BCOJ Symposium: Technology for the Future Session
Tomoo Ogata, Asahi Breweries, Ltd., Moriya, Japan
ABSTRACT: Brewer's yeast has unique characteristics different
from other yeasts, such as high wort fermentation ability and
flocculation. We investigated these characteristics of brewer's yeast by
genome analysis, which has rapidly advanced in recent years, to
contribute to the construction of more adequate yeast strains.
Bottom-fermenting yeast, Saccharomyces pastorianus, is a natural hybrid between S. cerevisiae (SC) and S. bayanus (SB). Therefore, it is different from S. cerevisiae,
which laboratory yeast strains and top-fermenting yeast belong to. This
fact has been confirmed by Southern hybridization and other experiments
(Yamagishi and Ogata, System. Appl. Microbiol. 22:341-353, 1999).
Bottom-fermenting yeast has both SC- and SB-types of genes and
chromosomes. But, our genome analysis revealed that bottom-fermenting
yeast has some characteristic chromosomes, and some of these chromosomes
have SC and SB sequences crossing each other (Ogata et al, J. Applied
Microbiol. 107:1098-1107, 2009). One of the characteristic chromosome
structures of bottom-fermenting yeast is SC-type chromosome VIII. The
Lg-FLO1 gene, which encodes the specific agglutinin, is located
on the right arm end of SC-type chromosome VIII. In the case of the
laboratory yeast S. cerevisiae S288C, FLO5 is located on
this region. In most bottom-fermenting yeast strains, this region is
heterozygous. In the case that LOH (loss of heterozygosity) occurs and
Lg-FLO1 is missing, these yeast strains lose flocculation ability
(Ogata et al, J. Applied Microbiol. 105:1186-1198, 2008). We
constructed new yeast strains using the genome information of
bottom-fermenting yeast. Bottom-fermenting yeast has both an SC- and
SB-type SSU1 gene that encodes for the sulfite efflux pump. We successfully constructed a brewer's yeast with high SSU1
expression that enhanced the sulfite-excreting ability and diminished
the production ability of hydrogen sulfide, MBT, and 2M3MB. This new
brewer's yeast strain would contribute to the production of superior
quality beer (Iijima and Ogata, J. Applied Microbiol. 109:1906-1913,
2010).
Tomoo Ogata received an M.S. degree in pharmacology science
from Chiba University. After graduation in 1985, he worked on brewing
microbiology at the Research Laboratories for Brewing, Asahi Breweries,
Ltd. He received a Ph.D. degree in microbiology science from the
University of Tokyo in 1997 and an award from the Brewing Society of
Japan in 2001.
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