BACKGROUND Saccharomyces cerevisiae is the micro-organism of choice for the conversion of fermentable sugars during beverage or bioethanol fermentations. These fermentations are characterised by high osmotic stress on a yeast cell, with selected brewing fermentations beginning at 20-25% fermentable sugars and bioethanol fermentations at 13% fermentable sugars. RESULTS RCK2 encodes for a MAPKAP (MAPK-activated protein kinase) enzyme and was identified on a locus by QTL analysis in yeast cells under osmotic stress, RCK2 expression was placed under a tetracycline regulatable vector and rescued glucose, sorbitol or glycerol induced osmotic stress in an rck2 null strain. A strain overexpressing RCK2 had significantly faster fermentation rates when compared with the empty vector control strain. CONCLUSIONS Presence of RCK2 increased rates of glucose utilisation (~40 g glucose in first 8 h) during a 15% glucose fermentation and concurrent production of ethanol when compared with empty vector controls. Tolerance to osmotic stress using the tetracycline regulatable vectors could be turned off with the addition of tetracycline returning a rck2 null strain back to osmotic sensitivity.

中文翻译：

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RCK2 MAPKAP（MAPK 活化蛋白激酶）的表达可挽救酵母细胞对渗透压的敏感性。

背景技术酿酒酵母是饮料或生物乙醇发酵过程中可发酵糖转化的首选微生物。这些发酵的特点是对酵母细胞的高渗透压力，选择的酿造发酵从 20-25% 可发酵糖开始，生物乙醇发酵在 13% 可发酵糖开始。结果 RCK2 编码 MAPKAP（MAPK 活化蛋白激酶）酶，通过 QTL 分析在渗透胁迫下的酵母细胞中鉴定出一个基因座，将 RCK2 表达置于四环素可调节载体下并挽救葡萄糖、山梨糖醇或甘油诱导的渗透胁迫一个 rck2 零菌株。与空载体对照菌株相比，过表达 RCK2 的菌株具有明显更快的发酵速率。结论 与空载体对照相比，RCK2 的存在增加了 15% 葡萄糖发酵和同时生产乙醇期间的葡萄糖利用率（前 8 小时约 40 g 葡萄糖）。使用四环素可调节载体对渗透压的耐受性可以通过添加四环素来关闭，从而使 rck2 无效菌株恢复到渗透敏感性。