tag:theconversation.com,2011:/africa/topics/yeast-10662/articlesYeast – The Conversation2024-03-28T00:38:13Ztag:theconversation.com,2011:article/2126982024-03-28T00:38:13Z2024-03-28T00:38:13ZA eucharist of sourdough or wafer? What a thousand-year-old religious quarrel tells us about fermentation<figure><img src="https://images.theconversation.com/files/549735/original/file-20230922-28-twwr4t.jpg?ixlib=rb-1.1.0&rect=35%2C447%2C3936%2C2150&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A Byzantine depiction of the Eucharist in Saint Sophia Cathedral, Kyiv.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Eucharist_mosaic_(Saint_Sophia_Cathedral_in_Kiev)_detail.jpg">Jacek555/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>A nasty quarrel arose in the 11th century over what kind of bread should be used in holy communion. </p>
<p>The view in Constantinople was the bread for the eucharist must be sourdough. But in Rome, an unleavened wafer had been used for longer than anyone could remember and the Vatican argued unleavened bread was more authentic.</p>
<p>It might sound like a storm in a chalice, but it mattered a lot because church authority seemed to be at stake. </p>
<p>Neither side could back down, and the grand fracas – known as the “azyme controversy of 1054” – became so divisive that it led, among other quibbles, to <a href="https://en.wikipedia.org/wiki/East%E2%80%93West_Schism">the schism of east and west</a>. Today, the sourdough loaf in the Orthodox liturgy is cut up and mixed with wine, while the Catholic church still uses a small circular wafer.</p>
<p>Scholars have difficulty accounting for this unfortunate brawl. Was it politically motivated, or just an escalation of insults among bickering headstrong men that’s best forgotten? </p>
<p>But rather than reading the controversy as a case study in antagonism, it occurred to me the historical record is <a href="https://www.academia.edu/104057468/A_visceral_history_of_bread_from_First_Nations_Australia_to_Byzantium">useful in illuminating</a> medieval attitudes to bread and fermentation.</p>
<h2>Christ’s sacrifice</h2>
<p>The Byzantine Greeks had a gut reaction to the Latin wafer or matzo (<em>azymon</em>). They were disgusted by the idea of an inflexible board representing the Saviour. The Lord’s body had to be figured in a more flesh-like genuine bread. </p>
<p>They accused the Latin wafer of being like the clay of a brick; the Latin unleavened bread as being “dead” (<em>nekron</em>). Even in the 8th century, John of Damascus described this characterless wafer as “insipid” (<em>moron</em>).</p>
<p>Much of the debate concerned doctrine. </p>
<p>The Byzantines thought the Latins didn’t really understand the point of the sacrament, because their unleavened bread was a throw-back to Jewish practice. The Byzantines said they must not Judaicise (<em>ioudaïzein</em>) the holiest rite, which is all about Christ’s sacrifice that Jews don’t recognise.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/549734/original/file-20230922-21-s3c85l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="The original owner of this manuscript and his family kneel before an altar in adoration of the Eucharist, shown in an elaborate gold monstrance." src="https://images.theconversation.com/files/549734/original/file-20230922-21-s3c85l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/549734/original/file-20230922-21-s3c85l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=939&fit=crop&dpr=1 600w, https://images.theconversation.com/files/549734/original/file-20230922-21-s3c85l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=939&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/549734/original/file-20230922-21-s3c85l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=939&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/549734/original/file-20230922-21-s3c85l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1180&fit=crop&dpr=1 754w, https://images.theconversation.com/files/549734/original/file-20230922-21-s3c85l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1180&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/549734/original/file-20230922-21-s3c85l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1180&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 Adoration of the Eucharist, early 1460s, Willem Vrelant (Flemish, died 1481, active 1454– 1481).</span>
<span class="attribution"><a class="source" href="https://www.getty.edu/art/collection/object/103S6S">Getty Museum</a></span>
</figcaption>
</figure>
<p>Aside from these dogmatic arguments, an important part of the Greek revulsion against the wafer was aesthetic. The leaven in the sourdough process was identified with life and warmth and the bread itself – though technically sour – is endowed with sweetness (<em>hedytes</em>).</p>
<p>The Latin church retorted the fermentation of the dough introduces an impurity into the angelic substance of the eucharist. After all, they said, the process of sourdough must be a bit like rot or putrefaction. </p>
<p>It seemed to them the original unadulterated ingredients of wheat and flour are sullied by (the then) unknown alien substance that eventually results in degradation and spoiling (<em>vitiatio</em>).</p>
<h2>Observing the yeast</h2>
<p>Behind this disagreeable theological dispute between eastern and western churches, we gain precious insight into how the premodern mind understood fermentation, and especially what distinguishes it from rot and decay. </p>
<p>The debate brings out intuitions that anticipate the <a href="https://en.wikipedia.org/wiki/Louis_Pasteur">findings of Louis Pasteur</a> 800 years later, who understood the action of yeasts as an additive process rather than a form of decay.</p>
<p>Actually, the positive interpretation of yeast begins with Jesus himself. In a Biblical verse quoted repeatedly during the squabble, Jesus <a href="https://biblehub.com/matthew/13-33.htm">compares heaven to sourdough</a>: </p>
<blockquote>
<p>The kingdom of heaven is like unto leaven (<em>zyme</em>), which a woman took, and hid in three measures of meal, till the whole was leavened.</p>
</blockquote>
<p>As the Byzantines argued, Jesus wouldn’t have proposed this analogy if he thought the leaven was some form of corruption that takes over and damages the food. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/549737/original/file-20230922-31-rqcd5l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/549737/original/file-20230922-31-rqcd5l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/549737/original/file-20230922-31-rqcd5l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=791&fit=crop&dpr=1 600w, https://images.theconversation.com/files/549737/original/file-20230922-31-rqcd5l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=791&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/549737/original/file-20230922-31-rqcd5l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=791&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/549737/original/file-20230922-31-rqcd5l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=994&fit=crop&dpr=1 754w, https://images.theconversation.com/files/549737/original/file-20230922-31-rqcd5l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=994&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/549737/original/file-20230922-31-rqcd5l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=994&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 Adoration of the Magi, about 1240, unknown artist.</span>
<span class="attribution"><a class="source" href="https://www.getty.edu/art/collection/object/107TX3">Getty Museum</a></span>
</figcaption>
</figure>
<p>His parable envisages good things (think divine love) spreading miraculously in the holy environment, in the same way the lump of dough is enriched by the discrete amounts of leaven that end up permeating it.</p>
<p>The Byzantines and Pasteur would agree with Jesus. Following Pasteur, we identify the wild yeast in sourdough as <em><a href="https://www.discovermagazine.com/planet-earth/the-biology-of-sourdough">lactobacillus</a></em> – but there was no microscope in the middle ages and a scientific approach could only be based on what could be seen, which is marvellously enigmatic.</p>
<p>The Latin view rejected the homely Greek interpretation. Their <a href="https://en.wikipedia.org/wiki/Vulgate">Vulgate Bible</a> mistranslates <a href="https://www.bibleref.com/Galatians/5/Galatians-5-9.htm">a line of Paul</a>, saying “a little leaven spoils (<em>corrumpit</em>) the whole lump”, instead of “a little leaven leaveneth (<em>zymoi</em>) the whole lump”. </p>
<p>A belligerent <a href="https://en.wikipedia.org/wiki/Humbert_of_Silva_Candida">Cardinal Humbert</a> dismissed the analogy of heaven and leaven, scoffing that Jesus also compares heaven to a seed of mustard. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/549739/original/file-20230922-23-j03l4y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/549739/original/file-20230922-23-j03l4y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/549739/original/file-20230922-23-j03l4y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=545&fit=crop&dpr=1 600w, https://images.theconversation.com/files/549739/original/file-20230922-23-j03l4y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=545&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/549739/original/file-20230922-23-j03l4y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=545&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/549739/original/file-20230922-23-j03l4y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=684&fit=crop&dpr=1 754w, https://images.theconversation.com/files/549739/original/file-20230922-23-j03l4y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=684&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/549739/original/file-20230922-23-j03l4y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=684&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Mold for a Eulogia (Blessing) Bread, 600s-900s. Byzantium, Palestine, Byzantine period.</span>
<span class="attribution"><a class="source" href="https://www.clevelandart.org/art/1951.152">The Cleveland Museum of Art</a></span>
</figcaption>
</figure>
<p>Humbert argued the yeast in the leaven has to <a href="https://www.academia.edu/104057468/A_visceral_history_of_bread_from_First_Nations_Australia_to_Byzantium">come from somewhere</a>: its origins belong with similar yeasts in beer, and these in turn are related to the scum of foul organic matter.</p>
<p>Humbert also reminds us of what happens when you leave the leavened dough for too long: it goes off and becomes inedible.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-every-new-baker-should-know-about-the-yeast-all-around-us-137687">What every new baker should know about the yeast all around us</a>
</strong>
</em>
</p>
<hr>
<h2>Heavenly sourdough</h2>
<p>Today we might say that the Latins came to the wrong biochemical conclusions, but in many ways their approach was more empirical and scientific. Observing how leavened dough easily becomes foul, they reasoned that fermentation must involve impurities.</p>
<p>For those of us who haven’t looked at a microscope since high school, the Byzantine polemic in general helps us understand how we still <a href="https://theconversation.com/what-every-new-baker-should-know-about-the-yeast-all-around-us-137687">imagine microbiological processes</a> without being able to see or name the various bacteria and enzymes at work.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/552214/original/file-20231004-23-befe4s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/552214/original/file-20231004-23-befe4s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/552214/original/file-20231004-23-befe4s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/552214/original/file-20231004-23-befe4s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/552214/original/file-20231004-23-befe4s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/552214/original/file-20231004-23-befe4s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/552214/original/file-20231004-23-befe4s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/552214/original/file-20231004-23-befe4s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Bread baked by the author, embossed with a bread-stamp from a monastery in Greece.</span>
<span class="attribution"><span class="source">Robert Nelson</span></span>
</figcaption>
</figure>
<p>Even after <a href="http://theconversation.com/the-historical-roots-of-your-lockdown-sourdough-obsession-137528">peak sourdough</a> during the lockdowns, sourdough strikes me as mysterious as a process and seductive in its results, with a tough texture and pleasantly sour taste arising from unseen bugs. </p>
<p>And though our secular bakers are remote from the passionate theology of Byzantine clerics, we know deep down that sourdough is heavenly and the most charismatic of breads.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-communion-matters-in-catholic-life-and-what-it-means-to-be-denied-the-eucharist-163560">Why Communion matters in Catholic life -- and what it means to be denied the Eucharist</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/212698/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robert Nelson 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>The ‘azyme controversy of 1054’ became so divisive it contributed to the schism of east and west. But it has a lot to tell us about how we understand bread.Robert Nelson, Honorary Principal Fellow, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2191492024-01-05T16:14:45Z2024-01-05T16:14:45ZCan you really be allergic to alcohol?<figure><img src="https://images.theconversation.com/files/565241/original/file-20231212-17-cvmrru.jpg?ixlib=rb-1.1.0&rect=14%2C21%2C4876%2C3233&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/close-two-people-cheering-cocktails-bar-2293053559">guys who shoot/Shutterstock</a></span></figcaption></figure><p>Some people get allergy-like symptoms when drinking alcohol, but can you really be allergic to alcohol? </p>
<p>Alcohol allergies are rare, with documented cases primarily involving a <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1369-1600.2004.tb00533.x">rash</a>. However, what often perplexes people are the symptoms that <a href="https://www.sciencedirect.com/science/article/pii/S108112061300690X">mimic allergies</a>, such as wheezing, headaches and skin flushing. </p>
<p>These reactions, more often than not, are attributed to alcohol <a href="https://onlinelibrary.wiley.com/doi/abs/10.1080/1355621031000069828">exacerbating underlying conditions</a> like asthma, urticaria (hives) and rhinitis. The reason is that alcohol dilates <a href="https://www.sciencedirect.com/science/article/pii/S108112061300690X">blood vessels</a>, which then sets the stage for a symphony of bodily responses.</p>
<p>The term <a href="https://link.springer.com/content/pdf/10.1007/978-3-642-74904-9.pdf">“alcohol intolerance”</a> becomes key in deciphering these reactions. Unlike allergies, which involve the immune system, intolerances arise when the body lacks the necessary <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6527027/#:%7E:text=Alcohol%20is%20eliminated%20from%20the,(CYP2E1)%2C%20and%20catalase.">enzymes</a> to digest and eliminate alcohol. The consequence? Unusual symptoms that may leave one questioning whether the drink in hand is a source of enjoyment or distress.</p>
<h2>Not just the alcohol</h2>
<p>As we peer into the bottom of our glasses, it becomes clear that the source of these reactions is not just the alcohol but the complex composition of the drink. </p>
<p>Red wine often takes centre stage as a provocateur of reactions, followed by whisky, beer and other wines. The usual suspects, however, are not the alcohol molecules but the enigmatic chemicals known as <a href="https://pubmed.ncbi.nlm.nih.gov/20712591/#:%7E:text=Congeners%20are%20minor%20compounds%20other,of%20distilling%20and%20fermenting%20processes.">congeners</a>.</p>
<p><a href="https://link.springer.com/article/10.1007/s12024-013-9411-0">Congeners</a>, responsible for the body, aroma and flavour of a drink, play a subtle yet significant role in the orchestration of reactions. But can these congeners induce true allergic reactions? To answer this, we delve into the substances within alcoholic beverages that might induce bodily responses.</p>
<p><a href="https://academic.oup.com/alcalc/article/34/2/141/192121">Histamine</a>, a familiar name to allergy sufferers, emerges as a prominent figure in this narrative. Present in abundance, particularly in red wines, histamine can be the <a href="https://pubmed.ncbi.nlm.nih.gov/17490952/">instigator of</a> headaches, flushing, nasal symptoms, gut disturbances or even asthma. Those intolerant to histamine may grapple with these symptoms because their body is unable to break down and eliminate this compound.</p>
<p>While yeast allergies are <a href="https://www.hindawi.com/journals/crii/2017/7958924/">not unheard of</a>, studies cast a reassuring light on the low levels of yeast allergens in alcoholic drinks. True allergic reactions stemming from yeasts are a rare occurrence, dampening the suspicion that this microscopic organism is the chief cause.</p>
<p>Sulphur dioxide, commonly found in home-brewed beers and wines, especially in the form of sodium metabisulphite, is another potential culprit. About one in ten asthmatics may find themselves wheezing in response to <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2222.2009.03362.x">sulphites</a>, with rashes and anaphylactic reactions being the exception rather than the rule. </p>
<figure class="align-center ">
<img alt="Woman holding asthma pump to her mouth" src="https://images.theconversation.com/files/567698/original/file-20240103-25-otofoy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/567698/original/file-20240103-25-otofoy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/567698/original/file-20240103-25-otofoy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/567698/original/file-20240103-25-otofoy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/567698/original/file-20240103-25-otofoy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/567698/original/file-20240103-25-otofoy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/567698/original/file-20240103-25-otofoy.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">One in ten asthmatics find themselves wheezing in response to sulphites.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/young-woman-using-asthma-inhaler-on-611711816">Africa Studio/Shutterstock</a></span>
</figcaption>
</figure>
<p>Sulphites are one of <a href="https://www.food.gov.uk/business-guidance/allergen-labelling-for-food-manufacturers">14 allergens</a> that must be listed in bold in all prepared foods and restaurants.</p>
<p>In the realm of additives, substances like <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2222.1977.tb01471.x">tartrazine and sodium benzoate</a> emerge as potential instigators of urticaria and asthma. As we sift through the components that constitute our favourite drinks, the awareness of these additives becomes pivotal for those navigating sensitivities.</p>
<p>The very essence of alcoholic beverages lies in the plants from which they derive – be it grapes, apples, juniper berries, coconuts, oranges, hops or malt. While these plant-derived allergens can theoretically trigger true allergic reactions, most are <a href="https://onlinelibrary.wiley.com/doi/abs/10.1002/mnfr.200800236">destroyed</a> during processing. </p>
<p>An exception, albeit a rare one, is the potential trouble posed by fungal spores (mould) from the corks of wine bottles. Sensitivity to this fungus is uncommon, but for those at risk, a visible <a href="https://www.mdpi.com/2076-2607/8/1/12">mould-laden cork</a> could expose them to an unwarranted dose of allergen.</p>
<h2>Discover the culprit</h2>
<p>For those grappling with these enigmatic reactions, avoidance is often the best course of action. </p>
<p>Keeping meticulous records of the drink type, accompanying consumables, and physical activities during the episode can assist in identifying triggers. If all alcoholic drinks seem to induce reactions, it might signal an exaggerated response to alcohol or an exacerbation of an <a href="https://onlinelibrary.wiley.com/doi/abs/10.1080/1355621031000069828">underlying condition</a>.</p>
<p>As we raise our glasses to the complexity of alcohol-related reactions, a journey through the nuances of <a href="https://link.springer.com/article/10.1007/s12024-013-9411-0">congeners</a>, <a href="https://pubmed.ncbi.nlm.nih.gov/17490952/">histamines</a>, <a href="https://www.hindawi.com/journals/crii/2017/7958924/">yeasts</a>, <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2222.2009.03362.x">sulphites</a>, additives and plant-derived allergens unfolds. In the spirit of scientific exploration, the quest for a comprehensive understanding of these reactions continues, promising insights that may one day unveil the mysteries behind the intricate dance between our bodies and the libations we savour.</p><img src="https://counter.theconversation.com/content/219149/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>If you wheeze or your skin flushes when you drink alcohol, read on.Samuel J. White, Senior Lecturer in Genetic Immunology, Nottingham Trent UniversityPhilippe B. Wilson, Professor of One Health, Nottingham Trent UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2118122023-09-14T12:27:36Z2023-09-14T12:27:36ZThe complex chemistry behind America’s spirit – how bourbon gets its distinctive taste and color<figure><img src="https://images.theconversation.com/files/546742/original/file-20230906-27-yxfzwi.jpg?ixlib=rb-1.1.0&rect=8%2C5%2C1997%2C1485&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Most bourbon is made in Kentucky. </span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/whisky-pour-from-a-bottle-into-a-cut-glass-tumbler-royalty-free-image/1358320148?phrase=bourbon&adppopup=true">Catherine Falls Commercial/Moment via Getty Images</a></span></figcaption></figure><p>Few beverages have as rich a heritage and as complicated a chemistry as bourbon whiskey, often called “<a href="https://slate.com/human-interest/2015/05/bourbon-empire-lewis-rosenstiel-and-how-bourbon-became-americas-native-spirit.html">America’s spirit</a>.” Known for its deep amber hue and robust flavors, bourbon has <a href="https://caskx.com/2021/01/18/behind-the-bourbon-boom-and-where-its-headed/">captured the hearts</a> of <a href="https://caskx.com/2021/01/18/behind-the-bourbon-boom-and-where-its-headed/">enthusiasts across the country</a>.</p>
<p>But for a whiskey to be called a bourbon, it has to <a href="https://www.quarto.com/books/9780760351727/bourbon">adhere to very specific rules</a>. For one, it needs to be made in the U.S. or a U.S. territory – although almost all is made in Kentucky. The other rules have more to do with the steps to make it – how much corn is in the grain mixture, the aging process and the alcohol proof.</p>
<p>I’m a <a href="https://doi.org/10.1016/j.jfca.2022.105019">bourbon researcher</a> and <a href="https://miamioh.edu/profiles/cas/michael-crowder.html">chemistry professor</a> who teaches classes on fermentation, and I’m a bourbon connoisseur myself. The <a href="https://www.aiche.org/resources/publications/cep/2021/august/chemistry-bourbon">complex science</a> behind this aromatic beverage reveals why there are so many distinct bourbons, despite the strict rules around its manufacture.</p>
<h2>The mash bill</h2>
<p>All whiskeys have what’s called a mash bill. The mash bill refers to the recipe of grains that makes up the spirit’s flavor foundation. To be classified as bourbon, a spirit’s mash bill must have <a href="https://www.thewhiskyexchange.com/p/58414/the-bourbon-bible">at least 51% corn</a> – the corn gives it that characteristic sweetness. </p>
<p>Almost all bourbons also have malted barley, which lends a nutty, smoky flavor and provides enzymes that <a href="https://thewhiskeywash.com/whiskey-styles/american-whiskey/whiskey-flavor-by-grain-part-i-the-big-four/">turn starches into sugars</a> later in the production process.</p>
<p>Many distillers also use <a href="https://www.americanbourbonassociation.com/posts/wheat-versus-rye-which-better-bourbon">rye and wheat</a> to flavor their bourbons. Rye makes the bourbon spicy, while wheat produces a softer, sweeter flavor. Others might use <a href="https://whiskyadvocate.com/explore-whiskey-made-from-alternative-grains/">grains like rice or quinoa</a> – but each grain chosen, and the amount of each, affects the flavor down the line.</p>
<h2>The chemistry of yeast</h2>
<p>Once distillers grind the grains from the mash bill and mix them with heated water, they add yeast to the mash. This process is called “pitching the yeast.” The yeast consumes sugars and produces ethyl alcohol and carbon dioxide as byproducts during the process called fermentation – that’s how the <a href="https://www.whisky.com/the-production-of-whisky-at-a-glance/how-bourbon-whiskey-is-made.html">bourbon becomes alcoholic</a>. </p>
<p>The fermented mash is now called “beer.” While similar in structure and taste to the beer you might buy in a six-pack, this product still has a way to go before it reaches its final form.</p>
<p>Yeast fermentation yields other byproducts besides alcohol and carbon dioxide, including <a href="https://thewhiskeywash.com/whiskey-science/congeners-much-hangovers/">flavor compounds called congeners</a>. Congeners can be esters, which produce a fruity or floral flavor, or complex alcohols, which can taste strong and aromatic.</p>
<p>The longer the fermentation period, the longer the yeast has to create more <a href="https://whiskyand.com/flavours-in-bourbon/">flavorful byproducts</a>, which enhances the complexity of the spirit’s final taste. And different yeasts produce <a href="https://bourbonwomen.org/yeast-bourbon-flavor/">different amounts of congeners</a>. </p>
<h2>Separating the fermentation products</h2>
<p>During distillation, distillers separate the alcohol and congeners from the fermented mash of grains, resulting in a liquid spirit. To do this, they use <a href="https://vendomecopper.com/batch-distillation-systems/">pot or column stills</a>, which are large kettles or columns, respectively, often made at least partially of copper. These stills heat the beer and any congeners that have a boiling point of less than 350 degrees Fahrenheit (176 degrees Celsius) to form a vapor.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/546743/original/file-20230906-23-alklug.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A row of large copper apparatuses, with a bottom like an upturned bowl and a long cylindrical column protruding from the center." src="https://images.theconversation.com/files/546743/original/file-20230906-23-alklug.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/546743/original/file-20230906-23-alklug.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/546743/original/file-20230906-23-alklug.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/546743/original/file-20230906-23-alklug.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/546743/original/file-20230906-23-alklug.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/546743/original/file-20230906-23-alklug.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/546743/original/file-20230906-23-alklug.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">Pot stills in a distillery.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/view-of-copper-whiskey-stills-in-a-distillery-royalty-free-image/182841793?phrase=whiskey+pot+still&adppopup=true">FocusEye/E+ via Getty Images</a></span>
</figcaption>
</figure>
<p>The <a href="https://www.youtube.com/watch?v=A2DhKD-8w2I">type of still</a> will influence the beverages’ final flavor, because pot stills often do not separate the congeners as precisely as column stills do. Pot stills result in a spirit that often contains a more <a href="https://www.diffordsguide.com/encyclopedia/209/bws/distillation-pot-v-column-distillation">complex mixture of congeners</a>. </p>
<p>The desired vapors that exit the still are condensed back to liquid form, and this product is <a href="https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Book%3A_How_to_be_a_Successful_Organic_Chemist_(Sandtorv)/02%3A_COMMON_ORGANIC_CHEMISTRY_LABORATORY_TECHNIQUES/2.02%3A_Distillation">called the distillate</a>.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/546745/original/file-20230906-34535-z0t7j7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A cylindrical copper apparatus with silver holes lined up in the middle and pipes coming off it." src="https://images.theconversation.com/files/546745/original/file-20230906-34535-z0t7j7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/546745/original/file-20230906-34535-z0t7j7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/546745/original/file-20230906-34535-z0t7j7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/546745/original/file-20230906-34535-z0t7j7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/546745/original/file-20230906-34535-z0t7j7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/546745/original/file-20230906-34535-z0t7j7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/546745/original/file-20230906-34535-z0t7j7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&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 column still.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Inside_Rabbit_Hole_Distillery_-_Copper_Column.jpg">MattBarlow92/Wikimedia Commons</a></span>
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<p>Different chemical compounds have different boiling points, so distillers can separate the different chemicals by collecting the distillate <a href="https://www.britannica.com/topic/distilled-spirit/Distillation">at different temperatures</a>. So in the case of the pot still, as the kettle is heated, chemicals that have lower boiling points are collected first. As the kettle heats further, chemicals with higher boiling points vaporize and then are <a href="https://www.tommacy.com/distillation">condensed and collected</a>. </p>
<p>By the end of the distillation process with a pot still, the distillate has been divided <a href="https://help.stillspirits.com/hc/en-us/articles/360021479173-What-are-the-heads-hearts-and-tails-in-distilling-">into a few fractions</a>. One of these fractions is <a href="https://distiller.com/articles/distiller-cuts">called the “hearts</a>,” containing mostly ethanol and water, but also small amounts of congeners, which play a big role in the final flavor of the product.</p>
