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'''Saccharomyces''Saccharomyces' is considered a yeast, although this term is historical and ill-defined. ''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 [[Saccharomyces#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.
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 Yeast Subphylum, 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).
See also:
* [https://en.wikipedia.org/wiki/Saccharomyces ''Saccharomyces'' at Wikipedia''.]
* [https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/saccharomyces ScienceDirect AI generated topic article.]
==Species==
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| ''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>.
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| ''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>.
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** [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:
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>
[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://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==
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===[[Bootleg Biology]]/[[Spot Yeast]]===
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| JY064 - Belgian Ale VII || Belgium || 70-80 || Low || 59-75 || Belgian Abbey yeast producing intense esters at higher temperatures, and strong spice notes at lower temperatures. <ref name="Jasper_Yeast" />
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| JY087 - Sacc Brux || Belgium || 70-80 || Very Low || 70-80 || Similar to Sacch Trois; forms a pellicle. Determined to be a [[Saccharomyces#Diastatic_strains_of_Saccharomyces_cerevisiae|diastatic strain of ''Saccharomyces cerevisiae'']] <ref name="Jasper_Yeast" />.
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| JY104 - Benedict Abbey || Small brewery in Flemish Brabant, Belgium. || 75-80 || Low || 68-77 || JY104 was handed to Jasper Akerboom when he toured some small microbreweries in the Netherlands and Belgium by a friendly microbrewer. This strain originally belonged to a small brewery in Flemish Brabant in Belgium. The brewery was acquired by a large macrobrewery, and management decided to do away with this precious yeast. Fortunately passionate homebrewers and beer enthusiasts were able to keep some of the yeast going and you can use it now as well! This strain ferments fast, and aggressive. It can be under pitched easily, and attenuates deep. Great esters and phenols, can be slightly peppery. Flocculates slow, but can withstand spunding without a problem. This yeast is great for lighter colored Belgians, but is great for darker Belgians as well. This strain has not been fully characterized, so we do not know what gravity this yeast will ferment. We do know that it attenuates very well, and the initial tests have indicated that can ferment easily to 10% ABV.