Editing Yeast (section)

== Uses ==
The useful physiological properties of yeast have led to their use in the field of [[biotechnology]]. [[fermentation (biochemistry)|Fermentation]] of sugars by yeast is the oldest and largest application of this technology. Many types of yeasts are used for making many foods: [[baker's yeast]] in bread production, brewer's yeast in [[beer fermentation]], and yeast in wine fermentation and for [[xylitol]] production.<ref name="Chen-2010"/> So-called [[red rice yeast]] is actually a [[Mold (fungus)|mold]], ''[[Monascus purpureus]]''. Yeasts include some of the most widely used [[model organism]]s for [[genetics]] and [[cell biology]].<ref name="Botstein-2011"/><!--cites previous sentence-->

=== Alcoholic beverages ===
Alcoholic beverages are defined as [[drink|beverages]] that contain [[ethanol]] (C<sub>2</sub>H<sub>5</sub>OH). This ethanol is almost always produced by [[fermentation (food)|fermentation]]&nbsp;– the [[metabolism]] of [[carbohydrate]]s by certain species of yeasts under anaerobic or low-oxygen conditions. Beverages such as mead, wine, beer, or [[distilled beverage|distilled spirits]] all use yeast at some stage of their production. A distilled beverage is a beverage containing ethanol that has been purified by [[distillation]]. Carbohydrate-containing plant material is fermented by yeast, producing a dilute solution of ethanol in the process. Spirits such as [[whiskey]] and [[rum]] are prepared by distilling these dilute solutions of ethanol. Components other than ethanol are collected in the condensate, including water, [[ester]]s, and other alcohols, which (in addition to that provided by the oak in which it may be aged) account for the [[Flavour (taste)|flavour]] of the beverage.

{{anchor|top-fermenting|bottom-fermenting}}

===={{anchor|Beer}}Beer ====
{{Main|Brewing}}
{{see also|Barm}}
[[File:NM.0019545 Jästkrans.jpg|thumb|[[Yeast ring]] used by Swedish farmhouse brewers in the 19th century to preserve yeast between brewing sessions.]]<!-- This section is linked from [[Swedish beer]], [[Brewer's yeast]], [[Brewers yeast]], [[Brewing yeast]], [[Brewing Yeast]], [[Brewer's Yeast]], and [[Brewers' yeast]] -->
[[File:2009-03-21 Beer brewing bubbles.jpg|right|thumb|Bubbles of [[carbon dioxide]] forming during beer-brewing<ref name="Ostergaard-2000"/>]]
Brewing yeasts may be classed as "top-cropping" (or "top-fermenting") and "bottom-cropping" (or "bottom-fermenting").<ref>{{cite book|vauthors=Priest FG, Stewart GG |date=2006 |url=https://books.google.com/books?id=TIYbNdrIsPEC&pg=PA84 |page=84 |publisher=CRC Press |title=Handbook of Brewing|isbn=9781420015171 }}</ref> Top-cropping yeasts are so called because they form a foam at the top of the [[wort]] during fermentation. An example of a top-cropping yeast is ''[[Saccharomyces cerevisiae]]'', sometimes called an "ale yeast".<ref name="Gibson-2010"/> Bottom-cropping yeasts are typically used to produce [[lager]]-type beers, though they can also produce [[ale]]-type beers. These yeasts ferment well at low temperatures. An example of bottom-cropping yeast is ''[[Saccharomyces pastorianus]]'', formerly known as ''S.&nbsp;carlsbergensis''.

Decades ago,{{vague|date=March 2018}} taxonomists reclassified ''S.&nbsp;carlsbergensis'' (uvarum) as a member of ''S.&nbsp;cerevisiae'', noting that the only distinct difference between the two is metabolic. {{dubious |reason=In conflict with newer sources cited by “Saccharomyces uvarum” article. Could be a lumper/splitter thing, but the names ain’t invalid yet.|date=January 2022}} Lager strains of ''S.&nbsp;cerevisiae'' secrete an enzyme called melibiase, allowing them to hydrolyse [[melibiose]], a [[disaccharide]], into more fermentable [[monosaccharide]]s. Top- and bottom-cropping and cold- and warm-fermenting distinctions are largely generalizations used by laypersons to communicate to the general public.<ref>For more on the taxonomical differences, see {{cite book |author=Dowhanick TM |chapter=Yeast&nbsp;– Strains and Handling Techniques |title=The Practical Brewer |editor=McCabe JT |publisher=Master Brewers Association of the Americas |year=1999}}</ref>

