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'''''Saccharomyces''''' is a genus of fungus including many species. The distinct species of ''Saccharomyces'' are revised frequently as more research is done. All species are unicellular and capable of fermentation. ''Saccharomyces cerevisiae'' is the most well-known species of yeast. It is used in the fermentation of beer, wine, and sake, and as a leavening agent in bread. It is commonly referred to as "ale yeast", "wine yeast" (see [[CategorySaccharomyces#Killer_Wine_Yeast|Killer Wine Yeast]] below), or "bread yeast". ''S. pastorianus'', known as lager yeast, is a hybrid closely related to ''S. cerevisiae'' but is not a true species. ''S. cerevisiae'' is commonly studied as a model organism and was the first eukaryote to have its genome entirely sequenced. In rare cases, ''Saccharomyces'' can form a [[pellicle]]. See ''[[Lactobacillus]]'', ''[[Pediococcus]]'', ''[[Brettanomyces]]'', [[Mixed Cultures]], [[Kveik#Commercial_Availability|Kveik]], and [[Nonconventional Yeasts and Bacteria]] charts for other commercially available cultures. ==Genus==The origin of ''S. cerevisiae'' and other species of ''Saccharomyces'', as well as the entire genus itself, is likely to be Asia, according to genomic studies. The presence of ancestral polymorphism (variations on the same genetic sequence between populations) suggests that these species arose during a short period of time during which a lot of genetic inheritance was shared before the speciation events occurred. Despite this, genetic differentiation between species of ''Saccharomyces'' is higher than in plants and animals <ref name=Peris_2023">[https://www.nature.com/articles/s41467-023-36139-2 Peris, D., Ubbelohde, E.J., Kuang, M.C. et al. Macroevolutionary diversity of traits and genomes in the model yeast genus Saccharomyces. Nat Commun 14, 690 (2023). https://doi.org/10.1038/s41467-023-36139-2.]</ref>. Some species could have originated in other parts of the world. For example, ''S. uvarum'' and ''S. eubayanus'' in South America, ''S. jurei'' and ''S. paradoxus'' in Europe, and ''S. arboricola'' in Oceana <ref name=Peris_2023" />. These speciation events occurred around 5-10 million years ago during the warm climate of the [https://www.britannica.com/science/Miocene-Epoch Miocene ephoc]<ref>[https://www.sciencedirect.com/science/article/pii/S0092867418313321 Xing-Xing Shen, Dana A. Opulente, Jacek Kominek, Xiaofan Zhou, Jacob L. Steenwyk, Kelly V. Buh, Max A.B. Haase, Jennifer H. Wisecaver, Mingshuang Wang, Drew T. Doering, James T. Boudouris, Rachel M. Schneider, Quinn K. Langdon, Moriya Ohkuma, Rikiya Endoh, Masako Takashima, Riichiroh Manabe, Neža Čadež, Diego Libkind, Carlos A. Rosa, Jeremy DeVirgilio, Amanda Beth Hulfachor, Marizeth Groenewald, Cletus P. Kurtzman, Chris Todd Hittinger, Antonis Rokas, Tempo and Mode of Genome Evolution in the Budding YeastSubphylum, Cell, Volume 175, Issue 6, 2018, Pages 1533-1545.e20, ISSN 0092-8674, https://doi.org/10.1016/j.cell.2018.10.023.]</ref>. Humans played a particularly important role in the genetic divergence of some strains of ''S. cerevisiae'' (see [[Saccharomyces#History_of_Domestication|History of Domestication]]below).
==Species==
''Saccharomyces cerevisiae'' is the type species of the genus ''Saccharomyces'', although and is well-known and highly studied. it is used in industrial production of baking and fermentation as well as bioenergy and biomedical fields. Wholke-genome sequencing was completed in 1996, and since then the body of scientific knowledge on the species of ''S. cerevisiae'' is higher than any other eukaryotic system. More recently, whole-genome sequencing has also been performed on other species of ''Saccharomyces paradoxus'', which has resulted in models for studies on population genomics, as well as insight into the evolution of this genus <ref>[https://academic.oup.com/femsyr/article/20/3/foaa013/5810663 Haya Alsammar, Daniela Delneri, An update on the diversity, ecology and biogeography of the Saccharomyces genus, FEMS Yeast Research, Volume 20, Issue 3, May 2020, foaa013, https://doi.org/10.1093/femsyr/foaa013.]</ref>. Species of ''Saccharomyces'' other than ''S. cerevisiae's'' closest relative, is likely older (and more globally ubiquitous than only certain strains of ''S. cerevisiae'') are generally unable to efficiently ferment maltotriose, although some can ferment maltose (such as ''S. eubayanus'') <refname="Cubillos_2019">ref needed[https://onlinelibrary.wiley.com/doi/10.1002/yea.3380 Bioprospecting for brewers: Exploiting natural diversity for naturally diverse beers. F.A. Cubillos, B. Gibson, N. Grijalva‐Vallejos, K. Krogerus, J. Nikulin. 2019. DOI: https://doi.org/10.1002/yea.3380.]</ref>.
{| class="wikitable sortable"
! Species !! Ecology !! Notes
|-
| ''S. cerevisiae '' || Domestic: Beer, Wine, Bread. Wild: Ripe fruits. || Believed to have been originally isolated from the skin of grapes|-| ''S. pastorianus'' || Lager-type Beer Fermentation. || Lager yeast; hybrid of ''S. eubayanus'' and ''S. cerevisiae'' <ref name="wikipedia_cereisiae">[https://en.wikipedia.org/wiki/Saccharomyces_pastorianus#Genomics Wikipedia. Saccharomyces pastorianus. Retrieved 02/12/2019.]</ref>|-| ''S. paradoxus'' || Deciduous trees (oak, maple, birch) || Closest known species to the baker's yeast|-| ''S. eubayanus'' || Patagonia || Probable parent of lager yeast <ref name="libkind_2011">[https://www.ncbi.nlm.nih.gov/pubmed/21873232 Microbe domestication and the identification of the wild genetic stock of lager-brewing yeast. Libkind D1, Hittinger CT, Valério E, Gonçalves C, Dover J, Johnston M, Gonçalves P, Sampaio JP. 2011. DOI: 10.1073/pnas.1105430108]</ref><ref name="bing_2014">[https://www.ncbi.nlm.nih.gov/pubmed/24845661 Evidence for a Far East Asian origin of lager beer yeast. Bing J, Han PJ, Liu WQ, Wang QM, Bai FY. DOI: 10.1016/j.cub.2014.04.031.]</ref>|-| ''S. mikatae'' || Decayed leaves in Japan || |-| ''S. kudriavzevii'' || Decayed leaves in Japan || Involved in hybrid strains used in commercial brewing and winemaking strains with ''S.uvarum'', ''S.cerevisiae'' and ''S.bayanus''.|-| ''S. bayanus'' || Wine || Hybrid of ''S. uvarum'', ''S. eubayanus'', and ''S. cerevisiae''. Once proposed to be the parent of ''S. pastorianus'', although this is no longer the consensus. Most wine making strains sold as ''S. baynus'' have been found to be ''S. cerevisiae'' instead <ref name="wikipedia_cereisiae" /><ref>[https://en.wikipedia.org/wiki/Saccharomyces_bayanus Wikipedia. Saccharomyces bayanus. Retrieved 02/12/2019.]</ref>.|-| ''S. florentinus'' || Drosophila and sulphurized grape must || |-| ''S. arboricola || Cold tolerant || Produces high levels of ethyl esters <ref>[https://www.ncbi.nlm.nih.gov/pubmed/28755430 Alternative Saccharomyces interspecies hybrid combinations and their potential for low-temperature wort fermentation. Nikulin J, Krogerus K, Gibson B. 2017. DOI: 10.1002/yea.3246.]</ref>|- | ''S. uvarum'' || Found in nature and fermented drinks, especially cold fermentated drinks <ref>[https://academic.oup.com/femsle/article/192/2/191/554355 Saccharomyces uvarum, a proper species within Saccharomyces sensu stricto. Andrea Pulvirenti, Huu-Vang Nguyen, Cinzia Caggia, Paolo Giudici, Sandra Rainieri, Carlo Zambonelli. 2000. DOI: https://doi.org/10.1111/j.1574-6968.2000.tb09381.x]</ref>. || Contains horizontal gene transfers from ''S. cerevisiae'' and ''S. kudriavzevii'' due to human-controlled beverage fermentation <ref>[https://www.ncbi.nlm.nih.gov/pubmed/28779574 Many interspecific chromosomal introgressions are highly prevalent in Holarctic Saccharomyces uvarum strains found in human-related fermentations. Albertin W, Chernova M, Durrens P, Guichoux E, Sherman DJ, Masneuf-Pomarede I, Marullo P. 2018. DOI: 10.1002/yea.3248.]</ref>.|-| ''S. jurei'' || Tolerant of cooler fermentation temperatures; discovered on oak tree bark (''Quercus robur'') in France. || Tolerant of high osmotic stress and high sugar concentrations. Discovered by Naseeb et al., 2017; 2018 <ref>[https://pubmed.ncbi.nlm.nih.gov/28639933/ Naseeb, S., James, S.A., Alsammar, H., Michaels, C.J., Gini, B., Nueno-Palop, C., Bond, C.J., McGhie, H., Roberts,I.N., Delneri, D., 2017. Saccharomyces jureisp. nov., isolation and genetic identification of a novel yeast species from Quercus robur. Int. J. Syst. Evol. Microbiol. 67.DOI: https://doi.org/10.1101/2021.01.08.425916.]</ref><ref>[https://pubmed.ncbi.nlm.nih.gov/30097472/ Naseeb, S., Alsammar, H., Burgis, T., Donaldson, I., Knyazev, N., Knight, C., Delneri, D., 2018. Whole genome sequencing, de novo assembly and phenotypic profiling for the new budding yeast species Saccharomyces jurei. G3 Genes, Genomes, Genet. 8, 2967–2977. https://doi.org/10.1534/g3.118.200476.]</ref>.|-| ''S. bayanus'' || Found only in brewing environments || A complex hybrid between ''S. eubayanus'', ''S. uvarum'', and ''S. cerevisiae'' <ref>[https://www.pnas.org/doi/abs/10.1073/pnas.1105430108 Microbe domestication and the identification of the wild genetic stock of lager-brewing yeast. Diego Libkind, Chris Todd Hittinger, Elisabete Valério, Carla Gonçalves, Jim Dover, Mark Johnston, Paula Gonçalves, and José Paulo Sampaio. DOI: https://doi.org/10.1073/pnas.1105430108. 2011.]</ref>.|-|} See also:* [https://www.preprints.org/manuscript/202107.0423/v1 Brewing Efficacy of Non-Conventional Saccharomyces Non-Cerevisiae Yeasts; 2021.] ===''S. cerevisiae''=======General Info====* [https://www.youtube.com/channel/UCEyCSmOUfkp_QPH1PClAxVQ/videos Escarpment Labs video presentations on yeast basics] and [https://www.youtube.com/watch?v=d5TFluCM3_4 Why do yeast cells need oxygen? | Yeast Basics 2: Lecture 1].* [https://www.escarpmentlabs.com/single-post/2020/07/14/fan-its-what-beer-yeast-craves Escarpment Labs blog post on FAN requirements for different strains of brewers yeast.]* [https://webcache.googleusercontent.com/search?q=cache%3ADKUyEeRhaNYJ%3Ahttps%3A%2F%2Fwww.novozymes.com%2F-%2Fmedia%2FProject%2FNovozymes%2FWebsite%2Fwebsite%2Fdocument-library%2FAdvance-your-business%2FBioenergy%2FYeast-Micronutrient-Requirements-2017.pdf%20&cd=1&hl=en&ct=clnk&gl=us "Yeast Micronutrient and Growth Factor Requirements," by Novozymes North America Technical Service - Bioenergy.]* [https://www.facebook.com/groups/MilkTheFunk/permalink/3758279604200226 MTF thread on using olive oil instead of oxygen for yeast growth, with link to New Belgium study and input from Lance Shaner.] ====Native Environment====Although it has been long understood that ''S. cerevisiae'' occurs naturally on bark and fruit, recent studies suggest that some ''Saccharomyces'' species are more abundant in leaf matter on the ground. See the [https://www.youtube.com/watch?v=ChHcR9qaxj0 "Where (Do) the Wild Yeast Roam" video by Bryan from Sui Generis blog] and these studies/discussions: * [http://onlinelibrary.wiley.com/doi/10.1111/1758-2229.12446/full A systematic forest survey showing an association of Saccharomyces paradoxus with oak leaf litter.]* [http://onlinelibrary.wiley.com/doi/10.1111/mec.13120/abstract The interaction of Saccharomyces paradoxus with its natural competitors on oak bark.]* [http://macau.uni-kiel.de/receive/dissertation_diss_00018537?lang=en The natural ecology of Saccharomyces yeasts.]* [https://www.facebook.com/groups/MilkTheFunk/permalink/1910439962317542/ Associated MTF thread.] Geographically speaking, studies such as [https://www.nature.com/articles/s41467-023-36139-2 Peris et al (2023)] have used DNA sequencing to determine that many species of ''Saccharomyces'' originated in East Asia <ref name=Peris_2023" />. ====History of Domestication====* [https://www.garshol.priv.no/blog/426.html "The Yeast Family Tree Grows," by Lars Marius Garshol, 10-26-2021.]* [https://www.cell.com/cell/fulltext/S0092-8674(16)31071-6 Domestication and Divergence of Saccharomyces cerevisiae Beer Yeasts, by Gallone et al (2016); the first look at the domesticated ''S. ceresiae'' family tree and the grouping of two major genetic groups for domesticated ale yeasts: Beer 1 and Beer 2.]** [http://www.garshol.priv.no/blog/374.html "A family tree for brewer's yeast" a review of a study on the family tree of brewer's yeast by Lars Garshol]. See also [http://www.garshol.priv.no/blog/390.html Lars's write up on the history of people reusing yeast as opposed to spontaneously fermenting].* Kristoffer Krogerus's attempts to map the Gallone et al. codes to the commercial White Labs/Wyeast products and updated family tree dendrograms:** [http://beer.suregork.com/?p=3919 Kristoffer Krogerus's attempt] to decode the strains in the above mentioned study ([http://www.cell.com/cell/fulltext/S0092-8674(16)31071-6?_returnURL=http%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0092867416310716%3Fshowall%3Dtrue "Domestication and Divergence of Saccharomyces cerevisiae Beer Yeasts"]) and a redraw of the dendrogram family tree of ale yeasts as well as a spreadsheet that makes a best guess to map the strains in the study to actual White Labs strains. ** [http://beer.suregork.com/?p=4000 First update to the family tree of all of the yeast strains in the previously mentioned studies with commercial product names, by Kristoffer Krogerus.] ** [http://beer.suregork.com/?p=4030 Second update to the family tree which includes kveik sequencing from Tyrawa et al (2018), as well as discussing strains that might be the same from different yeast labs.] ** See also comments by Krisoffer [https://www.facebook.com/groups/MilkTheFunk/permalink/1400297539998456 on this MTF thread].* Subsequent whole genome sequencing studies that grow the family tree of ''S. cerevisiae'':** [http://www.cell.com/current-biology/fulltext/S0960-9822(16)30984-8 Distinct Domestication Trajectories in Top-Fermenting Beer Yeasts and Wine Yeasts, by Gonçalves et al (2016).]** [https://www.nature.com/articles/s41467-018-05106-7 The origin and adaptive evolution of domesticated populations of yeast from Far East Asia, by Duan et al (2018); a study showing evidence for initial domestication of yeast in the Far East Asia.]** [https://www.nature.com/articles/s41586-018-0030-5 Genome evolution across 1,011 Saccharomyces cerevisiae isolates, by Peter et al (2018), which indicated that domestication of yeast might have begun in Asia.] See also [https://www.theatlantic.com/science/archive/2018/04/yeast-sequencing-china/557930/ this article] and the [https://www.facebook.com/groups/MilkTheFunk/permalink/2056777254350478/ associated MTF thread].