<h2>The alchemy of time and wood</h2>
<p>After distillation, the “hearts” fraction (which is clear and resembles water) is placed in a charred oak barrel for the aging process. Here, the bourbon interacts with chemicals in the barrel’s wood, and about <a href="https://www.theatlantic.com/magazine/archive/2013/11/the-new-science-of-old-whiskey/309522/">70% of the bourbon’s final flavor</a> is determined by this step. The bourbon gets all its amber color during the aging process. </p>
<p>Bourbon may rest in the barrel for several years. During the summer, when the temperature is hot, the distillate can pass through the inner charred layer of the barrel. The charred wood acts like a filter and <a href="https://www.rackhousewhiskeyclub.com/blogs/blog/what-is-barrel-aging-and-why-is-it-important">strains out</a> some of the chemicals before the distillate seeps into the wood. These chemicals bind to the charred layer and do not release, kind of like a water filter.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/547890/original/file-20230912-25-2kmu1a.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A dark, dusty wooden room with a wall lined with barrels stacked on wood shelves." src="https://images.theconversation.com/files/547890/original/file-20230912-25-2kmu1a.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/547890/original/file-20230912-25-2kmu1a.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/547890/original/file-20230912-25-2kmu1a.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/547890/original/file-20230912-25-2kmu1a.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/547890/original/file-20230912-25-2kmu1a.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/547890/original/file-20230912-25-2kmu1a.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/547890/original/file-20230912-25-2kmu1a.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Barrels of bourbon age in a rickhouse, where they take on flavors from the barrel’s wood.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/kentucky-rickhouse-royalty-free-image/1192365040?phrase=rickhouse&adppopup=true">The_Goat_Path/iStock via Getty Images</a></span>
</figcaption>
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<p>Under the charred layer of the barrel is a “red line,” a layer where the oak was toasted during the charring process of making the barrel. The toasting process <a href="https://whiskyadvocate.com/charring-toasting-wood-flavor/">breaks down starch and other polymers</a>, called lignins and tannins, in the oak. </p>
<p>When the distillate seeps to the red-line layer, it <a href="https://thebourbonmaster.com/bourbon-barrel-aging-unveiling-the-magic-behind-flavor-development/">dissolves the sugars</a> in the barrel, as well as lignin byproducts and tannins.</p>
<p>During the cold winter months, the distillate retreats back into the barrel, but it takes with it these sugars, tannins and lignin byproducts from the wood, which enhance the flavors. If you disassemble a barrel after it has aged bourbon, you can see a “<a href="https://doi.org/10.1038/s41598-018-34204-1">solvent line</a>,” which shows how far into the wood the distillate penetrated. The type of oak barrel can have a profound effect on the final taste, along with the barrel’s size and how charred it is.</p>
<p>For most distilleries, barrels are stored in large buildings <a href="https://whiskyride.com/whisky/what-is-a-rickhouse/">called rickhouses</a>. Ethyl alcohol and water in the distillate evaporate out of the barrel, and the humidity in that part of the rickhouse plays a big role. </p>
<p>Lower humidity often leads to higher-proof bourbon, as more water than ethanol leaves the barrel. In addition, air enters the barrel, and oxygen from the air reacts with some of the chemicals in the bourbon, creating new flavor chemicals. These reactions tend to <a href="https://www.thedrinksreport.com/news/2016/16889-special-report-oxidation-in-whisky-casks.html">soften the taste</a> of the final product.</p>
<p>There are <a href="https://www.americanbourbonassociation.com/brands">thousands of bourbons</a> on the market, and they can be distinguished by their unique flavors and aromas. The variety of brands reflects the many choices that distillers make on the mash bill, fermentation and distillation conditions, and aging process. No two bourbons are quite the same.</p><img src="https://counter.theconversation.com/content/211812/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael W. Crowder received funding from Sazerac Corp., as pass through funds from MindXAI, to characterize the chemical composition of bourbons that were part of the Single Oak Project using NMR spectroscopy. Michael is a Faculty Fellow at the James B. Beam Institute and a Certified Executive Bourbon Steward from the Stave and Thief Society.</span></em></p>The bourbon industry has been booming in recent years, but what sets all the different types of bourbon apart?Michael W. Crowder, Professor of Chemistry and Biochemistry, Miami 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>
<hr>
<p>
<em>
<strong>
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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</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>
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<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>
<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>
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</em>
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<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>
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<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>
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<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>
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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/2049172023-07-09T20:05:38Z2023-07-09T20:05:38ZA rose in every cheek: 100 years of Vegemite, the wartime spread that became an Aussie icon<figure><img src="https://images.theconversation.com/files/529978/original/file-20230605-233562-dr6a04.jpg?ixlib=rb-1.1.0&rect=2%2C0%2C644%2C851&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source"> The Australian Women's Weekly/Trove</span></span></figcaption></figure><p>There are roughly <a href="https://www.onlymelbourne.com.au/vegemite">22 million jars of Vegemite</a> manufactured in the original Melbourne factory every year. According to the Vegemite website, around 80% of Australian households have a jar in the cupboard. </p>
<p>The cultural status of Vegemite is so enduring that, in 2022, the City of Melbourne Council <a href="https://www.theguardian.com/australia-news/2022/jun/01/smell-of-vegemite-factory-given-special-heritage-recognition-by-melbourne-council">included the smell of the factory</a> at 1 Vegemite Way, Fishermans Bend, in a statement of heritage significance. </p>
<p>Vegemite first hit Australian supermarket shelves in 1923, but it took a while to find its feet. </p>
<p>Indeed, the now classic spread may have failed into obscurity as “Parwill” if not for a very clever advertising campaign in the second world war. </p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/YNiOZInvLog?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
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<h2>A product of war</h2>
<p>Vegemite has German U-boats to thank for its invention. </p>
<p>When the first world war began in 1914, Australians were big fans of <a href="https://www.marmite.co.uk/">Marmite</a>, the British yeast extract spread. </p>
<p>As the Germans began sinking ships full of British supplies to Australia, Marmite disappeared from the shelves. <a href="https://doi.org/10.1108/JHRM-06-2015-0019">Due to the conditions of its patent</a>, Marmite could only be manufactured in Britain. </p>
<p>As a result, there was a gap in the market for a yeast spread.</p>
<p><a href="https://adb.anu.edu.au/biography/walker-fred-8953">Fred Walker</a>, who produced canned foods, hired food technologist <a href="https://adb.anu.edu.au/biography/callister-cyril-percy-5468">Cyril P. Callister</a> to create a homegrown yeast spread using brewer’s yeast from the Carlton Brewery. </p>
<p>Callister’s experiments produced a thicker, stronger spread than the original Marmite. Callister’s inclusion of vegetable extracts to improve the flavour would <a href="https://doi.org/10.1080/08949468.1993.9966612">give the spread its name, Vegemite</a>, chosen by Walker’s daughter from competition entries. </p>
<p>Australians were wary of Vegemite when it first appeared on grocery shelves, perhaps due to brand loyalty to Marmite. </p>
<p>To try and combat this, <a href="https://vegemite.com.au/heritage/">Walker renamed Vegemite “Parwill”</a> in 1928 as a play on Marmite: “if Ma might, Pa will”. </p>
<p>This rebrand was short-lived. Australians were not any more interested in Parwill than they were in Vegemite. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/pass-the-iced-vovos-the-resurrection-of-australiana-34408">Pass the Iced VoVos: the resurrection of Australiana</a>
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<hr>
<h2>A nutritious food replacement</h2>
<p>In the 1930s, <a href="https://doi.org/10.1108/JHRM-06-2015-0019">Walker hired American advertiser J. Walter Thompson</a>. Thompson began offering free samples of Vegemite with purchases of other Kraft-Walker products, including the popular Kraft cheese. </p>
<p>Kraft-Walker also ran limerick competitions to advertise Vegemite. Entrants would write the final line of a limerick to enter into the draw to win a brand new car. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/524752/original/file-20230507-27-izpn0k.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/524752/original/file-20230507-27-izpn0k.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=526&fit=crop&dpr=1 600w, https://images.theconversation.com/files/524752/original/file-20230507-27-izpn0k.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=526&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/524752/original/file-20230507-27-izpn0k.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=526&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/524752/original/file-20230507-27-izpn0k.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=661&fit=crop&dpr=1 754w, https://images.theconversation.com/files/524752/original/file-20230507-27-izpn0k.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=661&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/524752/original/file-20230507-27-izpn0k.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=661&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Vegemite competition advertisement, 1937.</span>
<span class="attribution"><span class="source">Australian Women's Weekly</span></span>
</figcaption>
</figure>
<p>It would take another world war, however, before Vegemite became part of Australian national identity.</p>
<p>The second world war also disrupted shipping supply routes. <a href="https://www.oldtreasurybuilding.org.au/work-for-victory/housewives-to-action/food-rationing/">With other foodstuffs hard to come by</a>, Vegemite was marketed as a nutritious replacement for many foods. One 1945 advertisement <a href="http://nla.gov.au/nla.news-article1106308">read</a>:</p>
<blockquote>
<p>If you are one of those who don’t need Vegemite medicinally, the thousands of invalids and babies are asking you to deny yourself of it for the time being.</p>
</blockquote>
<p>With its long shelf life and high levels of B-vitamins, the Department of Supply also saw the advantages of Vegemite. The department began buying Vegemite in bulk and <a href="https://www.awm.gov.au/collection/C1070486">including it in ration kits</a> sent to soldiers on the front lines. </p>
<p>Due to this demand, Kraft-Walker foods rationed the Vegemite available to civilians. Yet the <a href="https://doi.org/10.1108/JHRM-06-2015-0019">brand increased advertisements</a>. Consumers were told Vegemite was limited because it was in demand for Australian troops due to its incredible health benefits. </p>
<figure class="align-center ">
<img alt="Drawing of a young boy in a slouch hat above an advertisement for Vegemite" src="https://images.theconversation.com/files/524753/original/file-20230507-15-a372m.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/524753/original/file-20230507-15-a372m.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=830&fit=crop&dpr=1 600w, https://images.theconversation.com/files/524753/original/file-20230507-15-a372m.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=830&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/524753/original/file-20230507-15-a372m.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=830&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/524753/original/file-20230507-15-a372m.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1043&fit=crop&dpr=1 754w, https://images.theconversation.com/files/524753/original/file-20230507-15-a372m.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1043&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/524753/original/file-20230507-15-a372m.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1043&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Vegemite WWII Advertisement.</span>
<span class="attribution"><span class="source">Australian Women's Weekly, Trove.</span></span>
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</figure>
<p><a href="http://nla.gov.au/nla.news-article1106308">One ad told Australians</a>: </p>
<blockquote>
<p>In all operational areas where our men and those of our Allies are engaged, and in military hospitals, Vegemite is in great demand, because of its value in fighting Vitamin B deficiency diseases. That’s why the fighting forces have first call on all Vegemite produced. And that is why Vegemite is in short supply for civilian consumption. But it won’t always be that way. When the peace is won and our men come home, ample stocks of this extra tasty yeast extract will be available for everyone.</p>
</blockquote>
<p>This clever advertising linked Vegemite with Australian nationalism. Though most could not buy the spread during the rationing years, the idea that Vegemite was vital for the armed forces cemented the idea that Vegemite was fundamentally Australian. </p>
<p>Buying Vegemite was an act of patriotism and a way to support Australian troops overseas. </p>
<h2>Happy little Vegemites</h2>
<p>In the postwar baby boom, Vegemite advertisements responded to concerns about the nation’s health and the need to rebuild a healthy population. </p>
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<p>This emphasis on <a href="http://nla.gov.au/nla.news-article46442748">Vegemite as part of a healthy diet</a> for growing children would remain the key advertising focus of the next 60 years. </p>
<p><a href="https://www.nfsa.gov.au/collection/curated/happy-little-vegemites-jingle-1953">The ear-catching jingle was composed</a> in the early 1950s, first for radio and then later used in the 1959 television ad. </p>
<p>The link between Australian identity and Vegemite was popularised internationally by Men At Work’s 1981 song Down Under, with the lyrics “He just smiled and gave me a Vegemite sandwich”. </p>
<p>The 1980s also saw <a href="https://youtu.be/h5r3HAJh8es">the first remake of the 1950s television campaign</a>, re-colourising it for nostalgic young parents who had grown up with the original. </p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/h5r3HAJh8es?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
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<p>In February 2022, the first international arrivals welcomed back into Australia post-COVID were greeted with a DJ playing Down Under, koala plushies and <a href="https://www.theguardian.com/australia-news/2022/feb/21/today-we-rejoined-the-world-hugs-tears-and-vegemite-as-australia-reopens-international-borders">jars of Vegemite</a>. </p>
<p>On Vegemite’s centenary in 2023, the unassuming spread is now firmly cemented as an Australian cultural icon. Love it or hate it, Vegemite is here to stay. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-why-do-some-people-find-some-foods-yummy-but-others-find-the-same-foods-yucky-77671">Curious Kids: why do some people find some foods yummy but others find the same foods yucky?</a>
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<img src="https://counter.theconversation.com/content/204917/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Hannah Viney works for the Old Treasury Building Museum. This research was originally conducted for an upcoming exhibition at the Museum.</span></em></p>Vegemite first hit Australian supermarket shelves in 1923, but it took a while to find its feet.Hannah Viney, Researcher, Monash UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2034952023-05-03T12:10:09Z2023-05-03T12:10:09ZHow do ‘Candida auris’ and other fungi develop drug resistance? A microbiologist explains<figure><img src="https://images.theconversation.com/files/523473/original/file-20230428-18-9slhum.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2073%2C1368&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Candidiasis is a severe fungal infection that can spread easily in medical facilities.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/8ysD2e">Atlas of Pulmonary Pathology/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>One of the scariest things you can be told when at a doctor’s office is “You have an antimicrobial-resistant infection.” That means the bacteria or fungus making you sick can’t be easily killed with common antibiotics or antifungals, making treatment more challenging. You might have to take a combination of drugs for weeks to overcome the infection, which could result in more severe side effects.</p>
<p>Unfortunately, this diagnosis is <a href="https://www.who.int/publications/i/item/9789240062702">becoming more common around the world</a>.</p>
<p>The yeast <em><a href="https://doi.org/10.1128/jcm.01588-17">Candida auris</a></em> has recently emerged as a potentially dangerous fungal infection for hospital patients and nursing home residents. First <a href="https://doi.org/10.3947%2Fic.2022.0008">discovered in the late 2000s</a>, <em>Candida auris</em> has very quickly become a <a href="https://doi.org/10.3390/microorganisms9040807">major health challenge</a> due to its ease of spread and ability to resist common antifungal drugs.</p>
<p>How did this fungus become so strong, and what can researchers and physicians do to combat it? </p>
<p><a href="https://scholar.google.com/citations?user=U69z9VsAAAAJ&hl=en&oi=ao">I am a microbiologist</a> researching new ways to kill fungi. <em>Candida auris</em> and other fungi use three common cellular tricks to overcome treatments. Luckily, exciting new research hints at ways we can still fight this fungus.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/VOn5Udfx7eQ?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Drug-resistant <em>Candida auris</em> infections are on the rise in the U.S. and around the world.</span></figcaption>
</figure>
<h2>Targeting the sensitive parts of fungal cells</h2>
<p>Fungal cells contain a structure called a <a href="https://doi.org/10.1128/microbiolspec.funk-0035-2016">cell wall</a> that helps maintain their shape and protects them from the environment. Fungal cell walls are constructed in part from several different types of polysaccharides, which are long strings of sugar molecules linked together. </p>
<p>Two polysaccharides found in almost all fungal cell walls are <a href="https://doi.org/10.1016/j.mib.2010.05.002">chitin</a> and <a href="https://doi.org/10.1016/j.tcsw.2019.100022">beta-glucan</a>. The fungal cell wall is an attractive target for drugs because human cells do not have a cell wall, so drugs that block chitin and beta-glucan production will have fewer side effects. </p>
<p>Some of the most common drugs used to treat fungal infections are called <a href="https://doi.org/10.4103%2F0253-7613.62396">echinocandins</a>. These drugs stop fungal cells from making beta-glucan, which significantly weakens their cell wall. This means the fungal cell can’t maintain its shape well. While the fungus is struggling to grow or is breaking apart, your immune system has a much better chance of fighting off the infection. </p>
<h2>How fungi become drug resistant</h2>
<p>Unfortunately, some strains of <em>Candida auris</em> are resistant to echinocandin treatment. But how does the fungus actually do it? For decades, scientists have been studying how fungi overcome drugs designed to weaken or kill them. In the case of echinocandins, <em>Candida auris</em> commonly uses three tricks to beat these treatments: <a href="https://doi.org/10.1128/AAC.00238-18">hide</a>, <a href="https://doi.org/10.1101%2Fcshperspect.a019752">build</a> and <a href="https://doi.org/10.3389/fmicb.2019.02573">change</a>. </p>
<p>The first trick is to hide in a complex mixture of sugars, proteins, DNA and cells <a href="https://doi.org/10.1128/msphere.00458-19">called a biofilm</a>. Made with irregular 3D structures, biofilms have lots of places for cells to hide. Drugs aren’t good at penetrating biofilms, so they can’t access and kill cells deep inside. Biofilms are especially problematic when they <a href="https://doi.org/10.3390/antibiotics4010001">grow on</a> <a href="https://doi.org/10.2147/ijn.s353071">medical equipment</a> like ventilators or catheters. Once free of a biofilm, cells that have gained the ability to resist the drugs a patient was taking become more dangerous.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/523471/original/file-20230428-26-n4nxfs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Microscopy image of two types of Candida attaching to each other" src="https://images.theconversation.com/files/523471/original/file-20230428-26-n4nxfs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/523471/original/file-20230428-26-n4nxfs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/523471/original/file-20230428-26-n4nxfs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/523471/original/file-20230428-26-n4nxfs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/523471/original/file-20230428-26-n4nxfs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/523471/original/file-20230428-26-n4nxfs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/523471/original/file-20230428-26-n4nxfs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=377&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 image shows <em>Candida albicans</em> (red) producing branching filaments that allow it to attach to <em>Candida glabrata</em> (green), forming biofilms. Both of these species can cause infections in people.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/HE7JbY">Edgerton Lab, State University of New York at Buffalo/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>The second trick fungi use to evade treatment is to build cell walls differently. Fungal cells treated with echinocandins can’t make beta-glucan. So instead, they start to <a href="https://doi.org/10.3109/13693786.2011.577104">make more chitin</a>, another important polysaccharide in the fungal cell wall. Echinocandins are unable to stop chitin production, so the fungus is still able to build a strong cell wall and avoid being killed. While there are some drugs that can <a href="https://doi.org/10.3390/jof6040261">stop chitin production</a>, none are currently approved for use in people. </p>
<p>The third trick fungi rely on is to <a href="https://doi.org/10.3389/fmicb.2019.02788">change the shape of the</a> <a href="https://doi.org/10.1093/cid/civ791">beta-glucan production enzyme</a> so echinocandins cannot block it. These mutations allow beta-glucan production to continue even in the presence of the drug. It is not surprising that <em>Candida</em> uses this trick to resist antifungal drugs since it is <a href="https://doi.org/10.1111%2Fnyas.12831">very effective</a> at keeping the cells alive. </p>
<h2>New tactics to fight fungi</h2>
<p>What can be done to treat echinocandin-resistant fungal infections? Thankfully, scientists and physicians are researching new ways to kill <em>Candida auris</em> and similar fungi. </p>
<p>The first approach is to find new drugs. For example, there are two drugs in development, <a href="https://doi.org/10.3390/antibiotics9050227">rezafungin</a> and <a href="https://doi.org/10.4155%2Ffmc-2018-0465">ibrexafungerp</a>, that appear to be able to stop beta-glucan production even in fungi resistant to echinocandins. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/523474/original/file-20230428-14-z7579n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Microscopy image of budding yeast cells" src="https://images.theconversation.com/files/523474/original/file-20230428-14-z7579n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/523474/original/file-20230428-14-z7579n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/523474/original/file-20230428-14-z7579n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/523474/original/file-20230428-14-z7579n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/523474/original/file-20230428-14-z7579n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/523474/original/file-20230428-14-z7579n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/523474/original/file-20230428-14-z7579n.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">This microscopy image shows budding yeast cells.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/budding-yeast-cell-in-gram-stain-royalty-free-image/1464904014">toeytoey2530/iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<p>A complementary approach my research group is exploring is whether a class of enzymes called <a href="https://doi.org/10.1007/s11274-016-2068-6">glycoside hydrolases</a> might also be able to combat drug-resistant fungi. Some of these enzymes actively destroy the fungal cell wall, breaking apart both beta-glucan and chitin at the same time, which could potentially help prevent fungi from surviving on medical equipment or on hospital surfaces.</p>
<p>My lab’s work on discovering enzymes that strongly degrade fungal cell walls is part of a new strategy to combat antifungal resistance that uses a combination of approaches to kill fungi. But the end goal of this research is the same: having a physician tell you, “You’ve got a fungal infection, but we have a good treatment for it now.”</p><img src="https://counter.theconversation.com/content/203495/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jeffrey Gardner receives funding from the National Science Foundation (NSF) and the National Institutes of Health (NIH).</span></em></p>Multidrug-resistant fungal infections are an emerging global health threat. Figuring out how fungi evade treatments offers new avenues to counter resistance.Jeffrey Gardner, Associate Professor of Biological Sciences, University of Maryland, Baltimore CountyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2025732023-04-27T05:16:58Z2023-04-27T05:16:58ZHow we discovered the true origins of a pint of lager – new research<figure><img src="https://images.theconversation.com/files/517440/original/file-20230324-22-nprn5a.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5449%2C3622&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Researchers have uncovered the likely genesis of the yeast used to make lager.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/group-multicultural-friends-drinking-toasting-beer-1957298368">DavidedeAngelini / Shutterstock</a></span></figcaption></figure><p>Despite a surge in interest in craft beers and ales, lager continues to dominate global sales, with <a href="https://www.statista.com/outlook/cmo/alcoholic-drinks/beer/worldwide">more than 150 billion litres</a> consumed around the world every year.</p>
<p>Lager is a beer brewed at low temperatures using yeast that are described as “bottom-fermenting”. Yeast are single-celled fungi used in brewing to <a href="https://en.wikipedia.org/wiki/Brewing">convert maltose to alcohol and carbon dioxide</a>, giving beer its booziness and fizz. They are either top- or bottom-fermenting. </p>
<p>In top fermentation, which occurs at warmer temperatures, the yeast cells collect near the surface of the fermenting liquid. In bottom fermentation, which occurs at cooler temperatures, the yeast is carried to the bottom of the fermenting liquid. Ales (which pre-date lager) have traditionally been made using the top-fermenting yeast species <em>Saccharomyces cerevisiae</em>.</p>
<p>The origins of the bottom-fermenting lager yeast <a href="https://en.wikipedia.org/wiki/Saccharomyces_pastorianus"><em>Saccharomyces pastorianus</em></a> have long been shrouded in mystery and controversy. However, by combining historical research with modern science, a team of scientists from the <a href="https://www.tum.de/en/">Technical University of Munich</a> and <a href="https://www.ucc.ie/en/">University College Cork</a> (including myself) have uncovered the likely genesis – and path to world dominance – of <em>S. pastorianus</em>.</p>
<p>This discovery started with the study of old central European brewing records by the Munich-based scientists Franz Meussdoerffer and Martin Zarnkow. It’s a tale of power, economics, science and innovation – with some sex thrown in for good measure. </p>
<p>But in short, the mating of the yeast species <a href="https://en.wikipedia.org/wiki/Saccharomyces_cerevisiae"><em>S. cerevisiae</em></a> from Bohemia with the Bavarian yeast <em>Saccharomyces eubayanus</em> in Munich at the start of the 17th century gave rise to the first lager yeast strain.</p>
<p>Until now, prevailing wisdom had been that the emergence of bottom fermentation in brewing coincided with the genesis of <em>S. pastorianus</em>. However, among many intriguing discoveries in our new report in the journal <a href="https://academic.oup.com/femsyr/article-lookup/doi/10.1093/femsyr/foad023">FEMS Yeast Research</a> is the finding that bottom fermentation in southern Germany pre-dated the birth of <em>S. pastorianus</em> by at least 200 years.</p>
<figure class="align-center ">
<img alt="Dark beer" src="https://images.theconversation.com/files/519878/original/file-20230406-18-vejhd2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/519878/original/file-20230406-18-vejhd2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/519878/original/file-20230406-18-vejhd2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/519878/original/file-20230406-18-vejhd2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/519878/original/file-20230406-18-vejhd2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/519878/original/file-20230406-18-vejhd2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/519878/original/file-20230406-18-vejhd2.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">At one time, most Bavarian beers were as dark as this one.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/mug-dark-beer-on-brown-background-2265743231">AlekSa Photo / Shutterstock</a></span>
