Katou Taku, Kitagaki Hiroshi, Akao Takeshi, Shimoi Hitoshi
Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashihiroshima 739-8530, Japan.
Yeast. 2008 Nov;25(11):799-807. doi: 10.1002/yea.1634.
Sake yeast exhibit various characteristics that make them more suitable for sake brewing compared to other yeast strains. Since sake yeast strains are Saccharomyces cerevisiae heterothallic diploid strains, it is likely that they have heterozygous alleles on homologous chromosomes (heterozygosity) due to spontaneous mutations. If this is the case, segregation of phenotypic traits in haploid strains after sporulation and concomitant meiosis of sake yeast strains would be expected to occur. To examine this hypothesis, we isolated 100 haploid strains from Kyokai No. 7 (K7), a typical sake yeast strain in Japan, and compared their brewing characteristics in small-scale sake-brewing tests. Analyses of the resultant sake samples showed a smooth and continuous distribution of analytical values for brewing characteristics, suggesting that K7 has multiple heterozygosities that affect brewing characteristics and that these heterozygous alleles do segregate after sporulation. Correlation and principal component analyses suggested that the analytical parameters could be classified into two groups, indicating fermentation ability and sake flavour.
与其他酵母菌株相比，清酒酵母具有多种使其更适合清酒酿造的特性。由于清酒酵母菌株是酿酒酵母异宗配合二倍体菌株，它们很可能因自发突变而在同源染色体上具有杂合等位基因（杂合性）。如果是这种情况，预计清酒酵母菌株在孢子形成和随之而来的减数分裂后，单倍体菌株的表型性状会发生分离。为了验证这一假设，我们从日本典型的清酒酵母菌株七号酵母（K7）中分离出100个单倍体菌株，并在小规模清酒酿造试验中比较了它们的酿造特性。对所得清酒样品的分析表明，酿造特性的分析值呈现出平滑且连续的分布，这表明K7具有多个影响酿造特性的杂合性，并且这些杂合等位基因在孢子形成后确实会发生分离。相关性分析和主成分分析表明，分析参数可分为两组，分别表明发酵能力和清酒风味。