The most common top-cropping brewer's yeast, ''S.&nbsp;cerevisiae'', is the same species as the common baking yeast.<ref name="Amendola-2002"/> Brewer's yeast is also very rich in [[essential mineral]]s and the [[B vitamin]]s (except B<sub>12</sub>), a feature exploited in food products made from leftover ([[by-product]]) yeast from brewing.<ref name="University of Maryland Medical Center"/> However, baking and brewing yeasts typically belong to different strains, cultivated to favour different characteristics: baking yeast strains are more aggressive, to carbonate [[dough]] in the shortest amount of time possible; brewing yeast strains act more slowly but tend to produce fewer off-flavours and tolerate higher alcohol concentrations (with some strains, up to 22%).

''[[Dekkera/Brettanomyces]]'' is a genus of yeast known for its important role in the production of '[[lambic]]' and specialty [[sour ale]]s, along with the secondary conditioning of a particular Belgian [[Trappist beer]].<ref name="Vanderhaegen-2003"/> The taxonomy of the genus ''Brettanomyces'' has been debated since its early discovery and has seen many reclassifications over the years. Early classification was based on a few species that reproduced asexually (anamorph form) through multipolar budding.<ref name="Custers-1940"/> Shortly after, the formation of ascospores was observed and the genus ''Dekkera'', which reproduces sexually (teleomorph form), was introduced as part of the taxonomy.<ref name="VanderWalt-1984"/> The current taxonomy includes five species within the genera of ''Dekkera/Brettanomyces''. Those are the anamorphs ''[[Brettanomyces bruxellensis]]'', ''[[Brettanomyces anomalus]]'', ''[[Brettanomyces custersianus]]'', ''[[Brettanomyces naardenensis]]'', and ''[[Brettanomyces nanus]]'', with teleomorphs existing for the first two species, ''[[Dekkera bruxellensis]]'' and ''[[Dekkera anomala]]''.<ref name="Oelofse-2008"/> The distinction between ''Dekkera'' and ''Brettanomyces'' is arguable, with Oelofse et al. (2008) citing Loureiro and Malfeito-Ferreira from 2006 when they affirmed that current molecular DNA detection techniques have uncovered no variance between the anamorph and teleomorph states. Over the past decade, ''Brettanomyces'' spp. have seen an increasing use in the craft-brewing sector of the industry, with a handful of breweries having produced beers that were primarily fermented with pure cultures of ''Brettanomyces'' spp. This has occurred out of experimentation, as very little information exists regarding pure culture fermentative capabilities and the aromatic compounds produced by various strains. ''Dekkera''/''Brettanomyces'' spp. have been the subjects of numerous studies conducted over the past century, although a majority of the recent research has focused on enhancing the knowledge of the wine industry. Recent research on eight ''Brettanomyces'' strains available in the brewing industry focused on strain-specific fermentations and identified the major compounds produced during pure culture anaerobic fermentation in wort.<ref name="Yakobson-2010"/>

==== Wine ====
{{Main|Yeast in winemaking}}
[[File:Schramsberg Vineyards, July 2019-7609.jpg|thumb|Yeast in a bottle during sparkling wine production at [[Schramsberg Vineyards]], Napa]]
Yeast is used in [[winemaking]], where it converts the sugars present ([[glucose]] and [[fructose]]) in [[grape juice]] ([[must]]) into ethanol. Yeast is normally already present on grape skins. [[Fermentation (wine)|Fermentation]] can be done with this endogenous "wild yeast",<ref name="Ross-1997"/> but this procedure gives unpredictable results, which depend upon the exact types of yeast species present. For this reason, a pure yeast culture is usually added to the must; this yeast quickly dominates the fermentation. The wild yeasts are repressed, which ensures a reliable and predictable fermentation.<ref name="González-2001"/>

