Changes

Heterofermentative [[Lactobacillus]] spp., particularly ''L. hilgardii'' and ''L. brevis'', as well as ''Leuconostoc oeni'' <ref name="Grbin_1996" />, can also produce high levels of ATHP and APY from L-lysine/L-ornithine, ethanol (must be present), and iron. A strain of ''L. plantarum'' (L11a) was shown to produce relatively low amounts. L-lysine stimulates production of ATHP, and L-ornitine ornithine stimulates the production of APY <ref name="Costello">[http://pubs.acs.org/doi/abs/10.1021/jf020341r Mousy Off-Flavor of Wine:  Precursors and Biosynthesis of the Causative N-Heterocycles 2-Ethyltetrahydropyridine, 2-Acetyltetrahydropyridine, and 2-Acetyl-1-pyrroline by Lactobacillus hilgardii DSM 20176. Peter J. Costello and Paul A. Henschke. 2002.]</ref><ref>[http://www.ajevonline.org/content/37/2/127.abstract Formation of Substituted Tetrahydropyridines by Species of Brettanomyces and Lactobacillus Isolated from Mousy Wines. Tamila Heresztyn. 1986.]</ref><ref>[http://onlinelibrary.wiley.com/doi/10.1111/j.1755-0238.2001.tb00205.x/abstract Ability of lactic acid bacteria to produce N-heterocycles causing mousy off-flavour in wine. PETER J. COSTELLO1, TERRY H. LEE1, and PAULA. HENSCHKE. 2008.]</ref><ref>Sparrows, Jeff. ''Wild Brews''. Brewers Publications. 2005. Pg. 112.</ref><ref>[https://books.google.com/books?id=tFjsAuo5WocC&pg=PA348&lpg=PA348&dq=lactobacillus+Tetrahydropyridine&source=bl&ots=QUVyoFtIwK&sig=h1cdjB0r1pIRX2Bms8wVA0UiLk4&hl=en&sa=X&ei=4DX_VPz5CsH6oQSAzoGgBA&ved=0CEwQ6AEwCQ#v=onepage&q=lactobacillus%20Tetrahydropyridine&f=false Lahtinen, Ouwehand, Salminen, von Wright. Lactic Acid Bacteria: Microbiological and Functional Aspects, Fourth Edition. Pg 348.]</ref><ref>[http://ajevonline.org/content/37/2/127.short Heresztyn, Tamila. Formation of Substituted Tetrahydropyridines by Species of Brettanomyces and Lactobacillus Isolated from Mousy Wines.]</ref>. Acetaldehyde has a stimulatory effect on ATHP and APY production, but is not required. No studies have been done to show whether or not oxygen plays a role in ATHP/APY production in LAB <ref name="Snowdon"></ref>. Most species of [[Pediococcus]] do not create forms of THP, although a few species do produce relatively small amounts. In particular, these include ''P. pentosaceus'' <ref>[http://www.uniprot.org/uniprot/Q03HT0 UniProt article. Retrieved 3/10/2015.]</ref><ref>[http://www.uniprot.org/uniprot/U5ZF76 UniProt article. Retrieved 3/10/2015.]</ref>, and ''P. clausenii'' <ref>[http://www.uniprot.org/uniprot/G8PEU4 UniProt article. Retrieved 3/10/2015.]</ref> (note that commercial cultures of [[Pediococcus]] are normally ''P. damnosus''). ''Oenococcus oeni'' and ''Leuconostoc mesenteroides'' have also been associated with creating ATHP, APY, and ETHP all above threshold amounts. Since only heterofermentative species produce significant amounts of THP, it is thought that its production is linked to the heterolactic pathway, and thus the metabolism of sugars in LAB <ref name="Costello"></ref>. A pathway for APY and ATHP production in ''Lactobacillus hilgardii'' was proposed by Costello and Henschke, which involves the intake of lysine or ornithine, along with ethanol (which is broken down into acetaldehyde) to produce APY and ATHP <ref name="Costello" />.