Chen Hongqi, Li Jie, Wan Chun, Fang Qing, Bai Fengwu, Zhao Xinqing
School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.
School of Life Science and Biotechnology, Dalian University of Technology, Dalian 116024, China.
FEMS Yeast Res. 2019 Sep 1;19(6). doi: 10.1093/femsyr/foz055.
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.
出芽酵母酿酒酵母被广泛用于木质纤维素生物精炼。然而，其发酵效率受到木质纤维素水解产物中各种抑制剂（如弱酸、糠醛）的挑战，并且乙酸通常作为主要抑制剂存在。氧化还原酶对酿酒酵母抑制剂耐受性的影响主要集中在糠醛和香草醛上，而醌氧化还原酶对乙酸耐受性的影响仍然未知。在本研究中，我们表明在酿酒酵母中过表达编码醌氧化还原酶的基因YCR102C，显著提高了在乙酸胁迫下以及抑制剂混合物中的乙醇产量，并且还提高了对40°C和3.6 g/L乙酸同时胁迫的抗性。在乙酸胁迫下通过YCR102C过表达观察到过氧化氢酶活性、NADH/NAD+比率以及几种金属（尤其是钾）的含量增加。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相关的首次报道。我们的研究提供了一种利用酵母细胞工厂提高木质纤维素生物精炼效率的新策略。
