有用清酒酵母の開発(物質生命化学科)

Abstract

In the case of sake, malic acid ethyl caproate and are considered to be closely associated with good taste and flavor. To development of useful sake yeast for ginjo-shu brewing, we have first isolated yeast strains from sake-mash made at sake breweries in Fukuoka Prefecture. 253 strains isolated were tested on their malic acid-producing acivity using koji extract culture medium. By the brewing tests on a small scale, 4 strains (16BY1-10, 16BY2-2, 16BY7-6, 16BY8-9) were selected as high malic acid-producing strains. After UV irradiation, 62 cerulenin-resistant mutants were isolated from these 4 strains. (Serulenin is an inhibitor of fatty acid synthase.) The sake brewing characteristics of each of five mutants were examined by using koji extract culture medum. Finally, 5 mutant strains (15BY14-6-C1, 16BY7-6-C2, 16BY8-9-C1, 16BY8-9-C2, 16BY8-9-C3) were selected as a result of that test. These mutant strains showed high producing ability for malic acid- and ethyl caproate-producing ability, but not enough fermentation ability. Thus, further studies such as hybridization are need to breeding of useful sake yeast.