** [https://www.nature.com/articles/s41586-020-2889-1 A yeast living ancestor reveals the origin of genomic introgressions.] ''From Dr. Bryan Heit:'' "This study may interest some here. A lot of yeast evolution is driven by introgression - interspecies hybridization which gets "cleaned up" by back-crosses with one of the parental species (but leaving pieces of the other parental species genome behind). But it's always been a bit of a mystery of how these hybrids can back-cross, since these hybrids are usually unable to reproduce sexually. These scientists found a '''living''' ancestor of a hybrid between ''S. cerevisiae'' and ''S. paradoxus'' that gave rise to many modern ''S. cerevisiae'' strains, and may have figured out how it regained the ability to reproduce with its parental species <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/4055441394484044 Dr. Bryan Heit. Milk The Funk post on a new study that found a living ancestor of a hybrid between ''S. cerevisiae'' and ''S. paradoxus'' that gave rise to many modern ''S. cerevisiae'' strains. 11/12/2020.]</ref>."** [https://www.sciencedaily.com/releases/2019/03/190305153648.htm Modern beer yeast emerged from mix of European grape wine, Asian rice wine yeast, by Science Daily. The two explanations of beer yeast ancestry are: beer yeasts might have evolved from a mix of European wine strains and Asian fermentation strains during trade on the Silk Route, as well as an unknown ancestor. The second explanation is that European wine strains themselves descended from Asian strains (whether European wine strains descended from Asia or were developed in Europe has not been clear and needs more research).]** [[Kveik#Recent_Yeast_Lab_Analysis_and_Commercial_Availability|Norwegian "kveik" yeast forms its own genetic group of yeast, indicating a subtree of the Beer 1 group.]]** [https://www.nature.com/articles/s41559-019-0998-8 Fermentation innovation through complex hybridization of wild and domesticated yeasts] - Hittinger lab sequencing of commercial and homebrew strains of yeast, analyzing their hybrid species makeup using WGS.** [https://beer.suregork.com/?p=4112 BREWING YEAST FAMILY TREE (OCT 2019 UPDATE)] Kristoffer Krogerus' updated family tree including the Hittinger WGS data.** [https://www.biorxiv.org/content/10.1101/2020.02.08.939314v2 "Domestication reprogrammed the budding yeast life cycle," De Chiara et al (2020).]** Genome analysis of 1800 isolates from all ''Saccharomyces'' species by [https://www.nature.com/articles/s41467-023-36139-2 Peris et al. (2023)] found that domesticated strains of ''S. cerevisiae'' displayed a higher rate of admixture (occurs when distinct lineages mix to create new genetic lineages) <ref name=Peris_2023" />.* Guinness yeast strains form their own mosaic (distinct genetic grouping) that is different than other Irish brewing strains (which are closely related to British brewing strains). Their closest related yeast is a Belgian ale strain that was used for "lagers" and was originally misidentified as lager yeast. The authors of the study that discovered this suggest that this Belgian strain originated from Dublin brewers. The two currently used Guinness yeast strains are very closely related to the original strains that were originally banked by Guinness: the 1903 Watling Laboratory Guinness yeast <ref>[https://www.nature.com/articles/s42003-023-05587-3 Kerruish, D.W.M., Cormican, P., Kenny, E.M. et al. The origins of the Guinness stout yeast. Commun Biol 7, 68 (2024). https://doi.org/10.1038/s42003-023-05587-3.]</ref>. See also [https://www.facebook.com/groups/MilkTheFunk/posts/7826465880714891/ this MTF post]. See also: * YouTube presentation by Kevin Verstrepen:: <youtube height="200" width="300">E6qBnBQuWF4</youtube>* [http://masterbrewerspodcast.com/101-the-yeasts-of-tomorrow Stijn Mertens and Jan Steensels talk about their work on the MBAA podcast.]* [https://www.ncbi.nlm.nih.gov/genome Genome searches] and [https://www.ncbi.nlm.nih.gov/Traces/study/? strain publication searches] (see [https://www.facebook.com/groups/MilkTheFunk/permalink/4506794029348776/?comment_id=4507353275959518 this example]).* Media stories of "ancient yeast" supposedly being revived:** [https://www.facebook.com/groups/MilkTheFunk/permalink/2934420516586143/ MTF discussion on a claim that a 4500 year old yeast was recovered from Egyptian pottery.]* [https://www.biorxiv.org/content/10.1101/2020.06.26.166157v1.full Modern brewing yeasts continue to adapt to the modern brewing environment as the brewing methods change from yeast lab propagation and serial re-pitching: "Genomic stability and adaptation of beer brewing yeasts during serial repitching in the brewery".]:<youtube height="200" width="300">sPHwItOxuK0</youtube>* [https://www.facebook.com/groups/MilkTheFunk/permalink/4374738789220968/ MTF thread] by Dr. Bryan Heit provides a summary of [https://elifesciences.org/articles/63910 "Phenotypic and molecular evolution across 10,000 generations in laboratory budding yeast populations"] ====Killer Wine Yeast====Many wine yeast strains are known to be "killer" yeast strains that produce toxins that kill nearby yeast cells in order to give the killer yeast strains a competitive edge over sensitive strains (the term for these toxins has been changed to "zymocides" in science <ref name="Stewart_2018">[https://link.springer.com/chapter/10.1007/978-3-319-69126-8_10 "Killer (Zymocidal) Yeasts." Brewing and Distilling Yeasts. Graham G. Stewart. 2018.]</ref>, but is also sometimes called "mycocins" or "zymocins" <ref name="Boynton_2019">[https://onlinelibrary.wiley.com/doi/pdf/10.1002/yea.3398 The ecology of killer yeasts: interference competition in natural habitats. Primrose J. Boynton. 2019. DOI: https://doi.org/10.1002/yea.3398.]</ref>). Unwanted killer strains of ''Saccharomyces'' have been suspected to cause stuck wine fermentations by killing off the sensitive wine strain that was pitched into the wine by the winemaker <ref name="Bajaj_2017">[https://link.springer.com/chapter/10.1007/978-981-10-2621-8_7 Biology of Killer Yeast and Technological Implications. Bijender Kumar Bajaj, Satbir Singh. 2017.]</ref>. In ''Saccharomyces'', killer strains are genetically determined to secrete toxins (in the form of extracellular proteins or glycoproteins) that kill sensitive strains (there is no evidence that these toxins affect humans). These killer strains are immune to their own toxin. The mycocin toxins can act on sensitive strains in a number of ways: by blocking DNA synthesis and preventing cell division, inhibiting the synthesis of beta-glucans (β-1,6-glucan) that a part of their cell wall formation, and by causing ions to leak through the cell wall. In low dosages, which is typical in the natural environment, toxin triggers active cell death ([http://www.biology-pages.info/A/Apoptosis.html apoptosis]), while large dosages cause necrotic cell killing ([https://en.wikipedia.org/wiki/Necrosis necrosis]). One study in wine found that the use of killer strains to outcompete sensitive strains resulted in off-flavors from yeast autolysis <ref>[http://www.nature.com/nrmicro/journal/v4/n3/full/nrmicro1347.html Yeast viral killer toxins: lethality and self-protection. Manfred J. Schmitt & Frank Breinig. 2006.]</ref><ref name="Hatoum2012">[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3525881/ Rima Hatoum, Steve Labrie, and Ismail Fliss. 2012.]</ref>. Another study found that a lager strain that was genetically modified to secrete killer toxins was able to eliminate all cells of a sensitive ale strain within 24 hours of beer fermentation at a pitching rate of 99% sensitive ale strain to 1% killer lager strain, indicating that even a small amount of killer cells can be enough to kill a larger population of sensitive cells <ref name="Stewart_2018" />. Ratios of killer cells to sensitive cells that have shown to completely eliminate or nearly eliminate the sensitive population on lab media includes 1:1, 1;10, and 1:100. In a starter of a sensitive strain that had 10% cells of a killer strain introduced, the viability of the sensitive strain was greatly reduced <ref name="Bajaj_2017" />. Neutral strains do not produce toxins, nor are they killed by them <ref>[https://books.google.com/books?hl=en&lr=&id=mvORN6OXHh4C&oi=fnd&pg=PA93&dq=Bussey,+H.+1981.+Physiology+of+killer+factor+in+yeast.+Adv.+Microb.+Physiol.+22:93-121&ots=jUY4T9NpgB&sig=aw-Y1um0KsDnGe6rRe5PTWIDYdI#v=onepage&q&f=false Advances in Microbial Physiology, Volume 22. Academic Press, Sep 15, 1981. Pg 94-95.]</ref>. Almost all domesticated ale and lager strains are sensitive to the toxins produced by killer strains <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1179271825434363/?comment_id=1179424538752425&offset=0&total_comments=5&comment_tracking=%7B%22tn%22%3A%22R%22%7D Conversation with Bryan of Sui Generis Blog on MTF on Killer Factor for Saccharomyces. 11/16/2015.]</ref><ref>[http://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.1973.tb03515.x/pdf Strains of Yeast Lethal to Brewery Yeasts. A.P. Maule and P.D. Thomas. 1972.]</ref>. In ''Saccharomyces cerevisiae'', four toxins have been identified: K1, K2, K28, and Klus, the first three of which can only kill other strains/species of ''Saccharomyces''. The Klus toxin has been found to kill all strains of ''S. cerevisiae'' (including those that produce the previous three toxins), as well as yeast from other genera, such as ''Hanseniaspora spp.'', ''Kluyveromyces lactis'', ''Candida albicans'', ''Candida dubliniensis'', ''Candida kefir'' and ''Candida tropicalis''. Rodriguez et al. (2011) reported that out of 1,114 strains of ''S. cerevisiae'' isolated from spontaneous wine fermentations, 38% of them were killer positive with most producing K2. Only 7% of produced the Klus toxin (no commercial wine yeast strains have been reported to produce the Klus toxin that we know of) <ref name="Rodriguez">[http://aem.asm.org/content/77/5/1822.long A New Wine Saccharomyces cerevisiae Killer Toxin (Klus), Encoded by a Double-Stranded RNA Virus, with Broad Antifungal Activity Is Evolutionarily Related to a Chromosomal Host Gene. Nieves Rodríguez-Cousiño, Matilde Maqueda, Jesús Ambrona, Emiliano Zamora, Rosa Esteban and Manuel Ramírez. 2011]</ref>. The K1 toxin is most active between a pH of 4.6 and 4.8, while K2 and Klus are active around a pH of 4.0 to 4.3 <ref name="Rodriguez"></ref>. The activity of the toxin is greatest during the log phase of growth, and decays during the stationary phase of fermentation <ref name="Buyuksirit"></ref>. Generally, none of the toxins secreted by killer strains of ''Saccharomyces'' have been found to kill ''Brettanomyces'' <ref>[http://www.scielo.org.za/scielo.php?pid=S2224-79042015000100010&script=sci_arttext&tlng=pt Non-Saccharomyces killer toxins: Possible biocontrol agents against Brettanomyces in wine? S. Afr. J. Enol. Vitic. vol.36 n.1 Stellenbosch. 2015.]</ref>. One study from India reported that a wild ''S. cerevisiae'' strain caught from flowers killed another wild caught strain of ''Brettanoyces anomulus'', however, their methodology was not explicit and potentially not scientifically rigorous enough <ref>[http://nopr.niscair.res.in/handle/123456789/7735 Production and effect of killer toxin by Saccharomyces cerevisiae and Pichia kluyveri on sensitive yeasts and fungal pathogens. Dabhole, Madhusudan P, Joishy, K N. 2005.]</ref>. For example, this study did not use DNA fingerprinting to identify the wild yeast strains used in the study and instead relied on morphology and media selection, and they did not identify the type of toxin produced by the killer strain of wild ''S. cerevisiae''. They also reported that the ''B. anamulus'' strain did not ferment glucose, which is not typical for this species and indicates that it might have been misidentified. Several strains of ''Saccharomyces eubayanus'' isolated from seeds from monkey puzzle trees in Patagonia, Argentina, were found to secrete a killer toxin that kills ''Brettanomyces'' and ''Pichia''. One strain was found to produce a lot of the toxin, which is called "SeKT". ''S. cerervisiae'' strains, including strains that are sensitive to the above toxins, are not sensitive to this toxin. Mazzucco et al. (2019) found that SeKT toxin produced by this one strain of ''S. eubaynus'' in a special growth medium designed to maximize the SeKT toxin production (WUJ medium, which is "ultrafiltered" apple and pear juice) inhibited a strain of ''B. bruxellensis'' to around 50% growth after 48 hours in a wine growth medium. It also inhibited ''Pichia guilliermondii'', ''Pichia manshurica'', and ''Pichia membranifaciens'' by 50-70%. Note that the toxin was applied directly to the ''Brettanomyces'' and ''Pichia'' species, and not in a co-fermentation setting. Since ''S. cerevisiae'' strains are not effected by the SeKT toxin, it has been proposed as a way to limit ''Brettanomyces'' and ''Pichia'' in wine fermentations <ref>[https://www.ncbi.nlm.nih.gov/pubmed/30671692?dopt=Abstract Production of a novel killer toxin from Saccharomyces eubayanus using agro-industrial waste and its application against wine spoilage yeasts. Mazzucco MB, Ganga MA, Sangorrín MP. 2019. DOI: 10.1007/s10482-019-01231-5.]</ref>. Various other yeast species have the ability to produce toxins that effect a range of other yeasts (but generally not bacteria), including species from the genera ''Candida'', ''Cryptococcus'', ''Debaryomyces'', ''Hanseniaspora'', ''Hansenula'', ''Kluyveromyces'', ''Metschnikowia'', ''Pichia'', ''Ustilago'', ''Torulopsis'', ''Williopsis'', ''Zygosaccharomyces'', ''Aureobasidium'', ''Zygowilliopsis'', and ''Mrakia'' <ref name="Buyuksirit">[http://waset.org/publications/9999528/antimicrobial-agents-produced-by-yeasts Antimicrobial Agents Produced by Yeasts. T. Buyuksirit, H. Kuleasan. 2014.]</ref><ref name="Stewart_2018" />. For example, strains of the yeast species ''Candida pyralidae'' <ref name="Buyuksirit"></ref>, ''Wickerhamomyces anomalus'', ''Kluyveromyces wickeramii'', ''Torulaspora delbrueckii'' and ''Pichia membranifaciens'' have been found to produce toxin that inhibits ''Brettanomyces'' <ref name="Ciani_2016">[https://www.researchgate.net/publication/301581233_Yeast_Interactions_in_Inoculated_Wine_Fermentation Yeast Interactions in Inoculated Wine Fermentation. Maurizio Ciani, Angela Capece, Francesca Comitini, Laura Canonico, Gabriella Siesto and Patrizia Romano. 2016.]</ref><ref>[https://www.mdpi.com/1422-0067/24/2/1309 Agarbati A, Ciani M, Esin S, Agnolucci M, Marcheggiani F, Tiano L, Comitini F. Comparative Zymocidial Effect of Three Different Killer Toxins against Brettanomyces bruxellensis Spoilage Yeasts. International Journal of Molecular Sciences. 2023; 24(2):1309. https://doi.org/10.3390/ijms24021309 .]