Most added wine yeasts are strains of ''S. cerevisiae'', though not all strains of the species are suitable.<ref name="González-2001"/> Different ''S.&nbsp;cerevisiae'' yeast strains have differing physiological and fermentative properties, therefore the actual strain of yeast selected can have a direct impact on the finished wine.<ref name="Dunn-2005"/> Significant research has been undertaken into the development of novel wine yeast strains that produce atypical flavour profiles or increased complexity in wines.<ref name=YeastRef14/><ref name="McBryde-2006"/>

The growth of some yeasts, such as ''[[Zygosaccharomyces]]'' and ''[[Brettanomyces]]'', in wine can result in [[wine fault]]s and subsequent spoilage.<ref name="Loureiro-2003"/> ''Brettanomyces'' produces an array of [[metabolite]]s when growing in wine, some of which are volatile [[phenol]]ic compounds. Together, these compounds are often referred to as "''Brettanomyces'' character", and are often described as "[[antiseptic]]" or "barnyard" type aromas. ''Brettanomyces'' is a significant contributor to wine faults within the wine industry.<ref name="Lamar"/>

Researchers from the [[University of British Columbia]], Canada, have found a new strain of yeast that has reduced [[amine]]s. The amines in [[Wine color|red wine]] and [[Chardonnay]] produce off-flavors and cause headaches and hypertension in some people. About 30% of people are sensitive to biogenic amines, such as [[histamine]]s.<ref>{{Cite news|title=Eureka! Vancouver scientists take the headache out of red wine |url=https://vancouversun.com/health/Eureka+Vancouver+scientists+take+headache+wine/4281742/story.html |author=Shore R |date=15 February 2011 |work=[[The Vancouver Sun]] |archive-url=https://web.archive.org/web/20110217024652/http://www.vancouversun.com/health/Eureka%2BVancouver%2Bscientists%2Btake%2Bheadache%2Bwine/4281742/story.html |archive-date=17 February 2011 |url-status=dead }}</ref>

=== Baking ===
{{Main|Baker's yeast}}
{{More citations needed section|date=April 2013}}

Yeast, most commonly ''S.&nbsp;cerevisiae'', is used in baking as a [[leavening agent]], converting the [[fermentation (food)|fermentable]] sugars present in dough into [[carbon dioxide]]. This causes the dough to expand or rise as gas forms pockets or bubbles. When the dough is baked, the yeast dies and the air pockets "set", giving the baked product a soft and spongy texture. The use of potatoes, water from potato boiling, [[egg (food)|eggs]], or sugar in a bread dough accelerates the growth of yeast. Most yeasts used in baking are of the same species common in alcoholic fermentation. In addition, ''[[Saccharomyces exiguus]]'' (also known as ''S.&nbsp;minor''), a wild yeast found on plants, fruits, and grains, is occasionally used for baking. In breadmaking, the yeast initially respires aerobically, producing carbon dioxide and water. When the oxygen is depleted, [[fermentation (biochemistry)|fermentation]] begins, producing ethanol as a waste product; however, this evaporates during baking.<ref name="Moore-Landecker-1996"/>

[[File:Compressed fresh yeast - 1.jpg|right|thumb|A block of compressed fresh yeast]]

It is not known when yeast was first used to bake bread. The first records that show this use came from [[Ancient Egypt]].<ref name="Legras-2007"/> Researchers speculate a mixture of flour meal and water was left longer than usual on a warm day and the yeasts that occur in natural contaminants of the [[flour]] caused it to ferment before baking. The resulting bread would have been lighter and tastier than the normal flat, hard cake.

[[File:Dry yeast.jpg|thumb|right|Active dried yeast, a granulated form in which yeast is commercially sold]]

