BCOJ Symposium: Technology for the Future Session
Hiroyuki Yoshimoto, Kirin Brewery Company, Limited, Yokohama, Japan, Kirin Brewery Company, Limited, Yokohama, Japan
ABSTRACT: In Japan, alcoholic beverages such as beer and low- and
no-malt brews, are produced in line with the Japanese taxation system.
After the mid-1990s, a lot of new types of low- and no-malt brewed
beverages were launched in response to changes in the tax system. In
these beverages, various ingredients were used in place of malt to lower
applicable taxes. Because the performance of brewer's yeast is
unpredictable under these variable low- and no-malt conditions, many
problems can arise, such as those related to delayed fermentation and
off-flavor production, which are difficult to resolve using only
traditional yeast analysis methods. The bottom fermenting yeast Saccharomyces pastorianus is reported to have arisen as a natural hybrid of two Saccharomyces strains, S. cerevisiae and S. bayanus. The S. pastorianus genome includes S. cerevisiae (Sc)-type genes and orthologous lager-fermenting-yeast specific (Lg)-type genes derived from S. cerevisiae and S. bayanus, respectively. As the genome structure of S. pastorianus is complex, it was difficult to solve these problems using analytical approaches commonly applied to S. cerevisiae. Therefore, a need exists for the development of novel analysis systems suitable for the bottom fermenting yeast S. pastorianus.
Here, we developed a comprehensive analysis system for evaluating yeast
fermentation performance using not only established methods, but also
newer comprehensive methods in the bottom fermenting yeast S. pastorianus.
Our system analyzes DNA, gene expression, protein, and metabolite
levels, as well as phenotype, and thus comprises a powerful tool with
which to improve the fermentation performance of the bottom fermenting
yeast S. pastorianus. DNA level analysis by PCR, single
nucleotide polymorphisms (SNPs), and chromosomal structure was used to
distinguish between bottom fermenting yeast S. pastorianus
strains. In addition, DNA copy number profiling using array-based
comparative genomic hybridization was able to detect gene copy number
aberrations, which are useful for determining the stability of DNA to
evaluate fermentation performance. Analysis of gene expression level
using oligonucleotide microarrays for expression profiling of
orthologous genes demonstrated that the expression of particular Lg-type
genes differed from that of orthologous Sc-type genes, suggesting that
certain Lg-type and Sc-type genes may have different functional roles.
For analysis at the protein level, DNA identification from partially
purified proteins using genome information and gene disruption methods
was an effective approach to understand a mechanism. Analyses of
metabolites and phenotypes levels by determining intracellular
metabolite concentrations using CE-TOFMS and by quantifying cell
morphogenesis using the image processing program CalMorph were performed
for evaluating yeast physiological status to find clues to solve
problems. In this presentation, we focus on our yeast comprehensive
analysis system, which was specifically applied to predicting the
physiological state of S. pastorianus by combination analyses of intracellular metabolite concentrations and quantitative cell morphogenesis.
Yoshimoto received a Ph.D. degree in engineering from Hiroshima
University, Japan, in 1992. He began his career researching yeast in the
Central Laboratories for Key Technology with Kirin Brewery Company,
Limited. He also studied yeast technology at Stanford University, United
States, from 1999 to 2001. Since 2007, he has been working in the
Brewing Technology Development Center at Kirin Brewery Company, Limited.
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