</figcaption>
</figure>
<p>In fact, bottom fermentation originated in northern Bavaria. Not only was it common practice in this part of Germany, but the Bavarian Reinheitsgebot brewing regulations of 1516 only permitted bottom fermentation. Thus, from at least the 16th century onwards, Bavarian brown beer was produced by mixtures of different bottom-fermenting yeast species known as “stellhefen”. </p>
<h2>Exception to the rule</h2>
<p>These mixtures were dominated by yeast that preferred the lower temperatures that prevailed in Bavaria at this time, a hangover from the <a href="https://www.newyorker.com/magazine/2019/04/01/how-the-little-ice-age-changed-history">medieval little ice age</a>. Meanwhile the historic region of Bohemia, to the northeast, was under different political rule. Here, ales – including wheat beer – were produced with a preference for the top-fermenting species <em>S. cerevisiae</em>.</p>
<p>The 1516 Rheinheitsgebot barred Bavarians from brewing wheat beer, which led to a vibrant export market in the wheat-based beverages from Bohemia to Bavaria. This resulted in a loss of income to the Bavarian nobility who controlled brewing. Eventually, in 1548, the nobleman Hans VI von Degenberg was granted the privilege of brewing wheat beer in Bavaria, and his family built a famous wheat brewery in the town of Schwarzach.</p>
<figure class="align-center ">
<img alt="Brewing records." src="https://images.theconversation.com/files/522598/original/file-20230424-25-u53w6r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/522598/original/file-20230424-25-u53w6r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/522598/original/file-20230424-25-u53w6r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/522598/original/file-20230424-25-u53w6r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/522598/original/file-20230424-25-u53w6r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/522598/original/file-20230424-25-u53w6r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/522598/original/file-20230424-25-u53w6r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Researchers found key information in old brewing records from Germany and central Europe.</span>
<span class="attribution"><span class="source">Mathias Hutzler</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>But privileges needed to be protected. When Hans VIII Sigmund von Degenberg, grandson of Hans VI, died without an heir in 1602, his property, including the brewery, was seized by <a href="https://en.wikipedia.org/wiki/Maximilian_I,_Holy_Roman_Emperor">Maximilian I</a>, then duke of Bavaria and later prince-elector of the Holy Roman Empire. Historical records show that on October 24 1602, top-fermenting yeast was brought to the duke’s <a href="https://www.hofbraeu-muenchen.de/en">Hofbräuhaus brewery in Munich</a> where, at the time, the brewing of wheat beer alternated with the making of traditional barley-based Bavarian brown beer.</p>
<h2>Top to bottom</h2>
<p>My colleagues and I propose that, by the time a dedicated wheat beer brewery had opened in 1607, yeasts from within the top-fermenting Schwarzach wheat beer yeast mixture and the bottom-fermenting Munich Hofbräühaus stellhefen had mated, creating the new species we now know as <em>S. pastorianus</em>. Thus, sex in a beer cellar created the direct ancestor of all modern lager yeast strains. </p>
<p>This theory is consistent with published genetic evidence showing that the <em>S. cerevisiae</em> parent of <em>S. pastorianus</em> was closer to ones used to brew wheat beer than strains used for barley-based ale.</p>
<figure class="align-center ">
<img alt="Rock cellar in Franconia." src="https://images.theconversation.com/files/522599/original/file-20230424-14-lv4tj0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/522599/original/file-20230424-14-lv4tj0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/522599/original/file-20230424-14-lv4tj0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/522599/original/file-20230424-14-lv4tj0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/522599/original/file-20230424-14-lv4tj0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/522599/original/file-20230424-14-lv4tj0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/522599/original/file-20230424-14-lv4tj0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">One of the rock cellars in Franconia where bottom fermentation was established in the 14th and 15th centuries.</span>
<span class="attribution"><span class="source">Mathias Hutzler</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>That is not the end of the story, however. Two hundred years later, in 1806, the recruitment by the Munich Hofbräuhaus of a new master brewer, Gabriel Sedlmayr the Elder, transformed the world of beer forever. </p>
<p>Although Sedlmayr resigned and purchased the <a href="https://en.wikipedia.org/wiki/Spatenbr%C3%A4u">Oberspatenbräu</a> brewery after only a year, he took yeast mixtures with him and established a very successful brewing system based on technological innovation and links to local academics.</p>
<p>Later known as the Späten breweries, the enterprise begun by Sedlmayr became a centre of excellence that attracted brewers from all over Europe, who returned home with the Munich technology – and its yeasts. Among them was <a href="https://en.wikipedia.org/wiki/J._C._Jacobsen">J.C. Jacobsen</a>, founder of the Carlsberg brewery, who took the Munich stellhefen back to Denmark’s capital Copenhagen in 1845. </p>
<p>It was there, in 1883, that Emil Christian Hansen isolated the first pure strains of <em>S. pastorianus</em>. Jacobsen and Hansen of the Carlsberg brewery, Gabriel Sedlmayr the Younger, and Luis Aubry, a brewing scientist and microbiologist at the Munich Research Station, shared a friendship based on a passion for beer and progress. This contributed to some fertile scientific and technological exchanges between them.</p>
<p>Not long afterwards, the <a href="https://en.wikipedia.org/wiki/Paul_Lindner">German scientist Paul Lindner</a>, working at the Berlin Institute, <a href="https://books.google.co.uk/books/about/Mikroskopische_Betriebskontrolle_in_den.html?id=1VFIAAAAYAAJ&redir_esc=y">also isolated</a> <em>S. pastorianus</em> from mixtures derived originally from the Späten breweries, which were now in wide circulation among Munich breweries. </p>
<p>All modern lineages of <em>S. pastorianus</em> can be traced to the work of Hansen and Lindner, and so are ultimately descended from the Hofbräuhaus stellhefen. </p>
<p>Further intrigue followed, including bitter inter-brewery rivalries and heated academic debates about the evolutionary relationships between different strains. But for now, we can rest happy in the knowledge that a crucial missing piece has been found in the account of how the pint of lager was born.</p><img src="https://counter.theconversation.com/content/202573/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>John Morrissey receives research funding from the European Union, Science Foundation Ireland and Enterprise Ireland.</span></em></p>Little-known documents and scientific detective work helped pinpoint the origin of lager.John Morrissey, Lecturer in Microbiology, University College CorkLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2030962023-04-05T13:53:51Z2023-04-05T13:53:51ZEaster bunnies, cacao beans and pollinating bugs: A basket of 6 essential reads about chocolate<figure><img src="https://images.theconversation.com/files/519391/original/file-20230404-14-reloqo.jpg?ixlib=rb-1.1.0&rect=422%2C0%2C4914%2C3173&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Easter has its bunnies, but chocolate comes out for every holiday.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/chocolate-bunny-family-royalty-free-image/177875356">garytog/iStock via Getty Images Plus</a></span></figcaption></figure><p><a href="https://www.insider.com/surprising-easter-fun-facts-stats-2019-4#as-many-as-91-million-chocolate-bunnies-are-sold-in-the-us-for-easter-annually-8">Tens of millions of chocolate bunnies</a> get sold in the U.S. every Easter. Here are six articles about chocolate from The Conversation’s archive – great reading while you’re nibbling the ears off your own bunny (if you’re one of the <a href="https://www.insider.com/surprising-easter-fun-facts-stats-2019-4#as-many-as-78-of-americans-eat-the-ears-of-their-chocolate-bunny-first-11">three-quarters of Americans who start</a> at the top).</p>
<h2>1. Food scientist on cocoa chemistry</h2>
<p>Chocolate bunnies don’t grow on trees – but cacao pods do. It takes a lot of processing to get from the raw agricultural input to the finished output.</p>
<p>Food scientist <a href="https://scholar.google.com/citations?user=5iZjEckAAAAJ&hl=en&oi=ao">Sheryl Barringer</a> from The Ohio State University wrote about various chemical reactions that are part of the transformation of beans into chocolate. One is the Maillard reaction, the same thing that gives the browned bits on roasted meats or a bread’s golden crust their flavor. <a href="https://theconversation.com/chocolate-chemistry-a-food-scientist-explains-how-the-beloved-treat-gets-its-flavor-texture-and-tricky-reputation-as-an-ingredient-198222">Barringer also explains that weird white stuff</a> – known as bloom – that might appear on your Easter chocolates if they hang around for a while. (Don’t worry, it’s still edible.)</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/chocolate-chemistry-a-food-scientist-explains-how-the-beloved-treat-gets-its-flavor-texture-and-tricky-reputation-as-an-ingredient-198222">Chocolate chemistry – a food scientist explains how the beloved treat gets its flavor, texture and tricky reputation as an ingredient</a>
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<h2>2. Chocolate is a fermented food</h2>
<p>Food science Ph.D. candidate <a href="https://scholar.google.com/citations?user=QjIM6yUAAAAJ&hl=en&oi=ao">Caitlin Clark</a> from Colorado State University focuses her research on the microbes responsible for much of chocolate’s flavor. As a fermented food, chocolate depends on yeast and bacteria to help turn a raw ingredient into the treat you can recognize.</p>
<p>Clark described how the microorganisms that occur naturally in a given geographical location can give high-end chocolates their “terroir” – “<a href="https://theconversation.com/chocolates-secret-ingredient-is-the-fermenting-microbes-that-make-it-taste-so-good-155552">the characteristic flair imparted by a place</a>” you might be more used to thinking about with regard to wine.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/chocolates-secret-ingredient-is-the-fermenting-microbes-that-make-it-taste-so-good-155552">Chocolate's secret ingredient is the fermenting microbes that make it taste so good</a>
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<hr>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/519395/original/file-20230404-2112-yh79aj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Cacao pods and flowers on branch tree close up" src="https://images.theconversation.com/files/519395/original/file-20230404-2112-yh79aj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/519395/original/file-20230404-2112-yh79aj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/519395/original/file-20230404-2112-yh79aj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/519395/original/file-20230404-2112-yh79aj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/519395/original/file-20230404-2112-yh79aj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/519395/original/file-20230404-2112-yh79aj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/519395/original/file-20230404-2112-yh79aj.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">Tiny flies spread pollen from one cacao tree to another.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/cacao-pods-and-flower-on-branch-royalty-free-image/1165785501">dimarik/iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<h2>3. Pollinators are important part of process</h2>
<p>Cacao growers rely on another tiny ally to pollinate their crop. Entomologist <a href="https://scholar.google.com/citations?hl=en&user=qvmWZYwAAAAJ">DeWayne Shoemaker</a> from the University of Tennessee described the mini flies – particularly biting midges and gall midges – that get the job done. “Pollinators must pick up pollen from the male parts of a flower of one tree and deposit it on the female parts of a flower on another tree,” Shoemaker wrote.</p>
<p>But up to <a href="https://theconversation.com/tiny-cacao-flowers-and-fickle-midges-are-part-of-a-pollination-puzzle-that-limits-chocolate-production-154334">90% of cacao flowers don’t get pollinated</a> at all. People can hand-pollinate the little flowers, but it remains a mystery which other insects might do the job in the wild.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/tiny-cacao-flowers-and-fickle-midges-are-part-of-a-pollination-puzzle-that-limits-chocolate-production-154334">Tiny cacao flowers and fickle midges are part of a pollination puzzle that limits chocolate production</a>
</strong>
</em>
</p>
<hr>
<h2>4. Child labor is chocolate’s bitter secret</h2>
<p>Harvesting and processing cacao is labor-intensive. To meet this need, some farmers turn to child labor. Cultural anthropologist <a href="https://scholar.google.com/citations?user=1ErMxzgAAAAJ&hl=en&oi=ao">Robert Ulin</a> from the Rochester Institute of Technology described how the global chocolate industry is tied to inequality via exploitative labor practices.</p>
<p>“The largest chocolate companies signed a protocol in 2001 that <a href="https://theconversation.com/some-chocolate-has-a-dark-side-to-it-child-labor-179271">condemned child labor and childhood slavery</a>,” Ulin wrote. But he noted that consumers may want more information to make sure their purchase power supports “fair labor practices in the chocolate sector.” </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/some-chocolate-has-a-dark-side-to-it-child-labor-179271">Some chocolate has a dark side to it – child labor</a>
</strong>
</em>
</p>
<hr>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/519398/original/file-20230404-18-7hqbi6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Dog and woman, both with Easter bunny ears on" src="https://images.theconversation.com/files/519398/original/file-20230404-18-7hqbi6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/519398/original/file-20230404-18-7hqbi6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/519398/original/file-20230404-18-7hqbi6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/519398/original/file-20230404-18-7hqbi6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/519398/original/file-20230404-18-7hqbi6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/519398/original/file-20230404-18-7hqbi6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/519398/original/file-20230404-18-7hqbi6.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">Do not share your chocolates with your pooch.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/dog-and-woman-with-costume-and-easter-decorations-royalty-free-image/1359250422">F.J. Jimenez/Moment via Getty Images</a></span>
</figcaption>
</figure>
<h2>5. Not safe for furry family members</h2>
<p>Eating a ton of chocolate is probably not a healthy choice for anyone. But even a little bit of chocolate can be deadly for dogs and cats. </p>
<p>In an article about all kinds of holiday foods that are unsafe for pets, veterinarian and researcher <a href="https://experts.okstate.edu/le.fanucchi">Leticia Fanucchi</a> from Oklahoma State University explained the chemicals in this human delicacy that can cause fatal “<a href="https://theconversation.com/holiday-foods-can-be-toxic-to-pets-a-veterinarian-explains-which-and-what-to-do-if-rover-or-kitty-eats-them-196453">chocolate intoxication</a>.” Don’t delay getting veterinary help if your pet does raid your Easter basket.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/holiday-foods-can-be-toxic-to-pets-a-veterinarian-explains-which-and-what-to-do-if-rover-or-kitty-eats-them-196453">Holiday foods can be toxic to pets – a veterinarian explains which, and what to do if Rover or Kitty eats them</a>
</strong>
</em>
</p>
<hr>
<h2>6. An enslaved chocolatier in colonial America</h2>
<p>An enslaved cook named Caesar, born in 1732, was one of the first chocolatiers in the American colonies. Historical archaeologist <a href="https://berkeley.academia.edu/KelleyFantoDeetz">Kelley Fanto Deetz</a> from the University of California, Berkeley described how Caesar “would have had to <a href="https://theconversation.com/oppression-in-the-kitchen-delight-in-the-dining-room-the-story-of-caesar-an-enslaved-chef-and-chocolatier-in-colonial-virginia-151356">roast the cocoa beans on the open hearth</a>, shell them by hand, grind the nibs on a heated chocolate stone, and then scrape the raw cocoa, add milk or water, cinnamon, nutmeg or vanilla, and serve it piping hot.”</p>
<p>Cocoa was a hot commodity for Virginia’s white elite during this period, when it was a culinary component – along with pineapples, Madeira wine, port, champagne, coffee and sugar – of the Columbian Exchange.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/oppression-in-the-kitchen-delight-in-the-dining-room-the-story-of-caesar-an-enslaved-chef-and-chocolatier-in-colonial-virginia-151356">Oppression in the kitchen, delight in the dining room: The story of Caesar, an enslaved chef and chocolatier in Colonial Virginia</a>
</strong>
</em>
</p>
<hr>
<p><em>Editor’s note: This story is a roundup of articles from The Conversation’s archives.</em></p><img src="https://counter.theconversation.com/content/203096/count.gif" alt="The Conversation" width="1" height="1" />
Two food scientists, an entomologist, an anthropologist, a veterinarian and a historian walk into a bar (of chocolate) and tell bitter and sweet stories of this favorite treat.Maggie Villiger, Senior Science + Technology EditorLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2024932023-03-29T12:01:41Z2023-03-29T12:01:41ZCandida auris: what you need to know about the deadly fungus spreading through US hospitals<p>A fungal superbug called <em>Candida auris</em> is spreading rapidly through hospitals and nursing homes in the US. The first case was identified in 2016. Since then, it has spread to <a href="https://www.cdc.gov/fungal/candida-auris/tracking-c-auris.html">half the country’s 50 states</a>. And, according to a <a href="https://www.acpjournals.org/doi/10.7326/M22-3469">new report</a>, infections tripled between 2019 and 2021. This is hugely concerning because <em>Candida auris</em> is resistant to many drugs, making this fungal infection one of the hardest to treat.</p>
<p><em>Candida auris</em> is a yeast-type fungus that is the first to have multiple international health alerts associated with it. It has been found in <a href="https://www.cdc.gov/fungal/candida-auris/candida-auris-qanda.html#:%7E:text=C.%20auris%20infections%20have%20been,countries%2C%20including%20the%20United%20States.">over 30 countries</a>, including the UK, since it was first identified in Japan in 2009.</p>
<p>It is related to other types of yeast that can cause infections, like <em>Candida albicans</em> which causes thrush. However, <em>Candida auris</em> is very different to these other fungi and in some ways, highly unusual.</p>
<p>First, it can grow, or “<a href="https://pubmed.ncbi.nlm.nih.gov/33385336/">colonise</a>”, human skin. Unlike many other Candida species that like to grow in our guts as part of the microbiome, <em>Candida auris</em> does not grow in this environment and <a href="https://pubmed.ncbi.nlm.nih.gov/33385336/">seems to prefer the skin</a>. This means that people who are colonised with <em>Candida auris</em> can shed lots of yeast from their skin, and this <a href="https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1008563">contaminates bed clothes and surfaces</a> with the fungus. This can lead to outbreaks.</p>
<p>It is unusual for a fungal infection to spread from person to person, but that seems to be how <em>Candida auris</em> infections spread. Outbreaks can happen with this fungus, especially in intensive care units (ICU) and nursing homes where people are at a higher risk for getting fungal infections generally. </p>
<p>The fungus can live on surfaces for <a href="https://www.cdc.gov/fungal/candida-auris/c-auris-drug-resistant.html">several weeks</a>, and getting rid of it can be difficult. <a href="https://www.gov.uk/government/publications/candida-auris-infection-control-in-community-care-settings">Enhanced cleaning and hand washing</a> is needed to try and limit the spread of the fungus and exposure to patients who get ill from it. </p>
<p>Most people who are colonised with <em>Candida auris</em> will not get ill from it, or even know it is there. It <a href="https://www.gov.uk/government/publications/candida-auris-a-guide-for-patients-and-visitors">causes infections</a> when it gets into surgical wounds or the blood from an intravenous line. Once it gets into the body, it can infect organs and the blood causing a very serious and potentially fatal disease. </p>
<p>The <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9344200/">mortality rate</a> for people infected (as opposed to colonised) with the fungus is between 30 and 60%. But a precise mortality rate can be hard to pin down as people who are infected are often critically ill with other conditions.</p>
<p>Diagnosing an infection can be difficult as there can be a <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7211321/#S0004title">wide range of symptoms</a> including fever, chills, headaches and nausea. It is for this reason that we need to keep a close eye on <em>Candida auris</em> as it can easily be confused with other conditions. </p>
<p>In the last few years, new tests to help identify this fungus accurately have been developed.</p>
<figure class="align-center ">
<img alt="A healthcare professional putting an IV line in the back of a patient's hand." src="https://images.theconversation.com/files/517943/original/file-20230328-480-mklbx5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/517943/original/file-20230328-480-mklbx5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/517943/original/file-20230328-480-mklbx5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/517943/original/file-20230328-480-mklbx5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/517943/original/file-20230328-480-mklbx5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/517943/original/file-20230328-480-mklbx5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/517943/original/file-20230328-480-mklbx5.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">Candida auris can get into the body via an infected IV line.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/cropped-image-female-nurse-attaching-iv-224584333">Tyler Olson/Shutterstock</a></span>
</figcaption>
</figure>
<p>The first <em>Candida auris</em> infection was reported in the UK in 2013. However, there may have been other cases before this – there is evidence that some early cases were <a href="https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1008563">misidentified</a> as unrelated yeasts.</p>
<p>The UK has so far managed to stop any major outbreaks, and most cases have been <a href="https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1008563">limited in their spread</a>. </p>
<p>Most patients who have become ill from <em>Candida auris</em> in the UK had recently travelled to parts of the world where the fungus is <a href="https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1008563">more common or has been circulating for longer</a>. </p>
<h2>Spurred by COVID</h2>
<p>Rising numbers of <em>Candida auris</em> infections are thought to be partially linked to the COVID pandemic. People who become very ill from COVID may need mechanical ventilation and long stays in the ICU, which are both <a href="https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1008563">risk factors</a> for <em>Candida auris</em> colonisation and infection. </p>
<p>It will take some time to figure out exactly how the pandemic has affected rates and numbers of fungal infections around the world, but these are important questions to answer to help predict how <em>Candida auris</em> cases might fluctuate in the future.</p>
<p>As for most life-threatening fungal infections, treatment is difficult and limited. We have only a handful of antifungal drugs to fight these infections, so when a species is resistant to one or more of these drugs, the options for treatment are extremely limited. Some <em>Candida auris</em> infections are resistant to <a href="https://www.cdc.gov/fungal/candida-auris/c-auris-drug-resistant.html#:%7E:text=It%20can%20spread%20in%20hospitals,on%20surfaces%20for%20several%20weeks.">all three types of antifungal drug</a>. </p>
<p>Healthcare professionals must remain vigilant to this drug-resistant fungus. Without close monitoring and enhanced awareness of this infection, we could see more outbreaks and serious disease associated with <em>Candida auris</em> in the future.</p><img src="https://counter.theconversation.com/content/202493/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rebecca A. Drummond receives funding from the Medical Research Council. </span></em></p>A drug-resistant fungus is a threat to human health.Rebecca A. Drummond, Associate Professor, Immunology and Immunotherapy, University of BirminghamLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2002242023-02-23T21:32:26Z2023-02-23T21:32:26ZThe fungus zombies in ‘The Last of Us’ are fictional, but real fungi can infect people, and they’re becoming more resistant<figure><img src="https://images.theconversation.com/files/511892/original/file-20230223-22-69v4bj.jpeg?ixlib=rb-1.1.0&rect=250%2C14%2C1667%2C1063&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">In the HBO series ‘The Last of Us,’ the parasitic fungus cordyeps mutates, and jumps from insects to humans and quickly spreads around the world, rendering its victims helpless to control their thoughts and actions.</span> <span class="attribution"><span class="source">(HBO)</span></span></figcaption></figure><p>Many of the people watching <a href="https://www.hbo.com/the-last-of-us"><em>The Last of Us</em></a> are likely there for the zombies.</p>
<p>I love the zombies too, but I’m really there for the fungus.</p>
<p>I’ve been studying fungi since my PhD work in the 1980s, and I grow more fascinated by these amazing organisms with every passing year.</p>
<p>In the HBO series and the <a href="https://www.playstation.com/en-ca/games/the-last-of-us-part-i/">video game that inspired it</a>, a parasitic fungus — a fictitious mutation of the <a href="https://www.nationalgeographic.com/animals/article/cordyceps-zombie-fungus-takes-over-ants">very real cordyceps</a> — jumps from insects to humans and quickly spreads around the world, rendering its victims helpless to control their thoughts and actions. Far-fetched fungal fear-mongering? It’s definitely fictional, but maybe not as preposterous as it might seem.</p>
<h2>Fascinating fungi</h2>
<p>From microscopic mould spores to <a href="https://www.scientificamerican.com/article/strange-but-true-largest-organism-is-fungus/">kilometres-long mycelium</a> under the forest floor, members of this distinct biological kingdom — neither plant nor animal — are incredible, and highly worthy of more attention.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/512053/original/file-20230223-16-mssl7i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An ant with fungal growths growing from its head and abdomen, on a green leaf" src="https://images.theconversation.com/files/512053/original/file-20230223-16-mssl7i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/512053/original/file-20230223-16-mssl7i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/512053/original/file-20230223-16-mssl7i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/512053/original/file-20230223-16-mssl7i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/512053/original/file-20230223-16-mssl7i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/512053/original/file-20230223-16-mssl7i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/512053/original/file-20230223-16-mssl7i.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">An ant infected with parasitic cordyceps fungus.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>Most of us may not think about them beyond the mushroom slices on our pizza, but fungi figure prominently in our everyday lives. Do you eat bread? Thank <a href="https://www.britannica.com/science/yeast-fungus">the fungus we call yeast</a>. Do you enjoy beer, wine or whisky? Raise a glass to your <a href="https://doi.org/10.3390%2Fmicroorganisms8081142">fungal friends responsible for the fermentation</a> that brings them to life.</p>
<p>Every time a round of antibiotics helps you recover from some form of infection, remember that <a href="https://www.acs.org/education/whatischemistry/landmarks/flemingpenicillin.html">a mould gave us the compounds that became penicillin</a> and its many derivatives.</p>
<p>Fungi are incredible chemists. They make many compounds that humans cannot easily replicate in the lab. Some make compounds that can affect behaviour. </p>
<p>Look at <a href="https://www.camh.ca/en/health-info/mental-illness-and-addiction-index/lsd">lysergic acid diethylamide</a>, commonly known as LSD, or “acid.” Its well-known psychedelic effects originate from a grain mould. Similarly, “magic” mushrooms are the source of <a href="https://www.canada.ca/en/health-canada/services/substance-use/controlled-illegal-drugs/magic-mushrooms.html">psilocybin</a>. LSD and magic mushrooms are both illegal recreational drugs but are also under study for their therapeutic value.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/albertas-new-policy-on-psychedelic-drug-treatment-for-mental-illness-will-canada-lead-the-psychedelic-renaissance-195061">Alberta’s new policy on psychedelic drug treatment for mental illness: Will Canada lead the psychedelic renaissance?</a>
</strong>
</em>
</p>
<hr>