Today, there are several retailers of baker's yeast; one of the earlier developments in North America is [[Fleischmann's Yeast]], in 1868. During World War II, Fleischmann's developed a [[wikt:granulate|granulated]] active dry yeast which did not require refrigeration, had a longer [[shelf life]] than fresh yeast, and rose twice as fast. Baker's yeast is also sold as a fresh yeast compressed into a square "cake". This form perishes quickly, so must be used soon after production. A weak solution of water and sugar can be used to determine whether yeast is expired.<ref>{{Cite web |last=John |date=2023-08-24 |title=Does Yeast Expire? [Active Dry vs Instant Yeast] |url=https://pizzaovenshub.com/does-yeast-expire/ |access-date=2023-09-27 |website=PizzaOvensHub |language=en-US}}</ref> In the solution, active yeast will foam and bubble as it ferments the sugar into ethanol and carbon dioxide. Some recipes refer to this as [[Proofing (baking technique)|proofing]] the yeast, as it "proves" (tests) the viability of the yeast before the other ingredients are added. When a [[sourdough]] starter is used, flour and water are added instead of sugar; this is referred to as proofing the [[Sponge and dough|sponge]].{{Citation needed|reason='Reliable sources needed for the whole paragraph, also maybe some irrelevant information for an WP article'|date=October 2016}}

When yeast is used for making bread, it is mixed with [[flour]], salt, and warm water or milk. The dough is [[Kneading|kneaded]] until it is smooth, and then left to rise, sometimes until it has doubled in size. The dough is then shaped into loaves. Some bread doughs are knocked back after one rising and left to rise again (this is called [[proofing (baking technique)|dough proofing]]) and then baked. A longer rising time gives a better flavor, but the yeast can fail to raise the bread in the final stages if it is left for too long initially.{{citation needed|date=August 2024}}

=== Bioremediation ===
Some yeasts can find potential application in the field of [[bioremediation]]. One such yeast, ''[[Yarrowia lipolytica]]'', is known to degrade [[palm oil]] mill [[effluent]], [[Trinitrotoluene|TNT]] (an explosive material), and other [[hydrocarbon]]s, such as [[alkane]]s, [[fatty acid]]s, fats and oils.<ref name="Zinjarde-2014"/> It can also tolerate high concentrations of salt and [[heavy metal (chemistry)|heavy metals]],<ref name="Bankar-2009b"/> and is being investigated for its potential as a heavy metal [[Biosorption|biosorbent]].<ref name="Bankar-2009a"/> ''Saccharomyces cerevisiae'' has potential to bioremediate toxic pollutants like [[arsenic]] from industrial effluent.<ref name="Soares-2012"/> Bronze statues are known to be degraded by certain species of yeast.<ref name="Cappitelli-2008"/> Different yeasts from Brazilian gold mines [[bioaccumulation|bioaccumulate]] free and [[Coordination complex|complexed]] silver ions.<ref name="Singh-2006"/>

=== Industrial ethanol production ===
{{See also|Biofuel#Bioalcohols|label 1=Bioethanol}}

The ability of yeast to convert sugar into ethanol has been harnessed by the biotechnology industry to produce [[ethanol fuel]]. The process starts by milling a feedstock, such as [[sugar cane]], [[field corn]], or other [[cereal grain]]s, and then adding dilute [[sulfuric acid]], or fungal alpha [[amylase]] enzymes, to break down the starches into complex sugars. A glucoamylase is then added to break the complex sugars down into simple sugars. After this, yeasts are added to convert the simple sugars to ethanol, which is then distilled off to obtain ethanol up to 96% in purity.<ref name="USDE-2009"/>

''Saccharomyces'' yeasts have been [[genetically engineered]] to ferment [[xylose]], one of the major fermentable sugars present in [[Lignocellulosic biomass|cellulosic biomasses]], such as agriculture residues, paper wastes, and wood chips.<ref name="Brat-2009"/><ref name="Ho-1998"/> Such a development means ethanol can be efficiently produced from more inexpensive feedstocks, making [[cellulosic ethanol]] fuel a more competitively priced alternative to gasoline fuels.<ref name="Madhavan-2012"/>

=== Nonalcoholic beverages ===
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A number of sweet [[soft drink|carbonated beverages]] can be produced by the same methods as beer, except the fermentation is stopped sooner, producing carbon dioxide, but only trace amounts of alcohol, leaving a significant amount of residual sugar in the drink.

