Du Zhaoli, Cheng Yanfei, Zhu Hui, He Xiuping, Zhang Borun
Sheng Wu Gong Cheng Xue Bao. 2015 Feb;31(2):231-41.
Flocculent gene FLO1 and its truncated form FLO1c with complete deletion of repeat unit C were expressed in a non-flocculent industrial strain Saccharomyces cerevisiae CE6 to generate recombinant flocculent strains 6-AF1 and 6-AF1c respectively. Both strains of 6-AF1 and 6-AF1c displayed strong flocculation and better cell growth than the control strain CE6-V carrying the empty vector under acetic acid stress. Moreover, the flocculent strains converted glucose to ethanol at much higher rates than the control strain CE6-V under acetic acid stress. In the presence of 0.6% (V/V) acetic acid, the average ethanol production rates of 6-AF1 and 6-AF1c were 1.56 and 1.62 times of that of strain CE6-V, while the ethanol production rates of 6-AF1 and 6-AF1c were 1.21 and 1.78 times of that of strain CE6-V under 1.0% acetic acid stress. Results in this study indicate that acetic acid tolerance and fermentation performance of industrial S. cerevisiae under acetic acid stress can be improved largely by flocculation endowed by expression of flocculent genes, especially FLO1c.
絮凝基因FLO1及其重复单元C完全缺失的截短形式FLO1c在非絮凝工业酿酒酵母菌株CE6中表达，分别产生重组絮凝菌株6-AF1和6-AF1c。在乙酸胁迫下，6-AF1和6-AF1c这两种菌株均表现出强烈的絮凝作用，且细胞生长优于携带空载体的对照菌株CE6-V。此外，在乙酸胁迫下，絮凝菌株将葡萄糖转化为乙醇的速率比对照菌株CE6-V高得多。在存在0.6%（V/V）乙酸的情况下，6-AF1和6-AF1c的平均乙醇产率分别是菌株CE6-V的1.56倍和1.62倍，而在1.0%乙酸胁迫下，6-AF1和6-AF1c的乙醇产率分别是菌株CE6-V的1.21倍和1.78倍。本研究结果表明，通过表达絮凝基因（尤其是FLO1c）赋予的絮凝作用，可以大大提高工业酿酒酵母在乙酸胁迫下的耐乙酸能力和发酵性能。
