceeds the capacity of any single country or sector to solve. Global political action is needed to ensure the international community works together to collectively mitigate AMR and support the conservation, development and equitable distribution of safe and effective antimicrobials.</p>
<p>By missing this opportunity to address AMR and safeguard antimicrobials in the Pandemic Instrument, we severely undermine the broader goals of the instrument: to protect nations and communities from future pandemic emergencies.</p>
<p>It is important going forward that Member States recognize the core infrastructural role that antimicrobials play in pandemic response and strengthen, rather than weaken, measures meant to safeguard antimicrobials. </p>
<p>Antimicrobials are an essential resource for responding to pandemic emergencies that must be protected. If governments are serious about pandemic preparedness, they must support bold measures to conserve the effectiveness of antimicrobials within the Pandemic Instrument.</p><img src="https://counter.theconversation.com/content/206932/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Susan Rogers Van Katwyk is a member of the WHO Collaborating Centre on Global Governance of Antimicrobial Resistance at York University. She receives funding from the Wellcome Trust and the Social Sciences and Humanities Research Council of Canada. </span></em></p>Drug-resistant microbes are a serious threat for future pandemics, but the new draft of the WHO’s international pandemic agreement may not include provisions for antimicrobial resistance.Susan Rogers Van Katwyk, Adjunct Professor, School of Global Health and Managing Director, AMR Policy Accelerator, York University, CanadaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2050872023-05-16T14:41:27Z2023-05-16T14:41:27ZHow does food get contaminated? The unsafe habits that kill more than 400,000 people a year<figure><img src="https://images.theconversation.com/files/526039/original/file-20230514-182951-p8iehb.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Food-borne illnesses usually present as diarrhoea, vomiting and stomach pains. </span> <span class="attribution"><span class="source">Getty Images</span></span></figcaption></figure><p><em>Unsafe foods, according to the <a href="https://www.who.int/news/item/07-03-2022-world-food-safety-day-2022-theme-highlights-the-role-that-safe-nutritional-food-plays-in-ensuring-human-health">World Health Organization</a> (WHO), contribute to poor health, including impaired growth and development, micro-nutrient deficiencies, noncommunicable and infectious diseases, and mental illness. Globally, one in ten people are affected by food-borne diseases each year. Antonina Mutoro, a nutrition researcher at the African Population and Health Research Center, explains what causes food contamination and how we can lower the risk of disease.</em></p>
<hr>
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<h2>What is food contamination?</h2>
<p>Access to safe and nutritious food is a basic human right which many do not enjoy, partly because of food contamination. This is defined as the presence of harmful chemicals and microorganisms in food that can cause illness. According to the WHO, food contamination affects about <a href="https://www.who.int/news-room/fact-sheets/detail/food-safety">one in every ten people</a> globally and causes about <a href="https://www.who.int/news-room/fact-sheets/detail/food-safety">420,000 deaths annually</a>. </p>
<p>Food contamination can be:</p>
<ul>
<li><p><strong>physical:</strong> foreign objects in food can potentially cause injury or carry disease-causing microorganisms. Pieces of metal, glass and stones can be choking hazards, or cause cuts or damage to teeth. Hair is another physical contaminant.</p></li>
<li><p><strong>biological:</strong> living organisms in food, including microorganisms (bacteria, viruses and protozoa), pests (weevils, cockroaches and rats) or parasites (worms), can cause disease. </p></li>
<li><p><strong>chemical:</strong> substances like soap residue, pesticide residue and toxins produced by microorganisms such as <a href="https://theconversation.com/what-must-be-done-to-get-toxin-out-of-kenyas-food-supply-127137">aflatoxins</a> can lead to poisoning.</p></li>
</ul>
<h2>What are the most common causes of food contamination?</h2>
<p>The most common cause of food contamination is poor food handling. This includes not washing your hands at the appropriate time – before eating and preparing food, after using the toilet, or after blowing your nose, coughing or sneezing. Using dirty utensils, not washing fruits and vegetables with clean water, and storing raw and cooked food in the same place can also be harmful. Sick people should not handle food. And you should avoid consuming under-cooked foods, particularly meat.</p>
<p>Poor <a href="https://theconversation.com/vegetable-farmers-in-urban-ghana-dont-worry-much-about-food-safety-but-they-should-143706">farming practices</a> can also contaminate food. This includes the heavy use of pesticides and <a href="https://theconversation.com/chickens-from-live-poultry-markets-in-nigeria-could-be-bad-for-your-health-scientists-explain-why-192646">antibiotics</a>, or growing fruits and vegetables using contaminated soil and water. The use of inadequately composted or raw animal manure or sewage is also harmful. </p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/power-cuts-and-food-safety-how-to-avoid-illness-during-loadshedding-200586">Power cuts and food safety: how to avoid illness during loadshedding </a>
</strong>
</em>
</p>
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<p>Fresh foods can lead to a number of illnesses. In Kenya, for instance, the <a href="https://bmcresnotes.biomedcentral.com/articles/10.1186/1756-0500-7-627">contamination of meat</a>, <a href="https://www.researchgate.net/publication/329170819_Consumer_Risk_Exposure_to_Chemical_and_Microbial_Hazards_Through_Consumption_of_Fruits_and_Vegetables_in_Kenya">fruits</a> and <a href="https://pubmed.ncbi.nlm.nih.gov/24968591/">vegetables</a> with human waste is relatively common. This is attributed to the use of contaminated water to wash food. Flies carrying contaminants can also directly transfer faecal matter and bacteria onto plant leaves or fruits.</p>
<p><a href="https://theconversation.com/informal-food-markets-what-it-takes-to-make-them-safer-161601">Street foods</a> are another common source of food contamination. These foods are widely consumed in low- and middle-income countries because they’re cheap and easily accessible. </p>
<h2>What are the signs that you’ve eaten contaminated food?</h2>
<p>Biological and chemical substances are the most common food contaminants. They account for <a href="https://www.who.int/news-room/fact-sheets/detail/food-safety">more than 200 food-borne illnesses</a>, including <a href="https://theconversation.com/explainer-causes-symptoms-and-cures-of-typhoid-fever-53645">typhoid</a>, <a href="https://theconversation.com/explainer-why-cholera-remains-a-public-health-threat-74444">cholera</a> and <a href="https://theconversation.com/what-led-to-worlds-worst-listeriosis-outbreak-in-south-africa-92947">listeriosis</a>. Food-borne illnesses usually present as diarrhoea, vomiting and stomach pains.</p>
<p>In severe cases, food-borne illnesses can lead to neurological disorders, organ failure and even death. It’s therefore advisable to seek immediate medical attention if you begin to experience symptoms like persistent diarrhoea and vomiting after eating or drinking.</p>
<p>Children aged under five are the most vulnerable to food-borne illnesses. They bear <a href="https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1001923">40%</a> of the food-borne disease burden. A child’s immune system is still developing and can’t fight off infections as effectively as an adult’s. </p>
<p>In low- and middle-income countries, reduced immunity in children can also occur as a result of malnutrition and frequent exposure to infections due to poor hygiene and sanitation, including a lack of access to safe water and toilets. Additionally, when children are ill, they tend to have poor appetites. This translates to reduced food intake. Coupled with increased nutrient losses through diarrhoea and vomiting, this can lead to a cycle of infection and malnutrition and, in extreme cases, death. </p>
<p>Pregnant women and people with <a href="https://theconversation.com/how-do-i-improve-my-immunity-expert-shares-tips-on-what-to-do-and-what-to-avoid-198537">reduced immunity</a> due to illness or age are equally vulnerable and extra care should, therefore, be taken to prevent food-borne illnesses among these groups.</p>
<h2>What can we do to prevent food contamination?</h2>
<p>Food-borne illnesses also have negative economic impacts, especially in low- and middle-income countries. The World Bank estimates it costs more than <a href="https://www.worldbank.org/en/news/press-release/2018/10/23/food-borne-illnesses-cost-us-110-billion-per-year-in-low-and-middle-income-countries#:%7E:text=The%20total%20productivity%20loss%20associated,estimated%20at%20US%24%2015%20billion.">US$15 billion</a> annually to treat these illnesses in these countries. So it’s important to have preventive strategies in place.</p>
<p>Food contamination can be prevented through simple measures:</p>
<ul>
<li><p>washing your hands at key times (before preparing, serving or eating meals; before feeding children, after using the toilet or after disposing of faeces) </p></li>
<li><p>wearing clean, protective clothing during food preparation </p></li>
<li><p>storing food properly</p></li>
<li><p>washing raw foods with clean water</p></li>