<h2>Fungal infections</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/511900/original/file-20230223-2553-wdgm71.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Pink flower-like blooms on translucent stems" src="https://images.theconversation.com/files/511900/original/file-20230223-2553-wdgm71.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/511900/original/file-20230223-2553-wdgm71.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=566&fit=crop&dpr=1 600w, https://images.theconversation.com/files/511900/original/file-20230223-2553-wdgm71.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=566&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/511900/original/file-20230223-2553-wdgm71.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=566&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/511900/original/file-20230223-2553-wdgm71.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=711&fit=crop&dpr=1 754w, https://images.theconversation.com/files/511900/original/file-20230223-2553-wdgm71.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=711&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/511900/original/file-20230223-2553-wdgm71.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=711&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Microscopic image of the fungus Aspergillus fumigatus.</span>
<span class="attribution"><span class="source">(CDC)</span></span>
</figcaption>
</figure>
<p>Fungi also have an aggressive side. Apart from breaking down dead plants and animals, some forms attack living creatures, including humans. Whole pharmacy shelves are stocked with remedies for <a href="https://www.cdc.gov/healthywater/hygiene/disease/athletes_foot.html">athlete’s foot</a>, <a href="https://www.cdc.gov/fungal/diseases/candidiasis/index.html">yeast infections</a> and <a href="https://www.cdc.gov/fungal/diseases/ringworm/treatment.html">jock itch</a>, all of them nasty fungal infections. Even <a href="https://doi.org/10.1016/j.jaad.2004.10.211">dandruff is caused by a fungus</a>.</p>
<p>Yet while we can access an array of medications to cure bacterial infections such as pneumonia and strep throat, there are only <a href="https://www.healthline.com/health/fungal-infection/antifungal">four known compounds</a> available to rid ourselves of fungal infections. Three are available in the various over-the-counter powders, sprays and ointments we use to treat common fungal infections. </p>
<p>The fourth and newest class, echinocandins, is reserved for hospital settings, where the consequences of fungal infections can be deadly.</p>
<p><a href="https://www.thewrightlab.com/">My team’s research lab</a> at McMaster is part of the university’s broader <a href="https://globalnexus.mcmaster.ca/">Global Nexus for Pandemics and Biological Threats</a>, and also works with the global research organization CIFAR’s <a href="https://cifar.ca/research-programs/fungal-kingdom/">Fungal Kingdom: Threats and Opportunities</a> program. </p>
<p>We are working to find ways to limit the potential harm humans face from fungal infections. We also seek to understand how we can use their abundant and as-yet barely tapped potential to make new antibiotics <a href="https://theconversation.com/antibiotic-resistant-infections-could-destroy-our-way-of-life-new-report-126670">before we lose the waning power of penicillin and its derivatives</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/future-infectious-diseases-recent-history-shows-we-can-never-again-be-complacent-about-pathogens-177746">Future infectious diseases: Recent history shows we can never again be complacent about pathogens</a>
</strong>
</em>
</p>
<hr>
<h2>Fungi adapt and evolve</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/512055/original/file-20230223-28-etvxfk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Blue organisms growing from a translucent stalk" src="https://images.theconversation.com/files/512055/original/file-20230223-28-etvxfk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/512055/original/file-20230223-28-etvxfk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=414&fit=crop&dpr=1 600w, https://images.theconversation.com/files/512055/original/file-20230223-28-etvxfk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=414&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/512055/original/file-20230223-28-etvxfk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=414&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/512055/original/file-20230223-28-etvxfk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=520&fit=crop&dpr=1 754w, https://images.theconversation.com/files/512055/original/file-20230223-28-etvxfk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=520&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/512055/original/file-20230223-28-etvxfk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=520&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Microscopic image of the fungal organism, Epidermophyton floccosum, which is a cause of infections such as athlete’s foot and jock itch.</span>
<span class="attribution"><span class="source">(CDC/Libero Ajello)</span></span>
</figcaption>
</figure>
<p>I was first attracted to fungus research as a student about to begin my PhD studies about 35 years ago. At that time, <a href="https://www.hiv.gov/hiv-basics/overview/history/hiv-and-aids-timeline">HIV-AIDS was still emerging</a>, shutting down the immune systems of otherwise healthy people, leaving them vulnerable to opportunistic infections, <a href="https://www.cdc.gov/fungal/infections/hiv-aids.html">including fungal infections</a>.</p>
<p>I wanted to understand more about how fungi worked.</p>
<p>Like bacteria and viruses, fungi are always evolving and adapting, <a href="https://www.who.int/news/item/25-10-2022-who-releases-first-ever-list-of-health-threatening-fungi">finding ways to survive under hostile conditions</a>. We are seeing many forms of fungi adapting to live at ever-higher temperatures, including body temperature, which has long been humans’ first line of defence.</p>
<p>We are also seeing growing antimicrobial resistance among some causes of fungal infection, yeasts such as <a href="https://cifar.ca/cifarnews/2019/04/30/tackling-a-global-superbug/">Candida auris</a> and moulds such as <a href="https://www.cdc.gov/fungal/diseases/aspergillosis/index.html">Aspergillus</a>, both of which can be causes of in-hospital infections.</p>
<h2>Potential for a fungal pandemic</h2>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/E5tSO9aR2Ds?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">In the HBO Max drama ‘The Last of Us,’ a fungal infection turns its victims into fungus-sprouting zombies.</span></figcaption>
</figure>
<p>While <em>The Last of Us</em> is a strictly dramatic projection of what might happen in a deadly fungal outbreak, it is at least based, if not in reality, in logic.</p>
<p>Fungi are able to influence perceptions and behaviour through chemistry. Are they getting closer? You bet. Do they make zombies? Not that we know of, but the thought is darkly entertaining, and that keeps me watching.</p>
<p>The show does do an excellent service by reminding us that we need to adapt to stay ahead of the possibility of a fungal pandemic.</p>
<p>In the same way the movie <em><a href="https://mediashift.org/2017/04/reading-presidents-men-age-trump/">All The President’s Men</a></em> once inspired a generation of journalists, and <em><a href="https://news.harvard.edu/gazette/story/2012/10/the-paper-chase-at-40/">The Paper Chase</a></em> later channelled many eager students toward law school, I am hopeful that <em>The Last of Us</em> may trigger new interest in studying fungi.</p>
<p>The more minds we can focus on unlocking the true magic in mushrooms, the better off we’ll all be.</p><img src="https://counter.theconversation.com/content/200224/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gerry Wright receives funding for antifungal research from the Canadian Institutes of Health Research and the Canadian Institute for the Advanced Research and is a consultant for Kapoose Creek, a Canadian biotechnology firm.</span></em></p>While ‘The Last of Us’ is a dramatic projection of a deadly fungal outbreak, it is based, if not in reality, in logic. And it’s a reminder that fungal infections are growing more resistant.Gerry Wright, Professor of Biochemistry and Biomedical Sciences, McMaster UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1897622022-10-02T11:38:23Z2022-10-02T11:38:23ZStudying yeast DNA in space may help protect astronauts from cosmic radiation<figure><img src="https://images.theconversation.com/files/487384/original/file-20220929-18-qzo2y7.jpg?ixlib=rb-1.1.0&rect=0%2C55%2C4096%2C4034&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The atmosphere protects life on Earth from the effects of the Sun's radiation, but space travel is a different matter.</span> <span class="attribution"><a class="source" href="https://www.nasa.gov/content/holiday-lights-on-the-sun-imagery-of-a-solar-flare">(NASA/SDO)</a></span></figcaption></figure><p><a href="https://phys.org/news/2015-12-sun-energy.html">Nuclear fusion reactions in the sun</a> are the source of heat and light we receive on Earth. These reactions release a massive amount of cosmic radiation — including x-rays and gamma rays — and charged particles that can be harmful for any living organisms. </p>
<p><a href="https://www.epa.gov/radtown/cosmic-radiation">Life on Earth has been protected</a> thanks to a magnetic field that forces charged particles to bounce from pole to pole as well as an atmosphere that filters harmful radiation. </p>
<p>During space travel, however, it is a different situation. To find out what happens in a cell when travelling in outer space, scientists are sending <a href="https://www.nasa.gov/mission_pages/station/research/news/Micro_4.html">baker’s yeast to the moon as part of NASA’s Artemis 1 mission</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/artemis-1-how-this-2022-lunar-mission-will-pave-the-way-for-a-human-return-to-the-moon-173130">Artemis 1: how this 2022 lunar mission will pave the way for a human return to the Moon</a>
</strong>
</em>
</p>
<hr>
<h2>Cosmic damage</h2>
<p>Cosmic radiation can damage cell DNA, significantly increasing human risk of <a href="https://doi.org/10.3389/fphy.2020.00362">neurodegenerative disorders</a> and fatal diseases, like cancer. Because the International Space Station (ISS) is located in one of two of Earth’s <a href="https://www.britannica.com/science/Van-Allen-radiation-belt">Van Allen radiation belts</a> — which provides a safe zone — astronauts are not exposed too much. Astronauts in the ISS experience microgravity, however, which is another stress that can <a href="https://doi.org/10.1126/science.aau8650">dramatically change cell physiology</a>. </p>
<p>As NASA is planning to send astronauts to the moon, and <a href="https://www.nasa.gov/sites/default/files/atoms/files/moon-investments-prepare-us-for-mars.pdf">later on to Mars</a>, these environmental stresses become more challenging. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/twins-in-space-how-space-travel-affects-gene-expression-107936">Twins in space: How space travel affects gene expression</a>
</strong>
</em>
</p>
<hr>
<p>The most common strategy to protect astronauts from the negative effects of cosmic rays is <a href="https://blogs.esa.int/orion/2019/04/08/shielding-astronauts-from-space-radiation-on-the-way-to-the-moon/">to physically shield them using state-of-the-art materials</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/487382/original/file-20220929-14-wf0mco.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="two astronauts suiting up" src="https://images.theconversation.com/files/487382/original/file-20220929-14-wf0mco.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/487382/original/file-20220929-14-wf0mco.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/487382/original/file-20220929-14-wf0mco.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/487382/original/file-20220929-14-wf0mco.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/487382/original/file-20220929-14-wf0mco.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/487382/original/file-20220929-14-wf0mco.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/487382/original/file-20220929-14-wf0mco.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">Technicians practice putting on Self-Contained Atmospheric Protective Ensemble (SCAPE) suits, which are designed to shield them from environmental stressors in space.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/image-feature/scape-operators-prepare-for-artemis-1">(NASA/Isaac Watson)</a></span>
</figcaption>
</figure>
<h2>Lessons from hibernation</h2>
<p>Several studies show that hibernators <a href="https://doi.org/10.1007/978-94-007-6488-0_10">are more resistant to high doses of radiation</a>, and some scholars have suggested the use of “<a href="https://www.euronews.com/next/2021/06/08/sleeping-with-the-fishes-how-hibernating-zebrafish-could-help-you-survive-the-journey-to-m">synthetic or induced torpor</a>” during space missions to protect astronauts. </p>
<p>Another way to protect life from cosmic rays is studying extremophiles — <a href="https://doi.org/10.3389/fmicb.2019.00780">organisms that can remarkably tolerate environmental stresses</a>. Tardigrades, for instance, are micro-animals that have shown an astonishing resistance to a number of stresses, including <a href="https://doi.org/10.1038/27576">harmful radiation</a>. This unusual sturdiness stems from a class of proteins known as “<a href="https://doi.org/10.1016/j.molcel.2017.02.018">tardigrade-specific proteins</a>.”</p>
<p><a href="https://www.ggcnlab.com/">Under the supervision of molecular biologist Corey Nislow</a>, I use baker’s yeast, <em>Saccharomyces cerevisiae</em>, to study cosmic DNA damage stress. We are participating in NASA’s Artemis 1 mission, where our collection of yeast cells will travel to the moon and back in the Orion spacecraft for 42 days.</p>
<p>This collection contains about 6,000 bar-coded strains of yeast, where in each strain, one gene is deleted. When exposed to the environment in space, those strains would begin to lag if deletion of a specific gene affects cell growth and replication.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/487380/original/file-20220929-24-ontc5y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a slide image of a tardigrade, a micro-animal with six legs and mouth parts" src="https://images.theconversation.com/files/487380/original/file-20220929-24-ontc5y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/487380/original/file-20220929-24-ontc5y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=367&fit=crop&dpr=1 600w, https://images.theconversation.com/files/487380/original/file-20220929-24-ontc5y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=367&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/487380/original/file-20220929-24-ontc5y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=367&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/487380/original/file-20220929-24-ontc5y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=461&fit=crop&dpr=1 754w, https://images.theconversation.com/files/487380/original/file-20220929-24-ontc5y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=461&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/487380/original/file-20220929-24-ontc5y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=461&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Tardigrade DNA may help increase resilience for other organisms.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>My primary project at Nislow lab is genetically engineering yeast cells to make them express tardigrade-specific proteins. We can then study how those proteins can alter the physiology of cells and their resistance to environmental stresses — most importantly radiation — with the hope that such information would come in handy when scientists try to engineer mammals with these proteins. </p>
<p>When the mission is completed and we receive our samples back, using the barcodes, the number of each strain could be counted to identify genes and gene pathways essential for surviving damage induced by cosmic radiation. </p>
<h2>A model organism</h2>
<p>Yeast has long served as a “model organism” in DNA damage studies, which means there is solid background knowledge about the mechanisms in yeast that respond to DNA-damaging agents. Most of the yeast genes playing roles in DNA damage response have been well studied. </p>
<p>Despite the differences in genetic complexity between yeast and humans, the function of most genes involved in DNA replication and DNA damage response have remained so conserved between the two that we can obtain a great deal of information about human cells’ DNA damage response by studying yeast. </p>
<p>Furthermore, the simplicity of yeast cells compared to human cells (yeast has 6,000 genes while we have more than 20,000 genes) allows us to draw more solid conclusions. </p>
<p>And in yeast studies, it is possible to automate the whole process of feeding the cells and stopping their growth in an electronic apparatus the size of a shoe box, whereas culturing mammalian cells requires more room in the spacecraft and far more complex machinery. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1558921292228747264"}"></div></p>
<p>Such studies are essential to understand how astronauts’ bodies can cope with long-term space missions, and to develop effective countermeasures. Once we identify the genes playing key roles in surviving cosmic radiation and microgravity, we’d be able to look for drugs or treatments that could help boost the cells’ durability to withstand such stresses. </p>
<p>We could then test them in other models (such as mice) before actually applying them to astronauts. This knowledge might also be potentially useful for <a href="https://www.freethink.com/space/cosmic-radiation">growing plants beyond Earth</a>.</p><img src="https://counter.theconversation.com/content/189762/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Hamid Kian Gaikani 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 the potential for space travel increases, it is necessary to develop methods to protect astronauts from environmental stresses in space. Studying the DNA of baker’s yeast may provide some clues.Hamid Kian Gaikani, PhD Candidate, Pharmaceutical Sciences, University of British ColumbiaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1555522021-03-31T19:19:15Z2021-03-31T19:19:15ZChocolate’s secret ingredient is the fermenting microbes that make it taste so good<figure><img src="https://images.theconversation.com/files/392677/original/file-20210330-21-2fmbyo.jpg?ixlib=rb-1.1.0&rect=0%2C249%2C4899%2C3408&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Underneath the shiny wrapper, a chocolate bunny is a fermented food.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/march-2021-brandenburg-hornow-chocolate-easter-bunnies-are-news-photo/1231995539">Patrick Pleul/picture alliance via Getty Images</a></span></figcaption></figure><p>Whether baked as chips into a cookie, melted into a sweet warm drink or molded into the shape of a smiling bunny, chocolate is one of the world’s <a href="https://doi.org/10.1016/j.clnu.2018.05.019">most universally consumed foods</a>.</p>
<p>Even the biggest chocolate lovers, though, might not recognize what this ancient food has in common with kimchi and kombucha: its flavors are due to fermentation. That familiar chocolate taste is thanks to tiny microorganisms that help transform chocolate’s raw ingredients into the much-beloved rich, complex final product.</p>
<p>In labs from Peru to Belgium to Ivory Coast, self-proclaimed <a href="https://scholar.google.com/citations?user=QjIM6yUAAAAJ&hl=en&oi=ao">chocolate scientists like me</a> are working to understand just how fermentation changes chocolate’s flavor. Sometimes we create artificial fermentations in the lab. Other times we take cacao bean samples from real fermentations “in the wild.” Often, we make our experimental batches into chocolate and ask a few lucky volunteers to taste it and tell us what flavors they detect.</p>
<p>After decades of running tests like this, researchers have solved many of the mysteries that govern cacao fermentation, including which microorganisms participate and how this step governs chocolate flavor and quality.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/392678/original/file-20210330-15-1c6otxd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="man reaches up toward pods growing from trunk of cacao tree" src="https://images.theconversation.com/files/392678/original/file-20210330-15-1c6otxd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/392678/original/file-20210330-15-1c6otxd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/392678/original/file-20210330-15-1c6otxd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/392678/original/file-20210330-15-1c6otxd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/392678/original/file-20210330-15-1c6otxd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/392678/original/file-20210330-15-1c6otxd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/392678/original/file-20210330-15-1c6otxd.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 plantation owner in Ivory Coast checks the pods on one of his cacao trees.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/david-youant-a-plantation-owner-checks-his-cocoa-trees-in-news-photo/77612213">Issouf Sanogo/AFP via Getty Images</a></span>
</figcaption>
</figure>
<h2>From seed pod to chocolate bar</h2>
<p>The food you know as chocolate starts its life as the seeds of <a href="https://doi.org/10.19103/as.2017.0021.01">football-shaped pods of fruit</a> growing directly from the trunk of the <em>Theobroma cacao</em> tree. It looks like something Dr. Seuss would have designed. But as long as <a href="https://doi.org/10.1038/s41559-018-0697-x">3,900 years ago the Olmecs of Central America</a> had figured out a multi-step process to transform these giant seed pods into an edible treat.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/392680/original/file-20210330-19-1h808e1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="woman holds a halved pod displaying the seeds" src="https://images.theconversation.com/files/392680/original/file-20210330-19-1h808e1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/392680/original/file-20210330-19-1h808e1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=691&fit=crop&dpr=1 600w, https://images.theconversation.com/files/392680/original/file-20210330-19-1h808e1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=691&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/392680/original/file-20210330-19-1h808e1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=691&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/392680/original/file-20210330-19-1h808e1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=868&fit=crop&dpr=1 754w, https://images.theconversation.com/files/392680/original/file-20210330-19-1h808e1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=868&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/392680/original/file-20210330-19-1h808e1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=868&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Inside the pods are seeds and pulp.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/close-up-on-cocoa-beans-in-a-halved-pod-on-septembre-25-news-photo/1270250558">Camille Delbos/Art In All of Us/Corbis via Getty Images</a></span>
</figcaption>
</figure>
<p>First, workers crack the brightly colored fruit open and scoop out the seeds and pulp. The seeds, now called “beans,” cure and drain over the course of three to 10 days before drying under the Sun. The dry beans are roasted, then crushed with sugar and sometimes dried milk <a href="https://www.newfoodmagazine.com/article/1949/using-science-to-make-the-best-chocolate/">until the mixture feels so smooth</a> you can’t distinguish the particles on your tongue. At this point, the chocolate is ready to be fashioned into bars, chips or confections.</p>
<p>It’s during the curing stage that <a href="https://doi.org/10.1080/10408690490464104">fermentation naturally occurs</a>. Chocolate’s complex flavor consists of <a href="https://doi.org/10.1021/jf0114177">hundreds of individual compounds</a>, many of which are generated during fermentation. Fermentation is the process of improving the qualities of a food through the controlled activity of microbes, and it allows the bitter, otherwise tasteless cacao seeds to <a href="https://doi.org/10.1080/10408390701719272">develop the rich flavors associated with chocolate</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/392681/original/file-20210330-15-16bcdtk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Drying beans fill trays outside under a sunny blue sky" src="https://images.theconversation.com/files/392681/original/file-20210330-15-16bcdtk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/392681/original/file-20210330-15-16bcdtk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/392681/original/file-20210330-15-16bcdtk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/392681/original/file-20210330-15-16bcdtk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/392681/original/file-20210330-15-16bcdtk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/392681/original/file-20210330-15-16bcdtk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/392681/original/file-20210330-15-16bcdtk.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>
<figcaption>
<span class="caption">Beans dry in the Sun at a plantation in Madagascar, and microbes invisibly do their work.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/cocoa-harvest-on-the-millot-plantation-in-the-north-west-of-news-photo/590675091">Andia/Universal Images Group via Getty Images</a></span>
</figcaption>
</figure>
<h2>Microorganisms at work</h2>
<p>Cacao fermentation is a multi-step process. Any compound microorganisms produced along the way that changes the taste of the beans will also change the taste of the final chocolate. </p>
<p>The first fermentation step may be familiar to home brewers, because it involves yeasts – some of them the <a href="https://doi.org/10.1111/jam.13045">same yeasts that ferment beer and wine</a>. Just like the yeast in your favorite brew, yeast in a cacao fermentation produces alcohol by digesting the sugary pulp that clings to the beans.</p>
<p>This process generates fruity-tasting molecules called esters and floral-tasting fusel alcohols. These compounds soak into the beans and are later present in the finished chocolate. </p>
<p>As the pulp breaks down, oxygen enters the fermenting mass and the <a href="https://doi.org/10.1080/10408690490464104">yeast population declines as oxygen-loving bacteria take over</a>. These bacteria are known as acetic acid bacteria because they convert the alcohol generated by the yeast into acetic acid.</p>
<p>The acid soaks into the beans, causing biochemical changes. The sprouting plant dies. Fats agglomerate. Some enzymes break proteins down into smaller peptides, which become very “chocolatey”-smelling during the subsequent roasting stage. Other enzymes break apart the <a href="https://doi.org/10.3389/fnut.2018.00087">antioxidant polyphenol molecules</a>, <a href="https://doi.org/10.1093/jaoac/102.5.1388">for which chocolate has gained renown as a superfood</a>. As a result, contrary to its reputation, most chocolate contains very few polyphenols, or even none at all.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/392682/original/file-20210330-13-1ygq6ov.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A man in a hat rakes a large tray of drying cacao seeds" src="https://images.theconversation.com/files/392682/original/file-20210330-13-1ygq6ov.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/392682/original/file-20210330-13-1ygq6ov.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/392682/original/file-20210330-13-1ygq6ov.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/392682/original/file-20210330-13-1ygq6ov.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/392682/original/file-20210330-13-1ygq6ov.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/392682/original/file-20210330-13-1ygq6ov.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/392682/original/file-20210330-13-1ygq6ov.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">As the drying progresses, different microorganisms naturally emerge to do their job preparing the beans.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/man-dries-cacao-beans-at-a-plantation-in-jutiapa-news-photo/1001093156">Orlando Sierra/AFP via Getty Images</a></span>
</figcaption>
</figure>
<p>All the reactions kicked off by acetic acid bacteria have a major impact on flavor. These acids encourage the degradation of heavily astringent, deep purple polyphenol molecules into milder-tasting, brown-colored chemicals called o-quinones. Here is where cacao beans turn from bitter-tasting to rich and nutty. This flavor transformation is accompanied by a color shift from reddish-purple to brown, and it is the reason the chocolate you’re familiar with is brown and not purple.</p>
<p>Finally, as acid slowly evaporates and sugars are used up, other species – including <a href="https://doi.org/10.1080/10408690490464104">filamentous fungi and spore-forming <em>Bacillus</em> bacteria</a> – take over.</p>
<p>As vital as microbes are to the chocolate-making process, sometimes organisms can ruin a fermentation. <a href="https://doi.org/10.1016/j.foodres.2014.04.032">An overgrowth of the spore-forming <em>Bacillus</em> bacteria</a> is associated with compounds that lead to rancid, cheesy flavors.</p>
<h2>Terroir of a place and its microbes</h2>
<p>Cacao is a wild fermentation – farmers rely on natural microbes in the environment to create unique, local flavors. This phenomenon is known as “terroir”: the characteristic flair imparted by a place. In the same way that grapes take on regional terroir, these wild microbes, combined with each farmer’s particular process, confer terroir on beans fermented in each location.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/392683/original/file-20210330-23-1kgttxf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a chocolate maker's hands remove finished candies from a chocolate mold" src="https://images.theconversation.com/files/392683/original/file-20210330-23-1kgttxf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/392683/original/file-20210330-23-1kgttxf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/392683/original/file-20210330-23-1kgttxf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/392683/original/file-20210330-23-1kgttxf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/392683/original/file-20210330-23-1kgttxf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/392683/original/file-20210330-23-1kgttxf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/392683/original/file-20210330-23-1kgttxf.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">High-end chocolate-makers are choosy about their beans.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/chocolate-production-royalty-free-image/175490857">twohumans/E+ via Getty Images</a></span>
