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===Brettanomyces===
Oxygen has a stimulatory effect in it's production, but this is probably because ''Brett'' has a higher biomass formation under aerobic conditions <ref>[http://www.brettanomycesproject.com/dissertation/introduction/ Yakobson, Chad. The Brettanomyces Project; Introduction. Retrieved 3/10/2015.]</ref><ref>[http://pubs.acs.org/doi/abs/10.1021/jf071243e The Role of Lysine Amino Nitrogen in the Biosynthesis of Mousy Off-Flavor Compounds by Dekkera anomala. Paul R. Grbin, Markus Herderich, Andrew Markides, Terry H. Lee, and Paul A. Henschke. J. Agric. Food Chem., 2007.]</ref><ref name="Oelofse">[http://scholar.sun.ac.za/handle/10019.1/8437 Significance of Brettanomyces and Dekkera during Winemaking: A Synoptic Review. A. Oelofse, I.S. Pretorius, and M. du Toit. 2008.]</ref>. Therefore, limiting oxygen exposure during kegging/force carbonating is recommended for helping to reduce THP production. The level of THP production varies widely between species and strains of ''Brett'', with some strains not producing it at all and some producing very high amounts above taste threshold. Additionally, THP production appears to require glucose or fructose, which explains why THP may be seen more often in stuck wine fermentations rather than wine that has finished fermenting. ATHP production by ''Brett'' was observed in wine with glucose or fructose added, along with synthetic growth media, suggesting that the type of growth substrate does not effect production <ref>[http://www.ncbi.nlm.nih.gov/pubmed/18194246 Growth and volatile compound production by Brettanomyces/Dekkera bruxellensis in red wine. Romano A, Perello MC, de Revel G, Lonvaud-Funel A. J Appl Microbiol. 2008 Jun.]</ref>.
As ''Brett'' continues through it's growth cycle, ATHP is produced as . This production is not efficient, meaning that the amount of ATHP produced is not proportional to the amount of L-lysine consumed, so the production of ATHP appears to be a byproduct (secondary metabolite ) of L-lysine catabolism <ref name="Snowdon"></ref>. ATHP is further metabolized into 2-ethyltetrahydropyridine (ETHP/ETPY) by ''Brettanomyces'', although not much is known about this metabolic process <ref>[http://ucce.ucdavis.edu/files/repositoryfiles/Joseph_5_Aromatic_Diverswity_of_Brettanomyces-82350.ppt Joseph, C.M. Lucy. ''Aromatic Diversity of Brettanomyces''. U.C. Davis. Retrieved 3/10/2015.]</ref>. ETHP has a significantly higher taste threshold, and is often not detected in contaminated wine <ref name="Oelofse"></ref>.
Although ''Brett'' is capable of producing APY from L-ornithine, the production rate is much less than that of LAB. In wine, there isn't enough L-ornithine present to production significant amounts of APY from L-ornithine. Therefore, the presence of APY (which can be detected aromatically, while ATHP cannot) indicates a bacterial contamination <ref name="Snowdon"></ref>. The presence of the "mousy off-flavor" caused by THP appears to be temporary in beer. Although not much is known about the degradation or metabolic break down of ATHP/ETHP, it tends to age out of beer after 2-6 months. Another unknown is why ''Brett'' produces THP shortly after kegging and force carbonating a beer that has reached final gravity. Pitching fresh ''Saccharomyces'' for bottle conditioning a beer with ''Brett'' in it has reportedly reduced THP production, perhaps through the quicker metabolism of both the oxygen and sugar that is introduced during packaging time.
===LAB===