<li><p>keeping raw and cooked foods separate</p></li>
<li><p>using separate utensils for meats and for food meant to be eaten raw. </p></li>
</ul>
<p>Good farming practices, such as the use of clean water and application of approved pesticides in recommended amounts, can help prevent food contamination. </p>
<p>Food vendors also need to be trained on food safety, and provided with clean water and proper sanitation. </p>
<p>As part of the research team at the African Population and Health Research Center, I’m working on the <a href="https://healthyfoodafrica.eu/blog/promoting-access-to-nutritious-food-in-nairobi-urban-poor-settings/">Healthy Food Africa project</a>, which aims to boost food security in urban informal settlements through the promotion of food safety. In Kenya, the project is working closely with the Nairobi county government to develop a food safety training manual targeting street food vendors. This will go a long way towards improving food safety in the city.</p><img src="https://counter.theconversation.com/content/205087/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Antonina Mutoro does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Biological and chemical substances are the most common food contaminants and account for over 200 food-borne illnesses.Antonina Mutoro, Postdoctoral Research Scientist, African Population and Health Research CenterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2048882023-05-04T19:06:29Z2023-05-04T19:06:29ZReconstructing ancient bacterial genomes can revive previously unknown molecules – offering a potential source for new antibiotics<figure><img src="https://images.theconversation.com/files/523906/original/file-20230502-2182-swsnio.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C8256%2C5499&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Ancient DNA preserved in the tooth tartar of human fossils encodes microbial metabolites that could be the next antibiotic.</span> <span class="attribution"><a class="source" href="https://www.eurekalert.org/multimedia/983784?">Werner/Siemens Foundation</a></span></figcaption></figure><p>Microorganisms – in particular bacteria – are skillful chemists that can produce an impressive diversity of chemical compounds known as <a href="https://theconversation.com/nature-is-the-worlds-original-pharmacy-returning-to-medicines-roots-could-help-fill-drug-discovery-gaps-176963">natural products</a>. These metabolites provide the microbes major evolutionary advantages, such as allowing them to interact with one another or their environment and helping defend against different threats. Because of the diverse functions bacterial natural products have, many have been <a href="https://doi.org/10.1021/acs.jnatprod.5b01055">used as medical treatments</a> such as antibiotics and anti-cancer drugs.</p>
<p>The microbial species alive today represent only a tiny fraction of the vast diversity of microbes that have inhabited Earth over the past <a href="https://theconversation.com/were-viruses-around-on-earth-before-living-cells-emerged-a-microbiologist-explains-197880">3 billion years</a>. Exploring this microbial past presents exciting opportunities to recover some of their lost chemistry. </p>
<p>Directly studying these metabolites in archaeological samples is virtually impossible because of their <a href="https://doi.org/10.1007/s11306-017-1270-3">poor preservation</a> over time. However, reconstructing them using the genetic blueprints of long-dead microbes could provide a path forward. </p>
<p>We are a team of <a href="https://scholar.google.com/citations?user=cDFcc3cAAAAJ&hl=en">anthropologists</a>, <a href="https://scholar.google.de/citations?user=trnMQ7MAAAAJ&hl=en">archaeogeneticists</a> and <a href="https://scholar.google.com/citations?user=26MgwRgAAAAJ&hl=en">biochemists</a> who study ancient microbes. By <a href="https://www.science.org/doi/10.1126/science.adf5300">generating previously unknown chemical compounds</a> from the reconstructed genomes of ancient bacteria, our newly published research provides a proof of concept for the potential use of fossil microbes as a source of new drugs.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/524480/original/file-20230504-17-ivzxrf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Researcher weighing tooth fossil on a scale" src="https://images.theconversation.com/files/524480/original/file-20230504-17-ivzxrf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/524480/original/file-20230504-17-ivzxrf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=565&fit=crop&dpr=1 600w, https://images.theconversation.com/files/524480/original/file-20230504-17-ivzxrf.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=565&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/524480/original/file-20230504-17-ivzxrf.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=565&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/524480/original/file-20230504-17-ivzxrf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=710&fit=crop&dpr=1 754w, https://images.theconversation.com/files/524480/original/file-20230504-17-ivzxrf.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=710&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/524480/original/file-20230504-17-ivzxrf.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=710&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A single ancient tooth preserves the genomes of millions of ancient bacteria.</span>
<span class="attribution"><span class="source">Felix Wey/Werner Siemens Foundation</span></span>
</figcaption>
</figure>
<h2>Reconstructing ancient genomes</h2>
<p>The cellular machinery producing bacterial natural products is encoded in genes that are typically in close proximity to one another, forming what are called <a href="https://doi.org/10.1016/j.tim.2016.07.006">biosynthetic gene clusters</a>. Such genes are difficult to detect and reconstruct from ancient DNA because very old genetic material breaks down over time, fragmenting into thousands or even millions of pieces. The end result is numerous tiny DNA fragments <a href="https://doi.org/10.1038/s43586-020-00011-0">less than 50 nucleotides long</a> all mixed together like a jumbled jigsaw puzzle.</p>
<p>We sequenced billions of such ancient DNA fragments, then improved a bioinformatic process called <a href="https://doi.org/10.1007/s40484-019-0166-9">de novo assembly</a> to digitally order the ancient DNA fragments in stretches of up to 100,000 nucleotides long – a 2,000-fold improvement. This process allowed us to identify not only what genes were present, but also their order in the genome and the ways they differ from bacterial genes known today – key information to uncovering their evolutionary history and function. </p>
<p>This method allowed us to take an unprecedented look at the genomes of microbes living up to 100,000 years ago, including species not known to exist today. Our findings push back the <a href="https://doi.org/10.1038/s41586-021-03532-0">previously oldest</a> <a href="https://doi.org/10.1186/s40168-021-01132-8">reconstructed microbial genomes</a> by more than 90,000 years.</p>
<p>In the microbial genomes we reconstructed from DNA extracted from ancient tooth tartar, we found a gene cluster that was shared by a high proportion of Neanderthals and anatomically modern humans living during the <a href="https://www.britannica.com/event/Stone-Age/Middle-Paleolithic">Middle and Upper Paleolithic</a> that lasted from 300,000 to 12,000 years ago. This cluster bore the <a href="https://doi.org/10.1038/s43586-020-00011-0">molecular hallmarks of very ancient DNA</a> and belonged to the bacterial genus <em>Chlorobium</em>, a group of green sulfur bacteria capable of photosynthesis.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/524154/original/file-20230503-26-5xqprb.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Chemical structure of paleofurans produced using ancient microbial DNA." src="https://images.theconversation.com/files/524154/original/file-20230503-26-5xqprb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/524154/original/file-20230503-26-5xqprb.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=280&fit=crop&dpr=1 600w, https://images.theconversation.com/files/524154/original/file-20230503-26-5xqprb.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=280&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/524154/original/file-20230503-26-5xqprb.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=280&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/524154/original/file-20230503-26-5xqprb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=351&fit=crop&dpr=1 754w, https://images.theconversation.com/files/524154/original/file-20230503-26-5xqprb.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=351&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/524154/original/file-20230503-26-5xqprb.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=351&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">These paleofurans were produced from ancient microbial DNA.</span>
<span class="attribution"><span class="source">Pierre Stallforth</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>We inserted a synthetic version of this gene cluster into a “modern” bacterium called <em>Pseudomona protegens</em> so it could produce the chemical compounds encoded in the ancient genes. Using this method, we were able to isolate two previously unknown compounds we named <a href="https://www.science.org/doi/10.1126/science.adf5300">paleofuran A and B</a> and determine their chemical structure. Resynthesizing these molecules in the lab from scratch confirmed their structure and allowed us to produce larger quantities for further analysis.</p>