</figcaption>
</figure>
<p>Market demand for these <a href="https://damecacao.com/craft-chocolate-continue-to-grow/">fine, high-quality beans is growing</a>. Makers of gourmet, small-batch chocolate hand-select beans based on their distinctive terroir in order to produce chocolate with an impressive range of flavor nuances. </p>
<p>If you’ve experienced chocolate only in the form of a bar you might grab near the grocery store checkout, you probably have little idea of the range and complexity that truly excellent chocolate can exhibit.</p>
<p>[<em>Over 100,000 readers rely on The Conversation’s newsletter to understand the world.</em> <a href="https://theconversation.com/us/newsletters/the-daily-3?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=100Ksignup">Sign up today</a>.]</p>
<p>A bar from Akesson’s Madagascar estate may be reminiscent of raspberries and apricots, while Canadian chocolate-maker Qantu’s wild-fermented Peruvian bars taste like they’ve been soaked in Sauvignon Blanc. Yet in both cases, the bars contain nothing except cacao beans and some sugar. </p>
<p>This is the power of fermentation: to change, convert, transform. It takes the usual and make it unusual – thanks to the magic of microbes.</p><img src="https://counter.theconversation.com/content/155552/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Caitlin Clark 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>Sauerkraut, sourdough, beer…and chocolate? They’re all fermented foods that rely on microbes of various types to transform the flavor of their raw ingredients into something totally different.Caitlin Clark, Ph.D. Candidate in Food Science, Colorado State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1405152020-06-23T12:20:13Z2020-06-23T12:20:13ZCrop pathogens are more adaptable than previously thought<figure><img src="https://images.theconversation.com/files/341061/original/file-20200611-114102-1pu5vjx.jpg?ixlib=rb-1.1.0&rect=0%2C10%2C1016%2C619&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Bananas in Java, Indonesia, infected by the fungal pathogen _Fusarium oxysporum f.sp. cubense_, which causes Fusarium Wilt.</span> <span class="attribution"><span class="source">Clare Thatcher</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p><em>The Research Brief is a short take about interesting academic work.</em></p>
<h2>The big idea</h2>
<p>Many of the pathogens threatening the world’s major crops and food security are either <a href="https://doi.org/10.1111/j.1364-3703.2011.00783.x">fungi</a> or fungus-like organisms known as <a href="https://doi.org/10.1111/mpp.12190">oomycetes</a>. In a <a href="https://doi.org/10.1038/s41467-020-16778-5">recent study published in the journal Nature Communications</a>, researchers found that these microorganisms have the ability to rapidly adapt to environmental conditions and to the plant hosts they infect. This finding adds to growing concerns around these types of pathogens, which could become harder to control in both agriculture and forestry. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/341038/original/file-20200610-114090-3h9wkx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/341038/original/file-20200610-114090-3h9wkx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/341038/original/file-20200610-114090-3h9wkx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=535&fit=crop&dpr=1 600w, https://images.theconversation.com/files/341038/original/file-20200610-114090-3h9wkx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=535&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/341038/original/file-20200610-114090-3h9wkx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=535&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/341038/original/file-20200610-114090-3h9wkx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=672&fit=crop&dpr=1 754w, https://images.theconversation.com/files/341038/original/file-20200610-114090-3h9wkx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=672&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/341038/original/file-20200610-114090-3h9wkx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=672&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Potato infected with the oomycete <em>Phytophthora infestans</em>. This oomycete was the cause of the Irish potato famine that led to the starvation and death of more than 1 million people in the 19th century. <em>Phytophthora</em> infections cause annual damages that amount to billions of U.S. dollars.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Phytophtora_infestans-effects.jpg">Wikipedia</a></span>
</figcaption>
</figure>
<p>To understand why only certain organisms are pathogens and others are not, ecologists like to think of each organism’s lifestyle or “ecological niche.” An organism’s niche is a space defined by its relationship to other organisms, such as the host organisms it interacts with, and preferred environmental conditions, such as temperature and humidity. For example, <a href="https://apsjournals.apsnet.org/doi/abs/10.1094/PHYTO-95-0092">the oomycete <em>Phytophthora infestans</em></a> that causes potato late blight thrives at lower temperatures, around 15 degrees Celsius, whereas <em>Botryosphaeria</em> fungi causing apple “bot rots” prefer temperatures around or above 25°C.</p>
<p>While the ecological niches of many plant and animal pathogens are well understood, this is not the case for microbial pathogens, such as fungi and oomycetes. To begin filling this gap, the <a href="https://doi.org/10.1038/s41467-020-16778-5">new study</a> synthesized and analyzed temperature and host plant range data from hundreds of fungal and oomycete pathogens.</p>
<p>The researchers found that although some pathogens infect just one or a few plant hosts, others infect a broad range. The same was true of temperature; some pathogens can grow in a broad range of temperatures, while others thrive in only a narrow range. Simply put, there’s not one pathogen lifestyle; rather, any lifestyle could be that of a pathogen.</p>
<p>But an even bigger surprise came when the researchers discovered that the two traits, temperature range and plant host range, did not correlate with one another. Thus, crop pathogen lifestyles cannot easily be grouped into general categories, such as generalists that grow in a wide range of temperatures and infect many plant hosts, and specialists, which is the opposite. What’s more, the new study found that both temperature range and plant host range change rapidly during evolution. </p>
<h2>Why it matters</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/341036/original/file-20200610-114090-1xq1t1w.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/341036/original/file-20200610-114090-1xq1t1w.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/341036/original/file-20200610-114090-1xq1t1w.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=790&fit=crop&dpr=1 600w, https://images.theconversation.com/files/341036/original/file-20200610-114090-1xq1t1w.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=790&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/341036/original/file-20200610-114090-1xq1t1w.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=790&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/341036/original/file-20200610-114090-1xq1t1w.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=993&fit=crop&dpr=1 754w, https://images.theconversation.com/files/341036/original/file-20200610-114090-1xq1t1w.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=993&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/341036/original/file-20200610-114090-1xq1t1w.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=993&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Rice infected with the rice blast fungus <em>Magnaporthe grisea</em>. Annually, rice blast destroys a quantity of rice that could feed 60 million people.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:J_Sendra_with_Magnaporthe_grisea.jpeg">Wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Knowledge that crop pathogens exhibit diverse ecological lifestyles and evolve rapidly is decidedly not good news for our crops and global food security. On a <a href="https://climate.nasa.gov/">planet where the climate is changing</a>, highly adaptable pathogens are likely to be harder to control. In addition, much of the world relies on an outdated system of agriculture that favors <a href="https://doi.org/10.1038/s43016-020-0075-0">monoculture and reliance on fungicides to which pathogens quickly evolve resistance</a>. This combination make for a deadly mix, with <a href="https://doi.org/10.1371/journal.pbio.3000302">new outbreaks of emerging plant diseases on the rise</a>.</p>
<h2>What still isn’t known</h2>
<p>We still know little about the ecological niches of microbes. Examining host range and temperature, two important traits to the lifestyles of crop pathogens, is but the first step. In the future, researchers will need to examine additional facets of the ecological niches of these pathogens, such as humidity or competition with other organisms, which will be key for understanding why some microbes are pathogens and others are innocuous.</p>
<p>[<em>Like what you’ve read? Want more?</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=likethis">Sign up for The Conversation’s daily newsletter</a>.]</p><img src="https://counter.theconversation.com/content/140515/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Antonis Rokas and his laboratory receive or have received funding from the National Science Foundation, the John Simon Guggenheim Memorial Foundation, the Burroughs Wellcome Trust, the National Institutes of Health, the Beckman Scholars Program, the March of Dimes, the Howard Hughes Medical Institute, and Vanderbilt University.</span></em></p>Fungi and other organisms called oomycetes are
highly adaptable. That’s bad news for the global food supply.Antonis Rokas, Cornelius Vanderbilt Chair in Biological Sciences, Professor of Biological Sciences and Biomedical Informatics, and Director of the Vanderbilt Evolutionary Studies Initiative, Vanderbilt UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1376872020-05-11T11:51:39Z2020-05-11T11:51:39ZWhat every new baker should know about the yeast all around us<figure><img src="https://images.theconversation.com/files/333491/original/file-20200507-49589-2n233a.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5120%2C3272&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">An invisible organism with worldwide influence</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/yeast-saccharomyces-cerevisiae-illustration-royalty-free-illustration/1088373806?adppopup=true"> KATERYNA KON/SCIENCE PHOTO LIBRARY via Getty Images</a></span></figcaption></figure><p>With people confined to their homes, there is more interest in home-baked bread than ever before. And that means a lot of people are making friends with yeast for the first time. I am a <a href="https://www.chhs.colostate.edu/bio-page/jeffrey-miller-1070">professor of hospitality management and a former chef, and I teach in my university’s fermentation science program</a>. As friends and colleagues struggle for success in using yeast in their baking – and occasionally brewing – I’m getting bombarded with questions about this interesting little microorganism. </p>
<h2>A little cell with a lot of power</h2>
<p>Yeasts are single-celled organisms in the fungus family. There are <a href="https://wiki.yeastgenome.org/index.php/What_are_yeast%3F">more than 1,500 species of them on Earth</a>. While each individual yeast is only one cell, they are surprisingly complex and contain a nucleus, DNA and many other cellular parts found in more complicated organisms.</p>
<p>Yeasts break down complex molecules into simpler molecules to produce the energy they live on. They can be found on most plants, floating around in the air and in soils across the globe. There are 250 or so of these yeast species that can <a href="http://zythophile.co.uk/2008/09/11/a-short-history-of-yeast/">convert sugar into carbon dioxide and alcohol</a> – valuable skills that humans have used for millennia. Twenty-four of these make foods that actually taste good. </p>
<p>Among these 24 species is one called <em>Saccharomyces cerevisiae</em>, which means “sugar-eating fungus.” This is bread yeast, the yeast we humans know and love most dearly for the food and drinks it helps us make.</p>
<p>The process starts out the same whether you are making bread or beer. Enzymes in the yeast convert sugar into alcohol and carbon dioxide. With bread, a baker wants to <a href="https://www.bakeinfo.co.nz/Facts/Bread-making/Science-of-bread-making/Rising-fermentation-">capture the carbon dioxide to leaven the bread</a> and make it rise. With beer, a brewer wants to capture the alcohol. </p>
<p>Bread has been “the staff of life” for <a href="https://www.exploratorium.edu/cooking/bread/overview.html">thousands of years</a>.
The first loaf of bread was probably a <a href="https://www.history.com/news/a-brief-history-of-bread">happy accident</a> that occurred when some yeast living on grains began to ferment while some dough for flatbreads – think matzo or crackers – was being made. The first purposely made leavened bread was likely made by <a href="https://www.livescience.com/62536-who-invented-bread.html">Egyptians about 3,000 years ago</a>. Leavened bread is now a staple in almost every culture on Earth. Bread is inexpensive, nutritious, delicious, portable and easy to share. Anywhere wheat, rye or barley could be grown in sufficient quantities, bread became the basic food in most people’s diet. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/333493/original/file-20200507-49542-1i03tyq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/333493/original/file-20200507-49542-1i03tyq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/333493/original/file-20200507-49542-1i03tyq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/333493/original/file-20200507-49542-1i03tyq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/333493/original/file-20200507-49542-1i03tyq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/333493/original/file-20200507-49542-1i03tyq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/333493/original/file-20200507-49542-1i03tyq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/333493/original/file-20200507-49542-1i03tyq.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">Yeast makes bread fluffy and flavorful.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/midsection-of-woman-holding-bread-dough-in-royalty-free-image/1125892159?adppopup=true&uiloc=thumbnail_same_series_adp">Poh Kim Yeoh/EyeEm via Getty Images</a></span>
</figcaption>
</figure>
<h2>No yeast, no bread</h2>
<p>When you mix yeast with a bit of water and flour, the yeast begins to eat the long chains of carbohydrates found in the flour called starches. This does two important things for baking: It changes the chemical structure of the carbohydrates, and it makes bread rise. </p>
<p>When yeast breaks down starch, it produces carbon dioxide gas and ethyl alcohol. This CO2 is trapped in the dough by stringy protein strands called gluten and causes the dough to rise. After baking, those little air pockets are locked into place and result in airy, fluffy bread.</p>
<p>But soft bread is not the only result. When yeast break down the starches in flour, it turns them into flavorful sugars. The longer you let the dough rise, the <a href="https://www.finecooking.com/article/yeasts-crucial-roles-in-breadbaking">stronger these good flavors will be</a>, and some of the <a href="https://cooking.nytimes.com/recipes/11376-no-knead-bread">most popular bread recipes</a> use this to their advantage. </p>
<h2>The supermarket’s out of yeast; now what?</h2>
<p>Baking bread at home is fun and easy, but what if your store doesn’t have any yeast? Then it’s sourdough to the rescue!</p>
<p>Yeast is everywhere, and it’s really easy to collect yeast at home that you can use for baking. These wild yeast collections tend to gather yeasts as well as bacteria – usually <em>Lactobacillus brevis</em> that is used in cheese and yogurt production – that add the complex sour flavors of sourdough. Sourdough starters have been made from fruits, vegetables or even dead wasps. Pliny the Elder, the Roman naturalist and philosopher, was the first to suggest the dead wasp recipe, and it works because <a href="https://www.npr.org/sections/thesalt/2012/08/02/157606554/thank-the-simple-wasp-for-that-complex-glass-of-wine-">wasps get coated in yeasts</a> as they eat fruit. But please don’t do this at home! You don’t need a wasp or a murder hornet to make bread. All you really need to make sourdough starter is wheat or rye flour and water; the yeast and bacteria floating around your home will do the rest. </p>
<p>To make your own sourdough starter, mix a half-cup of distilled water with a half-cup of whole wheat flour or rye flour. Cover the top of your jar or bowl loosely with a cloth, and let it sit somewhere warm for 24 hours. After 24 hours, stir in another quarter-cup of distilled water and a half-cup of all-purpose flour. Let it sit another 24 hours. Throw out about half of your doughy mass and stir in another quarter-cup of water and another half-cup of all-purpose flour.</p>
<p>Keep doing this every day until your mixture begins to bubble and smells like rising bread dough. Once you have your starter going, you can use it to make bread, pancakes, <a href="https://www.mercurynews.com/2020/05/04/recipe-tartine-approved-sourdough-pizza-dough/">even pizza crust</a>, and you will never have to buy yeast again. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/333494/original/file-20200507-49584-1f1diyn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/333494/original/file-20200507-49584-1f1diyn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/333494/original/file-20200507-49584-1f1diyn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/333494/original/file-20200507-49584-1f1diyn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/333494/original/file-20200507-49584-1f1diyn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/333494/original/file-20200507-49584-1f1diyn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/333494/original/file-20200507-49584-1f1diyn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/333494/original/file-20200507-49584-1f1diyn.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">Yeast is used in laboratories and factories as well as kitchens.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/biotechnological-laboratory-royalty-free-image/177979818?adppopup=true">borzywoj/iStock/Getty Images Plus via Getty Images</a></span>
</figcaption>
</figure>
<h2>More than just bread and booze</h2>
<p>Because of their similarity to complicated organisms, large size and ease of use, yeasts have been central to scientific progress for hundreds of years. Study of yeasts played a huge role in <a href="https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.26089-0">kick-starting the field of microbiology</a> in the early 1800s. More than 150 years later, one species of yeast was the first organism with a nucleus to have <a href="https://doi.org/10.1038/387s007">its entire genome sequenced</a>. Today, scientists use yeast in <a href="https://doi.org/10.1007/s10142-002-0059-1">drug discovery</a> and as tools to study <a href="https://doi.org/10.15252/embj.201696010">cell growth in mammals</a> and are exploring ways to use yeast to make biofuel <a href="https://www.sciencedaily.com/releases/2018/08/180809175054.htm">from waste products like cornstalks</a>. </p>
<p>Yeast is a remarkable little creature. It has provided delicious food and beverages for millennia, and to this day is a huge part of human life around the world. So the next time you have a glass of beer, toast our little friends that make these foods part of our enjoyment of life.</p>
<p>[<em>Insight, in your inbox each day.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=insight">You can get it with The Conversation’s email newsletter</a>.]</p><img src="https://counter.theconversation.com/content/137687/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jeffrey Miller 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>Yeast is a single-celled organism that’s everywhere around us. Understanding how yeast works can help you make better bread and appreciate this old friend of humanity.Jeffrey Miller, Associate Professor, Hospitality Management, Colorado State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1281652019-12-05T16:02:32Z2019-12-05T16:02:32ZA 6,000-year-old fruit fly gave the world modern cheeses and yogurts<figure><img src="https://images.theconversation.com/files/305365/original/file-20191205-39023-1xjlqu8.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3458%2C2427&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">He died so that we might eat cheese.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/fruit-fly-380208508?src=2726c309-ebfc-414d-861f-cab0b366c33b-1-24">Vasekk/Shutterstock</a></span></figcaption></figure><p>Historians often trace the dawn of human civilisation back 10,000 years, when Neolithic tribes first settled and began farming in the Fertile Crescent, which stretches through much of what we now call the Middle East. Prehistoric peoples domesticated plants to create the cereal crops we still grow today, and in the Zagros mountains of Iran, Iraq and Turkey, <a href="https://science.sciencemag.org/content/287/5461/2254">sheep, goats and cows</a> were bred from their wild relatives to ensure a steady supply of meat and milk. But around the same time as plants and animals were tamed for agriculture, long before anyone even knew of microscopic life, early humans were domesticating microbes too.</p>
<p><a href="https://www.cell.com/current-biology/fulltext/S0960-9822(19)31384-3">In a paper published in Current Biology</a>, we discovered how “milk yeast” – the handy microorganism that can decompose lactose in milk to create dairy products like cheese and yoghurt – originated from a chance encounter between a fruit fly and a pail of milk around 5,500 years ago. This happy accident allowed prehistoric people to domesticate yeast in much the same way they domesticated crop plants and livestock animals, and produce the cheeses and yogurts billions of people enjoy today.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/305229/original/file-20191204-70126-jxdaj1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/305229/original/file-20191204-70126-jxdaj1.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/305229/original/file-20191204-70126-jxdaj1.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/305229/original/file-20191204-70126-jxdaj1.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/305229/original/file-20191204-70126-jxdaj1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/305229/original/file-20191204-70126-jxdaj1.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/305229/original/file-20191204-70126-jxdaj1.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">
<figcaption>
<span class="caption">Milk yeast cells are large and oval and here surrounded by rod-shaped bacterial cells.</span>
<span class="attribution"><span class="source">Loughlin Gethins & Suzanne Crotty, UCC</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>The domesticated diet</h2>
<p>Domestication is evolution directed by a human hand. After wild parents have bred, farmers retain the offspring with properties that are beneficial for future breeding. Take farmed wheat, for example. This crop species produces a lot more seeds than wild grasses do, because these seeds are the grain that humans harvest. Early farmers <a href="https://theconversation.com/what-3-000-year-old-egyptian-wheat-tells-us-about-the-genetics-of-our-daily-bread-126387">deliberately bred pairs of wheat plants</a> that produced lots of grain so that their offspring would inherit this trait. As these pairings were repeated over many generations, grain-rich descendants were gradually created. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-3-000-year-old-egyptian-wheat-tells-us-about-the-genetics-of-our-daily-bread-126387">What 3,000-year-old Egyptian wheat tells us about the genetics of our daily bread</a>
</strong>
</em>
</p>
<hr>
<p>It’s survival of the fittest, but the fittest are variants that have characteristics that are useful for humans. The wary and vicious wolf <a href="https://theconversation.com/why-dog-breeds-arent-considered-separate-species-56113">becomes the friendly and obedient dog</a>.</p>
<p>Neolithic farmers stumbled on the practice of domesticating microbes when they tried to preserve food by fermenting it. Fermentation relies on microbes, such as bacteria, yeast and fungi, increasing the acidity of the food to protect it against spoilage. Microbes that were good at making fermented products that were palatable and safe were kept to start the next batch, and so useful microbes were evolved and domesticated. “Baker’s yeast,” or <em>Saccharomyces cerevisiae</em>, was a microbe selected from nature to make beer, wine and other fermented drinks <a href="https://theconversation.com/thank-fungi-for-cheese-wine-and-beer-this-holiday-season-125793">13,000 years ago</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/gourmet-meals-are-filled-with-bacteria-and-they-taste-delicious-57008">Gourmet meals are filled with bacteria – and they taste delicious</a>
</strong>
</em>
</p>
<hr>
<p><em>Kluyveromyces lactis</em>, or milk yeast, is found in French and Italian cheeses made from unpasteurised milk, and in natural fermented dairy drinks like <a href="https://www.bbcgoodfood.com/howto/guide/health-benefits-kefir">kefir</a>. But the ancestor of this microbe was originally associated with the fruit fly, so how did it end up making many of the dairy products that people eat today? We believe milk yeast owes its very existence to a fly landing in fermenting milk and starting an unusual sexual liaison. The fly in question was the common fruit fly, <em>Drosophila</em>, and it carried with it the ancestor of <em>K. lactis</em>. Although the fly died, the yeast lived, but with a problem – it could not use the lactose in milk as a food source. Instead, it found an unconventional solution – sex with its cousin.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/305359/original/file-20191205-39028-rntflh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/305359/original/file-20191205-39028-rntflh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/305359/original/file-20191205-39028-rntflh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/305359/original/file-20191205-39028-rntflh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/305359/original/file-20191205-39028-rntflh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/305359/original/file-20191205-39028-rntflh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/305359/original/file-20191205-39028-rntflh.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">Humans began fermenting milk to create cheeses and yogurts around 6,000 years ago.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/assorted-dairy-product-1161597100?src=f146c918-59b0-4df3-a58e-2cf3193d20d8-1-5">Margouillat photo/Shutterstock</a></span>
</figcaption>
</figure>
<p>When <em>K. lactis</em> arrived with the fly, its cousin <em>K. marxianus</em> was already happily growing in the milk. <em>K. marxianus</em> is able to use lactose for growth because it has two extra proteins which can help break down lactose into simple sugars that it then uses for energy. The cousins reproduced and the genes needed to use lactose transferred from <em>K. marxianus</em> to <em>K. lactis</em>. The end result was that <em>K. lactis</em> acquired two new genes and could then grow on lactose and survive on its own. The fermented product that <em>K. lactis</em> made must have been particularly delicious as it was used to start a new fermentation – a routine that has continued to the present day.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/do-humans-need-dairy-heres-the-science-70434">Do humans need dairy? Here's the science</a>
</strong>
</em>
</p>
<hr>
<p>We think that by 6,000 years ago, farmers were using fermented goat and sheep milk to make tasty beverages like yoghurt and kefir. We know that milk-producing animals – cows, sheep, goats – were all domesticated between 8,000 and 10,000 years ago, and <a href="https://www.bbc.com/news/science-environment-49650806">analysis of human tartar</a> found on teeth shows that humans were consuming milk, most likely as cheese or other fermented products by 5,500 years ago. The chance encounter between two yeast species and a little bit of illicit sex made all of this possible. </p>
<p>Who could’ve imagined that such a random series of events would produce so many of the world’s great culinary delicacies?</p><img src="https://counter.theconversation.com/content/128165/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>John Morrissey receives funding from the European Union Horizon 2020 Programme and from Science Foundation Ireland.</span></em></p>Your taste for cheese and yoghurt may never have been satisfied were it not for illicit microbial sex.John Morrissey, Lecturer in Microbiology, University College CorkLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1257932019-11-25T21:47:11Z2019-11-25T21:47:11ZThank fungi for cheese, wine and beer this holiday season<figure><img src="https://images.theconversation.com/files/303049/original/file-20191121-113012-1yidb57.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">These foods are all dependent on microorganisms for their distinctive flavor.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/assorted-winebread-cheese-328891478">margouillat photo/Shutterstock.com</a></span></figcaption></figure><p>It’s hard to imagine a holiday table without bread, meat, vegetables, wine, beer or a board of French cheeses for those with more adventurous palates. Savoring these delicacies with family and friends is part of what makes the holidays so much fun.</p>
<p>These foods and drinks are courtesy of the domestication of several different animals, plants and microbes. Plant and animal domestication has been well studied, since it is thought to have been <a href="https://doi.org/10.1038/nature01019">the most momentous change</a> in recent human history. </p>