</ref>. In addition, the toxin produced by ''Wickerhamomyces anomalus'' and ''Williopsis markii'' have been found to inhibit a wide range of spoilage and pathogenic fungi <ref name="Hatoum2012"></ref>. Killer strains of ''S. cerevisiae'' and other yeast can occur naturally in the wild on fruit and can have a negative impact on other flora that are found in the same environment <ref name="Buyuksirit"></ref>. Strains of ''Torulaspora delbrueckii'' have been shown to kill killer strains of ''S. cerevisae'' (wine strains), as well as to kill ''Pichia'' species <ref name="Ciani_2016"></ref>. The occurrence of killer strains of yeast in the wild is also wide spread. For example, out of 210 yeasts from various genera isolated from molasses, 13 of them were killer strains. Out of 1,000 isolates of various ''Candida'' species isolated from human skin, 52 were killer strains. Out of 65 strains of various yeasts isolated from fermented foods, soil samples, and spoiled fruits/vegetables, 12 were killer strains <ref name="Bajaj_2017" />. It has been hypothesized that toxin production is ubiquitous throughout nearly all genera of yeast; the more studies that have been done on a particular genus of yeast, the more likely it is that toxin production has been found by species and strains within that genus. Yeasts that produce toxins have been found on every continent and in every natural habitat of yeast, including leaf surfaces, leaf litter, tree slime fluxes, fruits, cactus stems and cladodes, insect guts, mammal feces, leaf-cutting ant nests, lake water, ocean sediment, soil, wine, bakeries, and dairy products <ref name="Boynton_2019" />. A newly discovered toxin that is related to the K1 toxin, called "K1-like" or K1L, has been identified in ''Saccharomyces paradoxus''. The ability for this species to produce this toxin is caused by a virus that binds to the DNA of the yeast cells, and spread via horizontal gene transfer. The K1L toxin has a pH optimum mostly between 4.5 and 5, with no inhibitory activity at pH 5.5. It is denatured at a temperature of 98°C. A screening of this genetic change, called “K1-like Killer Toxin” (KKT) genes, in other yeasts showed that many other species can also produce toxins similar to the K1L toxin but slightly different in effect, including ''Kazachstania africana'', ''Naumovozyma castellii'', ''Naumovozyma dairenensis'', ''Tetrapisispora phaffii'', and ''Pichia membranifaciens''. Each of the identified species could kill at least one other type of yeast with its toxin, and was immune to its own toxin, but susceptible to other K1-like toxins from other yeast species. Differences in the production of these K1-like toxins between 5 different strains of ''P. membranifaciens'' indicated that the toxins can be strain-specific, rather than species-specific. Using the genetic relatedness between the different KKT genes, the researchers concluded that this family of K1-like toxins originated outside of the ''Saccharomyces'' genus. This research uncovered a new family of K1-like antifungal killer toxins amoung many species of yeast in the Saccharomycotina subphylum <ref>[https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1009341 Fredericks LR, Lee MD, Crabtree AM, Boyer JM, Kizer EA, Taggart NT, et al. (2021) The Species-Specific Acquisition and Diversification of a K1-like Family of Killer Toxins in Budding Yeasts of the Saccharomycotina. PLoS Genet 17(2): e1009341. https://doi.org/10.1371/journal.pgen.1009341]</ref>. Scientists have used genetic modification to create ''S. cerevisiae'' strains that produce various killer toxins that can assist in completing fermentation in the baking, wine, distillation, and beer making processes. These yeasts are able to inhibit undesired yeast contaminants, preventing various off-flavors and other unwanted characteristics in the finished products. Ale and lager strains that have been modified to release these toxins have reportedly retained the positive fermentation and flavor characteristics of the original strains <ref name="Bajaj_2017" />. Branco et al. (2017 and 2019) discovered several strains of ''S. cerevisiae'' that excrete a biocin toxin that is active against several other genera of yeast, including ''Brettanomyces bruxellensis''. The toxin is composed of peptides derived from the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH), which is a protein that serves many different roles in different species of microbes and animals. This toxin is produced by some strains of ''S. cerevisiae'' as they enter the stationary phase after primary fermentation. However, the amount of the toxin needed to inhibit ''B. bruxellensis'' was 10 times the amount that is produced naturally during fermentation. The researchers later genetically modified a strain of ''S. cerevisiae'' to over-produce the toxin, which they named "saccharomycin", at levels required to completely inhibit ''B. bruxellensis'' when co-pitched at a 1:1 ratio (10^5 cells/ml for both). This toxin was also reported to be highly active against ''Hanseniaspora guilliermondii'', ''Kluyveromyces marxianus'', ''Lactobacillus thermotolerans'' (inhibited at 250 μg/ml of toxin), while inhibition of ''Torulaspora delbrueckii'' and ''B. bruxellensis'' required very high amounts of the toxin (500 μg/ml and 1000-2000 μg/ml) <ref>[https://link.springer.com/article/10.1007%2Fs00253-016-7755-6 Antimicrobial properties and death-inducing mechanisms of saccharomycin, a biocide secreted by Saccharomyces cerevisiae. Patrícia Branco, Diana Francisco, Margarida Monteiro, Maria Gabriela Almeida, Jorge Caldeira, Nils Arneborg, Catarina Prista, Helena Albergaria. 2017. DOI: 10.1007/s00253-016-7755-6.]</ref><ref>[https://link.springer.com/article/10.1007/s00253-019-09657-7 Biocontrol of Brettanomyces/Dekkera bruxellensis in alcoholic fermentations using saccharomycin-overproducing Saccharomyces cerevisiae strains. Patrícia Branco, Farzana Sabir, Mário Diniz, Luísa Carvalho, Helena Albergaria, Catarina Prista. 2019.]</ref>. They later demonstrated that using 1.0 mg/mL of saccharomycin with 25 mg/L of SO<sub>2</sub> in grape must fermentation completely eliminated ''B. bruxellensis'' <ref>[https://www.mdpi.com/2076-2607/9/12/2528#cite Branco P, Coutinho R, Malfeito-Ferreira M, Prista C, Albergaria H. Wine Spoilage Control: Impact of Saccharomycin on Brettanomyces bruxellensis and Its Conjugated Effect with Sulfur Dioxide. Microorganisms. 2021; 9(12):2528. https://doi.org/10.3390/microorganisms9122528]</ref>. See also:* [https://www.facebook.com/groups/MilkTheFunk/permalink/4640413255986852/?comment_id=4640439825984195 None of the wine yeast strains from White Labs are killer positive, according to Kara Taylor, White Labs Senior Lab Manager.]* [https://www.facebook.com/groups/MilkTheFunk/permalink/2202753476419521/?comment_id=2202936416401227&comment_tracking=%7B%22tn%22%3A%22R0%22%7D Bryan Heit's simple method for testing for killer sensitivity using nothing more than agar plates.]* [https://www.homebrewtalk.com/threads/from-the-lab-wine-yeast-pof-and-killer-status.648095/ List of killer strains as well as phenol production (4VG and 4VP) in various wine yeasts, compiled from a scientific study Hisamoto et al. (2010).]* For the implications of this on re-yeasting beer with wine yeast at packaging, see the [[Packaging#Re-yeasting|Packaging]] page.* For concerns about using bottle dregs from commercial sour beers that are bottled with wine or champagne yeast, see [[Commercial_Sour_Beer_Dregs_Inoculation#Potential_Problems_and_Issues|Commercial Sour Beer Dregs]].* [http://www.math.fsu.edu/~gmizell/mead/Lallemand%20Yeast%20Quick%20Reference.pdf Lallemand chart of wine yeasts and their Killer Factor.]* [http://www.piwine.com/media/pdf/yeast-selection-chart.pdf Another chart of wine yeast strain and killer factor (column labeled "Competitive Factor").]* [http://www.lewybrewing.com/2012/12/wine-yeast-in-beer-experiment.html?m=1 Chris Lewis's write up on wine yeast character/Killer Factor on Lewy Brewing Blog.]* [http://www.babblebelt.com/newboard/thread.html?tid=1108752780&th=1275037001 Shea Comfort notes on wine yeast on the BBB.]* [https://byo.com/article/brewing-with-wine-yeast/ "Brewing With Wine Yeasts" by Michael Tonsmeire"]. See also [https://www.facebook.com/groups/MilkTheFunk/permalink/1392709617423915/ Dara McMains's MTF thread on beer fermentation with wine yeast and ''Brettanomyces''].* [https://www.asianbeernetwork.com/brewing-beer-with-wine-yeast "Brewing Beer with Wine Yeast," by Neil Playfoot, Asian Beer Network.] To do: https://www.researchgate.net/publication/317177883_Biology_of_Killer_Yeast_and_Technological_Implications =====Using Killer Yeast to Inhibit Diastatic Yeast=====* [https://brewing.confex.com/brewing/2020/meetingapp.cgi/Paper/1383 WBC 2020 Presentation "Can we rescue Beer infected with Diastaticus during fermentation: A profile in killer yeast and the effect of co-fermentation on the superattenuative characteristics of diastaticus."]* [https://www.masterbrewerspodcast.com/193 MBAA Podcast episode 193 with Nicholas Ketchum, "Could beer infected with diastaticus be rescued by killer yeast?"] * [https://www.facebook.com/groups/MilkTheFunk/permalink/4220596401301875 MTF post on using CBC-1 killer positive to limit primary yeast.] =====Autotoxin===== - https://journals.plos.org/plosbiology/article?id=10.1371%252Fjournal.pbio.3001844 ====Diastatic strains of ''Saccharomyces cerevisiae''====<blockquote style="background-color: lightgrey; border: solid thin grey; padding:10px;">:Do a page search (CTRL+F) on this wiki page for the term "diastatic" or "diastaticus" to see all of the confirmed or suspected diasatic strains listed in the [[Saccharomyces#Commercial_Farmhouse.2FBelgian_Strains_of_Saccharomyces|commercial culture charts]] below. :Another list is available [https://drive.google.com/file/d/11HC4sWBWLAZ41Xhzfx-rOl-uXVHwl9XR/view here] from [http://craftlabs.se/ Craft Labs]. </blockquote> Diastatic strains of ''Saccharomyces cerevisiae'', historically designated as a variant of ''S. cerevisiae'' (''Saccharomyces cerevisiae'' var. ''diastaticus''), is a group of ''S. cerevisiae'' strains that can ferment certain types of starches and dextrins, and has been identified as a contaminant in breweries and is responsible for a few large recalls. The variant based nomenclature has been called into question (classifying it as a true variant based on one phenotype is not typical in microbiology), and terms like "''STA1+'' strains of ''S. cerevisiae''" or "diastatic ''cerevisiae''" have been proposed as a more scientifically correct designation <ref name="Omega_diastaticus_2020">[https://omegayeast.com/news/improved-functional-assays-and-risk-assessment-for-sta-strains-of-saccharomyces-cerevisiae Improved Functional Assays and Risk Assessment for STA+ Strains of Saccharomyces cerevisiae. Laura T. Burns, Christine D. Sislak, Nathan L. Gibbon, Nicole R. Saylor, Marete R. Seymour, Lance M. Shaner, and Patrick A. Gibney. 2020. Awaiting peer review and publication.]</ref><ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/3308119659216225/?comment_id=3308312722530252&reply_comment_id=3308849332476591 Kristoffer Krogerus. Milk The Funk Facebook group post on diastatic ''cerevisiae'' nomenclature. 02/27/2020.]</ref><ref name="krogerus_diastatic_2020">[https://link.springer.com/article/10.1007/s00253-020-10531-0 A re-evaluation of diastatic Saccharomyces cerevisiae strains and their role in brewing. Kristoffer Krogerus and Brian Gibson. Applied Microbiology and Biotechnology (2020). DOI: https://doi.org/10.1007/s00253-020-10531-0.]</ref>. These strains generally do not produce flavors that are considered unpleasant. For example, acetaldehyde and sulfur dioxide are produced in very low amounts compared to other brewing strains. With the exception of a few strains, such as the "Sacch Trois" strain, most diastatic ''cerevisiae'' strains also produce phenols (POF+), which are considered off-flavors in many beer styles other than Belgian ale styles and German Hefeweizen (there is no genetic link between POF+ and STA1 genes, and the link may just be coincidental due to human selection). Most strains also produced significant amounts of isoamyl acetate (banana ester) and other fruity esters, making them taste very similar to German wheat strains. A small number of strains also produce above flavor threshold levels of diacetyl <ref name="Meier-Dörnberg_2018">[https://www.ncbi.nlm.nih.gov/pubmed/29518233 Saccharomyces cerevisiae variety diastaticus friend or foe? Spoilage potential and brewing ability of different Saccharomyces cerevisiae variety diastaticus yeast isolates by genetic, phenotypic and physiological characterization. Meier-Dörnberg T, Kory OI, Jacob F, Michel M, Hutzler M. 2018. DOI: 10.1093/femsyr/foy023.]</ref>. This variant is often viewed as a contaminant because of its ability to over-attenuate. A survey of contamination reports in the last ten years at European breweries (50% of which were German breweries, which are obligated by law to report such contaminations) found an increase in reports from 2015, 2016, and 2017. 71% of the contamination incidents originated from the packaging systems (bottling/canning lines). These contaminations were tracked down to the filler environment and/or biofilms in the pipework system of the filler which stemmed from hygienic problems. As such, sometimes contamination can be sporadic with some bottles being contaminated while others are not. The other 29% of the contaminations were tracked down to primary contaminations in the brewhouse, fermentation cellar, and storage cellar <ref name="Meier-Dörnberg">[https://www.mbaa.com/publications/tq/tqPastIssues/2017/Pages/TQ-54-4-1130-01.aspx Incidence of Saccharomyces cerevisiae var. diastaticus in the Beverage Industry: Cases of Contamination, 2008–2017. Tim Meier-Dörnberg, Fritz Jacob, Maximilian Michel, and Mathias Hutzler. 2017. MBAA Technical Quarterly; http://dx.doi.org/10.1094/TQ-54-4-1130-01.]</ref>. ''STA1+'' strains of S. cerevisiae can produce extracellular glucoamylase (also called [https://en.wikipedia.org/wiki/Alpha-glucosidase alpha-glucosidase], which is the same enzyme that ''[[Brettanomyces]]'' produces to break down starches and dextrins). This enzyme is released outside of the cell and can break down the α-1,4 linkages of starches and dextrins releasing glucose that is then fermented by the yeast. The capability to produce this enzyme is encoded by the ''STA1'' gene, which is a fusion of two other genes that are present separately in all ''S. cerevisiae'' yeasts, ''FLO11'' and ''SGA1'' (the ''STA2'' and ''STA3'' genes are the same as ''STA1''; they were initially found on different chromosomes and so they received different names, but they are all the same gene <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/2697088176986046/?comment_id=2697419373619593&reply_comment_id=2698451940183003&comment_tracking=%7B%22tn%22%3A%22R%22%7D Kristoffer Krogerus. Milk The Funk Facebook thread post on the significance of STA2 and STA3 genes in diastatic strains. 