<p>By reconstructing these ancient compounds, our findings highlight how archaeological samples could serve as new sources of natural products. </p>
<h2>Mining ancient natural products</h2>
<p>Microbes are constantly evolving and adapting to their surrounding environment. Because the environments they inhabit today differ from those of their ancestors, microbes today likely produce different natural products than ancient microbes from tens of thousands of years ago.</p>
<p>As recently as <a href="https://www.doi.org/10.1007/978-1-4613-1145-4_1">25,000 to 10,000 years ago</a>, the Earth underwent a major climate shift as it transitioned from the colder and more volatile <a href="https://www.britannica.com/science/Pleistocene-Epoch">Pleistocene Epoch</a> to the warmer and more temperate <a href="https://www.britannica.com/science/Holocene-Epoch">Holocene Epoch</a>. Human lifestyles also dramatically changed over this transition as people began living outside of caves and increasingly experimented with food production. These changes brought them into contact with different microbes through agriculture, animal husbandry and their new built environments. Studying Pleistocene-era bacteria may yield insights into bacterial species and biosynthetic genes no longer associated with humans today, and perhaps even microbes that have gone extinct.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/JfX06NINZpk?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Changes in human lifestyles changed our genomes.</span></figcaption>
</figure>
<p>While the amount of data collected by scientists on biological organisms has exponentially increased over the past few decades, the <a href="https://theconversation.com/antibiotic-resistance-is-at-a-crisis-point-government-support-for-academia-and-big-pharma-to-find-new-drugs-could-help-defeat-superbugs-169443">number of new antibiotics has stagnated</a>. This is particularly problematic when bacteria are able to evade existing antibiotic treatments faster than researchers can develop new ones. </p>
<p>By reconstructing microbial genomes from archaeological samples, scientists can tap into the hidden diversity of natural products that would have otherwise been lost over time, increasing the number of potential sources from which they can discover new drugs.</p>
<h2>Scaling up ancient molecules</h2>
<p>Our study has shown that it is possible to access natural products from the past. To tap into the vast diversity of chemical compounds encoded in ancient DNA, we now need to streamline our methodology to be less labor-intensive. </p>
<p>We are currently optimizing and automating our process to identify biosynthetic genes in ancient DNA more quickly and reliably. We are also implementing robotic liquid handling systems to complete the time-consuming pipetting and bacterial cultivation steps in our methods. Our goal is to scale up the process to be able to translate a vast amount of data on ancient microbes into the discovery of new therapeutic agents. </p>
<p>Although we can recreate ancient molecules, their biological and ecological roles are difficult to decipher. Since the bacteria that originally produced these compounds no longer exist, we cannot culture or genetically manipulate them. Further study will need to rely on similar bacteria that can be found today. Whether or not the functions of these compounds have remained the same in the modern relatives of ancient microbes remains to be tested. Although the original functions of these compounds for ancient microbes may be unknown, they still have the potential to be repurposed to treat modern diseases.</p>
<p>Ultimately, we aim to shed new light on microbial evolution and fight the current antibiotic crisis by providing a new time axis for antibiotic discovery.</p><img src="https://counter.theconversation.com/content/204888/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christina Warinner receives funding from the Werner Siemens Foundation, the Francis Goelet Charitable Trust, the European Research Council, the United States National Science Foundation, and the Deutsche Forschungsgemeinschaft. She is affiliated with the Max Planck Institute for Evolutionary Anthropology, the Leibniz Institute of Natural Product Research and Infection Biology (Leibniz-HKI), and the Biological Faculty of Friedrich Schiller University Jena. </span></em></p><p class="fine-print"><em><span>Alexander Hübner receives funding from the Werner Siemens Foundation, the European Research Council, and the Deutsche Forschungsgemeinschaft. He is affiliated with with the Leibniz Institute of Natural Product Research and Infection Biology (Leibniz-HKI).</span></em></p><p class="fine-print"><em><span>Pierre Stallforth receives funding from the Werner Siemens Foundation, the Deutsche Forschungsgemeinschaft, and the Leibniz Association. He is affiliated with with the Leibniz Institute of Natural Product Research and Infection Biology (Leibniz-HKI) and the Friedrich Schiller University, Jena, Germany.</span></em></p>Ancient microbes likely produced natural products their descendants today do not. Tapping into this lost chemical diversity could offer a potential source of new drugs.Christina Warinner, Associate Professor of Anthropology, Harvard UniversityAlexander Hübner, Postdoctoral Researcher in Archaeogenetics, Max Planck Institute for Evolutionary AnthropologyPierre Stallforth, Professor of Bioorganic Chemistry and Paleobiotechnology, Friedrich-Schiller-Universität JenaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2039882023-04-24T16:14:01Z2023-04-24T16:14:01ZThe dirty truth about your phone – and why you need to stop scrolling in the bathroom<figure><img src="https://images.theconversation.com/files/522188/original/file-20230420-1700-nz53nk.png?ixlib=rb-1.1.0&rect=14%2C26%2C1970%2C1461&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Using your phone when you're on the toilet is a horrid habit. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/cropped-image-beautiful-young-woman-using-488716744">Canva/Shutterstock</a></span></figcaption></figure><p>We carry them everywhere, take them to bed, to the bathroom and for many people they’re the first thing they see in the morning – more than 90% of the world owns or uses a <a href="https://doi.org/10.3390/microorganisms11020523">mobile phone</a> and many of us couldn’t manage without one.</p>
<p>But while health concerns about phones use usually focus on the <a href="https://theconversation.com/why-using-a-mobile-phone-while-driving-is-so-dangerous-even-when-youre-hands-free-71833">distraction they can cause</a> while driving, the possible effects of <a href="https://theconversation.com/theres-no-evidence-5g-is-going-to-harm-our-health-so-lets-stop-worrying-about-it-120501">radiofrequency exposure</a>, or just how <a href="https://theconversation.com/seven-tips-for-a-healthier-relationship-with-your-phone-202215">addictive they can be</a>. The microbial infection risk of your phone is much less appreciated – <a href="https://www.nature.com/articles/s41598-021-93622-w">but it’s very real</a>.</p>
<p><a href="https://yougov.co.uk/topics/society/articles-reports/2019/02/28/most-britons-use-their-phone-toilet">A 2019 survey</a> found that most people in the UK use their phones on the toilet. So it’s not surprising to discover studies have found our mobile phones to be <a href="https://cals.arizona.edu/news/why-your-cellphone-has-more-germs-toilet">dirtier that toilet seats</a>. </p>
<p>We give our phones to children to play with (who aren’t exactly well known for their hygiene). We also eat while using our phones and put them down on all sorts of (dirty) surfaces. All of which can transfer microbes onto your phone along with food deposits for those microbes to eat. </p>
<p>It’s been estimated that people touch their phone <a href="https://www.dailymail.co.uk/news/article-2276752/Mobile-users-leave-phone-minutes-check-150-times-day.html">hundreds</a> if not <a href="https://dscout.com/people-nerds/mobile-touches">thousands</a> of times a day. And while many of us wash our hands regularly after say, going to the bathroom, cooking, cleaning, or gardening, we are much less likely to consider washing our hands after <a href="https://www2.deloitte.com/content/dam/insights/articles/us175371_tmt_connectivity-and-mobile-trends-interactive-landing-page/DI_Connectivity-mobile-trends-2022.pdf">touching our phones</a>. But given how disgusting and germ-infested phones can be, maybe it’s time to think more about <a href="https://pubmed.ncbi.nlm.nih.gov/19267892/">mobile phone hygiene</a>.</p>
<h2>Germs, bacteria, viruses</h2>
<p>Hands pick up bacteria and viruses all the time and are <a href="https://www.cdc.gov/handwashing/when-how-handwashing.html">recognised as a route</a> for <a href="https://www.ncbi.nlm.nih.gov/books/NBK144014/#parti_ch7.s3">acquiring infection</a>. So too are the phones we touch. <a href="https://www.nature.com/articles/s41598-022-14118-9">A number</a> of <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7196688/">studies</a> conducted on the microbiological colonisation of mobile phones show that they can be contaminated with many different kinds of potentially pathogenic bacteria.</p>
<p>These include the diarrhoea-inducing <em>E. coli</em> (which, by the way, comes from human poo) and the skin-infecting <em>Staphylococcus</em>, as well as <em>Actinobacteria</em>, which can cause tuberculosis and diphtheria, <em>Citrobacter</em>, which can lead to painful urinary tract infections, and <em>Enterococcus</em>, which is known to cause meningitis. <em>Klebsiella</em>, <em>Micrococcus</em>, <em>Proteus</em>, <em>Pseudomonas</em> and <em>Streptococcus</em> have also been found on phones and all can have equally nasty effects on humans.</p>
