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Other than sugars, nitrogen in the form of amino acids is an essential nutrient for yeast and generally occurs . One significant source for nitrogen in wort in the form of amino acids is boiling hops and dry hopping <ref>Principles of Brewing Science, A Study of Serious Brewing Issues. George Fix. Brewers Publications. 1999. Pg 40.</ref><ref>[https://www.researchgate.net/publication/286126882_Transfer_of_nitrate_and_various_pesticides_into_beer_during_dry_hopping Transfer of nitrate and various pesticides into beer during dry hopping. M. Kippenberger, S. Hanke, M. Biendl, G. Stettner and A. Lagemann. 2014.]</ref>. ''Brettanomyces'' can survive in environments that are very low in nitrogen, with one report being as low as 6 mg N/L of yeast assimilable nitrogen (YAN) which is less than most finished wines contain <ref>[https://www.ncbi.nlm.nih.gov/m/pubmed/25475334/ Impact of available nitrogen and sugar concentration in musts on alcoholic fermentation and subsequent wine spoilage by Brettanomyces bruxellensis. Childs BC, Bohlscheid JC, Edwards CG. 2015.]</ref>. While nitrogen usage for ''S. cerevisiae'' is well understood, the general utilization of nitrogen by ''Brettanomyces'' and its preferred sources for nitrogen under the stressful conditions of fully fermented beer and wine are not yet well known. However, it is known that ''Brettanomyces'' can use a wide range of sources for nitrogen, and its requirements for nitrogen as a nutrient are extremely low when oxygen is available. When oxygen is not present, nitrogen is required for the survival and growth of ''Brettanomyces''. Preferred sources of nitrogen include the amino acids glutamine (aerobically and anaerobically), glutamate and aspartate (anaerobically) <ref>[https://www.ncbi.nlm.nih.gov/pubmed/29065215 On the catabolism of amino acids in the yeast Dekkera bruxellensis and the implications for industrial fermentation processes. Parente DC, Cajueiro DBB, Moreno ICP, Leite FCB, De Barros Pita W, De Morais MA Jr. 2018. DOI: 10.1002/yea.3290.]</ref>, as well as possible secondary sources such as lysine, histidine, arginine, asparagine, aspartic cid, glutamic acid, and alanine <ref name="smith_divol_2016" />. Some strains of ''Brettanomyces'' can metabolize other nitrogen sources, such as the amino acids proline and arginine <ref name="Crauwels1"></ref>. Ammonium nitrates may also be utilized by some strains of ''B. bruxellensis''. Although studies have been contradictory and some have not documented whether conditions were aerobic or anaerobic (these contradictions might also be due to strain differences between the ''B. bruxellensis'' strains that were used in different studies), it appears as though some strains of ''B. bruxellensis'' might be able to take advantage of trace amount of amino acids that ''S. cerevisiae'' does not use during fermentation, and nitrates and nitrites that ''S. cerevisiae'' is not able to consume, as well as amino acids from yeast autolysis (proline, leucine, tryptophan, and gamma aminobutyric acid) <ref name="smith_divol_2016"></ref>. Other compounds from ''Saccharomyces'' autolysis may also be used by ''Brettanomyces'', such as glucose, fatty acids, nucleotides, polysaccharides, polypeptides, and other proteins <ref>Private correspondence with Richard Preiss by Dan Pixley. 08/23/2016.</ref><ref>[http://oeno-one.eu/article/view/1701 Influence of yeast autolysis after alcoholic fermentation on the development of Brettanomyces/Dekkera in wine. Michèle Guilloux-Benatier, D. Chassagne, Hervé Alexandre, Claudine Charpentier, Michel Feuillat. 2001.]</ref>. The role that oxygen plays in the ability of ''B. bruxellensis'' to uptake nitrogen from various sources might be an important one, and something that should be examined in science going forward <ref name="smith_divol_2016"></ref>.