06/01/2019.]</ref>). Not all strains containing one of these genes produce the glucoamylase enzyme or are as effective as others at metabolizing dextrins <ref>[https://link.springer.com/article/10.1007%2FBF00365634 STA10: A gene involved in the control of starch utilization by Saccharomyces. Julio Polaina, Melanie Y. Wiggs. 1983.]]</ref><ref>[http://onlinelibrary.wiley.com/doi/10.1002/yea.1102/full Structural analysis of glucoamylase encoded by the ''STA1'' gene of Saccharomyces cerevisiae (var. diastaticus). Ana Cristina Adam, Lorena Latorre-Garcia, Julio Polaina. 2004.]</ref>. It has been reported by some microbiologists that most brewing strains that contain the ''STA1'' gene do produce the glucoamylase enzyme <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1935201836508021/?comment_id=1936604203034451&reply_comment_id=1937166892978182&comment_tracking=%7B%22tn%22%3A%22R7%22%7D Richard Preiss. Milk the Funk thread about ''STA1'' gene correlation to glucoamylase production. 12/31/2017.]</ref><ref name="mbaa_diastaticus">[http://masterbrewerspodcast.com/068-diastaticus-part-1 Matthew Peetz of Inland Island and Tobias Fischborn of Lallemand. "Master Brewers Association Podcast" 12/25/2017.]</ref>(~16 mins). A study that surveyed 18 strains of ''S. cerevisiae'' that contain the ''STA1'' gene found that only one was not able to ferment dextrins <ref name="Meier-Dörnberg_2018" />. Richard Preiss has also reported that WLP351 has the ''STA1'' gene, but is not able to ferment dextrins <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1888017211226484/?comment_id=2013050695389801&reply_comment_id=2013355312026006&comment_tracking=%7B%22tn%22%3A%22R9%22%7D Richard Preiss. Milk The Funk Facebook group thread on diastatic strains that do not ferment dextrins. March 2018.]</ref>. Krogerus et al. (2019) discovered that a region of 1162 base pairs just upstream of the ''STA1'' gene called "a promoter gene" is missing in strains that test positive for the ''STA1'' gene but do not test positive for fermenting starches, dextrins, or secreting the enzyme. They were able to demonstrate that this promoter gene region is needed for the ''STA1'' gene to become expressed. They also discovered that ''STA1'' gene is found in the Beer 2 group of yeast (see [[Saccharomyces#History_of_Domestication|History of Domestication]] above), and wild ''S. cerevisiae'' strains do not carry the ''STA1'' gene. Coincidentally, Beer 2 yeast strains lack the genes that the Beer 1 yeast strains do for fermenting maltotriose, yet Beer 2 yeasts ferment maltotriose just fine; it was discovered by Krogerus et al. (2019) that the ''STA1'' gene allows the Beer 2 yeasts to ferment maltotriose (although this exact mechanism is not known yet). It was proposed that the ''STA1'' gene evolved in the Beer 2 yeast strains as a means to take advantage of grain fermentation as an evolutionary advantage, and the existence of strains that are missing the promoter gene could be because humans later started selecting for strains that didn't dry the beer out too much <ref name="krogarus_2019">[https://link.springer.com/article/10.1007/s00253-019-10021-y A deletion in the ''STA1'' promoter determines maltotriose and starch utilization in ''STA1+'' Saccharomyces cerevisiae strains. Kristoffer Krogerus, Frederico Magalhães, Joosu Kuivanen, Brian Gibson. 2019. DOI: https://doi.org/10.1101/654681.]</ref>. For more details on the Krogerus et al. (2019) study, see [http://beer.suregork.com/?p=4068 this Suregork Loves Beer blog post] and [https://www.facebook.com/groups/MilkTheFunk/permalink/2697088176986046/ this MTF thread posted by Kristoffer Krogerus]. When beer containing this yeast is packaged too early, it will continue to slowly ferment dextrins and cause over-carbonation. When pitching a proper cell count or pitching rate of a diastatic yeast strain into the wort, some strains will fully ferment as quickly or nearly as quickly as any other brewers yeast, while other strains may take as long as 16 days to fully ferment a simple 12.4°P (1.050 SG) wort. A highly dextrinous wort may take longer to fully ferment. The problem of slow fermentation in already packaged beer is usually only a concern when diastatic ''cerevisiae'' is introduced as a very small cell count, for example as an accidental contamination <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1982499288444942/?comment_id=1983013578393513&comment_tracking=%7B%22tn%22%3A%22R1%22%7D Caroline Whalen Taggart. Milk The Facebook post on how quickly diastatic ferments. 02/09/2018.]</ref>. The enzyme produced by these strains is heat stable and can continue to work on starches and dextrins even after the yeast is killed by heat pasteurization <ref>[https://www.mbaa.com/publications/tq/tqPastIssues/1983/Abstracts/tq83ab19.htm Factors That Control the Utilization Of Wort Carbohydrates by Yeast. G. G. Stewart, I. Russell, and A. M. Sills. MBAA Technical Quarterly, Vol. 20, No. 1, 1983.] </ref>. Almost all diastatic strains of ''S. cerevisiae'' are able to ulilize all of the sugars found in wort (e.g. glucose, fructose, sucrose, maltose, maltotriose), although one strain tested in a recent study could not efficiently ferment starch, maltose, (80%) or maltotriose (45%) <ref name="Meier-Dörnberg_2018" />. ''STA1+'' strains of ''S. cerevisiae'' can grow at 37°C and can also remain viable at refrigeration temperatures <ref>[http://www.ebc2017.com/inhalt/uploads/P095_Begrow.pdf Wade Begrow. "Recent notable microbiological contaminations of craft beer in the United States". Presentation poster at EBC 2017. Retrieved 11/19/2017.]</ref>. Some strains of diastatic ''cerevisiae'' are as flocculant as typical ale strains, while others are less flocculant <ref name="Meier-Dörnberg_2018" />. One strain of diastatic ''cerevisiae'', the Belle Saison strain from Lallemand, is killer neutral, which means that killer wine strains will not kill it (it is not verified if Belle Saison is the same as WY3711, although it is suspected to be). Other strains of diastatic ''cerevisiae'' may or may not be killer neutral (more data is needed; see [[Saccharomyces#Killer_Wine_Yeast|killer wine strains]] for more information on this topic). Diastatic ''cerevisiae'' contamination in breweries has been a recent hot topic. These strains are effectively eliminated by standard cleaning and sanitation practices, although inadequate cleaning hygiene can lead to biofilm formation which makes them more resistant to cleaning regiments <ref name="Meier-Dörnberg" />. The source of some contaminations has also been suspected to potentially come from yeast suppliers, although there is no known percentage of infections which originate from yeast suppliers versus poor hygiene in the brewery. For example, a lawsuit by Left Hand Brewing Co. accused White Labs as being the source for the brewery's diastatic yeast contamination issues (see also [https://www.whitelabs.com/diastaticus this statement by White Labs]) <ref>[https://www.courthousenews.com/wp-content/uploads/2017/11/Left-Hand-v-White-Labs-COMPLAINT.pdf District Court, Boulder County, Colorado. Case Number 2017CV31132. Filed 11/14/2017.]</ref>. Detection of ''STA1+'' strains of ''S. cerevisiae'' as a contaminant can be difficult (see "Detection Methods" below). Contamination usually occurs as a secondary contaminant (meaning in the packaging system), and can come from contact with beer lines, by air circulation in the area of the packaging equipment, or by insufficient heat treatment of the packaging line. Since one viable cell that is able to divide can be enough to contaminate beer, contaminations can be sporadic with only a percentage of bottles being contaminated <ref name="Meier-Dörnberg_2018" />. Documented attenuation percentages above 75% for any strain of ''S. cerevisiae'' is also an indicator that the strain could be diastatic, however, some non-diastatic strains can also attenuate higher than 75%, so this indicator is not a reliable method to be sure that a given strain is ''STA1+'' <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/2004689559559248/?comment_id=2004695002892037&reply_comment_id=2005133672848170&comment_tracking=%7B%22tn%22%3A%22R1%22%7D Adi Hastings. Milk The Funk Facebook Group post on non-diastatic strains with high attenuation. 02/27/2018.]</ref><ref name="mbaa_diastaticus" />. Often this contamination can only be detected by sensory testing weeks after packaging. =====Detection Methods===== This yeast can been detected using [http://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.1981.tb04005.x/pdf LCSM agar plates], although other species of wild ''Saccharomyces'' yeast can grow on this media <ref name="mbaa_diastaticus" />(~18 mins) and PCR DNA analysis is required to give a positive identification of ''STA1+'' strains of ''S. cerevisiae''. Additionally, the default level of CuSO<sub>4</sub> which is ~550 ppm (this can vary depending on manufacturer) can inhibit some strains of diastatic ''cerevisiae''; Wade Begrow of Founders Brewing Co. recommends diluting the LCSM media with a basic malt media so that the CuSO<sub>4</sub> reaches around 200 ppm, or using LCSM plates modified with a gradient of CuSO<sub>4</sub> <ref name="Begrow_MBAA" /> (~22 mins in). Adding p-coumaric acid or other cinnamic acids to the LCSM agar media which can then test for POF+ yeast and then confirmed for the presence of phenols via a gas chromatography or some other method can also be used to indicate that a yeast might be ''STA1+'' since most strains produce phenols from these cinnamic acids <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/2149139905114212/?comment_id=2150763631618506&reply_comment_id=2158975484130654&comment_tracking=%7B%22tn%22%3A%22R0%22%7D Shawn Savuto and linked references. Milk The Funk Facebook book post on POF+ correlation with diastatic ''cerevisiae''. July 2018.]</ref> (see also [https://www.facebook.com/groups/MilkTheFunk/permalink/1903290776365794/ this MTF thread] on using cinnamic acids to identify phenolic off flavor strains). Cheaper methods of doing PCR are recently becoming available, and could help breweries with smaller budgets sufficiently detect this as a contaminant (see [[Laboratory_Techniques#PCR.2FqPCR|PCR Lab Techniques]]). A recent study used agar plates with 15 g/L<sup>-1</sup> of starch as the only nutrient with 40 mg/L<sup>-1</sup> bromophenol blue in anaerobic conditions to detect the fermentation of starch (a pH drop from 5.2 to 4.6-3.0 will change the color of the agar plate to blue/violet). For some of the slower growing strains, 14 days were required to verify that they were ''STA1+'' while other strains grew as quickly as two days and most strains grew after five days. The yeast cells had to be thoroughly washed of all other carbohydrate material and starved in order to avoid false positives. Using dextrin agar plates instead of starch also led to false positives <ref name="Meier-Dörnberg_2018" />. Note that diastatic ''S. cerevisiae'' cells look the same under a microscope as regular ''S. cerevisiae'', so cell morphology is not an effective way to identify ''STA1+'' strains <ref name="Begrow_MBAA">[https://www.mbaa.com/education/webinars/Pages/webcast.aspx?vid=diastaticus Wade Begrow. "S. cerevisiae var. diasttaicus". MBAA webinar. July 2018.]</ref> (~8 minutes in). Other methods of detection include using a Durham tube/fermentation tube test to see if the beer produces CO<sup>2</sup> after fermentation, although this method does not identify the cause of the additional fermentation <ref name="Begrow_MBAA" /> (~18 mins in). More recently, Krogerus et al. (2019) developed more precise PCR primers to detect ''STA1'' active, ''STA1'' non-active, and non-''STA1'' based on their discovered role of an ''STA1'' promoter called ''1162 bp'' that is required for the ''STA1'' gene to be effective at producing the glucoamylase enzyme, however, PCR and qPCR have limited detection rates of 10<sup>-4</sup> and 10<sup>-5</sup> cells (see [http://beer.suregork.com/?p=4068 this Suregork Loves Beer blog post] and [https://www.facebook.com/groups/MilkTheFunk/permalink/2697088176986046/ this MTF thread posted by Kristoffer Krogerus]). Detection of ''STA1+'' strains of ''S. cerevisiae'' as a contaminant can be difficult. While using PCR to detect the ''STA1'' gene and the promoter gene, the presence of the promoter gene alone does not completely explain the wide variance of diastatic power between strains. Additionally, PCR genotyping is sucseptable to user error or DNA detection from dead cells. Detection of the presence of starch degrading enzymes can come from other contaminants such as ''Brettanomyces'' <ref name="Omega_diastaticus_2020" />. Some agar media products and even starch/dextrin materials have been suspected to contain small amounts of glucose or other simple sugar contaminants that can support the growth of non-diastatic yeasts <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/3308119659216225/ Lance Shaner and Joshua Mayers. Milk The Funk Facebook thread on Omega Yeast's STA1+ detection methods. 03/04/2020.]</ref>. [[Omega Yeast Labs]] reported that a slight alteration to the classic LCYM media recipe had significantly more reliable detection than classic LCYM and the proprietary Weber diastatic agar for all ''STA1+'' strains in Omega's collection, including detecting slow growing strains within 2-3 days and strains with the non-active promoter genes as per Krogerus et al (2019) and limited false positives. See [[Laboratory_Techniques#Saccharomyces|''Saccharomyces'' agar plates]] for the recipe and [https://www.facebook.com/groups/MilkTheFunk/permalink/2874530432575152/ this MTF thread] by Laura Burns from Omega Yeast Labs, as well as their [https://omegayeast.com/news/improved-functional-assays-and-risk-assessment-for-sta-strains-of-saccharomyces-cerevisiae associated peer reviewed study on recommended detection methods)] <ref>[https://www.tandfonline.com/doi/full/10.1080/03610470.2020.1796175 Laura T. Burns, Christine D. Sislak, Nathan L. Gibbon, Nicole R. Saylor, Marete R. Seymour, Lance M. Shaner & Patrick A. Gibney (2020) Improved Functional Assays and Risk Assessment for STA1+ Strains of Saccharomyces cerevisiae, Journal of the American Society of Brewing Chemists, DOI: 10.1080/03610470.2020.1796175 .]