<p><a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6130244/">Research</a> has found that many pathogens on phones are often antibiotic resistant, meaning they can’t be treated with conventional drugs. This is worrying as these bacteria can cause skin, gut and respiratory infections that can be life-threatening. </p>
<p>Research has also found that even if you clean your phone with antibacterial wipes or alcohol it can still be recolonised by microorganisms, indicating that <a href="https://www.mdpi.com/2076-2607/11/2/523">sanitisation</a> must be a <a href="https://www.nature.com/articles/s41598-022-14118-9">regular process</a>. </p>
<figure class="align-center ">
<img alt="Woman wearing yellow jumper cleaning phone screen with a wipe." src="https://images.theconversation.com/files/522184/original/file-20230420-23-ne9bdl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/522184/original/file-20230420-23-ne9bdl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/522184/original/file-20230420-23-ne9bdl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/522184/original/file-20230420-23-ne9bdl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/522184/original/file-20230420-23-ne9bdl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/522184/original/file-20230420-23-ne9bdl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/522184/original/file-20230420-23-ne9bdl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The importance of cleaning your phone and how to do it safely.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/coronavirus-global-epidemic-woman-disinfecting-phone-1677416521">Volurol/Shutterstock</a></span>
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<p>Phones contain plastic which can harbour and <a href="https://www.clinicalmicrobiologyandinfection.com/article/S1198-743X(15)01034-4/fulltext">transmit viruses</a> some of which (the common cold virus) can live on hard plastic surfaces for up to a week. Other viruses such as COVID-19, rotavirus (a highly infectious stomach bug that typically affects babies and young children), influenza and norovirus – which can cause serious respiratory and gut infections – can persist in an infectable form for several days. </p>
<p>Indeed, since the beginning of the COVID pandemic, the US Centers for Disease Control and Prevention has introduced <a href="https://www.cdc.gov/hygiene/cleaning/cleaning-your-home.html">guidelines for cleaning and disinfecting mobile phones</a> – which, along with door handles, cash machines and <a href="https://theconversation.com/from-the-bed-sheets-to-the-tv-remote-a-microbiologist-reveals-the-shocking-truth-about-dirt-and-germs-in-hotel-rooms-202195">lift buttons</a>, are considered <a href="https://www.clinicalmicrobiologyandinfection.com/article/S1198-743X(15)01034-4/fulltext">reservoirs of infection</a>. </p>
<p>In particular, concern has been raised about the role mobile phones can play in the spread of infectious microbes in <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7196688/">hospital and healthcare settings</a>, as well as in <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5466825/">schools</a>. </p>
<h2>Clean your phone</h2>
<p>So it’s clear that you need to start cleaning your phone regularly. The US Federal Communications Commission actually recommends <a href="https://www.fcc.gov/consumers/guides/how-sanitize-your-phone-and-other-devices">daily sanitation</a> of your phone and other devices – not least because we are still within an active COVID-19 pandemic and the virus can survive for several days on hard plastic surfaces. </p>
<p>Use <a href="https://www.fcc.gov/consumers/guides/how-sanitize-your-phone-and-other-devices">alcohol-based wipes or sprays</a>. They need to contain at least 70% alcohol to disinfect phone casings and touch screens, and it needs to be done every day if possible. </p>
<p>Do not spray sanitisers directly onto the phone and keep liquids away from connection points or other phone openings. Absolutely avoid using bleach or abrasive cleaners. And wash your hands thoroughly after you’ve finished cleaning.</p>
<p>Thinking about how you handle your phone will also help to avoid it becoming colonised with germs. When not at home, keep your phone in your pocket, or bag and use a disposable paper list of to-do items, rather than constantly consulting your phone. Touch your phone with clean hands – washed with soap and water or disinfected with alcohol-based hand sanitiser. </p>
<p>There are other things you can do to avoid your phone becoming a source of viruses. Do not share your phone with others if you have any infection, or have not first sanitised it. If children are allowed to play with your phone, sanitise it as soon as possible afterwards. </p>
<p>And get in the habit of putting your phone away when not in use, then sanitising or washing your hands. You might also want to occasionally sanitise your phone charger when you are cleaning your phone.</p><img src="https://counter.theconversation.com/content/203988/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Primrose Freestone does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Your mobile phone is 10 times dirtier than a toilet seat. Here’s what to do about it.Primrose Freestone, Senior Lecturer in Clinical Microbiology, University of LeicesterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2034502023-04-19T11:22:04Z2023-04-19T11:22:04ZHumans weren’t the first engineers, doctors and farmers – bacteria, plants and animals have lots to teach us<figure><img src="https://images.theconversation.com/files/521613/original/file-20230418-22-hx9xij.jpg?ixlib=rb-1.1.0&rect=23%2C0%2C5134%2C2992&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">There are hidden worlds in nature</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/water-gives-life-closeup-shot-droplet-2136956871">PeopleImages.com/Yuri A/Shutterstock</a></span></figcaption></figure><p>Life existed without human beings for more than 99.9% of Earth’s history. Yet we often ignore the achievements of species that preceded us by billions of years. </p>
<p>I explore the concept of nonhuman civilisations in my new book, <a href="https://www.chelseagreen.com/product/biocivilisations/">Biocivilisations</a>, which retells the story of life acknowledging the contributions of other species. Bacteria, plants, fungi, insects, birds, whales and other species demonstrate language, engineering, science, medicine, agriculture and more. These are all elements of civilisation that we associate with humans.</p>
<h2>Speaking nature’s language</h2>
<p>Whales communicate with each other using a series of sound clicks called codas. Sperm whales seem to <a href="https://asa.scitation.org/doi/10.1121/1.4949478">announce themselves</a> using a <a href="https://risweb.st-andrews.ac.uk/portal/en/researchoutput/individual-vocal-production-in-a-sperm-whale-physeter-macrocephalus-social-unit(e754bbe3-9305-4b57-85ba-545f224cf354).html">unique click sequence</a>, or name. By pooling their acoustic datasets, an international team of 27 researchers studying Pacific Ocean sperm whales identified <a href="https://www.pnas.org/doi/full/10.1073/pnas.2201692119">seven sperm whale vocal clans</a>, each with their own dialect and identity codas. Now, scientists from around the world are collaborating as part of the <a href="https://www.projectceti.org/">Cetacean Translation Initiative</a> to use powerful AI algorithms and decode the language of sperm whales. </p>
<p>Plants <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/pce.13910">communicate with each other using hormones</a> such as <a href="https://bmcbiol.biomedcentral.com/articles/10.1186/s12915-016-0308-8">jasmonate</a>, which redirects resources from growth to repairing damage. They release hormones into the air when in distress, such as when insects attack them. Neighbouring plants then pick up on the signal and respond by preparing for attacks – for example, by releasing toxins to ward off the insects.</p>
<p>Meanwhile, bacteria have been <a href="https://www.annualreviews.org/doi/10.1146/annurev.cellbio.21.012704.131001">“talking” to each other </a>for billions of years by exchanging chemical messages via hormone-like molecules called autoinducers. They use these chemicals to synchronise action. For example, bacteria may only invade a cell if enough neighbouring bacteria are releasing autoinducers. This is called <a href="https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1002953">quorum sensing</a>. </p>
<p>Bacteria also communicate with the cells of other species, including ours. Recent research showed certain chemicals that bacteria release influence the development of our brains, <a href="https://www.cell.com/cell-host-microbe/fulltext/S1931-3128(21)00380-2?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS1931312821003802%3Fshowall%3Dtrue">allowing the brain tissue to mature properly</a>. Studies into premature babies have shown the relationship between gut bacteria and human cells are crucial for cognitive development. </p>
<h2>Skilled engineers</h2>
<p>Our planet also reverberates with construction noise. It is a permanent building site where bacteria, insects and humans alike create cities. </p>
<p>The engineering skills of honeybees are so sophisticated that a honeybee expert and a group of engineers used <a href="https://www.youtube.com/watch?v=elTfueXcYaU">an algorithm inspired by honeybees</a> to resolve internet traffic problems. They copied the process bees use to distribute foragers searching a floral field for nectar. </p>
