Yeast comprehensive analysis system for evaluating fermentation performance

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.

Hiroyuki 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.