</ref>. A summary of the Omega Yeast Lab detection methodology findings by Lance Shaner is available [https://www.facebook.com/groups/MilkTheFunk/permalink/3308119659216225/ here on MTF]. Escarpment Labs built upon the work by Burns et al. and developed a modified version of the Omega LCYM, and they reported it to have less false positives for non-diastatic strains and it has reportedly been used for growing beer strains of ''Brettanomyces'' and ''Pichia''. See the [[Laboratory_Techniques#Saccharomyces|Escarpment SCCM media]]. In 2022, Ida Uotila and Kristoffer Krogerus developed a simple detection technique that only requires basic lab equipment (pipettes, centrifuge, and heat block), gives results from beer or yeast samples in 75 minutes, and with accuracy as good as traditional PCR-based methods. The test result can be visualized on a lateral flow strip. For more information, see [https://www.biorxiv.org/content/10.1101/2022.11.23.517627v1 their published paper] ([https://www.facebook.com/groups/MilkTheFunk/posts/6360775983950562 associated MTF thread]). =====Commercial Strains===== WY3711 saison yeast has been determined to be ''STA1+'' <ref name="preiss_diastaticus" />. Since yeast cannot be patented, many yeast labs are thought to offer this strain to customers. In the [[Saccharomyces#Commercial_Farmhouse.2FBelgian_Strains_of_Saccharomyces|commercial culture]] lists below where we believe a lab is selling this strain or another strain of diastatic yeast, we note that it is determined or suspected to be ''STA1+''. White Labs now reports that the strains [https://www.whitelabs.com/yeast-bank/wlp045-scotch-whisky-yeast WLP045], [https://www.whitelabs.com/yeast-bank/wlp073-artisanal-country-ale-yeast WLP073], [https://www.whitelabs.com/yeast-bank/wlp099-super-high-gravity-ale-yeast WLP099], [https://www.whitelabs.com/yeast-bank/wlp545-belgian-strong-ale-yeast WLP545], [https://www.whitelabs.com/yeast-bank/wlp566-belgian-saison-ii-ale-yeast WLP566], [https://www.whitelabs.com/yeast-bank/wlp570-belgian-golden-ale-yeast WLP570], [https://whitelabs.com/yeast-bank/wlp590-french-saison-ale-yeast WLP590], [https://www.whitelabs.com/yeast-bank/wlp644-saccharomyces-bruxellensis-trois WLP644], [https://www.whitelabs.com/yeast-bank/wlp740-merlot-red-wine-yeast WLP740], and [https://www.whitelabs.com/yeast-bank/wlp885-zurich-lager-yeast WLP885] are potentially diastatic (thanks to [https://gist.github.com/thcipriani/c303e39d6e8044307fa292cac6de6bd6 "thcipriani's" python script]), however, they do not designate if these strains actually ferment dextrins. Some hints as to which other White Labs products might also be diastatic have been deduced from the [[Saccharomyces#History_of_Domestication|Gallone et al. study]] which published DNA sequencing on most of the yeast strains in the White Labs bank. However, the codes used in the Gallone paper for each strain of yeast were not defined as far as which White Labs products they correspond to. Some of the codes have been speculated on which White Labs strains they might refer to (see [[Saccharomyces#History_of_Domestication|History of Domestication]] above). The strains from the Gallone paper that appear to contain ''STA1'' are Beer002, Wine019, Beer092 and Beer059. The Beer059 code might correspond to WLP026 according to this speculative [https://www.facebook.com/groups/MilkTheFunk/permalink/1400297539998456/?comment_id=1908170505877821&comment_tracking=%7B%22tn%22%3A%22R0%22%7D table], which has had reports of high attenuation and has been independently confirmed to be ''STA1+'' by Kristoffer Krogerus (it is also only one of two known examples of a diastatic strain that are not also POF+; the other diastatic strain that is POF- is WLP644) <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/2095461573815379/?comment_id=2096044890423714&reply_comment_id=2105481916146678&comment_tracking=%7B%22tn%22%3A%22R%22%7D Kristoffer Krogerus. Milk The Funk Facebook thread on WLP026. 05/25/2018.]</ref><ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1400297539998456/?comment_id=1909596632401875&reply_comment_id=1910328215662050&comment_tracking=%7B%22tn%22%3A%22R9%22%7D MTF thread on ''STA1'' gene and White Labs strains that might have it or not. Milk The Funk Facebook group. 12/07/2017.]</ref>. There has been a report by Richard Preiss of [[Escarpment Laboratories]] that WLP570 (confirmed by White Labs) and [https://www.whitelabs.com/yeast-bank/wlp585-belgian-saison-iii-ale-yeast WLP585] both have the ''STA1'' gene, but it takes weeks before they hyper-attenuate <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1888017211226484/?comment_id=1911782002183338&reply_comment_id=1982274298467441&comment_tracking=%7B%22tn%22%3A%22R9%22%7D Richard Preiss. Milk The Funk Facebook group post on WLP570 and WLP585 being diastatic. 02/08/2018.]</ref>. Other yeast labs such as [http://www.lallemand.com/ Lallemand], [https://inlandislandyeast.com/yeast-library/inis-491-saison-french/ Inland Island], [https://www.escarpmentlabs.com/strains Escarpment Labs], and [https://www.theyeastbay.com The Yeast Bay] also list which strains they offer are diastatic. See also:* [https://www.youtube.com/watch?v=6lA-EAZ0ggE Dr. Bryan Heit of Sui Generis blog gives a layman video explaining the genetics of diastatic yeast.]* [https://www.milkthefunk.live/podcast/2019/10/14/episode-009-diastaticus-with-kristoffer-krogerus-of-beersuregorkcom-and-richard-preiss-of-escarpment-labs MTF "The Podcast" episode on STA1+ strains of ''S. cerevisiae'' with Kristoffer Krogerus and Richard Preiss.]* [http://beer.suregork.com/?p=4068 Kristoffer Krogerus explains his discovery of the ''STA1'' promoter gene that explains why some ''STA1'' positive strains do not effectively ferment starches or dextrins, as well as the occurence of this promoter gene within the Beer 2 yeast group and lack of it in wild yeast, new PCR primers for detecting active vs non-active ''STA1'' strains.]* [https://www.escarpmentlabs.com/single-post/2018/10/16/Demystifying-diastaticus-part-1 Escarpment Labs PCR protocol for testing for ''STA1'', including details on the limitations of PCR testing] and [https://www.escarpmentlabs.com/single-post/2018/10/22/Demystifying-diastaticus-part-2 Part 2, identifying using starch agar plating and LCSM plating.]* [http://suigenerisbrewing.com/index.php/2017/11/22/contamination-detection-1/ Sui Generis Brewing blog articles on using practical methods of PCR to identify diastatic and other contamination for small breweries.]* [https://www.facebook.com/groups/MilkTheFunk/permalink/1888017211226484/ This MTF thread] on White labs lawsuit, identification via PCR and different agar media, and general contamination handling.* [https://www.asbcnet.org/publications/journal/vol/abstracts/0630-04a.htm ASBC "Rapid Methods for Detecting Saccharomyces diastaticus, a Beer Spoilage Yeast, Using the Polymerase Chain Reaction."]* [https://www.reddit.com/r/TheBrewery/comments/5cx15c/qc_folks_any_experience_testing_for_s_diastaticus/ Reddit thread on detecting diastatic ''cerevisiae''.]* [http://masterbrewerspodcast.com/068-diastaticus-part-1 MBAA Podcast on diastaticus Part 1] and [http://masterbrewerspodcast.com/069-diastaticus-part-2 Part 2]. Also [https://www.masterbrewerspodcast.com/152 Using FPDM media from Dr. Farber vs Weber, and issues with media getting too old after a day or two].* [https://www.mbaa.com/education/webinars/Pages/webcast.aspx?vid=diastaticus MBAA webinar by Wade Begrow (free for MBAA members, $50 for non-members).]* [https://www.masterbrewerspodcast.com/193 MBAA Podcast Episode 193, "Killer Yeast" with Nicholas Ketchum on using killer yeast strains to kill diastatic yeast.]* [https://brulosophy.com/podcasts/the-bru-lab/ Bru Lab Podcast, Episode 021 | Detection and Risk Assessment of Diastatic Yeast w/ Dr. Laura Burns.] ====''Saccharomyces cerevisiae'' var ''boulardii''====Although originally designed as a separate species (''S. boulardii''), it is actually a variety of ''S. cerevisiae'' and shares more than 99% of the genetic makeup of ''S cerevisiae'' <ref>[https://en.wikipedia.org/wiki/Saccharomyces_boulardii ''Saccharomyces boulardii''. Wikipedia. Retrieved 12/07/2017.]</ref>. This strain is sold by [[East Coast Yeast]] in their ECY03 Farmhouse Blend and [[Bootleg Biology]] as their "Chardonnay" strain <ref>[https://bootlegbiology.com/product/chardonnay "Chardonnay (S. cerevisiae boulardii)". Bootleg Biology website. Retrieved 11/20/2019.]</ref>. ====Genetic Engineering====* [https://www.lallemandbrewing.com/en/united-states/product-details/sourvisiae Lallemand SOURVISIAE®] is GE California ale yeast based strain that produces lactic acid as a by product of fermentation. See also [http://suigenerisbrewing.com/index.php/2021/02/19/diving-deep-in-to-sourvisiae/ "Diving Deep In To Sourvisiae" by Dr. bryan Heit].* [https://link.springer.com/article/10.1007/s00253-021-11626-y Efficient breeding of industrial brewing yeast strains using CRISPR/Cas9-aided mating-type switching.] ===''S. jurei''===Newly discovered ''S. jurei'' was screened for use in beer, as well as hybrids between two strains of ''S. jurei'' and two strains of ''S. cerevisiae'' (Omega Labs OYL200 "Tropical IPA" and OYL500 Saisonstein). The hybrids were non-GMO type hybrids (natural mating). As expected, the hybrids were better at fermentation in wort (better utilization of maltose and maltotriose). The hybrids were reported to be "tropical and floral" from esters characterized by a combination of both parents, and one of the hybrids appeared to have lost the ability to produce phenols (4-vinyl guaiacol; clove) from the ''S. jurei'' parent <ref>[https://www.biorxiv.org/content/10.1101/2021.01.08.425916v1.full.pdf Biotechnological exploitation of Saccharomyces jureiand its hybrids in craft beer fermentation uncovers new aroma combinations. Konstantina Giannakou, Federico Visinoni, Penghan Zhang, Nishan Nathoo, Paul Jones, Mark Cotterrell, Urska Vrhovsek, and Daniela Delneri. 2020. doi: https://doi.org/10.1101/2021.01.08.425916 .]</ref>. ===''S. ludwigii''===Some species of this genus cannot ferment maltose or maltotriose, which make up the majority of sugar in brewer's wort. For example, Bellut et al. (2018) found that one strain that was isolated from kombucha could not ferment these complex sugars. This is due to the lack of a maltose transporter and the enzyme maltase. It also could not ferment melibiose, but could ferment glucose, fructose, sucrose, raffinose, and cellobiose. As such, they have been proposed as being potentially useful in non-alcoholic beer fermentation. Additionally, these species were able to grow in 7◦ Plato wort with a range of IBU (50 IBU was the maximum IBU tested), indicating that IBU's don't impact the growth of these species. They also lacked the ability to produce phenols. It was described as moderately flocculant, with the flocculation depending on the ''FLO'' gene and the presence of calcium in the wort (the same as ''Saccharomyces''). They produced much less higher alcohols (n-propanol, isobutanol, and isoamyl alcohol) than the WLP001 control yeast, and fewer esters, and about the same amount of acetaldehyde and diacetyl than WLP001 <ref name="Bellut_2018">[http://www.mdpi.com/2311-5637/4/3/66 Application of Non-Saccharomyces Yeasts Isolated from Kombucha in the Production of Alcohol-Free Beer. Konstantin Bellut, Maximilian Michel, Martin Zarnkow, Mathias Hutzler, Fritz Jacob, David P. De Schutter, Luk Daenen, Kieran M. Lynch, Emanuele Zannini, and Elke K. Arendt. 2018. DOI: https://doi.org/10.3390/fermentation4030066.]</ref>. ===''S. thermantitonum''===This species may not be genetically distinct from ''S. cerevisiae'' <ref>[http://www.cbs.knaw.nl/Collections/BioloMICS.aspx?Table=CBS+strain+database&Rec=681&Fields=All Search on : CBS strain database. CBS. Retreived 04/12/2016.]</ref>.* [https://www.facebook.com/groups/MilkTheFunk/permalink/1850919251602947/ MTF thread on ''S. Thermantitonum''.] ===''S. paradoxus''=== * [https://phdinbeer.com/2014/06/17/saccharomyces-species-experiment-1-paradoxus-ale-recipe-14-batch-2014-07/ "Saccharomyces species experiment #1: Paradoxus Ale," by Matt Humbard on A PhD in Beer Blog.]* [https://link.springer.com/article/10.1007/s00217-020-03572-2 Brewing potential of the wild yeast species ''Saccharomyces paradoxus''.] ===''S. eubayanus''===[[File:Mardones 2020 Fig1C.JPG|thumb|300px|Utilization of maltose by 10 strains of ''S. eubayanus''; higher utilization corresponds with higher ethanol production. Figure 1C from [https://sfamjournals.onlinelibrary.wiley.com/doi/full/10.1111/1751-7915.13545 Mardones et al (2020)]. Uploaded with permission from Kristoffer Krogerus.]][[File:Mardones 2020 Fig1D.JPG|thumb|300px|Volatile compound production of interest in beer by 10 strains of ''S. eubayanus''. Figure 1D from [https://sfamjournals.onlinelibrary.wiley.com/doi/full/10.1111/1751-7915.13545 Mardones et al (2020)]. Uploaded with permission from Kristoffer Krogerus.]] ''S.eubayanus'' is one of the probable parents of lager yeast (''S. pastorianus'') via the hybridisation with ''S. cerevisiae'' <ref name="libkind_2011"></ref><ref name="bing_2014"></ref>.It was first isolated and described in 2011 growing within ''Nothofagus'' trees in Patagonia, Argentina. Since then, strains of this species have also been found in cold regions across the globe, including Tibet, China, the United States, Chile, and New Zealand. It has also been isolated from the wild in Ireland <ref>[https://academic.oup.com/femsyr/article/22/1/foac053/6874782 Sean A Bergin, Stephen Allen, Conor Hession, Eoin Ó Cinnéide, Adam Ryan, Kevin P Byrne, Tadhg Ó Cróinín, Kenneth H Wolfe, Geraldine Butler, Identification of European isolates of the lager yeast parent Saccharomyces eubayanus, FEMS Yeast Research, Volume 22, Issue 1, 2022, foac053, https://doi.org/10.1093/femsyr/foac053.]</ref>. ''S. eubayanus'' has been described as being cold-tolerant, and can grow between 4–25°C. It has been suggested that this trait was inherited by lager yeast. Although only a small number of strains have been collected from the wild by scientists, ''S. eubayanus'' has a wide range of genetic diversity between different strains. Some strains show potential for brewing purposes, which is primarily characterized by how well they ferment maltose. [https://sfamjournals.onlinelibrary.wiley.com/doi/full/10.1111/1751-7915.13545 Mardones et al. (2020)] evaluated 10 strains of ''S. eubayanus'' and their potential for fermenting wort. Four of the strains were isolated from Chile, four from Patagonia, one from Argentina, and one from New Zealand. All of the strains efficiently fermented glucose and fructose, while none fermented maltotriose. Maltose utilization varied greatly across all of the strains with the Argentinian strain (CBS-12357) utilizing maltose the most and producing the most ethanol. Overall, there was no correlation to how well strains fermented maltose based on what country they were from. There was also a wide range of esters, higher alcohols, and carbonyl compounds produced by the different strains. For example, two of the strains of Patagonia (CL465.1 and CL450.1) produced some higher alcohols and acetate esters like 2-phenyethyl acetate (rose, honey) and 3-methylbutyl acetate (banana), while other strains (Argentinian strain CBS-12357 and Chilean strain CL216.1) produced more ethyl octanoate and ethyl decanoate (fruity and apple-like). Nearly half the strains produced very low levels of all of the compounds measured. Most strains produced insignificant levels of acetaldehyde, except for two of the Chilean strains <ref name="Mardones_2020">[https://sfamjournals.onlinelibrary.wiley.com/doi/full/10.1111/1751-7915.13545 Molecular profiling of beer wort fermentation diversity across natural Saccharomyces eubayanus isolates. Wladimir Mardones, Carlos A. Villarroel, Kristoffer Krogerus, Sebastian M. Tapia, Kamila Urbina, Christian I. Oporto, Samuel O’Donnell, Romain Minebois, Roberto Nespolo, Gilles Fischer, Amparo Querol, Brian Gibson, Francisco A. Cubillos. 