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'''Brettanomyces''', also known as ''Brett'' or ''Bretta'', is a yeast that was originally thought of as a spoilage yeast. The genus name ''Dekkera'' is used interchangeably with Brettanomyces, as it describes the teleomorph or spore forming form of the yeast <ref>[http://en.wikipedia.org/wiki/Brettanomyces Wikipedia. Brettanomyces. Retrieved 2/24/2015.]</ref>. Known for it's barnyard, fecal, horsey, metallic or Band-Aid flavors, ''Brett'' was unwelcome in most breweries. However, in some styles like Saison and Lambic these flavors add a layer of complexity to the beer. ''Brett'' can form a [[pellicle]]. See [[Lactobacillus]], [[Pediococcus]], [[Saccharomyces]], and [[Mixed Cultures]] charts for other commercially available cultures.
==Introduction of Characteristics==
''Brettanomyces'', first discovered by Hjelte Claussen in 1904, has traditionally been identified as a contaminate in wineries and brewers due to some of the phenols and esters and phenols that it produces. These have generally been described as barnyard, burnt plastic, wet animal, fecal, and horse sweat <ref name="Schifferdecker">[http://onlinelibrary.wiley.com/doi/10.1002/yea.3023/pdf The wine and beer yeast Dekkera bruxellensis. Anna Judith Schifferdecker, Sofia Dashko, Olena P. Ishchuk, and Jure Piškur. 7 July 201.]</ref>. However, positive flavor components have been identified in beer such as pineapple, stone fruits, and to some degree acetic acid.
''Brett'' has been identified on the skins of fruit <ref name="Schifferdecker"></ref>, as well as vectors (insects) <ref>[http://www.sciencedirect.com/science/article/pii/S0168160515001865 Brettanomyces yeasts — From spoilage organisms to valuable contributors to industrial fermentations. Jan Steensels, Luk Daenen, Philippe Malcorps, Guy Derdelinckx, Hubert Verachtert, Kevin J. Verstrepen. International Journal of Food Microbiology Volume 206, 3 August 2015, Pages 24–38.]</ref>. ''Brett'' is not considered to be airborne, however studies have shown that a very small amount of cells in the air at wineries where wine with ''Brett'' in it was handled. These set of studies also determined that very specific methodology was needed to capture Brett from the air, and indicated that the yeast was "stressed". <ref>[http://www.sciencedirect.com/science/article/pii/S0956713513002284 Screening of yeast mycoflora in winery air samples and their risk of wine contamination. E. Ocón, P. Garijo, S. Sanz, C. Olarte, R. López, P. Santamaría, A.R. Gutiérrez. Food Control Volume 34, Issue 2, December 2013, Pages 261–267.]</ref>. While it is possible for ''Brett'' to be briefly carried by gusts of air, it only happens where the yeast is active. Good cleaning and sanitation and cold temperatures should be employed to keep ''Brett'' from infecting other equipment, and flying insects are a probably the likely cause for cross contamination of ''Brett''.
It is common in scientific literature to see the names ''Dekkera'' and ''Brettanomyces'' used as the genus name, with ''Dekkera'' being the [https://en.wikipedia.org/wiki/Teleomorph,_anamorph_and_holomorph teleomorph] version and ''Brettanomyces'' being the [https://en.wikipedia.org/wiki/Teleomorph,_anamorph_and_holomorph anamorph]. There are five species within the genus of Brettanomyces: ''B. anomola'', ''B. bruxellensis'', ''B. custersianus'', ''B. nanus'', and ''B. naardenensis''. ''B. anomola'' and ''B. bruxellensis'' are the only two species that have been identified to have a teleomorph version; in their teleomorph version they are referred to as ''Dekkera anomola'', ''Dekkera bruxellensis'' <ref name="Schifferdecker"></ref>. All of the other names such as the ones often used by yeast labs are derived by old nomenclature that is no longer used <ref name="yakobson_introduction">[http://www.brettanomycesproject.com/dissertation/introduction/ Yakobson, Chad. The Brettanomyces Project. Introduction. Retrieved 8/11/2015.]</ref>.
Unlike most yeasts, ''Brett'' has the characteristics of being highly tolerant of high amounts of alcohol, low pH, and low nitrogen sources <ref name="Schifferdecker"></ref>. Perhaps the most differentiating characteristic of ''Brett'' is it's preference to ferment glucose in the presence of oxygen, which is the opposite of [[Saccharomyces]]. This was initially dubbed the "negative Pasteur effect" by Custers, and later the "Custers effect" <ref name="yakobson_introduction"></ref>.
==''Brettanomyces'' Metabolism==
===Secondary Metabolites===
''Secondary metabolites'' are compounds that are not essential to the life of an organism <ref>[http://en.wikipedia.org/wiki/Secondary_metabolite Wikipedia. Secondary Metabolite. Retrieved 6/2/2015.]</ref>. ''Brettanomyces'' will use a range of secondary metabolites to produce many of the fruity and funky esters, phenols, and acids that this genus of yeast has become known for.
====Ester Production====