Characterization of the sake yeast Saccharomyces cerevisiae: Its increase of the activity of general amino acid permease (GAP) and the effect on sake brewing

Keiko KOHAMA, Yoshihito ITO, Yuichi YONEKURA, Tadashi YAMAMOTO, Hiroshi SAKURAI, Junya OHSAWA
General amino acid permease (GAP), which is nitrogen-regulated, transports all naturally occurring amino acids in Saccharomyces cerevisiae. The activity of GAP is coordinately derepressed during growth on poor nitrogen sources such as proline, and it is inactivated in the presence of ammonia or glutamate. To analyze the effect of GAP activity on sake brewing, we examined a sake yeast with a high expression of the GAP1 gene by constitutive promoter . In sake mash, intracellular amino acid
more » ... r amino acid contents of the yeast were higher than that of the parent strain except for proline during fermentation. With increasing GAP, changes in sake components were observed including high contents of isoamyl acetate and the composition of organic acids. Because of GAP inactivation, the parent strain was not able to grow on a methylamine medium including proline as a nitrogen source, while constitutive GAP1 expression resulted in the utilization of proline on the same medium. Methylamine resistant mutants were obtained, almost all producing a high content of isoamyl acetate. In one of the mutants, E 136, intracellular amino acid contents increased during the sake fermentation test, and the GAP1 gene was highly expressed under a rich nitrogen medium compared with the parent strain.
doi:10.6013/jbrewsocjapan1988.98.575 fatcat:jqgsv5ftavgu5h2dz37bh5677a