* '''[[Root beer]]''', originally made by Native Americans, commercialized in the United States by [[Charles Elmer Hires]] and especially popular during [[Prohibition in the United States|Prohibition]]
* '''[[Kvass]]''', a [[fermented drink]] made from [[rye]], popular in Eastern Europe. It has a recognizable, but low alcoholic content.<ref name="Smith-2013"/>
* '''[[Kombucha]]''', a fermented sweetened tea. Yeast in [[symbiosis]] with [[acetic acid bacteria]] is used in its preparation. Species of yeasts found in the tea can vary, and may include: ''[[Brettanomyces bruxellensis]]'', ''[[Candida stellata]]'', ''[[Schizosaccharomyces pombe]]'', ''[[Torulaspora delbrueckii]]'' and ''[[Zygosaccharomyces bailii]]''.<ref name="Teoh-2004"/> Also popular in Eastern Europe and some [[Post-Soviet states|former Soviet republics]] under the name ''chajnyj grib'' ({{langx|ru|Чайный гриб}}), which means "tea mushroom".
* '''[[Kefir]]''' and '''[[kumis]]''' are made by fermenting milk with yeast and bacteria.<ref name="de Oliveira-2013"/>
* '''[[Mauby]]''' ({{langx|es|mabí}}), made by fermenting sugar with the wild yeasts naturally present on the bark of the ''[[Colubrina elliptica]]'' tree, popular in the [[Caribbean]]
{{See also|Tibicos}}

=== Foods and {{vanchor|nutritional supplements}} ===
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| image2 = Marmite.jpg
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| caption1 = [[Marmite]] and [[Vegemite]], products made from [[yeast extract]]
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Yeast is used as an ingredient in foods for its [[umami]] flavor, in much of the same way that [[monosodium glutamate]] (MSG) is used and, like MSG, yeast often contains free [[glutamic acid]]. Examples include:<ref>{{Cite book|last1=Stewart|first1=Graham G.|url=https://books.google.com/books?id=TIYbNdrIsPEC&pg=PA691|title=Handbook of Brewing, Second Edition|last2=Priest|first2=Fergus G.|date=2006-02-22|publisher=CRC Press|isbn=978-1-4200-1517-1|language=en|page=691}}</ref>
* {{anchor|Yeast extract}}[[Yeast extract]], made from the intracellular contents of yeast and used as [[food additive]]s or [[Flavoring|flavour]]s. The general method for making yeast extract for food products such as [[Vegemite]] and [[Marmite]] on a commercial scale is ''heat autolysis'', i.e. to add salt to a suspension of yeast, making the solution hypertonic, which leads to the cells' shrivelling up. This triggers [[autolysis (biology)|autolysis]], wherein the yeast's [[digestion|digestive]] enzymes break their own [[protein]]s down into simpler compounds, a process of self-destruction. The dying yeast cells are then heated to complete their breakdown, after which the husks (yeast with thick cell walls that would give poor texture) are removed. Yeast autolysates are used in [[Vegemite]] and [[Promite]] (Australia); [[Marmite]] (the United Kingdom); the unrelated [[Marmite (New Zealand)|Marmite]] (New Zealand); [[Vitam-R]] (Germany); and [[Cenovis]] ([[Switzerland]]).
* [[File:Hefeflocken Naturata.jpg|thumb|150px|Nutritional yeast flakes are yellow in colour]]<!--
-->[[Nutritional yeast]], which is whole dried, deactivated yeast cells, usually ''S.&nbsp;cerevisiae''. Usually in the form of yellow flake or powder, its nutty and umami flavor makes it a vegan substitute for [[Powdered cheese|cheese powder]].<ref name="Thaler-2014"/> Another popular use is as a topping for popcorn. It can also be used in mashed and fried potatoes, as well as in [[scrambled egg]]s. It comes in the form of flakes, or as a yellow powder similar in texture to [[cornmeal]]. In Australia, it is sometimes sold as "savoury yeast flakes".<ref name="Lee"/>

