Akamatsu S, Kamiya H, Yamashita N, Motoyoshi T, Goto-Yamamoto N, Ishikawa T, Okazaki N, Nishimura A
Research & Development Department, Hakutsuru Sake Brewing Co. Ltd., 4-5-5 Sumiyoshiminami-machi, Higashinada-ku, Kobe 658-0041, Japan.
J Biosci Bioeng. 2000;90(5):555-60.
To reveal the mechanism of the production of acetate by sake yeast (Saccharomyces cerevisiae), the expression of genes encoding aldehyde dehydrogenase (ALD), acetyl-CoA synthetase (ACS) and acetyl-CoA hydrolase (ACH), which are related to acetate production, was investigated. Northern blot analysis using total RNA of sake yeast isolated from sake mash revealed that all of the tested genes, ACS1, ACS2, ALD2/3, ALD4, ALD6 and ACH1, were transcribed during sake fermentation. Transcription of ALD2/3 was detected only in the early stage of sake fermentation. A static culture of sake yeast in hyperosmotic media including 1 M sorbitol or 20% glucose resulted in high acetate production and increased transcription of ALD2/3. This is the same result as reported in an aerobic condition, and induction of ALD2/3 seemed to be one reason for high acetate production at high glucose concentration during fermentation. Overexpression of ACS2 resulted in low acetate production both during small-scale sake fermentation and in a static liquid culture. On the other hand, over-expression of ACS1 did not change acetate productivity significantly in a static culture. These results indicate that ALD2/3 and ACS2 play important roles for acetate production during sake fermentation.
为揭示清酒酵母（酿酒酵母）产生乙酸盐的机制，研究了与乙酸盐产生相关的醛脱氢酶（ALD）、乙酰辅酶A合成酶（ACS）和乙酰辅酶A水解酶（ACH）编码基因的表达。使用从酒醪中分离的清酒酵母总RNA进行的Northern印迹分析表明，所有测试基因，即ACS1、ACS2、ALD2/3、ALD4、ALD6和ACH1，在清酒发酵过程中均被转录。仅在清酒发酵的早期阶段检测到ALD2/3的转录。将清酒酵母在含有1 M山梨醇或20%葡萄糖的高渗培养基中进行静置培养，导致乙酸盐产量增加且ALD2/3的转录增加。这与有氧条件下报道的结果相同，并且ALD2/3的诱导似乎是发酵过程中高葡萄糖浓度下乙酸盐产量高的一个原因。ACS2的过表达在小规模清酒发酵和静置液体培养过程中均导致乙酸盐产量降低。另一方面，ACS1的过表达在静置培养中并未显著改变乙酸盐生产率。这些结果表明，ALD2/3和ACS2在清酒发酵过程中乙酸盐的产生中起重要作用。