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<p>Bacteria are skilled engineers too. In one study, scientists used powerful microscopes and time-lapse imaging to record the <a href="https://www.nature.com/articles/s41467-020-15165-4">city-building skills</a> of a bacterial species that lives in human mouths, <em>Streptococcus mutans</em>. Bacteria produce their own building materials when they settle at a new site, normally a hard surface. These materials include carbohydrates, proteins and even DNA secreted by their tiny bodies. The building material is carefully distributed so that the village structure acquires a three-dimensional shape. </p>
<p>Some of these bacteria-settlers remain stationary and meld themselves to the surface that the village is built on, enhancing its structural stability. Bacteria can also move within villages and divide their bodies to increase the population. Villages grow, join together and form bacterial cities and megacities – much like modern London is a <a href="https://www.mattbarrett-travel.com/london/london-villages/index.htm">collection of former villages and towns</a>.</p>
<p>The communication between bacterial megacities is <a href="https://www.nature.com/articles/nature15709">conducted through electrical impulses</a>. Indeed, the entire planet was turned into a kind of <a href="https://theconversation.com/microbes-have-their-own-version-of-the-internet-75642">bacterial internet</a> three billion years ago.</p>
<h2>Doctors and surgeons</h2>
<p>Arguably, bacteria were also the first practitioners of medicine. Viruses invade bacteria and hijack their cellular machinery to make copies of themselves – a process which kills the bacteria. So, three billion years ago, bacteria became “epidemiologists” to defend themselves. </p>
<p>Bacterial bodies produce enzymes <a href="https://www.nature.com/articles/s41579-019-0278-2">that attack and kill virus DNA</a>, a technique known as <a href="https://pubmed.ncbi.nlm.nih.gov/26771483/">Crspr</a>. It can target a section of DNA, bind to it and turn the gene off. Scientists only recently discovered this system, and in future hope to use it for cancer treatments and to <a href="https://www.nobelprize.org/prizes/chemistry/2020/press-release/">cure genetic conditions</a>. It has already been used to make <a href="https://www.frontiersin.org/articles/10.3389/fcimb.2021.663949/full">COVID-19 detection tests</a>.</p>
<p>Some people think of ants as tiny insects barely worth thinking about. But ants from the species <em>Megaponera analis</em>, found in sub-Saharan Africa, are <a href="https://www.science.org/doi/10.1126/sciadv.1602187">talented surgeons</a>. These warrior ants specialise in raiding termite nests. The larger ants, majors, break termites’ defensive mud barriers, then their smaller colleagues, minors, rush through these openings to pull termites out of the nest.</p>
<p>After the raids, the ants form orderly columns again and majors carry dead termites back to the ant nest. But entomologists noticed that some majors also transport injured ants, while others treat their comrades’ wounds with antimicrobial chemicals secreted by <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1634922/">fellow ants’ glands</a>.</p>
<p>The ants also use their powerful mandibles to remove termites that are clinging to warrior ant bodies by their teeth, and to stitch wounds. These ant surgeons were so effective that patients were spotted on the battlefield the next day.</p>
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<h2>Successful farmers</h2>
<p>Farming in the way humans know it is planting, protecting and harvesting crops for nourishment. Research shows that the soil fungus <em>Morchella crassipes</em> also <a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2013.2242">does this to the bacteria <em>Pseudomonas putida</em></a> for its carbon, which the soil fungus needs to grow. </p>
<p><a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2022.1458">In turn, ambrosia beetles transport fungus spores</a> in a pouch-like structure in their gut to tunnels bored into trees. Ambrosia fungi produce asexual fruit only in the presence of the beetles. This fruit is their sole food source, and the beetles even remove “weed” fungus. </p>
<p>Leafcutter ants <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5118115/">also farm fungi from the genus <em>Leucoagaricus</em></a>, and even use antibiotic bacteria to <a href="https://www.nature.com/articles/19519">protect their crops from parasites</a>. Ants don’t just stick to agriculture, though; they herd aphids too. Just as we humans milk cows, <a href="https://www.youtube.com/watch?v=NJmCKaX0AGg">ants “milk” aphids</a> for the nutritious honeydew they produce. </p>
<p>So, these tiny beings were all farmers millions of years before humans had even thought of it.</p>
<p>Human civilisation is the most recent addition to an ever-changing landscape of ancient societies. Learning to value nonhuman civilisations may help reveal the ancient wisdom of species that preceded us. In so doing, this newly discovered wisdom could help us resolve the environmental crisis caused by our civilisation.</p><img src="https://counter.theconversation.com/content/203450/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Predrag Slijepcevic received funding from various organisations including Department of Health, EU, Royal Society and British Council. He is the author of Biocivilisations: A New Look at the Science of Life (Chelsea Green Publishing).</span></em></p>Ants are skilled surgeons, bacteria have their own internet, and scientists think sperm whales have names.Predrag Slijepcevic, Senior Lecturer in Biology, Brunel University LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1991662023-02-27T12:05:07Z2023-02-27T12:05:07ZSwimming pools v wild swimming – a germs expert on which is worse<figure><img src="https://images.theconversation.com/files/511428/original/file-20230221-18-axh3j6.jpg?ixlib=rb-1.1.0&rect=0%2C40%2C5464%2C3432&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.alamy.com/wild-or-open-water-women-swimmers-wearing-wetsuits-with-buoyancy-floats-enter-the-firth-of-forth-sea-north-berwick-east-lothian-scotland-uk-image416629506.html?imageid=FCA7E8A4-6ACE-4DCC-94AB-64CDB9B6F5C2&p=373051&pn=1&searchId=bf5dfdc822516e443cf4c25d554e4dd2&searchtype=0"> Sally Anderson/Alamy Stock Photo</a></span></figcaption></figure><p><a href="https://www.bbc.com/travel/article/20210603-why-wild-swimming-is-britains-new-craze">Wild swimming</a> has grown massively in popularity in recent times. Not only is swimming outdoors a pleasant way to enjoy the sunshine, fresh air and green leafy surroundings, it can also <a href="https://www.swimnow.co.uk/the-psychology-of-swimming/why-do-humans-like-to-swim/">help to</a> relieve stress and elevate our endorphins. This creates a sense of wellbeing as well as burning calories and exercising muscles. </p>
<p>But along with the joys of outdoor swimming come some dangers. Not only are wild swimmers more at risk from tides, currents and swells, there can also be nasty bugs and bacteria lurking in the water. And with <a href="https://www.gov.uk/government/news/sewage-in-water-a-growing-public-health-problem">untreated sewage</a> regularly flowing into seas, rivers and lakes across the country, it can be hard to find a safe spot for a paddle.</p>
<p>Of course, swimming in a pool comes with its <a href="https://www.cdc.gov/dotw/rwis/index.html">own set of risks</a>. Urinary tract infections, ear infections and tummy bugs are the most common illnesses caught here. <a href="https://www.iflscience.com/a-grim-amount-of-people-pee-in-the-pool-heres-why-you-shouldnt-63515#:%7E:text=In%20one%20survey%2C%20at%20least,as%20high%20as%2040%20percent.">Dirty pools</a> can also cause your eyes to sting and harbour all sorts of bacteria and germs – including urine, faeces and sweat. In many ways, swimming pools are like a <a href="https://theconversation.com/faeces-urine-and-sweat-just-how-gross-are-hot-tubs-a-microbiologist-explains-198367">big bath</a> filled with lots of strangers.</p>
<p>But while it’s clear that swimming in outdoor waters carries different risks from swimming in a pool, the question of where’s safest to swim may not seem immediately obvious. So where’s cleanest for a dip: swimming pools, or rivers, lakes, canals and the sea? Let’s look at the evidence.</p>
<h2>Toxic waters</h2>
<p>Unlike swimming pools where waters are carefully monitored, outdoor waters are constantly changing in composition. This means that chemicals can leach into wild waters from nearby farms or industrial areas, animals can defecate in water, and in certain areas human sewage may be legally or otherwise dumped into the water (if you can see pipes, do not get in). </p>
<p>There may not be signposts warning of local dangers, and the presence of toxic agents might not be obvious. When in doubt about the <a href="https://www.gov.uk/government/publications/swim-healthy-leaflet/swim-healthy#:%7E:text=designated%20bathing%20waters.-,Health%20risks,are%20more%20susceptible%20to%20infection">chemical safety of outdoor waters</a>, it’s better to not enter them. If the water <a href="https://outdoorswimmer.com/featured/wild-swimming-how-to-spot-a-clean-river/">doesn’t look or smell right</a>, trust your instinct.</p>
