Sake yeasts have a range of brewing characteristics that are particularly beneficial for sake making including high ethanol fermentability, high proliferative capacity at low temperatures, lactic acid tolerance, and high ester productivity. On the other hand, sake yeasts also accumulate a diverse range of functional components. For example, significantly greater accumulation of S-adenosylmethionine (SAM), a compound that plays important regulatory roles in a range of biological processes as a major donor of methyl groups, occurs in sake yeasts compared to other microorganisms. Significantly greater accumulation of folate, a bioactive water-soluble vitamin (vitamin B9), also occurs in sake yeasts compared to laboratory yeasts, and the methyl group on SAM is supplied by folate. Accordingly, fully characterizing ‘sake yeast identity’ requires detailed understanding of the mechanisms underlying both the nutritional characteristics (functional components) and the brewing characteristics in sake yeasts. Therefore, this mini-review focuses on the accumulation of SAM and folate in sake yeast including descriptions of the genes known to contribute to SAM and folate accumulation and the underlying mechanisms.

中文翻译：

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S-腺苷甲硫氨酸和叶酸在清酒酵母中积累的重要性和机制

清酒酵母具有一系列特别有利于清酒酿造的酿造特性，包括高乙醇发酵性、低温下的高增殖能力、乳酸耐受性和高酯生产率。另一方面，清酒酵母也积累了多种功能成分。例如，与其他微生物相比，清酒酵母中 S-腺苷甲硫氨酸 (SAM) 的积累显着增加，SAM 是一种在一系列生物过程中作为甲基的主要供体发挥重要调节作用的化合物。与实验室酵母相比，清酒酵母中叶酸（一种具有生物活性的水溶性维生素（维生素 B9））的积累显着增加，SAM 上的甲基由叶酸提供。因此，充分表征“清酒酵母特性”需要详细了解清酒酵母的营养特性（功能成分）和酿造特性背后的机制。因此，这篇小综述侧重于 SAM 和叶酸在清酒酵母中的积累，包括对已知有助于 SAM 和叶酸积累的基因及其潜在机制的描述。