2020. DOI: https://doi.org/10.1111/1751-7915.13545.]</ref>. Two of the strains were selected to brew beer on a pilot brewery system. The strains selected were one from Villarrica, Chile (CL216.1) and one from Coyhaique, Patagonia (CL450.1). The beers started off at 15 °Plato all‐malt wort and were fermented at a temperature of 15°C. Fermentation was finished after 24 days due to the cooler fermentation temperature. This resulted in a 5.6% ABV and 5.1% ABV beers, demonstrating the difference in maltose utilization between the two strains. Maltose was consumed after 10 days of fermentation, demonstrating that this species ferments simple sugars first (glucose repression), similar to other species of ''Saccharomyces''. Significant differences in esters and other volatile compounds were developed towards the end of fermentation, demonstrating that significant differences in flavor were developed after most of the sugars have been consumed. The Chilean strain showed a better fermentation profile and the production of greater levels of desirable esters. They also observed significant differences in each of the strains' ability to utilize different nitrogen and carbon sources, such as amino acids, which can account for the differences in flavor production <ref name="Mardones_2020" />. All of the strains tested also produced phenols (POF+), so these strains are probably not suitable for lager-style beers but could be suitable for saison and other Belgian style beers <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/3310179085676949/?comment_id=3311361805558677 Kristoffer Krogerus. Milk The Funk Facebook thread about ''S. eubayanus'' flavor profiles and recent research. 02/29/2020.]</ref>. See also:* Example beer made with ''eubayanus'' by Kris Krogerus: [https://beer.suregork.com/?p=2827 "Brewing With ''Saccharomyces eubayanus''"] ===''S. pastorianus''===Commonly known as lager yeast to brewers, this yeast is a hybrid of ''S. eubayanus'' and ''S. cerevisiae'' <ref name="wikipedia_cereisiae" />. ''S. pastorianus'' is named after the first description by Max Reess in 1870 following his work with German breweries utilizing bottom-fermenting lager yeast, naming it originally after Louis Pasteur. For a long time the origins of the hybrid were unknown and were postulated to be a hybrid between ''S. cerevisiae'' and ''S.uvarum'', or ''S. cerevisiae'' and ''S.bayanus''. Recent work eg. Libkind et al 2011 proved that the hybridisation was between ''S. eubayanus'', which had been recently found in South America and ''S. cerevisiae'' <ref name="libkind_2011" />. Further work points to a Tibetan lineage of ''S.eubayanus'' being the most likely from those discovered in the wild so far <ref name="bing_2014" /> (see also [https://www.facebook.com/groups/MilkTheFunk/posts/6399366356758191/?comment_id=6399963343365159 this MTF post]). It is hypothesized that the hybridization event occurred in a Bavarian brewery (Hofbräuhaus in Munich has been proposed as the most likely site for the hybridization event) in the 16th century by the chance interaction of ''S. eubayanus'' with ale yeast; however, an alternative hypothesis is that bottom-fermentation with ''S. eubayanus'' was in practice before lager yeast was created <ref>[https://academic.oup.com/femsyr/article/doi/10.1093/femsyr/foad023/7142826 Mathias Hutzler, John P Morrissey, Andreas Laus, Franz Meussdoerffer, Martin Zarnkow, A new hypothesis for the origin of the lager yeast Saccharomyces pastorianus, FEMS Yeast Research, Volume 23, 2023, foad023, https://doi.org/10.1093/femsyr/foad023.]</ref>. This species is separated into two main lineages, "Saaz" and "Frohberg". The two lineages are believed to have descended from different hybridization events between ''S. eubayanus'' and ''S. cerevisiae''. The two lineages also have different genetic structure, with Frohberg types having two copies of each of the ''S. eubayanus'' and ''S. cerevisiae'' chromosomes (triploid), and Saaz types having one copy of the ''S. cerevisiae'' chromosomes and two copies of the ''S. eubayanus'' chromosomes (allotetraploid) <ref><[https://www.ncbi.nlm.nih.gov/pubmed/24578374 Genome sequence of Saccharomyces carlsbergensis, the world's first pure culture lager yeast. Walther A, Hesselbart A, Wendland J. 2014. DOI: 10.1534/g3.113.010090.]</ref> Emil Christian Hansen was the first in the world to isolate a single pure strain of ''S. pastorianus'' while he was working at the Carlsberg brewery, leading to its the synonymous classification name, ''S. carlbergensis''. The type that Hansen isolated was a Saaz type, and it's believed that Saaz types are also prevalent in Bohemian / Czech ''S. pastorianus'' strains while German types are typically Frohberg. ([https://onlinelibrary.wiley.com/doi/full/10.1002/yea.2960] , [https://genome.cshlp.org/content/18/10/1610.full] ) With recent whole genome sequencing data, it has been discovered that some strains of commercial yeast have been misidentified as either lager yeast or ale yeast. [http://sykesey.id.au/?p=20 Ben Sykes reported] that publicly available genetic data for an upcoming study indicates that WLP800, the Czech lager yeast from White Labs, is potentially ''S. cerevisiae'' (ale yeast). WLP029 German Ale/ Kölsch Yeast is potentially lager yeast. [https://www.whitelabs.com/yeast-bank/wlp051-california-v-ale-yeast WLP051 California V Ale] yeast is also ''S. pastorianus''. Recent gene sequencing / PCR work has led to it being re-classified as a ''S. pastorianus'' yeast, though it has been used successfully for American-style Ale production. Laboratory hybridization between different strains of ''S. cerevisiae'' and ''S. eubayamus'' strains from Patagonia has created new lager strains that have better fitness under fermentation, better maltotriose/maltose utilization, and fermentation capacity. These new strains offer more options to brewers who want to brew with lager yeast <ref>[https://www.biorxiv.org/content/10.1101/2024.01.29.577692v1 Wild Patagonian yeast improve the evolutionary potential of novel interspecific hybrid strains for Lager brewing. Jennifer Molinet, Juan P. Navarrete, Carlos A. Villarroel, Pablo Villarreal, Felipe I. Sandoval, Roberto F. Nespolo, Rike Stelkens, Francisco A. Cubillos. bioRxiv 2024.01.29.577692; doi: https://doi.org/10.1101/2024.01.29.577692.]</ref>. See also:* [https://www.crowdcast.io/e/escarpment-labs-fermentation-innovation Kristoffer Krogerus presentation on the genetics and evolution of lager yeast, hosted by Escarpment Laboratories, 4/20/2020.]* [https://phys.org/news/2019-12-pilsner-yeast-strains-ancestor.amp "All pilsner yeast strains originate from a single yeast ancestor," by Delft University of Technology], summarizing the study by [https://bmcgenomics.biomedcentral.com/articles/10.1186/s12864-019-6263-3 Salazar et al. (2019)].* [https://www.facebook.com/groups/MilkTheFunk/posts/4987612867933554/ MTF thread by Kristoffer Krogerus on how to use tetraploid interspecific hybrids to produce viable spores for designed lager yeast strain development, with a link to his peer reviewed article, 09/17/2021.]* [https://www.crowdcast.io/c/lager-brewers-yeast-origins "Yeast Research and Scaling Secrets," interview with Dan Carey by Doug Piper.] ==In Fermentation==(To do) https://www.researchgate.net/publication/320686420_Physiology_ecology_and_industrial_applications_of_aroma_formation_in_yeast ===Fermentation Under Low pH Conditions===''Saccharomyces'' species and individual strains have a wide range of tolerance to low pH and lactic/acetic acid concentrations, which have been identified as stressors for yeast fermentation. For ideal fermentation conditions for ''S. cerevisiae'', lactic acid should not exceed 0.8%, acetic acid should not exceed 0.5%, and wort should not fall below 4.0 pH. Since pH is on a log-based scale, even small differences in pH (especially below 3.5) can make a large impact on whether or not a given yeast strain is able to ferment. This obviously presents a challenge to brewers when [[Wort Souring]] or [[Packaging#Re-yeasting|naturally carbonating with yeast]] for sour beers <ref name="rogers2016">[http://www.sciencedirect.com/science/article/pii/S0740002016301605 Terminal acidic shock inhibits sour beer bottle conditioning by Saccharomyces cerevisiae. Cody M. Rogers, Devon Veatch, Adam Covey, Caleb Staton, Matthew L. Bochman. 2016.]</ref>. Yeast that fails to bottle condition sour beer may not be due to death of the cells. Rogers et al. <ref name="rogers2016"></ref> published a study that found that yeast used to bottle condition a sour beer at [http://uplandbeer.com/ Upland Brewing Co.] was still ~80% viable after two weeks, but the surviving cells were small and unbudded, indicating that they ceased growing and entered the stationary phase. This effect has been referred to as "terminal acid shock" <ref name="rogers2016"></ref>. As stated previously, lactic acid and low pH are identified as stressors for yeast, and can affect their ability to carbonate sour beer. Some strains tested display an ability to grow in higher lactic acid concentrations, while others do not, but this does not indicate that they are able to bottle condition sour beer. For example, WLP001 and WY1056 do not grow well in [https://en.wikipedia.org/wiki/YEPD YPD] dosed with lactic acid, whereas Lallemand CBC-1 ("Cask & Bottle Conditioned Beer Yeast") can still grow at a pH of 3. WY2007 and WLP300 grow well in moderate levels of lactic acid, but not once the pH gets down to 3. WLP715 Champagne Yeast grows fine in a pH of 3 (although lag time is effected). However, despite being able to grow in YPD with lactic acid dosages, CBC-1 and WLP715 both failed to carbonate an 8% ABV sour beer that had a comparable pH to the pH of the YPD plus lactic acid mediums. It is suggested that this might be due to the combination of stress from high alcohol, acetic acid, low nutrients, low oxygen, and tannins from fruit. Re-hydrating dried yeast may also lead to difficulties carbonating acidic and high ABV (8%+) sour beer due to the stress of desiccation and re-hydration on the yeast <ref name="rogers2016"></ref>. Rogers et al. found an easy solution to carbonating low pH, high ABV beers by first acclimating the yeast to the sour beer. Growing the yeast in YPD plus lactic acid plus ethanol was not enough to acclimate the yeast and reliably carbonate a highly acidic, alcoholic (8% ABV) beer. However, by growing the yeast first in a blend of YPD that was diluted with the sour beer itself in a 1:1 ratio, they found that both CBC-1 and WLP715 were then able to carbonate the sour beer (WLP001, WY1056, WY2007, and WLP300 were not given this treatment). This was explained as exploiting the microbes' resilience and ability to adapt to many environmental conditions by "pre-adapting" the yeast to the harsh conditions of the sour beer <ref name="rogers2016"></ref>. It has been speculated that brewers without access to YPD might be able to achieve similar results by growing the conditioning yeast in sour beer diluted with DME wort and yeast nutrients (Fermaid K and DAP, for example) <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1259063934121818/?comment_id=1262875587073986&reply_comment_id=1263142900380588&comment_tracking=%7B%22tn%22%3A%22R9%22%7D Conversation with Richard Preiss and Tamir Danon on acclimating yeast to sour beer for conditioning on MTF. 03/24/2016.]</ref>. A second study showed that a strain of ''S. cerevisiae'' was able to adapt and grow in a lab setting to increasing concentrations of lactic acid. After multiple generations and by slowly increasing the amount of lactic acid per generation, the researchers got the pH of the growth media (either raffinose or glucose plus lactic acid) all the way down to pH 2.8. At this low pH, the yeast began to use lactic acid as a food source. This might explain some anecdotal experiences by brewers who have seen the pH of kettle sour beers rise (more evidence is needed to confirm this hypothesis). The researchers found that the gene called ''ACE2'' is likely to be associated with the ability to adapt to low pH conditions. It is also a gene that controls the expression level of other genes, and is also responsible for forming "snowflake-like" structures (multicellular clumps of genetically identical cells that stick together after budding <ref>[https://www.quantamagazine.org/20151103-snowflake-yeast-multicellularity/ "Life’s Secrets Sought in a Snowflake". Emily Singer. Quantum Magazine. 11/03/2015. Retrieved 12/27/2016.]</ref>). The yeast strain began to form these "snowflake-like" clumps after being adapted to the low pH environment. Further work should be done to determine which strains of ''S. cerevisiae'' might be more easily adapted to low pH environments, or if possibly all strains of ''S. cerevisiae'' could be adapted to low pH environments over time <ref>[http://www.sciencedirect.com/science/article/pii/S1096717616301756 Evolutionary engineering reveals divergent paths when yeast is adapted to different acidic environments. Eugene Fletcher, Amir Feizi, Markus M.M. Bisschops, Björn M. Hallström, Sakda Khoomrung, Verena Siewers, Jens Nielsen. 2016.]</ref><ref>[http://www.nature.com/articles/ncomms7102 Origins of multicellular evolvability in snowflake yeast. William C. Ratcliff, Johnathon D. Fankhauser, David W. Rogers, Duncan Greig & Michael Travisano. 2015.]</ref>. <!-- <youtube>UiWsVQwtidE</youtube> video made private--> See also:* [[Lactic Acid]]* [[Packaging#Re-yeasting|Acid Shock Starters]]* [[Wort Souring]]* [http://www.thebrewingnetwork.com/the-sour-hour-episode-32/ The Sour Hour interview with Dr. Matt Bochman]* [https://phys.org/news/2016-03-biochemist-solution-acid-craft-brewers.html "Biochemist finds solution to 'acid shock' in craft brewers' sour beer production", article on Phys.org.]