Enhanced Antioxidant Activity in Streptococcus thermophilus by High-Level Expression of Superoxide Dismutase

文献类型： 外文期刊

第一作者： Kong, Linghui

作者： Kong, Linghui;Xiong, Zhiqiang;Song, Xin;Xia, Yongjun;Zhang, Hui;Ai, Lianzhong;Yang, Ying

作者机构：

关键词： Streptococcus thermophilus; superoxide dismutase; native constitutive promoter; multicopy gene expression; oxidative stress

期刊名称：FRONTIERS IN MICROBIOLOGY （ 影响因子：5.64； 五年影响因子：6.32 ）

ISSN： 1664-302X

年卷期： 2020 年 11 卷

页码：

收录情况： SCI

摘要： Superoxide dismutase (SOD) plays an essential role in eliminating oxidative damage of lactic acid bacteria. Streptococcus thermophilus, an important probiotic lactic acid bacterium, often inevitably suffers from various oxidative stress during dairy fermentation. In this study, to confer high-level oxidative resistance, the sod gene from Lactobacillus casei was heterologous expressed in S. thermophilus S-3 using our previous constructed native constitutive promoter library. The enzyme activity of SOD was significantly enhanced in engineered S. thermophilus by promoter #14 (2070 U/mg). Furthermore, the strategy of multi-copy sod-expressing cassettes was employed to improve SOD activity. The maximum activity (2750 U/mg) was obtained by the two-copy sod recombinant, which was 1.5-fold higher than that of one-copy recombinant. In addition, the survival rate of multi-copy sod recombinants was increased about 97-fold with 3.5 mmol/L H2O2 treatment. To our knowledge, this is the first report of multi-copy sod gene expression in S. thermophilus, which exerts a positive effect on coping with oxidative stress to enhance the potential of industrial application.

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