<p>There are also natural hazards to outdoor waters compared with pools, especially in the summer. <a href="https://consult.environment-agency.gov.uk/cumbria-and-lancashire/blue-green-algae-in-cumbria-and-lancashire/user_uploads/blue-green-algae-leaflet.pdf">Blue–green algae</a> is a type of bacteria naturally found in lake ecosystems. In warm summers, the algae tends to multiply and form a <a href="https://www.theguardian.com/uk-news/2022/aug/24/it-stinks-lake-windermere-plagued-by-blue-green-algae-as-toxic-as-cobra-venom">powdery green scum</a> (known as a bloom) on the surface of the lake. This blue-green algae bloom can release toxins which are harmful to humans and occasionally <a href="https://www.bluecross.org.uk/advice/dog/blue-green-algae-and-its-dangers-to-dogs">lethal to pets</a>.<br>
Swimming in or swallowing water containing toxin-releasing algal blooms can lead to skin rashes, eye irritation, severe gastrointestinal upset, fever, and muscle and joint pain.</p>
<h2>Bacteria and viruses</h2>
<p>Diarrhoea is the most common illness linked to open-water swimming, often due to sewage contamination. You become ill if you swallow <a href="https://www.cdc.gov/healthywater/swimming/swimmers/rwi/diarrheal-illness.html">contaminated water</a>, which can contain bacteria and viruses such as E.coli and Norovirus. </p>
<p>Rats living in sewers adjacent to freshwater rivers or canals can also carry in their urine the bacterial pathogen Leptospira, which causes <a href="https://www.nhs.uk/conditions/leptospirosis/">Leptospirosis</a> (Weil’s disease). The infection occurs if soil or water from a lake, river or canal that contains urine from infected animals is swallowed, gets in a swimmer’s eyes or a cut. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/faeces-urine-and-sweat-just-how-gross-are-hot-tubs-a-microbiologist-explains-198367">Faeces, urine and sweat – just how gross are hot tubs? A microbiologist explains</a>
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</em>
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<p>Leptospirosis can cause liver and kidney damage, and may be fatal if left untreated. If you develop flu or jaundice symptoms up to two weeks after swimming in a river or canal, it may be a good idea to ask your doctor for a Leptospirosis test.</p>
<p>As for the sea, <a href="https://evidence.nihr.ac.uk/alert/swimming-in-seawater-is-linked-with-an-increased-chance-of-some-illnesses/">a 2018 study</a> found that people swimming in seawater were more likely to experience infections of the ear, nose, throat and gastrointestinal system than those who stayed on the beach. So it’s a good idea to wash after swimming in any outdoor waters, and certainly before eating food.</p>
<h2>The verdict</h2>
<p>When you add it all up, even with the possibility of people peeing and pooping in the pool, a managed swimming pool will always be a safer environment for a swim. Especially when you consider things like jellyfish stings and the additional risks that come with <a href="https://rnli.org/safety/know-the-risks/cold-water-shock">swimming in cold water</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/511432/original/file-20230221-18-yofimv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Man swimming in pool." src="https://images.theconversation.com/files/511432/original/file-20230221-18-yofimv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/511432/original/file-20230221-18-yofimv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/511432/original/file-20230221-18-yofimv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/511432/original/file-20230221-18-yofimv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/511432/original/file-20230221-18-yofimv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/511432/original/file-20230221-18-yofimv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/511432/original/file-20230221-18-yofimv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Swimming pools are a safer bet.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/fit-swimmer-training-swimming-pool-professional-516633376">Jacob Lund/Shutterstock</a></span>
</figcaption>
</figure>
<p>Compared with a pool, wild swimmers are more likely to become unwell from swimming in outdoor water as there will always be potentially <a href="https://evidence.nihr.ac.uk/alert/swimming-in-seawater-is-linked-with-an-increased-chance-of-some-illnesses/">disease-causing microbes present</a>. </p>
<p>Swimming pool water, with adequate chlorine disinfection levels and pH maintenance, is much less likely to contain infectious microorganisms and so represents a much safer environment for recreational swimming. Injuries and drowning are also much less likely in pools where trained <a href="https://www.lifeguardtv.com/why-you-should-swim-near-a-lifeguard/">lifeguards</a> and safety equipment are present.</p>
<p>Perhaps, then, an outdoor managed swimming pool offers the best of both worlds – a swim with the sun on your back in a sanitary environment.</p><img src="https://counter.theconversation.com/content/199166/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Primrose Freestone does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>As well as the joy that comes with swimming, there can also be some dirty risks.Primrose Freestone, Senior Lecturer in Clinical Microbiology, University of LeicesterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2003382023-02-22T01:59:36Z2023-02-22T01:59:36ZThere could be alien life on Mars, but will our rovers be able to find it?<figure><img src="https://images.theconversation.com/files/511377/original/file-20230221-946-yjfk13.jpg?ixlib=rb-1.1.0&rect=0%2C187%2C4032%2C2158&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Scientists think Mars rovers may have some blind spots when it comes to finding signs of life. </span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Robotic rovers are currently exploring the surface of Mars. Part of a rover’s mission is to survey the planet for signs of life. There might be nothing to find – but what if there is, and the rovers just can’t “see” it?</p>
<p>New research published today in <a href="https://doi.org/10.1038/s41467-023-36172-1">Nature Communications</a> suggests the rovers’ current equipment might not actually be up to the task of finding evidence of life. </p>
<p>As an extreme environment microbiologist, the challenges of searching for life where it seems near-impossible are familiar to me. </p>
<p>In astrobiology, we study the diversity of life in sites on Earth with environmental or physical features that resemble regions already described on Mars. We call these terrestrial environments “Mars analogue” sites.</p>
<h2>Limits of detection</h2>
<p>The new research, led by Armando Azua-Bustos at the Center for Astrobiology in Madrid, tested the sophisticated instruments currently in use by NASA’s Curiosity and Perseverance rovers – as well as some newer lab equipment planned for future analysis – in the Mars analogue of the Atacama Desert. </p>
<figure class="align-center ">
<img alt="A red, dusty, barren landscape, with a medium size rock formation. One scientist is climing the rock. Another is crouched at its base." src="https://images.theconversation.com/files/511268/original/file-20230221-26-ixl70u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/511268/original/file-20230221-26-ixl70u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/511268/original/file-20230221-26-ixl70u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/511268/original/file-20230221-26-ixl70u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/511268/original/file-20230221-26-ixl70u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/511268/original/file-20230221-26-ixl70u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/511268/original/file-20230221-26-ixl70u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Scientists take samples from the Atacama Desert’s arid soil.</span>
<span class="attribution"><span class="source">Armando Azua-Bustos/Centro de Astrobiología</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Azua-Bustos and colleagues found the rovers’ testbed equipment – tools for analysing samples in the field – had limited ability to detect the traces of life we might expect to find on the red planet. They were able to detect the mineral components of the samples, but were not always able to detect organic molecules.</p>
<p>In my team’s case, our Mars analogue sites are the cold and hyper-arid deserts of the Dry Valleys and Windmill Islands in Antarctica.</p>
<p>In both of these sites, life exists despite extreme pressures. Finding evidence of life is challenging, given the harsh conditions and the scarcity of microbial life present. </p>
<p>First, we must define the biological and physical boundaries of life existing (and being detected) in analogue “extreme” environments. Then we need to develop tools to identify the “biosignatures” for life. These include organic molecules like lipids, nucleic acids and proteins. Finally, we determine how sensitive tools need to be to detect those biosignatures, on Earth and also Mars. This tells us the limits of our detection.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Y7eF-mjXkLU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Traces of life are scarce in the Atacama Desert.</span></figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/perseverance-the-mars-rover-searching-for-ancient-life-and-the-aussie-scientists-who-helped-build-it-141590">Perseverance: the Mars rover searching for ancient life, and the Aussie scientists who helped build it</a>
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</em>
</p>
<hr>
<h2>The search for a dark microbiome</h2>
<p>In my field of extreme microbiology, “microbial dark matter” is when the majority of microscopic organisms in a sample have not been isolated and/or characterised. To identify them, we require next-generation sequencing <strong>need to define</strong>. Azua-Bustos’s team go one step further, proposing a “dark microbiome” which contains potentially relic, extinct Earth species.</p>