<p>Scientists know much less about the domestication of microbes, however, and as a result, society fails to appreciate their pivotal contributions to the foods and drinks that we enjoy all year long.</p>
<p><a href="http://www.rokaslab.org">I am an evolutionary biologist studying fungi</a>, a group of microbes whose domestication has given us <a href="https://doi.org/10.1016/j.cub.2012.05.033">many tasty products</a>. I’ve long been fascinated by two questions: What are the genetic changes that led to their domestication? And how on Earth did our ancestors figure out how to domesticate them? </p>
<p>Curious too? Recent studies shed light on these questions, so grab some Camembert cheese and a beer, and keep on reading.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/303546/original/file-20191125-74567-z91mmt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/303546/original/file-20191125-74567-z91mmt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/303546/original/file-20191125-74567-z91mmt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=252&fit=crop&dpr=1 600w, https://images.theconversation.com/files/303546/original/file-20191125-74567-z91mmt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=252&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/303546/original/file-20191125-74567-z91mmt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=252&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/303546/original/file-20191125-74567-z91mmt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=317&fit=crop&dpr=1 754w, https://images.theconversation.com/files/303546/original/file-20191125-74567-z91mmt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=317&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/303546/original/file-20191125-74567-z91mmt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=317&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Thank the large variety of microbes, including fungi, for this assortment of international cheeses.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/large-assortment-international-cheese-specialities-on-1094617058">Umomos/Shutterstock.com</a></span>
</figcaption>
</figure>
<h2>The hybrids in your lager</h2>
<p>As far as domestication is concerned, it is hard to top the honing of brewer’s yeast. The cornerstone of the baking, brewing and wine-making industries, brewer’s yeast has the remarkable ability to turn the sugars of plant fruits and grains into alcohol. How did brewer’s yeast evolve this flexibility?</p>
<p>By discovering new yeast species and sequencing their genomes, scientists know that some yeasts used in brewing are hybrids; that is, they’re descendants of ancient mating unions of individuals from two different yeast species. Hybrids tend to resemble both parental species – <a href="https://www.nytimes.com/2010/09/14/science/14creatures.html">think of wholpins (whale-dolphin) or ligers (lion-tiger)</a>.</p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/302549/original/file-20191119-111697-fwhfmi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/302549/original/file-20191119-111697-fwhfmi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/302549/original/file-20191119-111697-fwhfmi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/302549/original/file-20191119-111697-fwhfmi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/302549/original/file-20191119-111697-fwhfmi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/302549/original/file-20191119-111697-fwhfmi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/302549/original/file-20191119-111697-fwhfmi.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">Cells of the mighty brewer’s yeast, the cornerstone of the baking, brewing and wine making industries.</span>
<span class="attribution"><span class="source">wikipedia</span></span>
</figcaption>
</figure>
<p>For example, lager beer yeasts are hybrids of two closely related species: <a href="https://doi.org/10.1073/pnas.1105430108">the brewer’s yeast <em>Saccharomyces cerevisiae</em> and <em>Saccharomyces eubayanus</em></a>. <em>Saccharomyces cerevisiae</em> produces tasty beers, such as the British ales, but grows better at warmer temperatures. In contrast, <em>Saccharomyces eubayanus</em> grows better in the cold but produces compounds that taint the beer’s flavor. Lager yeast hybrids combine the best of both - good flavors from <em>Saccharomyces cerevisiae</em> and growth at colder temperatures, thanks to <em>Saccharomyces eubayanus</em>. This makes these hybrids great for brewing beer in the cold winters of Europe, where lagers were invented. </p>
<p>Researchers have also discovered <a href="https://doi.org/10.1002/yea.3283">natural hybrids from the union of other <em>Saccharomyces</em> species</a>. What is still unknown is whether hybridization is the norm or the exception in the yeasts that humans have used for making fermented beverages for millennia. </p>
<p>To address this question, a team led by <a href="https://doi.org/10.1038/s41559-019-0998-8">graduate student Quinn Langdon at the University of Wisconsin</a> and another team led by <a href="https://doi.org/10.1038/s41559-019-0997-9">postdoctoral fellow Brigida Gallone at the Universities of Ghent and Leuven in Belgium</a> examined the genomes of hundreds of yeasts involved in brewing and wine making. Their bottom line? Hybrids rule.</p>
<p>For example, <a href="https://doi.org/10.1038/s41559-019-0997-9">a quarter of yeasts collected from industrial environments</a>, including beer and wine manufacturers, are hybrids. </p>
<p>Amazingly, some hybrids trace their origins to <a href="https://doi.org/10.1038/s41559-019-0998-8">three or four different parental species</a>. Why all this hybridization?, you may ask. Much like the lager hybrids, <a href="https://doi.org/10.1038/s41559-019-0997-9">these newly discovered hybrids differ in what they like to eat and how quickly they grow</a>. These preferences, which come courtesy of hybridization, influence not only how people use them in brewing but also the flavor profiles of the resulting brews.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/303531/original/file-20191125-74557-j2ezdo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/303531/original/file-20191125-74557-j2ezdo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/303531/original/file-20191125-74557-j2ezdo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/303531/original/file-20191125-74557-j2ezdo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/303531/original/file-20191125-74557-j2ezdo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/303531/original/file-20191125-74557-j2ezdo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/303531/original/file-20191125-74557-j2ezdo.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">This assortment of beer styles and flavors comes courtesy of brewer’s yeasts and their fondness for hybridization.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/refreshing-cold-craft-beer-assortment-ipa-1264196215">Brent Hofacker/Shutterstock.com</a></span>
</figcaption>
</figure>
<h2>The mutants in your cheese</h2>
<p>Comparing the genomes of domesticated fungi to their wild relatives helps scientists understand the genetic changes that gave rise to some favorite foods and drinks. But how did our ancestors actually domesticate these wild fungi? None of us was there to witness how it all started. To solve this mystery, scientists are experimenting with wild fungi to see if they can evolve into organisms resembling those that we use to make our food today. </p>
<p><a href="https://sites.tufts.edu/wolfelab/">Benjamin Wolfe, a microbiologist at Tufts University, and his team</a> addressed this question by taking wild <em>Penicillium</em> mold and growing the samples for one month in his lab on a substance that included cheese. That may sound like a short period for people, but it is one that spans many generations for fungi.</p>
<p>The wild fungi are very closely related to fungal strains used by the cheese industry in the making of Camembert cheese, but look very different from them. For example, wild strains are green and smell, well, moldy compared to the white and odorless industrial strains.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/302557/original/file-20191119-111686-cpbzko.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/302557/original/file-20191119-111686-cpbzko.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/302557/original/file-20191119-111686-cpbzko.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=455&fit=crop&dpr=1 600w, https://images.theconversation.com/files/302557/original/file-20191119-111686-cpbzko.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=455&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/302557/original/file-20191119-111686-cpbzko.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=455&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/302557/original/file-20191119-111686-cpbzko.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=572&fit=crop&dpr=1 754w, https://images.theconversation.com/files/302557/original/file-20191119-111686-cpbzko.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=572&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/302557/original/file-20191119-111686-cpbzko.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=572&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Colonies of <em>Penicillium</em> mold isolated from a blue cheese. The white colony is a domesticated version of the wild mold.</span>
<span class="attribution"><span class="source">Benjamin Wolfe</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>For Wolfe, the big question was whether he could experimentally recreate, and to what degree, the process of domestication. What did the wild strains look and smell like after a month of growth on cheese? Remarkably, what he and his team found was that, at the end of the experiment, the wild strains looked much more similar to known industrial strains than to their wild ancestor. For example, <a href="https://doi.org/10.1128/mBio.02445-19">they were white in color and smelled much less moldy</a>. </p>
<p>Fungi spend a lot of energy producing pigments and pungent compounds that enable them to compete and defend themselves. Living comfortably on a diet of cheese and safe from predators means that losing the ability to produce, say, pigments may actually be advantageous. That’s because the energy saved can instead be spent toward growth of the fungal colony.</p>
<p>But how did the wild strain turn into a domesticated version? Did it mutate? By sequencing the genomes of both the wild ancestors and the domesticated descendants, and measuring the activity of the genes while growing on cheese, Wolfe’s team figured out that these changes <a href="https://doi.org/10.1128/mBio.02445-19">did not happen through mutations in the organisms’ genomes</a>. Rather, they most likely occurred through <a href="https://ghr.nlm.nih.gov/primer/howgeneswork/epigenome">chemical alterations that modify the activity of specific genes</a> but don’t actually change the genetic code. Such so-called <a href="https://ghr.nlm.nih.gov/primer/howgeneswork/epigenome">epigenetic modifications</a> can occur much faster than mutations. The path toward domestication appears to be quicker than previously thought, which will perhaps encourage adventurous cheese makers to begin experimenting with domesticating wild fungi for new flavors.</p>
<p>While you savor your favorite foods and beverages this holiday season, spare a thought for these microscopic fungi, how they evolved their mighty powers and how much more bland our world would be without them.</p>
<p>[ <em>Like what you’ve read? Want more?</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=likethis">Sign up for The Conversation’s daily newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/125793/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Antonis Rokas and his laboratory receives funding from the National Science Foundation, the John Simon Guggenheim Memorial Foundation, the Burroughs Wellcome Trust, the National Institutes of Health, the Beckman Scholars Program, the March of Dimes, the Howard Hughes Medical Institute, and Vanderbilt University.</span></em></p>Bread. Yeast. Wine. Cheese. All these delicious foods are courtesy of various forms of domesticated fungi. So how, exactly, did humans tame wild fungi into the cooperative species that make our food?Antonis Rokas, Cornelius Vanderbilt Chair in Biological Sciences and Professor of Biological Sciences and Biomedical Informatics, Vanderbilt UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1270952019-11-19T19:16:43Z2019-11-19T19:16:43ZWhy the CDC warns antibiotic-resistant fungal infections are an urgent health threat<figure><img src="https://images.theconversation.com/files/302286/original/file-20191118-66979-1d8wwr3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">This is a medical illustration of an drug-resistant fungus, _Aspergillus fumigatus_. </span> <span class="attribution"><a class="source" href="https://phil.cdc.gov/Details.aspx?pid=23236">Stephanie Rossow/CDC</a></span></figcaption></figure><p>In 2013 I took care of a gentleman who underwent surgery for what all his physicians, including me, thought was liver cancer. Surgery revealed that the disease was a rare but benign tumor, rather than cancer. As you might imagine, he and his family were overjoyed and relieved. </p>
<p>However, two weeks after this surgery, he developed a liver abscess – an encapsulated tissue infection. Surgeons operated to remove the abscess. Two days later, test results revealed that the abscess was caused by a fungus called <em>Candida</em> that was resistant to echinocandins, our most powerful drugs against this fungus. </p>
<p>The patient underwent multiple surgeries and received various antibiotics thereafter, but his abscess kept growing back. He died four weeks after the first surgery to remove the abscess. The cause of death was sepsis due to his echinocandin-resistant <em>Candida</em> infection, which, at the time, was uncommon in the U.S. This tragic case demonstrated to me firsthand the devastating impact of drug-resistant fungal infections. </p>
<p>In the years since, I have cared for over a dozen patients who have died due to antibiotic-resistant fungal infections. On Nov. 13, 2019, the Centers for Disease Control and Prevention released a report on <a href="https://www.cdc.gov/drugresistance/biggest-threats.html">antibiotic resistance threats in the U.S.</a>, warning that drug-resistant fungi have become major public health problems. </p>
<p>The new report revealed that 18 microorganisms cause almost 3 million antibiotic resistant infections and 35,000 deaths annually. For the first time, this report includes several antibiotic resistant fungi: <em><a href="https://www.cdc.gov/drugresistance/pdf/threats-report/candida-auris-508.pdf">Candida auris</a></em>, other <a href="https://www.cdc.gov/fungal/diseases/candidiasis/index.html">drug-resistant <em>Candida</em></a> (as in my patient above) and azole-resistant <a href="https://www.cdc.gov/fungal/diseases/aspergillosis/index.html"><em>Aspergillus fumigatus</em></a>. These <a href="https://www.cdc.gov/fungal/antifungal-resistance.html">resistant fungi</a> are especially threatening because only three classes of antifungal medicines are currently available. </p>
<h2>Antibiotic-resistant fungi?</h2>
<p>We have heard a lot in recent years about the public health crisis of antibiotic-resistant bacteria, but less attention has been paid to antibiotic-resistant fungi. In part, this is because fungi became common causes of disease only over the past 30 years. During this time, the <a href="https://doi.org/10.1086/651262">risk for serious fungal infections</a> rose as more people suffered weakened immune systems stemming from increased bone marrow and organ transplantation, new drugs to treat cancer and other diseases, and complex surgeries. The <a href="https://www.mdpi.com/2076-0817/8/2/45">widespread use of more potent antibiotics</a> to treat resistant bacterial infections also has contributed by creating less competition for fungi to grow in human tissues. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/302343/original/file-20191119-169364-7mp9a8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/302343/original/file-20191119-169364-7mp9a8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/302343/original/file-20191119-169364-7mp9a8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=646&fit=crop&dpr=1 600w, https://images.theconversation.com/files/302343/original/file-20191119-169364-7mp9a8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=646&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/302343/original/file-20191119-169364-7mp9a8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=646&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/302343/original/file-20191119-169364-7mp9a8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=812&fit=crop&dpr=1 754w, https://images.theconversation.com/files/302343/original/file-20191119-169364-7mp9a8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=812&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/302343/original/file-20191119-169364-7mp9a8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=812&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>Candida auris</em> cultured in a petri dish. Some strains are resistant to all three major classes of antifungal drugs.</span>
<span class="attribution"><a class="source" href="https://phil.cdc.gov/Details.aspx?pid=21796">Shawn Lockhart/ CDC/ NCEZID; DFWED; MDB</a></span>
</figcaption>
</figure>
<p>Fungi include yeasts, which grow as spherical cells; and molds, which grow as elongated, tubular cells. Both yeasts and molds are more closely related genetically to humans than they are to bacteria. Therefore, it is hard to develop antibiotics that attack fungi without damaging human cells.</p>
<p><em>Candida</em> are yeasts that commonly cause skin rashes, urinary tract infections and vaginal infections. However, they are also the third-leading cause of <a href="https://www.nigms.nih.gov/education/pages/factsheet_sepsis.aspx">sepsis</a> and other life-threatening infections in U.S. hospitals.</p>
<p><em>Candida auris</em> was discovered in 2009, but it was <a href="https://academic.oup.com/cid/article/64/2/134/2706620">almost never encountered in a medical setting until 2015</a>, when numerous infections suddenly occurred on multiple continents. It is now one of CDC’s five most “urgent threats” for two principal reasons. </p>
<p>First, it demonstrates very high-level antifungal resistance. Ninety percent of strains are resistant to fluconazole, the frontline antifungal in many countries; 30% are resistant to two antifungal classes; and between 3% and 5% to all antifungals. </p>
<p>Another reason that the CDC is concerned about <em>C. auris</em> is that it has the unique ability to spread from person to person through contact with hands and clothes of health-care workers or contaminated medical devices. It also persists outside of humans in health-care environments, and causes large, long-standing infectious outbreaks. <em>C. auris</em> is a remarkably robust organism that can survive <a href="https://academic.oup.com/cid/article/64/2/141/2706383">standard disinfection methods, high temperatures and salt solutions</a> that kill other microbes. </p>
<p>Since the <a href="https://academic.oup.com/cid/article/64/2/141/2706383">first U.S. case in 2016</a>, <em>C. auris</em> has caused more than 800 infections in 13 states. CDC and local health departments currently are working to contain numerous health-care outbreaks. It is unclear why this fungus has arisen now, although <a href="https://mbio.asm.org/content/10/4/e01397-19.long">climate and other environmental changes</a> may have played a role. Likewise, it is unclear how widely <em>C. auris</em> will expand in the U.S. or globally.</p>
<h2>It’s not just <em>C. auris</em> we need to worry about</h2>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/302344/original/file-20191119-169364-1vdrb3f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/302344/original/file-20191119-169364-1vdrb3f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/302344/original/file-20191119-169364-1vdrb3f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=570&fit=crop&dpr=1 600w, https://images.theconversation.com/files/302344/original/file-20191119-169364-1vdrb3f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=570&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/302344/original/file-20191119-169364-1vdrb3f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=570&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/302344/original/file-20191119-169364-1vdrb3f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=716&fit=crop&dpr=1 754w, https://images.theconversation.com/files/302344/original/file-20191119-169364-1vdrb3f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=716&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/302344/original/file-20191119-169364-1vdrb3f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=716&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>Aspergillus fumigatus</em> grown from a soil sample.</span>
<span class="attribution"><a class="source" href="https://upload.wikimedia.org/wikipedia/commons/0/08/Aspergillus_fumigatus.jpg">Dr. David Midgley.</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Other drug-resistant fungi in the <em>Candida</em> family are also considered <a href="https://www.cdc.gov/drugresistance/biggest-threats.html#auris">“serious threats” by CDC</a>. These strains cause more than <a href="https://www.cdc.gov/drugresistance/biggest-threats.html#auris">34,000</a> infections annually, more than are caused by <em>C. auris</em>, but they are less likely to spread from person to person and cause outbreaks. Nevertheless, deeply invasive <em>C. auris</em> and other drug-resistant <em>Candida</em> infections are similar in severity, <a href="https://doi.org/10.1097/QCO.0000000000000215">resulting in the death of 40% of patients</a>. </p>
<p>Another dangerous fungus species the CDC singled out is <em>Aspergillus fumigatus,</em> which is a mold found in soil and vegetation that releases spores that most people inhale daily without problems. However, people with weakened immune systems – especially cancer patients or transplant recipients – can develop lung or other organ infections that kill between 50% and 75% of infected patients.</p>
<p><a href="https://academic.oup.com/cid/article/62/3/362/2462919">Azole antifungals</a> are the only drugs that kill <em>A. fumigatus</em> without causing serious side effects. Azoles also are used widely in agriculture. Azole-resistant <em>A. fumigatus</em> infections are most common in Europe, where they have been <a href="https://www.frontiersin.org/articles/10.3389/fmicb.2017.01024/full">linked to agricultural and patient use</a>. Although these infections still are uncommon in the U.S., CDC has placed azole-resistant <em>A. fumigatus</em> on its “resistance watch list” because azole use is so widespread in this country and vulnerable patient populations are large.</p>
<h2>Tackling antibiotic-resistant fungi requires many strategies</h2>
<p>How is the U.S. fighting antibiotic-resistant fungi? CDC and health departments are leading the way in surveillance for resistance and, in the case of <em>C. auris</em>, outbreak containment and prevention. Containment involves rapid and accurate diagnosis of <em>C. auris</em> infections, and the use of hospital gowns, gloves, equipment and cleaning materials that reduce the likelihood of spreading the fungus. </p>
<p>Various U.S. government agencies have funded research that is leading to <a href="https://carb-x.org/">new antifungal drugs and improved diagnostic tests</a>.</p>
<p>Organizations that grade the quality of medical care for the public now require health-care facilities to have antibiotic stewardship programs that reduce inappropriate prescribing and development of resistance. </p>
<p>Efforts are underway also to <a href="https://www.thefencepost.com/news/all-antibiotics-for-livestock-will-soon-require-a-vets-prescription/">control antibiotic use in agriculture and animals</a>, since resistance cannot be tackled by only focusing on human medicine. CDC and other U.S. agencies are working closely with international partners, because antibiotic-resistant microbes do not recognize geographic borders. Finally, the crucial first step in tackling a problem is to recognize it, which is why the CDC report on antibiotic resistance threats is so important.</p>
<p>[ <em>Deep knowledge, daily.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=deepknowledge">Sign up for The Conversation’s newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/127095/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Cornelius (Neil) J. Clancy receives investigator-initiated research funding from the National Institutes of Health, Astellas, Merck, Melinta, and Cidara, served on advisory boards or consulted for Astellas, Merck, the Medicines Company, Cidara, Scynexis, Shionogi, Qpex and Needham & Company, and spoken at symposia sponsored by Merck and T2Biosystems. . </span></em></p>Mention fungi and most people think of eating mushrooms or yeasts in bread or beer. But fungi are now on the CDC’s list of public health threats as the number of deadly infections they cause rise.Cornelius (Neil) J. Clancy, Associate Professor of Medicine and Director of Mycology, University of PittsburghLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1173592019-05-21T19:43:54Z2019-05-21T19:43:54ZAn outlaw yeast thrives with genetic chaos – and could provide clues for understanding cancer growth<figure><img src="https://images.theconversation.com/files/275516/original/file-20190520-69213-y3qnqf.jpg?ixlib=rb-1.1.0&rect=1847%2C14%2C3121%2C1661&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Researchers have discovered a lineage of yeast species that ignores the laws of cell growth.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/statue-justice-lady-iustitia-justitia-roman-692579545">Alexander Kirch/Shutterstock.com</a></span></figcaption></figure><p>“<a href="https://en.wikipedia.org/wiki/I_Fought_the_Law#The_Clash_version">I fought the law</a>,” the 1977 song popularized by the English punk-rock band <a href="https://en.wikipedia.org/wiki/The_Clash">The Clash</a>, features catchy lyrics about the dire consequences of life as an outlaw. In human affairs, the set of rules codified in our laws helps protect individuals and maintain order in our societies. Without rules, order is lost and chaos reigns. Life’s organisms have evolved their own set of checks and balances that help fight off chaos and ensure their survival and success.</p>
<p><a href="http://www.rokaslab.org">We are evolutionary biologists</a> who study the <a href="https://www.sciencedirect.com/science/article/pii/S0959437X15001082?via%3Dihub">evolution of budding yeasts</a>, a group of organisms that includes the baker’s yeast <em>Saccharomyces cerevisiae</em> that is essential for wine-making, brewing, baking, biotech and biofuel industries and several <em>Candida</em> species that cause <a href="https://www.cdc.gov/fungal/diseases/candidiasis/index.html">human infections</a>. </p>
<p>During our studies of budding yeast genome evolution, we serendipitously discovered that an ancient lineage of budding yeasts named <em>Hanseniaspora</em> <a href="http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3000255">appear to have lost genetic law and order</a>. Specifically, <em>Hanseniaspora</em> yeasts have done away with parts of their systems of checks and balances, in much the same way as cancerous cells do, challenging the existing paradigm that these processes are essential for cellular life.</p>
<h2>Checks and balances are evolutionarily conserved</h2>
<p>The entirety of an organism’s DNA, or the <a href="https://ghr.nlm.nih.gov/primer/hgp/genome">genome</a>, serves as the blueprint for life. From metabolism to movement, the DNA present in each cell contains the instructions for all aspects of its life. Alterations, or in biologists’ lingo “mutations,” in the parts of the DNA carrying these instructions are generally harmful – it is easier to break something than to improve it, and keeping mutations at very low levels is one of cellular life’s major rules. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/275501/original/file-20190520-69174-1dye24e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/275501/original/file-20190520-69174-1dye24e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/275501/original/file-20190520-69174-1dye24e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=429&fit=crop&dpr=1 600w, https://images.theconversation.com/files/275501/original/file-20190520-69174-1dye24e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=429&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/275501/original/file-20190520-69174-1dye24e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=429&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/275501/original/file-20190520-69174-1dye24e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=539&fit=crop&dpr=1 754w, https://images.theconversation.com/files/275501/original/file-20190520-69174-1dye24e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=539&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/275501/original/file-20190520-69174-1dye24e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=539&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Arrows point to breaks in chromosomes, a type of DNA damage.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/DNA_repair#/media/File:Brokechromo.jpg">https://en.wikipedia.org/wiki/DNA_repair#/media/File:Brokechromo.jpg</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Increases in the occurrence of mutations lead to <a href="https://doi.org/10.1093/jmcb/mjq057">cancer</a> and the death of an organism. Two central mechanisms that help cells do so are <a href="https://doi.org/10.1093/jmcb/mjq057">cell division and DNA repair processes</a>. These two systems of biological checks and balances not only ensure that cells divide properly but also that they detect and repair any damage that their DNA may have acquired. </p>
<p>Not surprisingly, these functions are <a href="https://www.nature.com/scitable/topicpage/dna-damage-repair-mechanisms-for-maintaining-dna-344">largely conserved across living organisms</a>, reflecting their fundamental importance and early evolutionary origins. The evolutionary conservation of these two systems runs so deep that, as the Nobel Prize winner <a href="https://en.wikipedia.org/wiki/Jacques_Monod">Jacques Monod</a> aptly put it, “<a href="https://www.ncbi.nlm.nih.gov/pubmed/15061168">Anything found to be true of <em>E. coli</em> [a bacterium] must also be true of elephants</a>.” </p>
