caa a22 4500 605501300 CHVBK 20210128100600.0 cr unu---uuuuu 210128e20150901xx s 000 0 eng 10.1007/s00253-015-6673-3 doi (NATIONALLICENCE)springer-10.1007/s00253-015-6673-3 Both BAT1 and ARO8 are responsible for unpleasant odor generation in halo-tolerant yeast Zygosaccharomyces rouxii [Elektronische Daten] [Jun Watanabe, Kenji Uehara, Yoshinobu Mogi] Soy sauce yeast Zygosaccharomyces rouxii plays a central role in the production of flavor compounds in soy sauce, while the flor-forming strain spoils its quality by producing 2-methylpropanoic acid, 2-methylbutanoic acid, and 3-methylbutanoic acid, which have an unpleasant odor. To investigate the relationship between flor formation and unpleasant odor, we measured the volatile compounds that accumulated under various growth conditions. As a result, marked amounts of 2-methylpropanoic acid, 2-methylbutanoic acid, or 3-methylbutanoic acid accumulated in synthetic medium containing valine, isoleucine, or leucine, respectively, under aerobic growth conditions. These results implied that the unpleasant compounds were produced from their corresponding branched chain amino acid (BCAA) when the cell was placed under aerobic condition through flor formation. The first step in BCAA catabolism and the last step in BCAA anabolism are both catalyzed by a BCAA transaminase. A mutant lacking the BCAA transaminase gene, BAT1, resulted in valine and isoleucine auxotrophy, while a mutant lacking both BAT1 and the α-aminoadipate aminotransferase gene, ARO8, resulted in valine, isoleucine, and leucine auxotrophy. Although the bat1∆ aro8∆ double mutant formed flor similarly to the wild-type strain, the mutant exhibited less unpleasant odor generation. These results suggest that the interconversion between 4-methyl-2-oxopentanoate and leucine is catalyzed by both Bat1p and Aro8p in Z. rouxii. Taken together, these results indicate that flor formation is not seemed to be directly linked to unpleasant odor generation. These findings encourage us to breed flor-forming yeasts without an unpleasant odor. Springer-Verlag Berlin Heidelberg, 2015 Zygosaccharomyces rouxii nationallicence Flor nationallicence FLO11 nationallicence Aminotransferase nationallicence Soy sauce nationallicence Off-flavor nationallicence Watanabe Jun Manufacturing Division, Yamasa Corporation, 2-10-1, Araoicho, 288-0056, Choshi, Chiba, Japan aut Uehara Kenji Manufacturing Division, Yamasa Corporation, 2-10-1, Araoicho, 288-0056, Choshi, Chiba, Japan aut Mogi Yoshinobu Manufacturing Division, Yamasa Corporation, 2-10-1, Araoicho, 288-0056, Choshi, Chiba, Japan aut Applied Microbiology and Biotechnology Springer Berlin Heidelberg 99/18(2015-09-01), 7685-7697 0175-7598 99:18<7685 2015 99 253 https://doi.org/10.1007/s00253-015-6673-3 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00253-015-6673-3 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Watanabe Jun Manufacturing Division, Yamasa Corporation, 2-10-1, Araoicho, 288-0056, Choshi, Chiba, Japan aut NATIONALLICENCE 700 1- Uehara Kenji Manufacturing Division, Yamasa Corporation, 2-10-1, Araoicho, 288-0056, Choshi, Chiba, Japan aut NATIONALLICENCE 700 1- Mogi Yoshinobu Manufacturing Division, Yamasa Corporation, 2-10-1, Araoicho, 288-0056, Choshi, Chiba, Japan aut NATIONALLICENCE 773 0- Applied Microbiology and Biotechnology Springer Berlin Heidelberg 99/18(2015-09-01), 7685-7697 0175-7598 99:18<7685 2015 99 253