* [http://www.themadfermentationist.com/2016/12/quick-sour-then-what-acid-tolerance-of.html "Quick Sour, then what? Acid Tolerance of Brewer’s Yeast" by Michael Tonsmeire] ===Esters===* [http://scottjanish.com/esters-and-fusel-alcohols/ "Esters and Fusel Alcohols" by Scott Janish.]* [http://sourbeerblog.com/understanding-esterification/ "Understanding Esterification", Sour Beer Blog.]* [https://www.facebook.com/groups/MilkTheFunk/permalink/3302131259815065/ Detailed biochemistry write up of what variables affect yeast derived esters, with links to a few scientific papers; MTF post by Cory Widmayer.] ===Phenolic Off Flavor Strains===Some strains of ''S. cerevisiae'' can convert the ferulic acid, which is found in malted barley and in wheat (malted wheat more so than raw wheat), into the phenol 4-vinyl guaiacol (4VG). 4VG is less toxic to microorganisms than the ferulic acid and other hydroxycinnamic acids. It gives a clove-like flavor to the beer. While most beer styles consider this an off-flavor, it is an important flavor component for certain styles of beer such as German Hefeweizen, saison, and some Belgian styles. Strains that convert ferulic acid into 4VG during fermentation are known as "phenolic off flavor positive" or "POF+" and are characteristic of wild ''Saccharomyces'', bread yeast, and a small number of brewers yeast. Most strains of brewers yeast, however, were selected for not having this capability, and are known as "phenolic off flavor negative" or "POF-". POF+ strains require two enzymes: phenylacrylic acid decarboxylase (Pad1) and a ferulic acid decarboxylase (Fdc1). The Pad1 enzyme creates a precursor required for the Fdc1 enzyme to work, which then converts the ferulic acid into 4VG. These enzymes are dictated by the presence of the ''PAD1'' and ''FDC1'' genes respectively <ref name="lentz_2018">[http://www.mdpi.com/2311-5637/4/1/20/html#B13-fermentation-04-00020 The Impact of Simple Phenolic Compounds on Beer Aroma and Flavor. Michael Lentz. 2018. doi: 10.3390/fermentation4010020.]</ref>. Yeast produced phenolic/clove aromas tend to dominate over hop aromas in dry hopped beer <ref name="Sharp_Presentation">"Recent Advances in Controlling Hoppy Aroma in Beer." Daniel C. Sharp. OSU Brewing Science Presentation.</ref>. Evidence, while sparse, shows that increased fermentation temperature can increase the concentration of phenols produced by ''S. cerevisiae'' yeast <ref>[https://onlinelibrary.wiley.com/doi/full/10.1002/jib.189 Enhancing the levels of 4‐vinylguaiacol and 4‐vinylphenol in pilot‐scale top‐fermented wheat beers by response surface methodology. Yunqian Cui, Aiping Wang, Zhuo Zhang, R. Alex. Speers. 2015. DOI: https://doi.org/10.1002/jib.189.]</ref>. In ''Brettanomyces'', fermentation temperature can make small differences for some strains, but the differences are probably not large enough to detect during sensory testing (see [[Brettanomyces#Phenol_Production|''Brettanomyces'' phenol production]]) <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/2776560529038810/?comment_id=2776928959001967&reply_comment_id=2776957078999155&comment_tracking=%7B%22tn%22%3A%22R%22%7D Richard Preiss. Milk The Funk Facebook group post on phenols and fermentation temperature. 07/09/2019.]</ref>. Schwarz et al. (2012) https://www.sciencedirect.com/science/article/pii/S0308814612006498 While most beer strains of ''S. cerevisiae'' are POF-, a survey of over 200 strains of ''S. cerevisiae'' showed that 81-95% of wine yeasts are POF+. It was also shown that 85-97% of wild strains of ''S. cerevisiae'' are POF+. Other genera of yeasts that tend to be POF+ include ''Rhodotorula'', ''Candida'', ''Cryptococcus'', ''Pichia'', ''Hansenula'', and ''Brettanomyces'' <ref>[https://www.ncbi.nlm.nih.gov/m/pubmed/16232824/ Distribution of phenolic yeasts and production of phenolic off-flavors in wine fermentation. Shinohara T, et al. J Biosci Bioeng. 2000.]</ref>. See also:* [[Brettanomyces#Phenol_Production|Phenols produced by ''Brettanomyces''.]]* [http://beer.suregork.com/?p=3877 Kristoffer Krogerus's blog article on removing POF gene from Saccharomyces hybrids.]* [https://www.facebook.com/groups/MilkTheFunk/permalink/1903290776365794/?comment_id=1904716159556589&comment_tracking=%7B%22tn%22%3A%22R1%22%7D&hc_location=ufi MTF thread on detecting POF+ on agar.] To do: https://www.ncbi.nlm.nih.gov/m/pubmed/18038991/ https://www.sciencedirect.com/science/article/pii/S0308814607007844 ==Commercial Saison/Belgian Strains of ''Saccharomyces''==In cooperation with Eric Bandauski <ref>[https://docs.google.com/spreadsheets/d/1qDMGwDKCDxgzoIZfQpOYE0IzSGiK_rr_txc29XmQrbc/edit#gid=211905165 Eric Bandauski's Yeast Strain Guide]</ref>. ===[[BAC Yeast]]==={| class="wikitable sortable"|-! Name !! Source !! Attenuation !! Flocculation !! Temp°F !! Notes|-| BY122 || Achouffe || 72-76% || High || 64-84 || One of many great beer yeast to produce classic Belgian ales. Phenolics develop with increased fermentation temperatures, mild fruitiness and complex spicy character. Similar to WLP550 or WY3522.|-| BY124 || || 77-83% || Low || 65-77 || French Saison yeast starter is a strain that enhances the use of spices and is extremely attenuative yet leaves an unexpected silky and rich mouthfeel in a very dry finished beer.Produces Saison or farmhouse-style beers that are highly aromatic with clean citrus esters. Expect peppery and spicy notes with no earthiness and low phenols. This strain enhances the use of spices and is extremely attenuative but leaves an unexpected silky and rich mouthfeel in a very dry finished beer. Similar to WY3711. Determined to be a [[Saccharomyces#Diastatic_strains_of_Saccharomyces_cerevisiae|diastatic strain of ''Saccharomyces cerevisiae'']] <ref name="preiss_diastaticus" />.|-| BY125 || Saison du Pont || 76-80% || Low || 70-85 || Belgian Saison Classic farmhouse ale yeast. Very tart and dry on palate with mild fruit. Finishes crisp and mildly acidic. Benefits from elevated temperatures.Classic farmhouse ale yeast. Spicy and complex aromatics including bubble gum. Very tart and dry on palate with mild fruit. Finishes crisp and mildly acidic. Benefits from elevated fermentation temperatures. Usually slow to attenuate. Similar to WLP565 or WY3724.|-| BY126 || Westmalle || 75-80% || Medium || 64-78 || Trappist Big ABV strain is a robust top cropping beer yeast with phenolic character. Trappist Big ABV beer yeast has an alcohol tolerance to 12%. It's ideal for Bière de Garde, as it ferments dry with rich ester profile and a malty palate. Similar to WLP530 or WY3787.|-| BY128 || Esen, Belgium (De Dolle) || 72-76% || Medium || 62-75 || This versatile witbier yeast strain can be used in a variety of Belgian style ales. This strain produces a complex flavor profile dominated by spicy phenolics with low to moderate ester production. It is a great strain choice when you want a delicate clove profile not to be overshadowed by esters. It will ferment fairly dry with a slightly tart finish that compliments the use of oats, malted and unmalted wheat. This strain is a true top cropping yeast requiring full fermenter headspace of 33%A tart, slightly phenolic yeast capable of producing distinctive witbiers and grand cru-style ales alike. Alcohol tolerant. Similar to WY3942.|-|} ===[[Bootleg Biology]]/[[Spot Yeast]]==={| class="wikitable sortable"|-! Name !! Source !! Attenuation !! Flocculation !! Temp°F !! Notes|-| BB22204 - ''S. arlingtonesis'' || Wild yeast starter jar in Arlington, VA || High || NA || 60-70 || This culture ferments extremely cleanly in the low 60’sF (Kölsch and Lager hybrids), and subtle fruity/citrus esters in the higher end of the Ale fermentation range (wheat-centric beers). May produce sulfur aromas during primary fermentation, but those will be eliminated within a couple weeks (allow longer aging if fermenting at lower temperatures). S. arlingtonesis is a higher attenuator than most ale strains, so adjustments made need to be made to grain bills or mash temperatures if a drier beer is not preferred.|-| BBX0104 – Saison Parfait: New World Saison Blend || A unique blend of previously unavailable commercially used Saison cultures. || 90-100 || Med-High || Normal to High Ale Temperatures || Saison Parfait is our New World Saison Blend, a new take on the modern saison yeast flavor and aroma profile. Saison Parfait pairs classic pepper & spice saison phenolics with prominent juicy fruit esters that evoke citrus and lemon peel, and a touch of banana for complexity. Even more unique, it finishes with a balanced, full-bodied and silky mouthfeel despite its high attenuation. Saison Parfait means the “Perfect Season”, and is our ode to the fall harvest season. A time for hard work and also celebration. The peasants of rural Flanders and Wallonia created the Saison, and what we now call Farmhouse beers, to drink for sustenance and merriment. Bruegel likely depicted the drinking of Saison beer in his classic paintings of rural country life, “The Harvesters” and “Peasant Wedding”.|-|} ===[[Community Cultures Yeast Lab]]==={| class="wikitable sortable"|-! Name !! Source !! Attenuation !! Flocculation !! Temp°F !! Notes|-| TCL21 Ocotillo || Ocotillo plant in Big Bend, Texas || 86-91 || High || 69-74 || Suggested Use: Saison, Belgians, Farmhouse ales, Cider, Braggot, and wine. Determined to be a [[Saccharomyces#Diastatic_strains_of_Saccharomyces_cerevisiae|diastatic strain of ''Saccharomyces bayanus'']]. Also POF+.|-| TCL22 Yucca || Torrey Yucca plant in Texas || 73-78 || Low || 68-72 || Determined to be a [[Saccharomyces#Diastatic_strains_of_Saccharomyces_cerevisiae|diastatic strain of ''Saccharomyces bayanus'']]. POF+. Suggested Use: Witbier, Belgian Blond, Hefeweizen, Kristalweizen, Barrel aged beers.|-| TCL32 Chisos || Chisos Mountains, Texas || 86-91 || Low || 65-72 || Determined to be a [[Saccharomyces#Diastatic_strains_of_Saccharomyces_cerevisiae|diastatic strain of ''Saccharomyces bayanus'']]. POF+. Suggested Use: Tripel, Belgians, Dubbels, Siason, Witbier, and farmhouse ales. |-| TCL25 Prickly Pear Blend || Big Bend, Texas || 73-80 || Med || 67-73 || Contains two strains of ''S. cerevisiae''. Determined to be a [[Saccharomyces#Diastatic_strains_of_Saccharomyces_cerevisiae|diastatic strain of ''Saccharomyces cerevisiae'']]. POF+. Suggested Use: American Pale Ale, IPAs, English pales, Hopped Sour (bacteria not provided), Gose.|-| TCL34 The Window || Prickly Pear Fruitin Big Bend, Texas || 70-75 || Med/High || 66-72 || Determined to be a [[Saccharomyces#Diastatic_strains_of_Saccharomyces_cerevisiae|diastatic strain of ''Saccharomyces cerevisiae'']]. POF+. Suggested Use: Belgians, Weizens, Trappist ale, Dubbels, German ales, and Saisons.|-| TCL31 The Falls || Columbine in Cattail Falls, Texas || 70-75 || Low || 62-72 || Determined to be a [[Saccharomyces#Diastatic_strains_of_Saccharomyces_cerevisiae|diastatic strain of ''Saccharomyces bayanus'']]. POF+. Suggested Use: Witbier, Sour Witbier, Apricot Witbier, Citrus Wit, Hefeweizen, Belgian Ales, Dubbels, Trappist, Trippel, Saisons.|-| TCL24 Buttercup || Rio Grande River, Texas || 73-85 || High || 66-71 || Determined to be a [[Saccharomyces#Diastatic_strains_of_Saccharomyces_cerevisiae|diastatic strain of ''Saccharomyces cerevisiae'']]. POF+. Suggested Use: Belgians, Barley wine, Winterale, Scotch ale, Heavy Ales, Stouts, Porters.|-| TCLH1 Swallowtail || Swallowtail butterfly, Texas || 76-81 || Med/Low || 69-75 || Determined to be a [[Saccharomyces#Diastatic_strains_of_Saccharomyces_cerevisiae|diastatic strain of ''Saccharomyces cerevisiae'']]. POF+. |-| TCL38 El Monte Manor || San Antonio, Texas || 87-92 || Med || 66-72 || STA1 negative and POF+ strain of ''S. cerevisiae''. Suggested Use: IPA, Belgian Saison, Brett Saison, Nordic Ales, Altbier, Tripel, Belgian Blonde.|-| TCLJ1 Cenote Sac Actun || Cenote Sac Actun (fresh water cave), Texas || 89-94 || Med || 68-72 || Determined to be a [[Saccharomyces#Diastatic_strains_of_Saccharomyces_cerevisiae|diastatic strain of ''Saccharomyces cerevisiae'']]. POF+. Suggested Use: East Coast IPA, New England IPA, English Ales, Irish Red Ale, Brown Ales.|-|} ===[[Craft Cultures]]==={| class="wikitable sortable"|-! Name !! Source !! Attenuation !! Flocculation !! Temp°F !! Notes|-| CCYL113 - Belgian Saison Ale Yeast || || || || || This yeast strain contributes clove flavor and aroma to the finished product. Fruity aromas are also experienced. Commercial pitches only.|-| CCYL114 - Belgian Ale Yeast || || || || || To produce any great distinctive Belgian style beer, do ferment with the Belgian Ale Yeast. Flavors emanating from beer produced by this yeast are rich in both spice and phenols and are mildly fruity. Commercial pitches only.|-| CCYL115 - Trappist Ale Yeast || || || || || The Trappist Ale Yeast has a unique fruit and plum flavor and aromas. It performs well in high gravity brews. Commercial pitches only.|-| CCYL116 - Belgian Wit Ale Yeast || || || || || The original yeast used to produce Belgian Witbier and a variety of other Belgian style ales. Commercial pitches only.|-| CCYL120 - French Saison Ale Yeast || || || || || The French Saison Ale Yeast is a versatile strain that works great for Saison or Farmhouse and other Belgian style beers where aromatic (estery), peppery, spicy and citrusy flavors are desired. Might be a [[Saccharomyces#Diastatic_strains_of_Saccharomyces_cerevisiae|diastatic strain of ''Saccharomyces cerevisiae'']] if this strain is the same as WY3711 <ref name="preiss_diastaticus" />. Commercial pitches only.|-| CCYL121 Abbey Ale Yeast || || || || || Used to produce Trappist, Belgian, Belgian doubles and triples This yeast contributes a fruity characteristics. Excellent alcohol tolerance for high gravity beers. Commercial pitches only.|-| CCY126 French Ale Yeast || || || || || Clean strain that complements malt flavor. Low to moderate esters, when fermentation temperature is below 70°F. Moderate plus ester character over 70°F. Low diacetyl production. Good yeast strain for Biere de Garde, blond, amber, brown ales, and specialty beers. Commercial pitches only.|-| CCYL128 - Belgian Saison Ale Yeast Blend || || || || || The Belgian Saison Ale Yeast Blend has some phenolic and clove-like flavor and aroma characteristic and fruitier esters than CCYL113. Ferments faster than CCYL113. Commercial pitches only.|-| CCYL129 - Eagle River Ale Yeast™ || || || || || Michigan indigenous. The Eagle River Ale Yeast is the second in a series of indigenous Michigan strains. It was isolated from the shore of Lake Superior near Eagle River Michigan. This yeast will produce excellent Belgian style ales. This yeast is rich in both spice and phenols exhibits predominantly fruity esters, similar to a Belgian ale strain. Commercial pitches only.