<p>Azua-Bustos’s team found sophisticated laboratory techniques could detect a dark microbiome in the Atacama Desert’s Martian-like hyper-arid soil samples. However, the rovers’ current equipment wouldn’t be able to detect it on Mars. </p>
<p>In samples with such scarce biomass, we use highly sensitive laboratory methods to detect microbial life, including gene sequencing and visualising cells using microscopic analysis. Prototypes for genome sequencing in the field are being developed, but they do not have the sensitivity needed for low biomass samples – yet.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/511372/original/file-20230221-26-9xc7jp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/511372/original/file-20230221-26-9xc7jp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/511372/original/file-20230221-26-9xc7jp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/511372/original/file-20230221-26-9xc7jp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/511372/original/file-20230221-26-9xc7jp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/511372/original/file-20230221-26-9xc7jp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/511372/original/file-20230221-26-9xc7jp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Professor Belinda Ferrari in Antarctica.</span>
<span class="attribution"><span class="source">Dr Eden Zhang</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/there-is-water-on-mars-but-what-does-this-mean-for-life-48310">There is water on Mars, but what does this mean for life?</a>
</strong>
</em>
</p>
<hr>
<h2>Different planet, different rules</h2>
<p>The search for life on other planets also relies on our understanding of what life would need to exist, with the <a href="https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.0020302">simplest list</a> being energy, carbon and liquid water. </p>
<p>On Earth, most organisms use photosynthesis to harness energy from sunlight. This process requires water, which is almost totally unavailable in dry desert environments like Antarctica and the Atacama Desert – and, most likely, Mars. We think a process we dubbed “atmospheric chemosynthesis” could be filling this gap.</p>
<p>My team first discovered atmospheric chemosynthesis in the cold desert soils of Antarctica. In this overlooked metabolic process, bacteria literally “<a href="https://www.nature.com/articles/nature25014">live on thin air</a>” by consuming trace levels of hydrogen and carbon monoxide gas from the atmosphere. </p>
<figure class="align-center ">
<img alt="A photo of the vast, barren Antarctic landscape. There is a cloudless blue sky, ice, ocean in the far distance, and a very tiny hut visible in the mid distance." src="https://images.theconversation.com/files/511374/original/file-20230221-26-1zucql.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/511374/original/file-20230221-26-1zucql.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=345&fit=crop&dpr=1 600w, https://images.theconversation.com/files/511374/original/file-20230221-26-1zucql.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=345&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/511374/original/file-20230221-26-1zucql.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=345&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/511374/original/file-20230221-26-1zucql.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=434&fit=crop&dpr=1 754w, https://images.theconversation.com/files/511374/original/file-20230221-26-1zucql.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=434&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/511374/original/file-20230221-26-1zucql.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=434&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Antarctica is one of the few places on Earth with permafrost similar to areas on Mars.</span>
<span class="attribution"><span class="source">Dr Belinda Ferrari</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>We think dry desert microbiomes may rely on this process for energy as well as water, which is a byproduct of the process. Ecosystems like the ones we’ve found in Antarctica now offer one of the most <a href="https://www.liebertpub.com/doi/full/10.1089/ast.2021.0066">promising ecological models</a> in the search for Martian life. </p>
<p>We now believe there is potential for life in the ice-cemented subsurface of Mars. My team – alongside collaborators at NASA and the University of Pretoria – <a href="https://www.liebertpub.com/doi/full/10.1089/ast.2021.0066">plan to investigate</a> this in Antarctica’s University Valley, by defining the environmental limits to energy, metabolic water and carbon production via trace gas consumption. </p>
<figure class="align-center ">
<img alt="A human in a red coat looks tiny, crouching in front of enormous reddish rock formations that have ice in between." src="https://images.theconversation.com/files/511563/original/file-20230222-20-sivq4n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/511563/original/file-20230222-20-sivq4n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/511563/original/file-20230222-20-sivq4n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/511563/original/file-20230222-20-sivq4n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/511563/original/file-20230222-20-sivq4n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/511563/original/file-20230222-20-sivq4n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/511563/original/file-20230222-20-sivq4n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">University Valley has a layer of dry permafrost soil overlaying ice-rich permanently frozen ground. Some Martian environments have similar features.</span>
<span class="attribution"><span class="source">Jackie Goordial/McGill University</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/discovery-of-microbe-rich-groundwater-in-antarctica-guides-search-for-life-in-space-40931">Discovery of microbe-rich groundwater in Antarctica guides search for life in space</a>
</strong>
</em>
</p>
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<h2>We won’t find what we can’t define</h2>
<p>Our new knowledge of target biosignatures and the level of sensitivity needed to detect them will be critical when designing or optimising future instrumentation to be deployed on missions aimed at finding life. </p>
<p>The goal of future missions to Mars, including the <a href="https://www.researchgate.net/publication/236125178_The_Icebreaker_Life_Mission_to_Mars_A_Search_for_Biomolecular_Evidence_for_Life">Icebreaker Life</a> mission planned for 2026, is to search for evidence of life. The Icebreaker Life will sample ice-cemented ground, similar to Antarctic dry permafrost, and if it detects signs of life, a Mars Sample Return mission would be a high priority.</p>
<p>Returning samples to Earth for laboratory analysis is risky. As we found with our Antarctic soil samples, challenges can include contamination, preservation of cold temperatures during transport, and the need for specialist quarantine laboratories, to analyse samples without destroying them. </p>
<p>But as Asua-Bustos suggests, bringing samples to Earth for detailed lab analyses may be the only sure way to detect – or rule out – the presence (or past presence) of life.</p><img src="https://counter.theconversation.com/content/200338/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Belinda Ferrari receives funding from the Australian Research Council. While not directly related to this article her previous funding has led to new research questions on the habitability of Mars.</span></em></p>Our Mars rovers might not be sensitive enough to detect signs of life. But lessons from Antarctica might make future missions more successful.Belinda Ferrari, Professor of Microbiology, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1978802023-02-20T13:19:21Z2023-02-20T13:19:21ZWere viruses around on Earth before living cells emerged? A microbiologist explains<figure><img src="https://images.theconversation.com/files/507461/original/file-20230131-26-ml6jvg.jpg?ixlib=rb-1.1.0&rect=0%2C3%2C2305%2C1292&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Maybe the first life on Earth was part of an 'RNA world.'</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/molecule-illustration-royalty-free-illustration/1359392488">Artur Plawgo/Science Photo Library via Getty Images</a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em><a href="https://theconversation.com/us/topics/curious-kids-us-74795">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">curiouskidsus@theconversation.com</a>.</em></p>
<hr>
<blockquote>
<p><strong>Were there already viruses on Earth when the first living cells appeared billions of years ago? – Aayush A., age 16, India</strong></p>
</blockquote>
<p>How life on Earth started has puzzled scientists for a long time. And it still does.</p>
<p>Fossils provide very important evidence about the evolution of plants and animals. Unfortunately, there are <a href="https://ucmp.berkeley.edu/bacteria/bacteriafr.html">very few fossils of ancient microbes available</a>, so scientists rely on modern microbes to devise theories about how life started. I studied bacteria and another type of microbe called archaea from hot environments <a href="https://scholar.google.com/citations?user=pN5i54IAAAAJ&hl=en">for many years</a> to learn how they might have evolved on early Earth, but I still have so many unanswered questions.</p>
