QTL Analysis of brewing performances in bottom fermenting yeast.
Osamu Kobayashi (1), Shoko Nakagawa (1), Shigehito Ikushima (1), Kaori Hashimoto (1), Shinji Kawasaki (2), Keiko Tanaka (1)
(1) Central Labs for Frontier Tech, Kirin Brewery Co., Ltd., 1-13-5, Fukuura, Yokohama-shi, 236-0004, Japan; (2) National Inst Agrobiol Science, 2-1-2, Kan-nondai, Tsukuba-shi, 305-8602, Japan
Bottom fermenting yeast, Saccharomyces pastorianus, is known to be allopolyploid containing two sets of genome; Sc-type subgenome similar to that of S. cerevisiae and Lg-type subgenome similar to that of S. bayanus. Meiotic segregants were obtained from a bottom fermenting yeast strain KBY011 by random sporulation method. FACS analysis revealed that DNA content of the meiotic segregants was almost half of that of the parental strain. The PFGE analysis revealed that some of the meiotic segregants possess chromosomes that were not found in the parental strain, suggesting that chromosomal rearrangements had occured during meiosis. However most of the karyotypes of the meiotic segregants were similar to each other. Small-scale fermentation test was carried out and brewing performances of the meiotic segregants were investigated. Great variations of brewing performances were observed among the meiotic segregants, suggesting that there were allelic differences in quantitative traits loci (QTL) in bottom fermenting yeast. These results also suggest that QTL analysis of meiotic segregants of allopolyploid bottom fermenting yeast is a potential powerful tool to determine the chromosomal region responsible for brewing performances. The results of QTL analysis of bottom fermenting yeast will be also presented.