banner 18. Fermentation ability of bottom fermenting yeast exhibiting defective entry into the quiescent state

M. Oomuro (1), T. KATO (1), H. Yamagishi (1), K. Suzuki (1), M. Aizawa (1), Y. Zhou (2), D. Watanabe (3), T. Akao (2), N. Goto (2); (1) Asahi Breweries Ltd., Moriya-shi, Japan; (2) National Research Institute of Brewing, Higashihiroshima-shi, Japan; (3) Nara Institute of Science and Technology, Ikoma-shi, Japan

Technical Session 6 - Yeast and Microbiology
Monday, June 15
2:00–3:45 p.m.
Flores 1–2

In beer brewing, the yeast plays an important role not only in the alcohol production but also in the flavor profiles of beer. Therefore, the fermentation ability of brewing yeast affects the quality of beer products. The fermentation ability of brewer’s yeast has been studied for a long time. Recently, it was reported that the elevated fermentation ability of Saccharomyces cerevisiae yeast used for Japanese sake brewing is related to the defective transition into the G0 phase (quiescent state) in the cell cycle. To investigate the relationship between the G0 entry and the fermentation ability of bottom-fermenting yeast, we constructed two genetically modified strains of Weihenstephan34/70. One is a S. cerevisiae type RIM15 gene-disrupted strain, the other is a S. cerevisiae type CLN3-1 mutant strain. Both strains exhibited the phenotypic properties characterized by the defective entry into the quiescent state. As a result of the fermentation test in the synthetic medium, it was revealed that the fermentation abilities of the constructed strains, such as sugar utilization efficiency, were enhanced compared to those of the wild-type strains. These results suggest that there is a relationship between the fermentation ability and cell cycle in bottom-fermenting yeast and that the manipulation of the relevant genes leads to the construction of yeast strains with higher fermentation ability. This is the first report that indicates the defective G0 entry may induce the modified fermentation profiles of bottom-fermenting yeast.

Taku Kato earned a Ph.D. degree in brewing microbiology in 2009 from the Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University. In 2009 Taku joined the Production Department in the Shikoku brewery of Asahi Breweries Ltd and since 2010 has worked in the Department of Brewing Microbiology, Research & Development Laboratories for Brewing of Asahi Breweries Ltd.

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