Budding yeast Saccharomyces cerevisiae is widely used for lignocellulosic biorefinery. However, its fermentation efficiency is challenged by various inhibitors (e.g. weak acids, furfural) in the lignocellulosic hydrolysate, and acetic acid is commonly present as a major inhibitor. The effects of oxidoreductases on the inhibitor tolerance of S. cerevisiae have mainly focused on furfural and vanillin, whereas the influence of quinone oxidoreductase on acetic acid tolerance is still unknown. In this study, we show that overexpression of a quinone oxidoreductase-encoding gene, YCR102C, in S. cerevisiae, significantly enhanced ethanol production under acetic acid stress as well as in the inhibitor mixture, and also improved resistance to simultaneous stress of 40°C and 3.6 g/L acetic acid. Increased catalase activities, NADH/NAD+ ratio and contents of several metals, especially potassium, were observed by YCR102C overexpression under acetic acid stress. To our knowledge, this is the first report that the quinone oxidoreductase family protein is related to acid stress tolerance. Our study provides a novel strategy to increase lignocellulosic biorefinery efficiency using yeast cell factory.

中文翻译：

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通过过量表达醌氧化还原酶家族基因YCR102C来提高酿酒酵母中的抑制剂耐受性。

发芽酵母酿酒酵母被广泛用于木质纤维素生物精炼。但是，其发酵效率受到木质纤维素水解产物中各种抑制剂（例如弱酸，糠醛）的挑战，乙酸通常作为主要抑制剂存在。氧化还原酶对酿酒酵母的耐受性的影响主要集中在糠醛和香兰素上，而醌氧化还原酶对乙酸耐受性的影响仍然未知。在这项研究中，我们表明，在啤酒酵母中过量表达醌氧化还原酶编码基因YCR102C，可显着提高乙酸胁迫下以及抑制剂混合物中乙醇的产生，并且还提高了对40°C同时胁迫的抵抗力和3.6 g / L乙酸。过氧化氢酶活性增加，通过YCR102C在乙酸胁迫下的过表达，观察到NADH / NAD +的比例和几种金属（尤其是钾）的含量。据我们所知，这是关于醌氧化还原酶家族蛋白与酸胁迫耐受性有关的第一个报道。我们的研究提供了一种使用酵母细胞工厂提高木质纤维素生物精炼效率的新策略。