Both types of yeast foods above are rich in [[Vitamin B|B-complex]] vitamins (besides vitamin B<sub>12</sub> unless fortified),<ref name="University of Maryland Medical Center"/> making them an attractive nutritional supplement to vegans.<ref name="Thaler-2014"/> The same vitamins are also found in some yeast-fermented products mentioned above, such as [[kvass]].<ref name="Līdums-2017">{{cite journal |last1=Līdums |first1=Ivo |last2=Kārkliņa |first2=Daina |last3=Ķirse |first3=Asnate |last4=Šabovics |first4=Mārtiņš |date=April 2017 |title=Nutritional value, vitamins, sugars and aroma volatiles in naturally fermented and dry kvass |url=http://llufb.llu.lv/conference/foodbalt/2017/FoodBalt_2017_Conference_Proceedings.pdf#page=61 |journal=Foodbalt |publisher=[[Faculty of Food Technology, Latvia University of Life Sciences and Technologies]] |pages=61–65 |doi=10.22616/foodbalt.2017.027 |issn=2501-0190}}</ref> Nutritional yeast in particular is naturally low in fat and [[sodium]] and a source of protein and vitamins as well as other minerals and [[cofactor (biochemistry)|cofactors]] required for growth. Many brands of nutritional yeast and yeast extract spreads, though not all, are fortified with [[Cyanocobalamin|vitamin B<sub>12</sub>]], which is produced separately by [[bacteria]].<ref name="Duyff-2012"/>

In 1920, the [[Fleischmann's Yeast|Fleischmann Yeast Company]] began to promote yeast cakes in a "Yeast for Health" campaign. They initially emphasized yeast as a source of vitamins, good for skin and digestion. Their later advertising claimed a much broader range of health benefits, and was censured as misleading by the [[Federal Trade Commission]]. The [[fad]] for yeast cakes lasted until the late 1930s.<ref name="Price-2015">{{cite journal|author1=Price C|title=The healing power of compressed yeast|journal=Distillations Magazine|date=Fall 2015|volume=1|issue=3|pages=17–23|url=https://www.sciencehistory.org/distillations/magazine/the-healing-power-of-compressed-yeast|access-date=20 March 2018}}</ref>

=== Probiotics ===
Some [[probiotic]] supplements use the yeast ''[[Saccharomyces boulardii|S.&nbsp;boulardii]]'' to maintain and restore the natural flora in the [[gastrointestinal tract]]. ''S.&nbsp;boulardii'' has been shown to reduce the symptoms of acute [[diarrhea]],<ref name="Dinleyici-2012"/> reduce the chance of infection by ''[[Clostridium difficile (bacteria)|Clostridium difficile]]'' (often identified simply as C. difficile or C. diff),<ref name="Johnson-2012"/> reduce bowel movements in diarrhea-predominant [[irritable bowel syndrome|IBS]] patients,<ref name="Dai-2013"/> and reduce the incidence of [[antibiotic-associated diarrhea|antibiotic]]-, [[travelers' diarrhea|traveler's]]-, and [[HIV/AIDS]]-associated diarrheas.<ref name="McFarland LV-2010"/>

=== Aquarium hobby ===
Yeast is often used by [[aquarium]] hobbyists to generate carbon dioxide (CO<sub>2</sub>) to nourish plants in [[Aquascaping|planted aquaria]].<ref name="Pedersen-2007"/> CO<sub>2</sub> levels from yeast are more difficult to regulate than those from pressurized CO<sub>2</sub> systems. However, the low cost of yeast makes it a widely used alternative.<ref name="Pedersen-2007"/>

=== Scientific research ===
[[File:Yeast cell english.svg|thumb|right|Diagram showing a yeast cell]]

Several yeasts, in particular ''[[S.&nbsp;cerevisiae]]'' and ''[[S. pombe]]'', have been widely used in genetics and cell biology, largely because they are simple [[eukaryote|eukaryotic]] cells, serving as a model for all eukaryotes, including humans, for the study of fundamental cellular processes such as the [[cell cycle]], [[DNA replication]], [[genetic recombination|recombination]], [[cell division]], and metabolism. Also, yeasts are easily manipulated and cultured in the laboratory, which has allowed for the development of powerful standard techniques, such as [[yeast two-hybrid]],<ref name="Brückner-2009"/> [[synthetic genetic array]] analysis,<ref name="Boone-2006"/> and [[tetrad (genetics)|tetrad analysis]]. Many proteins important in human biology were first discovered by studying their [[homology (biology)|homologues]] in yeast; these proteins include [[cell cycle protein]]s, [[Cell signaling|signaling proteins]], and protein-processing [[enzyme]]s.<ref name="Ishiwata-2007"/>