<h2>The yeast rule breakers</h2>
<p>At first glance, the lives of <em>Hanseniaspora</em> yeasts, <a href="https://doi.org/10.1016/j.cell.2018.10.023">close relatives of the more familiar baker’s yeast</a>, appear unremarkable. They are typically found on grapes, often making their way into wine fermentation. Though they were originally and most commonly regarded as wine pests, wine makers in more recent years have started to blend them into the wine-making process to <a href="https://doi.org/10.3390/fermentation4030076">diversify flavor profiles of wines</a>. </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/275493/original/file-20190520-69209-1x21woa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/275493/original/file-20190520-69209-1x21woa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/275493/original/file-20190520-69209-1x21woa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/275493/original/file-20190520-69209-1x21woa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/275493/original/file-20190520-69209-1x21woa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/275493/original/file-20190520-69209-1x21woa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/275493/original/file-20190520-69209-1x21woa.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"><em>Hanseniaspora uvarum</em>, a budding yeast species lives without many genes otherwise thought to be essential for life.</span>
<span class="attribution"><span class="source">Dr. Neža Čadež, University of Ljubljana, Slovenia</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>In a recent study published in <a href="http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3000255">PLOS Biology</a>, we and our collaborators, including <a href="https://www.linkedin.com/in/dana-opulente-a9625b87/">Dana O. Opulente</a> and <a href="https://hittinger.genetics.wisc.edu/">Chris T. Hittinger</a> from the <a href="https://www.wisc.edu/">University of Wisconsin</a>, discovered that the lives of <em>Hanseniaspora</em> yeasts are far more chaotic than they first appear.</p>
<p>Why is that so? Because tens of millions of years ago, <em>Hanseniaspora</em> yeasts appear to have lost numerous genes known for their roles in cell division and repairing DNA damage. As a consequence, the genomes of <em>Hanseniaspora</em> yeasts are riddled with many more mutations than other yeast species and show evidence of diverse types of DNA damage, such as that caused by UV radiation, which is associated with <a href="https://doi.org/10.1111/j.1365-4632.2010.04474.x">skin cancers in humans</a>. </p>
<p>In short, like cancer cells, <em>Hanseniaspora</em> have dismissed typical cellular checks and balances and embraced chaos in their genome. But the lives of cancer cells are short-lived because they generally kill their host, whereas the single-celled <em>Hanseniaspora</em> yeasts appear to have inhabited the planet for tens of millions of years. How can they survive without such critical genes? What, if any, was the advantage of losing these genes? </p>
<h2>The speed-accuracy trade-off</h2>
<p>We believe the <em>Hanseniaspora</em> life strategy is a quantity-over-quality issue. By losing genes that control the pace of cell division, <em>Hanseniaspora</em> cells start dividing too early and speed through the process. Like a NASCAR driver racing through red lights, <em>Hanseniaspora</em> cells sometimes make errors that have grave consequences. For example, their fast-paced cell division can, in the process of dividing, lead to the death of daughter cells. </p>
<p>However, by dividing quickly these yeasts also produce lots of offspring, which means that they can outnumber competing microbes. Strikingly, <em>Hanseniaspora</em> yeasts can divide nearly twice as fast as the baker’s yeast, one of the champions of rapid dividing.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/qFN9oZe5VlM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption"><em>Hanseniaspora uvarum</em> (left) grows roughly twice as fast as baker’s yeast <em>Saccharomyces cerevisiae</em> (right). Video uploaded by Genetik Universität Osnabrück.</span></figcaption>
</figure>
<p>So, it appears that <em>Hanseniaspora</em> yeasts have fought the law and the yeasts won. Understanding how <em>Hanseniaspora</em> yeasts have done so – a major question we’re now addressing – may hold clues that could one day be used in the war against cancer.</p><img src="https://counter.theconversation.com/content/117359/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jacob L. Steenwyk receives funding from the Graduate Program in Biological Sciences at Vanderbilt University. </span></em></p><p class="fine-print"><em><span>Antonis Rokas receives funding from the National Science Foundation, the John Simon Guggenheim Memorial Foundation, the Burroughs Wellcome Trust, the National Institutes of Health, the Beckman Scholars Program, the March of Dimes, and Vanderbilt University. </span></em></p>Yeast isn’t just important for the foods we consume. A rogue lineage of yeast species that evolves faster than any other is revealing secrets that may help illuminate the molecular causes of cancer.Jacob L. Steenwyk, Graduate Student of Biological Sciences, Vanderbilt UniversityAntonis Rokas, Cornelius Vanderbilt Chair in Biological Sciences and Professor of Biological Sciences and Biomedical Informatics, Vanderbilt UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/841792017-10-31T16:07:36Z2017-10-31T16:07:36ZSynthetic sex in yeast promises safer medicines for people<figure><img src="https://images.theconversation.com/files/192654/original/file-20171031-18720-13bi7tz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">What can mating yeast tell us about new drugs?</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/conchur/13316830914">Conor Lawless</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Our old friend <em>Saccharomyces cerevisiae</em> – the yeast that’s helped people bake bread and brew beer <a href="https://doi.org/10.1073/pnas.0407921102">for millennia</a> – has just had its sex life upgraded.</p>
<p>Bioengineers at the University of Washington have <a href="https://doi.org/10.1073/pnas.1705867114">reprogrammed the mating habits</a> of this single-celled organism, letting the fungus get it on like never before. The result? A sexual revolution that could lead scientists to safer future medicines.</p>
<h2>Yeast as lab guinea pig</h2>
<p>We already rely on yeast for a lot more than just fermented food. Much of our modern understanding of genetics and cell biology has come from careful study and manipulation of the fungus.</p>
<p>Scientists and drug designers love <a href="http://doi.org/10.1038/nrc1372">working with yeast</a> because of its rapid cell cycle (a new generation is born every 90 minutes) and the relative ease with which its genes can be tweaked. Even human genes and genes encoding protein-based drugs can be spliced in, allowing researchers to study them in the lab in detail. Anti-cancer drugs <a href="http://dx.doi.org/10.1038/nri1837">have been optimized</a> this way. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/186279/original/file-20170917-8076-cg1xmj.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/186279/original/file-20170917-8076-cg1xmj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/186279/original/file-20170917-8076-cg1xmj.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=408&fit=crop&dpr=1 600w, https://images.theconversation.com/files/186279/original/file-20170917-8076-cg1xmj.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=408&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/186279/original/file-20170917-8076-cg1xmj.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=408&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/186279/original/file-20170917-8076-cg1xmj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=512&fit=crop&dpr=1 754w, https://images.theconversation.com/files/186279/original/file-20170917-8076-cg1xmj.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=512&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/186279/original/file-20170917-8076-cg1xmj.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=512&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Our species’ relationship with yeast predates our use of gold, horses and writing.</span>
<span class="attribution"><span class="source">Ian Haydon</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>One of the most popular techniques for this type of biomolecular research is known as <a href="https://doi.org/10.1038/nbt0697-553">yeast surface display</a>. Using this method, a gene can be added to yeast and the protein that results will appear on the easily accessible outer surface of the cell. With a new protein displayed on the surface, researchers can easily determine what other biomolecules the protein interacts with.</p>
<p>This method, pioneered in the laboratory of <a href="http://kdw-lab.mit.edu/">Dane Wittrup</a>, exploits aspects of the fungus’ sexual machinery.</p>
<p>Yes, even single-cell microbes can have sex. But as is often the case outside the animal kingdom, the way DNA gets swapped can seem unusual to human observers.</p>
<h2>Fungal fornication</h2>
<p>The terms “male” and “female” don’t really apply to budding yeast. Instead of forming sperm or eggs, the sex cells of yeast all look the same – like tiny, single-cell blobs. What makes two yeast blobs able to sexually reproduce are their so-called mating types.</p>
<p>The proteins that decorate the outside of a yeast sex cell, or gamete, determine that cell’s mating type. Put on copies of one protein and you’re one mating type; swap them out for a different protein and you’re the other. Agglutination (the unsexy term for yeast sex) only happens when the surface proteins of yeast gametes from opposite mating types interact.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/186262/original/file-20170916-8121-vevpb8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/186262/original/file-20170916-8121-vevpb8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/186262/original/file-20170916-8121-vevpb8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=387&fit=crop&dpr=1 600w, https://images.theconversation.com/files/186262/original/file-20170916-8121-vevpb8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=387&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/186262/original/file-20170916-8121-vevpb8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=387&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/186262/original/file-20170916-8121-vevpb8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=487&fit=crop&dpr=1 754w, https://images.theconversation.com/files/186262/original/file-20170916-8121-vevpb8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=487&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/186262/original/file-20170916-8121-vevpb8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=487&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Single-celled yeast as seen under a scanning electron microscope.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Saccharomyces_cerevisiae_SEM.jpg">Mogana Das Murtey and Patchamuthu Ramasamy</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Inspired by this molecular precision, a team of synthetic biologists led by University of Washington graduate student David Younger realized they could convert the natural yeast mating system into a new tool that would let them precisely measure molecular interactions at a much larger scale. </p>
<p>Though tiny and difficult to measure, molecular interactions are a big deal in drug design. Virtually every drug works via specific interactions with its target, and drugs that bind where they shouldn’t can be lethal.</p>
<p>Some experts blame off-target interactions for last year’s failed phase III clinical trial of Alnylam Pharmaceuticals’ revusiran, an RNA drug designed to treat a rare heart disease. <a href="https://doi.org/10.1038/nbt1216-1213">Nineteen people died</a> before the trial was called off, and the company’s stock took a <a href="https://www.businessinsider.com.au/alnylam-stock-down-after-drug-trial-discontinued-2016-10">US$3 billion hit</a>.</p>
<p>Figuring out whether a new drug binds what it’s supposed to is relatively easy; figuring out whether it binds anything else in our cells is tough. Established laboratory techniques like yeast surface display have helped scientists screen new drugs for potentially dangerous off-target interactions before they make it to clinical trials, but that technique lets you look for off-target interactions only one at a time. Younger’s team envisioned a way to test hundreds of drugs against thousands of potential targets, all by redesigning yeast sex.</p>
<h2>Redesigning yeast sex with multiple mating types</h2>
<p>To start, Younger needed a way to precisely measure mating efficiency in lab-grown yeast. Perfect efficiency would mean every cell that could fuse would do so. The more efficient the mating, the better matched the two mating types.</p>
<p>The team linked genetically encoded fluorescent markers – one blue, one red – to each of the natural yeast mating types. That made it simple to measure mating efficiency for a whole yeast population: They could just count the cells that stayed blue or red (unmated) versus those that turned purple (mated). It turns out for typical yeast grown in the lab, mating efficiency is around 60 percent.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/192653/original/file-20171031-18730-17dpxn9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/192653/original/file-20171031-18730-17dpxn9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/192653/original/file-20171031-18730-17dpxn9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/192653/original/file-20171031-18730-17dpxn9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/192653/original/file-20171031-18730-17dpxn9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/192653/original/file-20171031-18730-17dpxn9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/192653/original/file-20171031-18730-17dpxn9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/192653/original/file-20171031-18730-17dpxn9.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"></a>
<figcaption>
<span class="caption">Example of fluorescent-tagged yeast, in this case red and green. Together the markers look yellow.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Yeast_membrane_proteins.jpg">Masur</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>The team then deleted the natural agglutination proteins and replaced them with a pair of foreign proteins known to interact weakly. The mating efficiency dropped tenfold to 5.7 percent. They swapped in another pair and saw it rise to 19 percent. When they tried a third pair of proteins known to interact with much higher affinity, mating efficiency rose to 51.6 percent – close to what was seen in natural agglutination.</p>
<p>Just by tracking mating efficiency, the team could tell how strongly any two protein molecules interact. When they checked a pair of proteins that shouldn’t interact at all, mating efficiency was a meager 0.2 percent.</p>
<p>Now, instead of just the two natural mating types, <a href="https://doi.org/10.1073/pnas.1705867114">scientists can quickly engineer thousands of “sexes”</a> by coaxing individual yeast to decorate the outside of their cells with new, human-specified proteins. If a pair of new mating types are sexually compatible – meaning the proteins decorating their cell surfaces interact – their offspring will rise in number. By tallying up each genetically distinct offspring in a tube not much bigger than a thimble, thousands of potential molecular interactions can be quantified.</p>
<h2>Improving drug safety</h2>
<p>To show that their new tool could aid in drug development, the team generated 1,400 distinct variants of an emerging anti-cancer drug known as <a href="https://doi.org/10.7554/eLife.20352">XCDP07</a>. The drug is supposed to disrupt the unrestrained growth of cancer cells by binding specific cellular targets, but as with every drug, significant off-target interactions could render it useless. By mixing yeast displaying different versions of the drug with other yeast displaying human proteins, the team was able to identify versions of XCDP07 which only bound to the intended target.</p>
<p>Younger is working to get his new tool into the hands of more scientists. He’s already gifted his engineered yeast strains to eager researchers at Stanford, Yale, UCSD and beyond. Concerns over the cost and safety of emerging drugs have motivated him to start a company – funded by scientific grants, not investors – to turn his results into the next generation of medicines. Younger says the goal is to provide “comprehensive preclinical drug screening, rather than the current practice of screening a very small subset of possible off-target interactions.”</p>
<p>The next blockbuster drugs may owe a debt to yeast and their mating practices. Who says you can’t teach an old fungus new tricks?</p><img src="https://counter.theconversation.com/content/84179/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ian Haydon is a researcher at the Institute for Protein Design at the University of Washington.</span></em></p>By exploiting the way yeast cells mate, researchers have figured out a quicker, easier way to identify on- and off-target drug interactions.Ian Haydon, Doctoral Student in Biochemistry, University of WashingtonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/695362016-12-05T17:13:48Z2016-12-05T17:13:48ZMicrobes: Our tiny, crucial allies<figure><img src="https://images.theconversation.com/files/148716/original/image-20161205-8034-4xqgz5.jpg?ixlib=rb-1.1.0&rect=0%2C1011%2C4000%2C2862&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">In us, on us and all around us.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/pic-229711243/stock-photo-surrounded-by-germs-everywhere-an-illustration-related-to-the-infectious-environment-of-viruses-and-bacteria-that-we-are-surrounded-with-everywhere-and-every-day-of-our-lives.html">Microbes image via www.shutterstock.com.</a></span></figcaption></figure><p>Most of us considered microbes little more than nasty germs before science recently began turning our view of the microbial world on its head. A “microbe” is a bacterium and any other organism too small to see with the naked eye. After decades of trying to sanitize them out of our lives, the <a href="https://theconversation.com/us/topics/microbiome-3734">human microbiome</a> – the communities of microbes living on and in us – is now all the rage. And yet, some insist that we can’t really call microbes “good.” That’s nonsense.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/148701/original/image-20161205-8023-1qmthok.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/148701/original/image-20161205-8023-1qmthok.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/148701/original/image-20161205-8023-1qmthok.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/148701/original/image-20161205-8023-1qmthok.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/148701/original/image-20161205-8023-1qmthok.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/148701/original/image-20161205-8023-1qmthok.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/148701/original/image-20161205-8023-1qmthok.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/148701/original/image-20161205-8023-1qmthok.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"></a>
<figcaption>
<span class="caption">You can’t escape the microbial world.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/fredisonfire/27742722465">Exile on Ontario St</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Of course no one thinks microbes can be morally righteous. They don’t have intentions – good or bad. But it is fast becoming clear that certain microbial communities are vital to our individual health and that of our crops. Most of them either benefit us or do no harm most of the time.</p>
<p>This new realization is driving discoveries and an ongoing reevaluation of practices at the heart of two of humanity’s essential and iconic endeavors – medicine and agriculture. Members of our microbiome, especially those living in the gut, not only help <a href="http://doi.org/10.1038/ni.2608">keep their disease-causing cousins at bay</a>, they also <a href="http://doi.org/10.1126/science.1124234">make many compounds</a> that we need, but that our own bodies cannot make. <a href="http://dx.doi.org/10.1111/j.1574-6968.2002.tb11467.x">Butyrate</a> is one such compound – without a steady supply, cells lining the colon start to malfunction, which can lead to certain cancers and leaky gut syndrome, among other ailments. The neurotransmitter <a href="http://www.apa.org/monitor/2012/09/gut-feeling.aspx">serotonin</a> is another compound that gut microbiota make. Insufficient levels of it can make us feel grumpy. </p>
<p>In the botanical world the <a href="http://dx.doi.org/10.1016/j.tplants.2016.01.005">beneficial microbes living in and on a plant’s roots</a> produce plant growth hormones and stimulate plants to produce their own defensive compounds. Plants, in turn, make and release sugars and proteins from their roots to feed microbial allies in the soil. Why? It’s mutually beneficial.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/148697/original/image-20161205-8027-11tysn8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/148697/original/image-20161205-8027-11tysn8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/148697/original/image-20161205-8027-11tysn8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/148697/original/image-20161205-8027-11tysn8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/148697/original/image-20161205-8027-11tysn8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/148697/original/image-20161205-8027-11tysn8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/148697/original/image-20161205-8027-11tysn8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/148697/original/image-20161205-8027-11tysn8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=499&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Applying pesticides to agricultural fields has repercussions for our microbial allies.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/aquamech-utah/24443679794">Aqua Mechanical</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>But like all allies, we and our crops can count on microbial partners only as long as interests align. When we scramble microbiomes through indiscriminately using microbial toxins like broad-spectrum antibiotics and agrochemicals, they can turn on us. Troublesome microbes – pests and pathogens previously held in check by their benign brethren – can proliferate and wreak havoc. In the long run, this undermines both the microbial foundation of the natural defenses of our crops and our own immune system.</p>
<p>Indeed, our century-long war on microbes has delivered both major victories and unforeseen consequences. While we’ve tamed many infectious diseases, we now face <a href="http://doi.org/10.1101/gr.147710.112">superbugs</a>, disease-causing microbes that we can no longer kill using antibiotics. <a href="http://doi.org/10.1186/s13073-016-0307-y">Loss or alteration of the human microbiome</a> is also implicated in some common chronic diseases that plague our modern lives, including both type 1 and type 2 diabetes, inflammatory bowel disease, certain cancers, multiple sclerosis, asthma and allergies.</p>
<p>And in agriculture, although we may have high crop yields most years, farmers also face fields more vulnerable to pest <a href="http://msue.anr.msu.edu/topic/grapes/integrated_pest_management/how_pesticide_resistance_develops">outbreaks and resurgence</a>, and global losses in <a href="http://world.time.com/2012/12/14/what-if-the-worlds-soil-runs-out">soil fertility</a>. Over the past several decades, we’ve been learning that in many cases these problems, and their solutions, are rooted in how we treat the microbial communities living <a href="http://doi.org/10.1111/1751-7915.12180">in the soil</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/148699/original/image-20161205-8009-uhb9j7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/148699/original/image-20161205-8009-uhb9j7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/148699/original/image-20161205-8009-uhb9j7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=428&fit=crop&dpr=1 600w, https://images.theconversation.com/files/148699/original/image-20161205-8009-uhb9j7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=428&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/148699/original/image-20161205-8009-uhb9j7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=428&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/148699/original/image-20161205-8009-uhb9j7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=538&fit=crop&dpr=1 754w, https://images.theconversation.com/files/148699/original/image-20161205-8009-uhb9j7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=538&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/148699/original/image-20161205-8009-uhb9j7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=538&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Scanning electron micrograph of methicillin-resistant <em>Staphylococcus aureus</em>.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/niaid/8436193898">NIAID</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>We need a different front-line strategy if we are to preserve our <a href="http://emerald.tufts.edu/med/apua/about_issue/antibiotic_res.shtml">dwindling choices of effective antibiotics</a> and pesticides for when we truly need them. What might work better? Promoting the interests of our microbial allies, the ones that benefit us when we partner with them. Conserving and protecting microbiomes is the direction in which new practices in medicine and agriculture should aim.</p>
<p>In our recent book, <a href="http://books.wwnorton.com/books/The-Hidden-Half-of-Nature/">“The Hidden Half of Nature</a>,” we lay out some guiding principles for how to recruit and work with microbial allies based on advances in microbiome science. Protecting, and where possible restoring, microbiomes is key. We can protect the <a href="http://www.gutmicrobiotaforhealth.com/en/missing-microbes-book-review/">microbiomes of children</a> by giving them antibiotics only when necessary. And for anyone, when a course of antibiotics can’t be avoided, medical professionals should consider following up with an additional prescription of <a href="http://doi.org/10.1093/cid/civ177">probiotics</a>. These are typically specific strains or species of bacteria, that, used properly, can help recover beneficial gut microbiota in the aftermath of antibiotics. </p>
<p>We can also practice cultivating microbiomes. For human beings, it’s pretty straightforward. Eating a <a href="http://doi.org/10.1111/apt.13248">fiber-rich diet</a> nourishes one’s gut microbiome and is the single best way to keep it humming along. Plants too can benefit from a well-fed microbiome. Using <a href="http://doi.org/10.3763/ijas.2009.0477">cover crops and diversified crop rotations</a> helps to build up the organic matter on which beneficial soil microbiota thrive. Practices such as these form a much-needed foundation for conserving and protecting the microbiomes we’ll need to keep our bodies healthy and our farms productive. Indeed, stewardship of beneficial microbes offers an effective, and perhaps the only, way to keep them around and on our side well into the future.</p>
<p>After all, there is a very simple strategic reason to recruit and keep legions of microbial allies on our side. They outnumber us <a href="http://doi.org/10.1186/s13073-016-0307-y">trillions to one</a>.</p>
<hr>
<p><em>This article was coauthored by Anne Biklé, who wrote <a href="http://books.wwnorton.com/books/The-Hidden-Half-of-Nature/">“The Hidden Half of Nature: The Microbial Roots of Life and Health”</a> with David R. Montgomery.</em></p><img src="https://counter.theconversation.com/content/69536/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David R. Montgomery 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>Long viewed simply as ‘germs,’ the hidden half of nature turns out to be crucial to the health of people and plants.David R. Montgomery, Professor of Earth and Space Sciences, University of WashingtonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/570082016-04-12T14:55:49Z2016-04-12T14:55:49ZGourmet meals are filled with bacteria – and they taste delicious<figure><img src="https://images.theconversation.com/files/118314/original/image-20160412-15864-1rcfgsn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>When diners sat down at a recent <a href="http://www.manchestersciencefestival.com/whatson/menumadebymicrobes">gourmet experience</a> held at the Harvey Nichols department store in Manchester, their food was filled with bacteria, fungus and mould. Far from being a public health hazard, this special five-course meal was designed to show how microorganisms are a fundamental part of the food we eat.</p>
<p>In general, microbes don’t have a good reputation. Yet while some cause disease and decay, the vast majority of the planet’s microorganisms are not harmful to us. In fact, they can be incredibly useful, producing alcohol, acids and other molecules that add flavour, texture and nutritional value to food, as well as helping to preserve it.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/118315/original/image-20160412-15885-1fvtqc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/118315/original/image-20160412-15885-1fvtqc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/118315/original/image-20160412-15885-1fvtqc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/118315/original/image-20160412-15885-1fvtqc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/118315/original/image-20160412-15885-1fvtqc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/118315/original/image-20160412-15885-1fvtqc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/118315/original/image-20160412-15885-1fvtqc.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">Baker’s yeast: keeping humanity fed for thousands of years.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Microorganisms are used to make many of the staples of our diets. Bread, cheese and wine all immediately spring to mind. But the roles of these tiny living cells is far more diverse than you might think. The term “<a href="http://www.nature.com/articles/nmicrobiol201639">artisanal food microbiology</a>” has even been coined recently to describe an emerging interest among cooks to explore the potential for microbes to create new flavours and dishes.</p>
