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Brettanomyces

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A genetic survey of 1488 different strains of ''B. bruxellensis'' from 29 countries, 5 continents, and 9 different fermentation niches was conducted in 2018 by Avramova et al. They found that these strains formed roughly 5 genetic groups with mostly separate ancestral lineages, and 1 group with a mixed ancestral lineage: 3 wine groups, 1 beer group, 1 kombucha group (most distantly related to the beer group), as well as 1 tequila/ethanol group that has multiple ancestral lineages. This was expressed mostly in the ploidy level of each group (the number of sets of chromosomes), with 2 of the wine groups, the tequila group, and the beer group containing more sets of chromosome pairs than the other groups (diploid vs triploid; this is thought to encourage adaption and hybridization). Additionally, the triploid wine group was generally more tolerant of SO<sup>2</sup> than the diploid wine groups. The genetic differences between the fermentation substrates (beer, wine, etc.) were lower but still significant, and this was explained by the frequent cross-over of equipment such as wine barrels being used for beer fermentation. When comparing the geographic differences, they found geography contributed only 5% of genetic differences, while geography explained more than 50% of genetic differences in non-wine strains, suggesting that beer, kombucha, and tequila strains are more localized genetically than wine strains and that humans probably helped the wine strains travel across the globe. They also found that although one study reported spore-forming versions of ''B. bruxellensis'' (referred to as ''Dekkera bruxellensis''), the genetic makeup of the analyzed strains determined their ability to sporulate to be non-existent or rare (only one study that we know of by [https://link.springer.com/article/10.1007%2FBF02539015 Walt and Kerken in 1960] has reported sporulation in ''Brettanomyces'' only on specific agar types with vitamins added, indicating that sporulation in ''Brettanomyces'' is extremely rare) <ref name="Avramova_2018" />. See also [https://www.facebook.com/groups/MilkTheFunk/permalink/2022801681081369/ Richard Preiss's discussion of this study on MTF].
Sulfite and SO<sub>2</sub> inhibits the growth of ''Brettanomyces'', and is often used in the wine industry to prevent the growth of ''Brettanomyces'' (some wineries have identified small amounts of flavors from ''Brettanomyces'' as being beneficial to certain wine styles, and is said to increase the complexity and impart an aged character in young wines <ref name="smith_divol_2016"></ref>) <ref>[http://onlinelibrary.wiley.com/doi/10.1111/j.1745-4549.2012.00702.x/abstract Removal of Brettanomyces Bruxellensis from Red Wine Using Membrane Filtration. Umiker, Descenzo, Lee, and Edwards. 04/24/2012.]</ref>. However, it has been shown that wine strains of ''B. bruxellensis'' could survive dosages of up to 1 mg/L of SO<sub>2</sub>, and the very high dosage of 2.1 mg/L was needed to kill ''Brettanomyces'' in wine <ref name="Agnolucci_2017" />. This dosage of SO<sub>2</sub> is beyond legal limits and has negative effects on wine. The tolerance of SO<sub>2</sub> of strains of ''Brettanomyces'' found in beer is lower than those found in wine strains. Some strains of ''Candida pyralidae'', ''Wickerhamomyces anomalus'', ''Kluyveromyces wickeramii'', ''Torulaspora delbrueckii'' and ''Pichia membranifaciens'' have been found to produce toxin that inhibits ''Brettanomyces'', and these toxins have been proposed as an alternative to SO<sub>2</sub> as a way to kill ''Brettanomyces'' (killer wine strains of ''Saccharomyces cerevisiae'' do not kill ''Brettanomyces''; see [[Saccharomyces#Killer_Wine_Yeast|Killer Wine Yeast]] for more information). [http://www.laboratoriosenosan.com/en/effectiveness-of-kaolin-silver-complex/ Kaolin silver complex (KAgC) ] has been found o to inhibit ''Brettanomyces'' and acetic acid bacteria in wine when used in legal dosages , and has been proposed as a replacement for SO<sup>2</sup> or to minimize the use of SO<sup>2</sup> <ref>[https://www.ncbi.nlm.nih.gov/pubmed/29666535?dopt=Abstract Effect of kaolin silver complex on the control of populations of Brettanomyces and acetic acid bacteria in wine. Izquierdo-Cañas PM, López-Martín R, García-Romero E, González-Arenzana L, Mínguez-Sanz S, Chatonnet P, Palacios-García A, Puig-Pujol A. 2018. DOI: 10.1007/s13197-018-3097-y.]</ref>.
The addition of vitamins can have a positive impact on ''Brettanomyces'' growth. For example, while ''Brettanomyces'' does not need riboflavin (vitamin B2) or thiamine (vitamin B1) in order to grow, the presence of either or both of these two vitamins encourages ''Brettanomyces'' growth <ref>[http://onlinelibrary.wiley.com/doi/10.1002/jib.385/full The influence of thiamine and riboflavin on various spoilage microorganisms commonly found in beer. Barry Hucker, Melinda Christophersen, Frank Vriesekoop. 2017.]</ref>.

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