Abstract：
The EHL1/2/3 genes were identified by whole-genome sequencing of Kyokai No. 7 (K7), which is a well-known representative Japanese sake yeast Saccharomyces cerevisiae. The genes are present in K7, but not in laboratory strain S288C. Although the genes were presumed to encode epoxide hydrolase based on homology analysis, their effect on cellular metabolism in sake yeast has not yet been clarified. We constructed ehl1/2/3 mutants harboring a stop codon in each gene using the haploid yeast strain H3 as the parental strain, which was derived from K701, and investigated the physiological role and effects of the EHL1/2/3 genes on sake quality. Metabolome analysis and vitamin requirement testing revealed that the EHL1/2/3 genes are partly responsible for the synthesis of pantothenate. For fermentation profiles, ethanol production by the ehl1/2/3 mutant was comparable with that of strain H3, but succinate production was decreased in the ehl1/2/3 mutant compared to strain H3 when cultured in yeast malt (YM) medium containing 10% glucose and during sake brewing. Ethyl hexanoate and isoamyl acetate levels in the ehl1/2/3 mutant strain were decreased compared to those of strain H3 during sake brewing. Thus, the EHL1/2/3 genes did not affect ethanol production but did affect the production of organic acids and aromatic components during sake brewing.
摘要：
通过KyokaiNo.的全基因组测序鉴定了EHL1/2/3基因。7(K7),这是日本著名的代表性清酒酵母酿酒酵母。这些基因存在于K7中,但不存在于实验室菌株S288C中。尽管根据同源性分析推测这些基因编码环氧化物水解酶，它们对清酒酵母细胞代谢的影响尚未明确。我们以单倍体酵母菌株H3为亲本菌株，构建了每个基因都有终止密码子的ehl1/2/3突变体，它来自K701，并研究了EHL1/2/3基因对清酒品质的生理作用和影响。代谢组分析和维生素需求测试表明，EHL1/2/3基因部分负责泛酸的合成。对于发酵概况，ehl1/2/3突变体的乙醇产量与H3菌株相当，但是当在含有10％葡萄糖的酵母麦芽（YM）培养基中培养时，与H3菌株相比，ehl1/2/3突变体的琥珀酸产量降低。在清酒酿造过程中。与清酒酿造过程中的H3菌株相比，ehl1/2/3突变菌株中的己酸乙酯和乙酸异戊酯水平降低。因此，EHL1/2/3基因不影响乙醇生产，但确实影响了清酒酿造过程中有机酸和芳香成分的生产。