<p>At the gourmet meal we introduced in Manchester – the first of four we are running to raise awareness of the importance of microbes in food – almost every aspect of the food had been touched in some way by microorganisms.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/118326/original/image-20160412-15871-2r746m.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/118326/original/image-20160412-15871-2r746m.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/118326/original/image-20160412-15871-2r746m.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/118326/original/image-20160412-15871-2r746m.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/118326/original/image-20160412-15871-2r746m.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/118326/original/image-20160412-15871-2r746m.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/118326/original/image-20160412-15871-2r746m.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">Crostini canapés.</span>
<span class="attribution"><span class="source">Devin Louttit</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Sourdough crostini were the base for our delicious Welsh Rarebit canapes. Bread is produced through the <a href="https://www.exploratorium.edu/cooking/bread/bread_science.html">action of the yeast</a> <em>Saccharomyces cerevisiae</em> (baker’s yeast). This type of fungus is dormant until activated by the warm water in the dough, at which point it starts feeding on the sugars in the flour, releasing carbon dioxide that makes bread rise. Yeast adds many of the distinctive flavours and aromas we associate with bread and also produces the alcohol in beer and wine.</p>
<p><a href="http://discovermagazine.com/2003/sep/featscienceof">Sourdough bread</a> dough ferments and rises more slowly because it uses lactic acid bacteria and wild yeasts found naturally on cereal grains, rather than baker’s yeast. This produces lactic acid that gives it a tart flavour and breaks down the gluten that some people <a href="http://www.theguardian.com/lifeandstyle/2014/aug/12/rise-sourdough-bread-slow-fermented-health-benefits">struggle to digest</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/118327/original/image-20160412-15861-1hh3pm8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/118327/original/image-20160412-15861-1hh3pm8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/118327/original/image-20160412-15861-1hh3pm8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/118327/original/image-20160412-15861-1hh3pm8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/118327/original/image-20160412-15861-1hh3pm8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/118327/original/image-20160412-15861-1hh3pm8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/118327/original/image-20160412-15861-1hh3pm8.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">Sauerkraut surprise.</span>
<span class="attribution"><span class="source">Devin Louttit</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Our first course was a prosciutto platter, with apple and sultana sauerkraut (sour cabbage). The sourness comes from lactic acid, which is produced by lactic acid bacteria naturally present on the cabbage that feed on sugars released when the vegetable is sliced. These bacteria also produce vitamins including vitamin C, which is why sailors used to take sauerkraut on long voyages to <a href="http://modernfarmer.com/2014/04/magical-sour-cabbage-sauerkraut-helped-save-age-sail/">help prevent scurvy</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/118328/original/image-20160412-15883-123naeu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/118328/original/image-20160412-15883-123naeu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/118328/original/image-20160412-15883-123naeu.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/118328/original/image-20160412-15883-123naeu.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/118328/original/image-20160412-15883-123naeu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/118328/original/image-20160412-15883-123naeu.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/118328/original/image-20160412-15883-123naeu.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">Deep-fried mould.</span>
<span class="attribution"><span class="source">Devin Louttit</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>A warm salad of deep-fried Roquefort with smoked tofu followed. Cheese is made using bacteria such as <em>Lactobacillus</em> and <em>Streptococcus</em> that ferment the sugar in milk (lactose) into lactic acid. This causes a decrease in pH, preventing the growth and survival of other microbes and clotting the milk protein, turning it into solid cheese. The <a href="http://www.scientificamerican.com/article/roquefort-cheese/">blue colour</a> and distinct flavour of Roquefort comes from the mould <em>Penicillium roqueforti</em>, which – as you can guess – is related to the fungus that makes the antibiotic penicillin. Moulds are filamentous (thread-like) fungi that produce coloured spores, giving their colonies a distinctive and powdery appearance.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/118330/original/image-20160412-15861-vw6cbl.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/118330/original/image-20160412-15861-vw6cbl.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/118330/original/image-20160412-15861-vw6cbl.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/118330/original/image-20160412-15861-vw6cbl.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/118330/original/image-20160412-15861-vw6cbl.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/118330/original/image-20160412-15861-vw6cbl.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/118330/original/image-20160412-15861-vw6cbl.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">Merely a truffle.</span>
<span class="attribution"><span class="source">Devin Louttit</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The main course was truffled mushroom risotto and beer flatbread with rosemary. Like mushrooms, truffles are the fruiting body (spore-forming part) of fungi – organisms that are neither plants nor animals. Truffles form a symbiotic relationship (mycorrhiza) with the tree roots they grow on. This means they help the plant to gather water and minerals from the soil in exchange for sugars. Their <a href="http://www.bbc.com/future/story/20151125-why-do-truffles-taste-so-weird">pungent, musky smell</a> is thought to come <a href="http://aem.asm.org/content/81/20/6946.full">from a combination</a> of molecules given off by the truffles themselves and more microbes – the bacteria that live on them. </p>
<h2>And for dessert …</h2>
<p>The dessert consisted of pears poached in sauternes, a sweet wine that is unusual because it is made from mouldy grapes. This concentrates the grape sugar so that a significant amount remains in the wine after the traditional fermentation converts most of it to alcohol. Because of the delicious flavour this develops, the mould is known as the “<a href="http://winefolly.com/tutorial/they-call-it-noble-rot-botrytis/">Noble Rot</a>”. The scientific name for this grey mould is <em>Botrytis cinerea</em> and it is closely related to species of <em>Penicillium</em>. It produces a chemical aroma compound, phenylacetaldehyde, which is also commonly found in buckwheat and milk chocolate.</p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/118331/original/image-20160412-15864-iutbt9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/118331/original/image-20160412-15864-iutbt9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1067&fit=crop&dpr=1 600w, https://images.theconversation.com/files/118331/original/image-20160412-15864-iutbt9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1067&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/118331/original/image-20160412-15864-iutbt9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1067&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/118331/original/image-20160412-15864-iutbt9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1340&fit=crop&dpr=1 754w, https://images.theconversation.com/files/118331/original/image-20160412-15864-iutbt9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1340&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/118331/original/image-20160412-15864-iutbt9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1340&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">From slime to sublime.</span>
<span class="attribution"><span class="source">Devin Louttit</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>We finished our gourmet microbe meal with chocolate tart with framboise beer sauce, followed by coffee and chocolate petit fours. Both chocolate and coffee beans, which are actually seeds, go through a fermentation process that is used to break down the slimy “mucilage” coating that holds the seeds in the pod and to develop delicious and important chemical compounds. <a href="http://accounts.smccd.edu/case/chocolate.html">A series of bacteria</a>, yeasts and moulds are used to develop these flavour compounds, natural chemicals that we enjoy for their aroma and flavour.</p>
<p>Although many of these food fermentations are thousands of years old, chefs at experimental restaurants such as <a href="http://www.theverge.com/2016/3/29/11320596/chefs-fermentation-microbe-flavor-cooking-nature-microbiology">noma in Copenhagen</a> are still playing with microbes to produce new flavours. There is even a <a href="http://fermentationfest.com">growing fermentation community</a> of professional and amateur microbiologists who can cook up new kinds of acid to help make your new dish taste just right. So when you’re looking for a special new ingredient, perhaps you should turn to some of the oldest lifeforms on the planet.</p><img src="https://counter.theconversation.com/content/57008/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>How microbes are the key ingredients when it comes to concocting a gourmet menu.Joanna Verran, Professor of microbiology, Manchester Metropolitan UniversityMike Dempsey, Head of Faculty Research Degrees, Manchester Metropolitan UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/460102015-08-14T05:02:47Z2015-08-14T05:02:47ZYes, you can make alcohol from Vegemite, but …<figure><img src="https://images.theconversation.com/files/91852/original/image-20150814-501-i4ww8w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The humble spread gets caught up in the home brew debate.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/davidmarcel/4308792801/">Flickr/atl trader</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Vegemite has been in the news of late for all the wrong reasons. It all started when Minister for Indigenous Affairs Nigel Scullion said he’d heard the yeast extract was being used in dry communities to <a href="http://www.news.com.au/national/is-vegemite-toast-in-rural-queensland-abbott-government-pulls-it-from-rural-community-shelves/story-e6frfkp9-1227475612650">brew alcohol</a>.</p>
<p>The question of <a href="http://www.sbs.com.au/nitv/nitv-news/article/2015/08/10/it-even-possible-make-vegemite-alcohol">whether it’s even possible</a> to brew alcohol from the black spread has since been raised. </p>
<p>There is a precedent for implicating Vegemite in alcohol production in marginalised communities. In <a href="http://www.theage.com.au/news/national/mite-not-right--in-prison/2007/10/13/1191696241416.html">2007</a>, the breakfast spread came under fire in Victorian prisons as part of the sly-grog supply chain. In <a href="http://www.abc.net.au/news/2013-11-11/vegemite-ribena-being-used-to-brew-alcohol-in-dry-communities/5084488">2013</a> both Vegemite and Ribena were linked to homebrew systems in Indigenous communities with alcohol management plans in place. </p>
<p>In the United Kingdom in <a href="http://www.telegraph.co.uk/news/uknews/law-and-order/6537219/Prisoners-banned-from-having-fruit-after-using-it-to-make-alcohol.html">2009</a>, when assaults by prisoners increased reportedly due to hooch, access to fruit (including fresh apples and pears, tinned fruit, fruit juices and syrups) was prohibited or restricted.</p>
<h2>Is it possible to make alcohol from Vegemite?</h2>
<p>The short answer is “yes,” sort of. But then again, you can make alcohol from just about any food by adding the right type of yeast at the right time. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/91678/original/image-20150812-18096-13qzc3f.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/91678/original/image-20150812-18096-13qzc3f.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/91678/original/image-20150812-18096-13qzc3f.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=388&fit=crop&dpr=1 600w, https://images.theconversation.com/files/91678/original/image-20150812-18096-13qzc3f.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=388&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/91678/original/image-20150812-18096-13qzc3f.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=388&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/91678/original/image-20150812-18096-13qzc3f.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=487&fit=crop&dpr=1 754w, https://images.theconversation.com/files/91678/original/image-20150812-18096-13qzc3f.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=487&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/91678/original/image-20150812-18096-13qzc3f.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=487&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An extract from The Compendium of Alcohol Ingredients and Processes shows some of the different ways of creating alcoholic drinks.</span>
<span class="attribution"><a class="source" href="http://www.winebags.com/The-Compendium-of-Alcohol-Ingredients-and-Processes-s/2054.htm">The Vine Daily</a></span>
</figcaption>
</figure>
<p>Fermentation is the process of converting sugars to acids, gases or alcohol using a variety of microbial organisms, including yeast and bacteria. Many nonalcoholic foods use fermentation in the production process, including bread, <a href="https://microbewiki.kenyon.edu/index.php/Chocolate">chocolate</a> and pickled foods (for example, sauerkraut or kimchi). </p>
<p>Naturally occurring alcohol predates human history, and has been discovered by animals on <a href="http://www.scientificamerican.com/article/animals-like-to-get-drunk/">a number of occasions</a>. The earliest fermented alcoholic beverage has been <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC539767/">reported</a> from what is now China, and dated around 7000BC.</p>
<p><a href="http://www.nature.com/scitable/topicpage/yeast-fermentation-and-the-making-of-beer-14372813">Modern brewing techniques</a> combine knowledge from the natural world and early human history with recent technological advances in food safety and quality.</p>
<p>Baker’s yeast, <em><a href="http://www.yeastgenome.org/">Saccharomyces cerevisiae</a></em>, is a fungus that lives naturally on every continent. This single celled organism may have already smuggled itself to Antarctica and into space, stowing away on its usual home: the surface of fruit. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/91680/original/image-20150812-32232-yoarw8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/91680/original/image-20150812-32232-yoarw8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/91680/original/image-20150812-32232-yoarw8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/91680/original/image-20150812-32232-yoarw8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/91680/original/image-20150812-32232-yoarw8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/91680/original/image-20150812-32232-yoarw8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/91680/original/image-20150812-32232-yoarw8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/91680/original/image-20150812-32232-yoarw8.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"></a>
<figcaption>
<span class="caption"><em>Saccharomyces cerevisiae</em>, baker’s yeast.</span>
<span class="attribution"><span class="source">Masur/Wikimedia Commons</span></span>
</figcaption>
</figure>
<p>The fungus is so ubiquitous and hardy, it can be found almost anywhere.</p>
<p>In fact, the next time you’re in Oregon, you can even have a craft beer fermented with <a href="http://mentalfloss.com/article/52658/beer-was-brewed-using-yeast-grown-beard">yeast from the master brewer’s beard</a>. Or, you can try a beer that’s been brewed with yeast that was <a href="http://www.ninkasibrewing.com/delicious/beers/special-release-series/ground-control.html?ageVerified=defaultValue">sent into space on a rocket</a>.</p>
<p>Scientists also use yeast in their research: for example, Ben uses yeast as a model system to mimic what happens in humans, to find out why many proteins have <a href="http://pubs.acs.org/doi/abs/10.1021/pr300599f">complex sugar structures attached to their surface</a>. Maggie uses yeast as part of a [recombinant expression system](https://en.wikipedia.org/wiki/Protein_expression_(biotechnology) to produce <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0073136">insecticidal peptides </a> found in spider venoms.</p>
<h2>How is Vegemite made?</h2>
<p>It’s ironic that one of the key byproducts of beer fermentation is yeast. Much of this yeast goes to animal feed or other food products, but some cultures have developed the habit of further processing this thick yeasty paste. </p>
<p>Salt is added and the mixture is heated, which causes the yeast cells to burst open. Any remaining cellular material is removed manually by filtration to produce the deliciously smooth local delicacy we call Vegemite.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/91677/original/image-20150812-9896-pwojsx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/91677/original/image-20150812-9896-pwojsx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/91677/original/image-20150812-9896-pwojsx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/91677/original/image-20150812-9896-pwojsx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/91677/original/image-20150812-9896-pwojsx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/91677/original/image-20150812-9896-pwojsx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/91677/original/image-20150812-9896-pwojsx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/91677/original/image-20150812-9896-pwojsx.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 photo of Vegemite and Marmite, two examples of yeast extract-based breakfast spreads.</span>
<span class="attribution"><span class="source">AZAdam/Wikimedia Commons</span></span>
</figcaption>
</figure>
<p>The salt and heat kill pretty much everything – almost certainly including yeast – so that makes it no good as a source of yeast for brewing. The yeast would have to be added back in just as you would with any food to make a fermented product (like alcohol, or bread). The same is true for any food: all you need is a sugar source and the right microorganism to ferment food.</p>
<p>But we are scientists who use yeast in our research, so why take it for granted that there’s no live yeast in Vegemite when we can run an experiment and see if it’s true?</p>
<p>So we bought fresh, unopened jars of Vegemite, and tried to grow anything at all from the contents. Nothing grew. You can see for yourself in the photos below.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/91853/original/image-20150814-477-vonebx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/91853/original/image-20150814-477-vonebx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=515&fit=crop&dpr=1 600w, https://images.theconversation.com/files/91853/original/image-20150814-477-vonebx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=515&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/91853/original/image-20150814-477-vonebx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=515&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/91853/original/image-20150814-477-vonebx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=647&fit=crop&dpr=1 754w, https://images.theconversation.com/files/91853/original/image-20150814-477-vonebx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=647&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/91853/original/image-20150814-477-vonebx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=647&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">We could not grow yeast from Vegemite (on the left); plenty of yeast grew on the control plate (visible as white streaks on the right plate), which didn’t contain Vegemite.</span>
<span class="attribution"><span class="source">B. Schulz</span></span>
</figcaption>
</figure>
<h2>Should Vegemite be banned in Indigenous communities?</h2>
<p>The <a href="http://www.who.int/substance_abuse/publications/global_alcohol_report/msb_gsr_2014_1.pdf?ua=1#page=13">World Health Organization</a> reported a quarter of alcohol consumed worldwide in 2010 was unrecorded (homebrew).</p>
<p>The <a href="http://www.who.int/substance_abuse/publications/global_alcohol_report/msb_gsr_2014_2.pdf?ua=1#page=261">Global Status Report on Alcohol and Health</a> shows Australia’s unrecorded alcohol consumption increased from an average of 0.1 litres per person in 2003–2005 to 1.8 litres per person from 2008–2010. The amount of recorded alcohol remained the same during both periods.</p>
<p>The first alcohol management plan was implemented by a Queensland Indigenous community in <a href="http://www.indigenousjustice.gov.au/briefs/brief016.pdf">2002</a>, in Aurukun. <a href="https://theconversation.com/new-singers-old-songs-alcohol-bans-in-aboriginal-communities-10051">Alcohol management plans</a> and subsequent legislation requiring <a href="https://theconversation.com/how-mandatory-treatment-for-public-drunkenness-is-failing-aboriginal-people-44145">mandatory treatment for public drunkenness</a> have been <a href="http://www.abc.net.au/news/2015-08-02/alcohol-prohibition-creating-teenage-prostitutes-sly-grog-in-wa/6664158">controversial</a>.</p>
<p>Even though there is no active yeast in Vegemite, it can still be used as a substrate for other microorganisms that could ferment the sugars and, ultimately, produce alcohol. That’s true of any sugar-containing food, including fruit and fruit juices. </p>
<p>Science tells us alcohol can be made from just about any food that contains sugar, in the presence of the right naturally occurring microorganisms. That doesn’t mean fresh fruits, or everyone’s favourite breakfast spread, should be prohibited.</p>
<p>Limiting access to fresh fruits, as the UK has done, is counter intuitive from a public health perspective. This would be especially damaging for Indigenous Australians, who have diabetes at <a href="http://www.aihw.gov.au/diabetes/populations-of-interest/">three times the rate</a> of non-Indigenous Australians. </p>
<p>Evidence-based, community-led, practical solutions should prevail to address complex challenges. Simply blaming a breakfast spread is not the solution.</p><img src="https://counter.theconversation.com/content/46010/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Maggie Hardy receives funding from the Australian Research Council, UniQuest Pty Ltd, and The University of Queensland. </span></em></p><p class="fine-print"><em><span>Ben Schulz receives funding from NHMRC. He is affiliated with Pirate Party Australia.</span></em></p>Vegemite has been used for many things over the years. But claims it was used to brew alcohol in dry Indigenous communities had many asking if that was even possible.Maggie Hardy, Senior Postdoctoral Research Fellow, The University of QueenslandBen Schulz, NHMRC R.D. Wright Biomedical Fellow, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/271282014-05-27T05:47:54Z2014-05-27T05:47:54ZMaking ‘designer genes’ from scratch begins with yeast<figure><img src="https://images.theconversation.com/files/49525/original/8rdrsmg7-1401169581.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Building yeast chromosomes – cheers to that!</span> <span class="attribution"><a class="source" href="http://www.flickr.com/photos/laughingsquid/2326398611">Scott Beale/Flicke</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>Australia is to play a significant role in the quest for artificial life as it joins an international project to create the world’s first synthetic yeast, we can announce today.</p>
<p>Under the leadership of <a href="http://www.bs.jhmi.edu/MBG/boekelab/">Jef Boeke</a> from New York University, the <a href="http://syntheticyeast.org/">Yeast 2.0</a> project is a consortium of yeast laboratories in the US, UK, China, Singapore, India and now Australia aims to produce the first synthetic yeast by 2017.</p>
<p>It marks a major breakthrough for Australian research in the field of synthetic biology which takes science and technology into a new dimension. From the treatment of malaria to the production of environmentally friendly biofuels, synthetic biologists are shifting the boundaries of science and technology to pioneer new life.</p>
<p>In 2010, the world witnessed a future-shaping breakthrough in re-programming the natural “software” of bacteria. Researchers at the Craig Venter Institute in the US <a href="http://www.jcvi.org/cms/press/press-releases/full-text/article/first-self-replicating-synthetic-bacterial-cell-constructed-by-j-craig-venter-institute-researcher/home/">successfully transplanted</a> an artificially constructed genome of <em>Mycoplasma mycoides</em> – all 1.1 million base pairs of its DNA – into a closely related bacterial cell, <em>Mycoplasma capricolum</em>.</p>
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<p>This marked a world-first: a “synthetic” genome, designed by computer, giving life to another living being with no ancestor.</p>
<p>The potential for future advances in synthetic genomics seems endless and the possibilities are revolutionary.</p>
<p>Synthetic biology aims to build novel and artificial biological parts (such as <a href="https://theconversation.com/explainer-what-is-a-gene-12951">genes</a> and chromosomes) devices and systems that can then be used to “fuel us, heal us and feed us” – as the UK Science Minster David Willetts <a href="http://www.bbc.com/news/science-environment-23274175">said last year</a>.</p>
<p>New organisms can be custom built to perform specific tasks for a range of purposes, ranging from medical diagnostic tests to the detection of bugs in water supplies.</p>
<p>There are plans for biological computers, where electronic circuits are replaced by synthetic biological systems and artificial photosynthesis, where fuel is produced from artificial leaves.</p>
<p>The humble yeast – a single-cell fungus – is vital to many of Australia’s key industries and are ideal for research because they are the most simple eukaryotic cells that are easily propagated and only survive in man-made environments such as laboratories. </p>
<p>The ability to design and create synthetic yeast “to order” so that it can perform specific tasks, stands to benefit a range of sectors from primary production to medical research. </p>
<p>The Yeast 2.0 program is an ambitious project. Earlier this year, Professor Boeke’s laboratory announced it had synthesised the first functional chromosome in yeast, marking an important first step.</p>
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<figcaption><span class="caption">Scientists synthesise the first functional ‘designer’ chromosome in yeast.</span></figcaption>
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<p>The next step requires an international mission to create the other 15 chromosomes that are needed to generate the first fully synthetic yeast by 2017. </p>
<p>I will be leading the Australian team at Macquarie University responsible for the synthesis of yeast’s chromosome 14. The other 15 chromosomes will be synthesised by the <a href="http://syntheticyeast.org/">Yeast 2.0 partners</a> and, as this synthetic genomics project continues, further universities will also become involved in synthetic biology beyond this yeast-focused project.</p>
<h2>Synthetic biology: different to genetic modification</h2>
<p>At this point, some clarification is needed.</p>
<p>While synthetic biology may involve “genes” and “engineering” it is very different from “genetic modification”. Synthetic biology does not change existing genes: it invents entirely new genomes. </p>
<p>These new genomes can be used to change the blueprint of a yeast cell enabling that cell to perform specialised tasks such producing new, life-saving antibiotics. </p>
<p>So under Macquarie’s leadership, Australia’s contribution to synthetic yeast genomics will also cross traditional disciplinary boundaries and seek meaningful, collaborative engagement between science and society.</p>
<p>In the UK, public understanding of this emerging field is sophisticated, engaged and collaborative. From the start, those working at the coalface of synthetic biology research have engaged closely with those who care about the impact of their work on wider society. </p>
<p>So from the outset, as in the UK, our panel of experts engaged on the project will not be limited to scientists, engineers and technologists. We will engage social scientists and ethicists, we will work closely with experts in philosophy, law and religious studies.</p>
<p>But our objective – without reservation – is to conduct research that puts systems biology at the service of society.</p><img src="https://counter.theconversation.com/content/27128/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Macquarie University has partnered with the Australian Wine Research Institute in the Yeast 2.0 project. This research is being funded by Macquarie University’s, NSW Department of Primary Industries, the NSW Department of Primary Industries, NSW Office for Science and Research, headed up by the NSW Chief Scientist and Engineer Professor Mary O'Kane</span></em></p>Australia is to play a significant role in the quest for artificial life as it joins an international project to create the world’s first synthetic yeast, we can announce today. Under the leadership of…Sakkie Pretorius, Deputy Vice-Chancellor (Research), Macquarie UniversityLicensed as Creative Commons – attribution, no derivatives.