|-| CCYL130 - Keweenaw Ale Yeast™ || || || || || Michigan indigenous. The Keweenaw Ale Yeast is the third in a series of indigenous Michigan yeast strains. This yeast was isolated in Michigan's Keweenaw Peninsula. It has prominent spicy phenolics and some fruity esters, very reminiscent of a Saison yeast. Commercial pitches only.|-| CCYL131 Belgian Wit Ale 2.0 || || || || || Less Belgian-like phenolics than CCYL116 and more spicy. Will leave a bit more sweetness, and flocculation is higher than CCYL116. Use to produce Belgian Wit, spiced Ales, wheat Ales, and specialty Beers. Commercial pitches only.|-| CCYL134 Rock Cut Ale Yeast™ || || || || || Michigan indigenous yeast coming soon. Commercial pitches only.|-| CCYL138 Rock Cut Ale Yeast II™ || || || || || Michigan indigenous yeast coming soon. Commercial pitches only.|-|} ===[[East Coast Yeast]]==={| class="wikitable sortable"|-! Name !! Source !! Attenuation !! Flocculation !! Temp°F !! Notes|-| ECY03 Farmhouse Blend || || || || || A saison blend (ECY08) with a wild isolate from a small producer of Saison. Can produce a funky and acidic farmhouse ale particularly when a secondary fermentable is added (i.e. priming sugar or fruit). The wild isolate, ECY03B, now identified as ''Saccharomyces boulardii'' - is a wild-type strain of ''Saccharomyces cerevisae''. Commercial orders will also include a small pitch of ECY03B with the ECY03 primary pitch. Pitching the 03B during high krausen also produces the "wildness" quickly without aging long-term <ref name="ecy_website">[http://www.eastcoastyeast.com/wild-stuff.html "Wild Yeast / Brettanomyces / Lactic Bacteria". East Coast Yeast website. Retrieved 04/27/2018.]</ref>.|-| ECY-03B Farmhouse || Fantome || 80 || || 70-84 || Previously misidentified as ''Brettanomyces'' <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/972543279440553/?comment_id=972571192771095&comment_tracking=%7B%22tn%22%3A%22R%22%7D&hc_location=ufi Lance Shaner. Milk The Funk Facebook thread on misclassification of Trois and ECY-03b. 12/06/2014.]</ref>. Fruity and funky profile with some acidity gradually increasing over time. Aeration has more of a muted effect. Identified as ''Saccharomyces boulardii'' <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/972543279440553/?comment_id=972571192771095&offset=50&total_comments=73&comment_tracking=%7B%22tn%22%3A%22R9%22%7D May not be Brett as per Lance Shaner on MTF.]</ref><ref>[https://www.fermentednj.com/shopfermented/ECY03B-Farmhouse-p131993356 Fermented Homebrew Store website. East Coast Yeast ECY-03B description. Retrieved 05/11/2019.]</ref>.|-| ECY08 Saison Brasserie || Several Strains || 80+ || || 75-85 || Several saison yeast strains for both fruity and spicy characteristics accompanied with dryness. See also [https://www.facebook.com/groups/MilkTheFunk/permalink/2135874903107379/?comment_id=2136076179753918&comment_tracking=%7B%22tn%22%3A%22R0%22%7D tasting notes from MTF members].|-| ECY14 Saison Single || Single Strain || 76-78 || || 75-82 || Smooth, full farmhouse character with mild esters reminiscent of apple pie spice|-| ECY46 Farmhouse 2 || || 80-84 || || 76-82 || An American farmhouse isolate (''Saccharomyces cerevisae'' / ''boulardii'') producing a pleasant tartness quickly upon fermentation (pH 4.0 - 4.1). Expect high attenuation, slight citrus esters and tartness <ref>[http://www.eastcoastyeast.com/ale---lager-yeast.html East Coast Yeast website. "Ale & Lager Yeast" page. Retrieved 03/27/2021.]</ref>.|-|} ===[[Escarpment Laboratories]]==={| class="wikitable sortable"|-! Name !! Source !! Attenuation !! Flocculation !! Temp°C !! Notes|-| Ardennes Belgian Ale || || 72-80 || Med-High || 18.3-24.4 || A very versatile and production-friendly Belgian ale yeast, producing balanced Belgian esters and spicy notes. One of the rare Belgian strains which flocculates relatively well, making repitching and/or cropping easier when compared to other Belgian yeasts. Alcohol tolerance: high <ref name="escarpment_strains" />.|-| Classic Witbier || || 72-78 || Med-Low || 19-24 || Medium alcohol tolerance. A genera-defining Witbier strain, famous for balanced phenol and ester character with slight tartness that emphasizes wheat flavour <ref name="escarpment_strains">[https://www.escarpmentlabs.com/strains Escarpment Labs Yeast website. Strain Collection. Retrieved 02/27/2018].</ref>|-| Dry Belgian Ale || || 85+ || Med-Low || 22-26 || Obtained from an American producer of Belgian-style beers. This strain exhibits classic dry Belgian flavours, and displays an aggressive primary fermentation. We especially like this strain for Strong Golden, Tripel, and other Belgian-style beers. NOTE: This strain contains the STA1 gene, meaning it might be a [[Saccharomyces#Diastatic_strains_of_Saccharomyces_cerevisiae|diastatic strain of ''Saccharomyces cerevisiae'']] (pending data on whether it actually ferments dextrins or not). Many industrial yeasts are diastatic, due to the desire for very high attenuation levels. However extra care must be taken to ensure these yeasts do not cross-contaminate non-diastatic yeasts. Contact us with any questions or concerns. Alcohol tolerance: >12% <ref name="escarpment_strains" />.|-| Fruity Witbier || || 70-75 || Med-Low || 17-24 || A Witbier strain which produces lots of complex fruity esters while still prominently displaying classic Witbier character. Medium-low flocculation helps ensure classic Witbier haze. Alcohol tolerance: 12% <ref name="escarpment_strains" />.|-| Old World Saison Blend || || 85+ || Med || 18-25 ||A characterful blend of two classic Saison strains. Produces complex fruit and black pepper notes along with a reliable, fast and high degree of attenuation. We strongly encourage a free rise fermentation, starting at 22C and rising to ~27C for optimal results. NOTE: One of the strains in this blend contains the STA1 gene, meaning it might be a [[Saccharomyces#Diastatic_strains_of_Saccharomyces_cerevisiae|diastatic strain of ''Saccharomyces cerevisiae'']] (pending data on whether it actually ferments dextrins or not). Many Saison yeasts are diastatic, due to the desire for very high attenuation levels. However extra care must be taken to ensure these yeasts do not cross-contaminate non-diastatic yeasts. Contact Escparment Labs with any questions or concerns. Alcohol tolerance: High <ref name="escarpment_strains" />.|-| St-Remy Abbey Ale || || 72-80 || Med || 18-24 || This yeast strain isolated from a Belgian abbey is an excellent choice for Belgian-style beers, including abbey ales. This strain produces mixed fruity esters, Oak Treeswhile also highlighting malt aroma. This strain can be used at higher fermentation temperatures without becoming overly phenolic/spicy. Alcohol tolerance: >10% <ref name="escarpment_strains" />.|-| St. Lucifer Belgian Ale || || 75-85 || Med || 20-24. 4 || ExampleA high-character Belgian ale strain, able to produce high gravity beers with strong fruity and medium phenolic character. Excellent for strong golden ales and Tripels, but versatile for all Belgian ale applications. NOTE: This strain contains the STA1 gene, meaning it might be a [[Saccharomyces#Diastatic_strains_of_Saccharomyces_cerevisiae|diastatic strain of ''Saccharomyces cerevisiae'']] (pending data on whether it actually ferments dextrins or not). Many industrial yeasts are diastatic, due to the desire for very high attenuation levels. However extra care must be taken to ensure these yeasts do not cross-contaminate non-diastatic yeasts. Contact us with any questions or concerns. Alcohol tolerance: >12% <ref name="escarpment_strains" />.|-| Wild Thing || Ontario || 75-82 || Med || 25+ || This wild Ontario ale yeast was isolated from an apple in a local orchard. Wild Thing produces distinct clove, spice, and subtle banana and apple fruit aroma. The taste is dry, spicy and clean. This yeast is most comparable to medium-attenuation Belgian-style ale yeasts. May require temperature ramping to 25C to ensure high attenuation. Alcohol tolerance: 9% <ref name="escarpment_strains" />.
|-
| S. paradoxus } ===[[Fermentis]]==={|| Oak trees || Exampleclass="wikitable sortable"
|-
|-
| S[https://fermentis. mikatae com/en/fermentation-solutions/you-create-beer/safale-t-58/ SafAle™ T-58 Dry] || Decayed leaves in Japan Fermentis || || 70 || Med || 12-25°C (53.6-77°F) ideally 15-20°C (59-68°F) || ExampleA specialty ale yeast selected for its estery, somewhat peppery and spicy flavor. Yeast with a good sedimentation: forms no clumps but a powdery haze when re-suspended in the beer.
|-
| S[https://fermentis. kudriavzevii com/en/fermentation-solutions/you-create-beer/safale-be-256/ SafAle™ BE-256 Dry] || Decayed leaves in Japan Fermentis || Example|| 82 || High || 12-25°C (53.6-77°F) ideally 15-20°C (59-68°F) || Active dry yeast recommended to brew a diversity of beers amongst which abbey style beers known for their high alcohol content. It ferments very fast and reveals subtle and well-balanced aromas. To maintain the aromatic profile at the end of the fermentation, we do recommend to crop the yeast as soon as possible after fermentation.
|-
| S[https://fermentis. bayanus* com/en/fermentation-solutions/you-create-beer/safale-be-134/ SafAle™ BE-134] || Wine Fermentis || Possible hybrid of S|| 90 || Low || 25-29°C (77-84°F) || This typical yeast strain is recommended for Belgian Saison-style beers and is characterized by a particularly high attenuation. It gives fruity aromas with a spicy character such as clove notes. eubayanus This strain will produce highly refreshing and Sdrinkable beers. Confirmed by the company to be a [[Saccharomyces#Diastatic_strains_of_Saccharomyces_cerevisiae|diastatic strain of ''Saccharomyces cerevisiae'']] <ref>[http://fermentis.com/wp-content/uploads/2018/02/SafAle-BE-134_Rev2.pdf Fermentis BE-134 Spec Sheet. Retrieved 02/10/2018. Possible parent of S]</ref><ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1890957430932462/ Private email correspondence with a Fermentis representative by Jeremy Johns; email forwarded to Dan Pixley for verification. 11/21/2017. pastorianus]</ref>.
|-
| S[https://fermentis. florentinus com/en/fermentation-solutions/you-create-beer/safale-wb-06/ SafeAle™ WB-06] || Drosophila Fermentis || || 86 || Low || 18-24°C (64-75 °F) || This typical yeast strain is recommended for wheat beer fermentations and produces subtle estery and sulphurized grape must phenol flavor notes (POF+) such as clove notes typical of wheat beers. Confirmed by the company to be a [[Saccharomyces#Diastatic_strains_of_Saccharomyces_cerevisiae|| Examplediastatic strain of ''Saccharomyces cerevisiae'']] <ref>[https://fermentis.com/en/fermentation-solutions/you-create-beer/safale-wb-06/ Fermentis SafeAle™ WB-06 webpage. Retrieved 02/10/2018.]</ref>
|-
| Example || Example || Example}
===[[GigaYeast]]===
{| class="wikitable sortable"
|-
! Name !! Source !! Attenuation !! Flocculation !! Temp°F !! Notes
|-
| GY003 Achouffe Belgian Ale || || 81-84 (medium gravity) 57-60 (7.7%+ abv) || Medium/Low || 68-77 || Abbey style yeast from the Belgian Ardennes. Produces aromatic, spicy clove-like notes and less fruity aromas than GY014. Moderately flocculant yeast that creates a slightly clearer beer than most Belgians.
|-
| GY007 Belgian Mix || || 79-81 (medium gravity) 67-70 (8.6%+ abv) || Low || 68-77 || A blend of Trappist Ale Yeast combine to create robust attenuation and a complex flavor profile. Spicy and fruity, this blend is slightly more flocculent than many Belgians. Good choice for High Gravity beers.
|-
| GY014 Scourmont Abbey Ale || || 79-81 || Low || 64-80 || Classic Belgian yeast from one of the best known Trappist breweries. A fragrant yeast that produces delicious fruity aroma. Good choice for high gravity beers. Generally, the warmer this yeast is fermented the higher the level of fruit aromas produced.
|-
| GY015 Trappist Tripel || || 70-76 || Low || 66-74 || Trappist Ale yeast from the mother of all Tripels. A balance of fruit and spice with a good malty finish provides a perfect complement for Belgian Ales, Dubbels and Tripels. Attenuation is on the slow side leaving more residual sweetness than our other Belgians. Less esters and phenolics than GY003 and GY014.
|-
| GY018 Saison 1 || French Brewery || 81-83 (medium gravity) 49-53 (6.2%+ abv) || Low || 64-80 || Traditional Saison yeast from a French craft brewery. Strong attenuator that produces a dry beer with a beautiful fragrance and the traditional Saison taste of fruit and pepper. Might be a [[Saccharomyces#Diastatic_strains_of_Saccharomyces_cerevisiae|diastatic strain of ''Saccharomyces cerevisiae'']] if this strain is the same as WY3711 <ref name="preiss_diastaticus" />.
|-
| GY027 Saison Yeast 2 || Traditional Saison || 79-83 (medium gravity) 44-47 (5.5%+ abv) || Low || 64-80 || Creates the fruity/spicy aroma traditional to the style. Warmer fermentation temps result in more intense flavor. Produces a tartness not found in most of our yeast and a slightly sweeter beer than GY018
|-
| GY028 Belgian Wit || || 74-79 || Very Low || 64-80 || Traditional Belgian Wit yeast from one of the classic producers of the style. Creates a delicious spicy nose and a somewhat tart beer. Attenuates dry and leaves a slightly cloudy beer - very low flocculation.
|-
| GY047 Saison Blend || || 80-83 (medium gravity) 49-53 (6.2%+ abv) || Low || 64-80 || A blend of Saison yeast. This Blend is a super robust attenuator that produces a complex flavor profile of fruit and spice.
|-
| GY048 Golden Pear Belgian Ale || Duvel Moortgat Brewery || 78-85 || Low || 65-80 || Traditional yeast from the originator of the Belgian Golden Strong Ale style. Robust attenuation makes this yeast an excellent choice for low or high gravity Belgian and farmhouse style ales. Leaves a dry, slightly tart finish with an estery profile reminiscent of apple and pear with a subdued level of spicy phenolics. This yeast produces a moderate amount of sulfide that will dissipate quickly with conditioning.
|-
| GY077 Quebec Abbey Ale || Canadian Brewery || 75-83 || Medium || 68-80 || From one of the first breweries in North America to create a successful line of traditional Abbey style ales. This Belgian ale yeast creates a malt forward beer with subtle fruity esters and a very small amount of clove notes. Robust attenuation makes this yeast an excellent choice for low or high gravity beers where a slightly sweet malty finish is desired. Perfect for the Belgian Dubbel and Tripel styles.
|-
|}
==Notes and referencesReferences==
<references/>
[[Category:Yeast]]