<p>Based on the fossil evidence we have, single-celled microbes appeared on Earth before larger cellular life like plants and animals. But which kinds of microbes were the very first kind of life?</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/de1hiS_XjWg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Some scientists think hydrothermal vents are the cradle of early life on Earth.</span></figcaption>
</figure>
<h2>Which microbes are considered alive?</h2>
<p>Microbes are living, single-celled creatures surrounded by a membrane. They consume and convert nutrients into biological molecules or energy and are too small to be seen without a microscope.</p>
<p>By this definition, bacteria, archaea and single-celled eukaryotes are microbes. <a href="https://bio.libretexts.org/Courses/University_of_California_Davis/BIS_2A%3A_Introductory_Biology_(Easlon)/Readings/02.2%3A_Bacterial_and_Archaeal_Diversity">Bacteria and archaea</a> are single-celled creatures that lack internal membrane-enclosed structures, like a nucleus to hold their genetic material. Single-celled eukaryotes have a nucleus and may have other membrane-enclosed structures.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/507680/original/file-20230201-8834-kxai71.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Diagram comparing a eukaryotic and prokaryotic cell" src="https://images.theconversation.com/files/507680/original/file-20230201-8834-kxai71.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/507680/original/file-20230201-8834-kxai71.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/507680/original/file-20230201-8834-kxai71.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/507680/original/file-20230201-8834-kxai71.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/507680/original/file-20230201-8834-kxai71.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/507680/original/file-20230201-8834-kxai71.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/507680/original/file-20230201-8834-kxai71.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Unlike prokaryotic cells, eukaryotic cells have membrane-enclosed structures like a nucleus and mitochondria.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/eukaryotic-vs-prokaryotic-cells-educational-royalty-free-illustration/1201105509">VectorMine/iStock via Getty Images Plus</a></span>
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<p>Some scientists <a href="https://www.genome.gov/genetics-glossary/Virus">consider viruses</a> to be microbes made of genetic material enclosed in a protein coat. They are unable to replicate on their own and hijack the machinery of other cells to make copies of themselves. Because they don’t have many <a href="https://www.khanacademy.org/test-prep/mcat/cells/viruses/a/are-viruses-dead-or-alive">features of living cells</a>, they are <a href="https://microbiologysociety.org/publication/past-issues/what-is-life/article/are-viruses-alive-what-is-life.html">not technically alive</a>.</p>
<h2>Evidence for early life on Earth</h2>
<p>Fossils can provide scientists with clues as to when life started, but they best record hard things like bones and teeth. Microbes are made of soft materials that do not fossilize well. However, some live together in very large groups of cells that can accumulate minerals and leave behind quite large fossils. </p>
<p>For example, cyanobacteria formed large structures called <a href="https://theconversation.com/ancient-microbial-life-used-arsenic-to-thrive-in-a-world-without-oxygen-146533">stromatolites</a> in the oceans of early Earth. Scientists have found fossil stromatolites that date back to <a href="https://www.sciencedaily.com/releases/2022/11/221107135817.htm">3.48 billion years ago</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/510650/original/file-20230216-759-docyl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Stromatolites near a river" src="https://images.theconversation.com/files/510650/original/file-20230216-759-docyl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/510650/original/file-20230216-759-docyl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/510650/original/file-20230216-759-docyl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/510650/original/file-20230216-759-docyl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/510650/original/file-20230216-759-docyl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/510650/original/file-20230216-759-docyl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/510650/original/file-20230216-759-docyl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Stromatolites can provide information about life on early Earth.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/stromatolites-found-by-the-ottawa-river-rock-royalty-free-image/1176691303">Jana Kriz/Moment via Getty Images</a></span>
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<p>Other scientists found what they believe are <a href="https://www.the-scientist.com/news-opinion/microbial-fossils-found-in-3-4-billion-year-old-subseafloor-rock-68975">fossilized archaea</a> in rocks from a 3.4 billion-year-old hot seafloor. The Earth became habitable about 4 billion years ago, so bacteria and archaea must have appeared between 3.5 billion and 4 billion years ago.</p>
<p>Looking at the chemical reactions that cells carry out can also provide clues. The reactions that make biological molecules and generate energy make up what’s called the cell’s metabolism. Scientists have found evidence that some metabolic reactions were occurring at least <a href="https://newsroom.ucla.edu/releases/life-on-earth-likely-started-at-least-4-1-billion-years-ago-much-earlier-than-scientists-had-thought">4.1 billion years ago</a>. These reactions may have been occurring on their own <a href="https://news.ncbs.res.in/research/unravelling-origin-life">before cells had evolved</a>, perhaps on the surfaces of <a href="https://doi.org/10.3390/life11080795">clays or minerals</a>.</p>
<h2>Theories about how life started on Earth</h2>
<p>Cells copy their genetic material, made of DNA and RNA, to pass it on to new generations. Although DNA is the form of genetic material most living organisms use today, some scientists believe that RNA was the <a href="https://news.ncbs.res.in/research/unravelling-origin-life">first information storage molecule</a> on early Earth because it can make copies of itself. </p>
<p>Because some modern viruses use RNA to store genetic information, some scientists believe that viruses could have <a href="https://doi.org/10.1016/j.biochi.2005.03.015">evolved from self-replicating RNAs</a>. This possibility would mean that viruses may have appeared before bacteria. But because viruses don’t leave fossils behind, there isn’t available evidence to support this idea.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/VYQQD0KNOis?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The RNA-world hypothesis proposes that self-replicating RNA evolved before DNA or proteins.</span></figcaption>
</figure>
<p>At some point, metabolic reactions and replication processes had to come together inside a membrane to make an early form of a cell: a pre-cell. Perhaps this happened when a viruslike structure infected a collection of metabolic reactions enclosed within a membrane. The pre-cell could then duplicate itself, leading to the <a href="https://doi.org/10.1098/rstb.2002.1183">evolution of the first living cell</a>. This cell would have been like today’s bacteria and archaea.</p>
<p>Maybe viruslike structures did form before cells. However, those simple viruslike structures might have been just pieces of DNA or RNA, so could they really be considered “viruses”? </p>
<p>Another popular theory states that viruses evolved from degenerated bacteria or archaea that lost most of the genetic instructions for carrying out metabolism and forming cells. There are <a href="http://www.biologyaspoetry.com/textbooks/microbes_and_evolution/symbioses_serial_endosymbiosis.html">many examples</a> of similar smaller degenerations that have occurred in the bacterial world today.</p>
<h2>Uncovering early life</h2>
<p>The surface of the Earth today is very different from <a href="https://eos.org/science-updates/rethinking-the-search-for-the-origins-of-life">what it was 4 billion years ago</a>. Some have speculated that deep under the Earth’s surface, where it is too hot for modern life, these early conditions <a href="https://www.chemistryworld.com/features/hydrothermal-vents-and-the-origins-of-life/3007088.article">might still be present</a>, allowing some protolife forms to continue to exist where they are protected from being consumed by other microbes. </p>
<p>When people can explore other planets or moons, perhaps we will find processes similar to those that were at work on early Earth. This kind of discovery could help us solve the puzzle of life’s origin here.</p>
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<p><em>Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to <a href="mailto:curiouskidsus@theconversation.com">CuriousKidsUS@theconversation.com</a>. Please tell us your name, age and the city where you live.</em></p>
<p><em>And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.</em></p><img src="https://counter.theconversation.com/content/197880/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kenneth Noll previously received funding from NSF, NASA, DOE and the Office of Naval Research. </span></em></p>Fossil evidence of how the earliest life on Earth came to be is hard to come by. But scientists have come up with a few theories based on the microbes, viruses and prions existing today.Kenneth Noll, Professor Emeritus of Microbiology, University of ConnecticutLicensed as Creative Commons – attribution, no derivatives.