title: Disruption of ubiquitin-related genes in laboratory yeast strains enhances ethanol production during sake brewing.
abstract: Sake yeast can produce high levels of ethanol in concentrated rice mash. While both sake and laboratory yeast strains belong to the species Saccharomyces cerevisiae, the laboratory strains produce much less ethanol. This disparity in fermentation activity may be due to the strains' different responses to environmental stresses, including ethanol accumulation. To obtain more insight into the stress response of yeast cells under sake brewing conditions, we carried out small-scale sake brewing tests using laboratory yeast strains disrupted in specific stress-related genes. Surprisingly, yeast strains with disrupted ubiquitin-related genes produced more ethanol than the parental strain during sake brewing. The elevated fermentation ability conferred by disruption of the ubiquitin-coding gene UBI4 was confined to laboratory strains, and the ubi4 disruptant of a sake yeast strain did not demonstrate a comparable increase in ethanol production. These findings suggest different roles for ubiquitin in sake and laboratory yeast strains.
authors.affiliation: National Research Institute of Brewing, 3-7-1 Kagamiyama, Higashihiroshima 739-0046, Japan.
authors.forename: Hong
authors.initials: H
authors.lastname: Wu
authors.forename: Tomoko
authors.initials: T
authors.lastname: Watanabe
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Araki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kitagaki
authors.forename: Takeshi
authors.initials: T
authors.lastname: Akao
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Takagi
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Shimoi
mesh_terms: D000434:Alcoholic Beverages; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D025801:Ubiquitin / Q000378:metabolism*
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D025801:Ubiquitin; D000431:Ethanol