On 24 April 1996, ''S.&nbsp;cerevisiae'' was announced to be the first eukaryote to have its [[genome]], consisting of 12 million [[base pair]]s, fully sequenced as part of the [[Genome Project]].<ref name="Williams-1996"/> At the time, it was the most complex organism to have its full genome sequenced, and the work of seven years and the involvement of more than 100 laboratories to accomplish.<ref name="Henahan-1996"/> The second yeast species to have its genome sequenced was ''Schizosaccharomyces pombe'', which was completed in 2002.<ref name="Wood-2002"/><ref name="Reinert-2002"/> It was the sixth eukaryotic genome sequenced and consists of 13.8&nbsp;million base pairs. As of 2014, over 50 yeast species have had their genomes sequenced and published.<ref name="Lin-2014"/>

Genomic and functional gene annotation of the two major yeast models can be accessed via their respective [[model organism databases]]: SGD<ref>{{cite web |url=https://www.yeastgenome.org |title=About SGD |website=Saccharomyces Genome Database}}</ref><ref>{{cite journal |last1=Cherry |first1=JM |last2=Hong |first2=EL |last3=Amundsen |first3=C |last4=Balakrishnan |first4=R |last5=Binkley |first5=G |last6=Chan |first6=ET |last7=Christie |first7=KR |last8=Costanzo |first8=MC |last9=Dwight |first9=SS |last10=Engel |first10=SR |last11=Fisk |first11=DG |last12=Hirschman |first12=JE |last13=Hitz |first13=BC |last14=Karra |first14=K |last15=Krieger |first15=CJ |last16=Miyasato |first16=SR |last17=Nash |first17=RS |last18=Park |first18=J |last19=Skrzypek |first19=MS |last20=Simison |first20=M |last21=Weng |first21=S |last22=Wong |first22=ED |title=Saccharomyces Genome Database: the genomics resource of budding yeast. |journal=Nucleic Acids Research |date=January 2012 |volume=40 |issue=Database issue |pages=D700–5 |doi=10.1093/nar/gkr1029 |pmid=22110037|pmc=3245034 }}</ref> and PomBase.<ref>{{cite web |url=https://www.pombase.org |title=PomBase | website=S. pombe Genome Database}}</ref><ref name="pmid38376816">{{cite journal | vauthors = Rutherford KM, Lera-Ramírez M, Wood V | title = PomBase: a Global Core Biodata Resource—growth, collaboration, and sustainability | journal = Genetics | volume = 227 | issue = 1 | date = May 2024 | pmid = 38376816 | pmc = 11075564  | doi = 10.1093/genetics/iyae007 }}</ref>

=== Genetically engineered biofactories ===
Various yeast species have been genetically engineered to efficiently produce various drugs, a technique called [[metabolic engineering]].<ref>{{Cite journal|first1=N. |last1=Milne|first2=P.  |last2=Thomsen|first3=N.  |last3=Mølgaard Knudsen|first4=P.  |last4=Rubaszka|first5=M.  |last5=Kristensen|first6=L.  |last6=Borodina|date=2020-07-01|title=Metabolic engineering of ''Saccharomyces cerevisiae'' for the ''de novo'' production of psilocybin and related tryptamine derivatives|journal=Metabolic Engineering|language=en|volume=60|pages=25–36|doi=10.1016/j.ymben.2019.12.007|pmid=32224264|pmc=7232020|issn=1096-7176|doi-access=free}}</ref> ''S.&nbsp;cerevisiae'' is easy to genetically engineer; its physiology, metabolism and genetics are well known, and it is amenable for use in harsh industrial conditions. A wide variety of chemical in different classes can be produced by engineered yeast, including [[phenols|phenolics]], [[isoprenoid]]s, [[alkaloid]]s, and [[polyketide]]s.<ref name="Siddiqui-2012"/> About 20% of [[biopharmaceutical]]s are produced in ''S.&nbsp;cerevisiae'', including [[insulin]], [[vaccine]]s for [[hepatitis]], and [[human serum albumin]].<ref name="Nilesen-2012"/>