College of Food Science and Nutritional Engineering, China Agricultural University, No. 17 Tsinghua East Road, Haidian District, PO Box 398, Beijing, 100083, China.
J Ind Microbiol Biotechnol. 2014 May;41(5):869-78. doi: 10.1007/s10295-014-1421-8. Epub 2014 Mar 15.
Excessive oxidative stress poses significant damage to yeast cells during fermentation process, and finally affects fermentation efficiency and the quality of products. In this paper, global transcription machinery engineering was employed to elicit Saccharomyces cerevisiae phenotypes of higher tolerance against oxidative stress caused by H2O2. Two strains from two plasmid-based mutagenesis libraries (Spt15 and Taf25), which exhibited significant increases in oxidative stress tolerance, were successfully isolated. At moderate H2O2 shock (≤3.5 mM), a positive correlation was found between the outperformance in cell growth of the oxidation-tolerate strains and H2O2 concentration. Several mutations were observed in the native transcription factors, which resulted in a different transcriptional profile compared with the control. Catalase and superoxide dismutase activities of the two mutants increased under H2O2 stress conditions. Fermentation experiments revealed that the mutant strain taf25-3 has a shorter lag phase compared to the control one, indicating that taf25-3 had improved adaptation ability to H2O2-induced oxidative stress and higher fermentation efficiency. Our study demonstrated that several amino acid substitutions in general transcription factors (Spt15 and Taf25) could modify the cellular oxidation defense systems and improve the anti-oxidation ability of S. cerevisiae. It could make the industrial ethanol fermentation more efficient and cost-effective by using the strain of higher stress tolerance.
在发酵过程中，过量的氧化应激会对酵母细胞造成严重的损伤，最终影响发酵效率和产品质量。本文采用全局转录机制工程来诱发酿酒酵母对 H2O2 引起的氧化应激的更高耐受性表型。从两个基于质粒的诱变文库（Spt15 和 Taf25）中成功分离出两株对氧化应激具有显著耐受性的菌株。在适度的 H2O2 冲击（≤3.5mM）下，氧化应激耐受性菌株在细胞生长方面的优异表现与 H2O2 浓度之间存在正相关关系。在天然转录因子中观察到几个突变，导致其与对照相比具有不同的转录谱。在 H2O2 胁迫条件下，两种突变体的过氧化氢酶和超氧化物歧化酶活性均增加。发酵实验表明，与对照菌株相比，突变菌株 taf25-3 的迟滞期更短，这表明 taf25-3 对 H2O2 诱导的氧化应激具有更好的适应能力和更高的发酵效率。我们的研究表明，一般转录因子（Spt15 和 Taf25）中的几个氨基酸取代可以修饰细胞氧化防御系统，提高酿酒酵母的抗氧化能力。通过使用具有更高应激耐受性的菌株，可以使工业乙醇发酵更高效、更具成本效益。
