The genome and transcriptome of Lactococcus lactis ssp. lactis F44 and G423: Insights into adaptation to the acidic environment

文献类型： 外文期刊

第一作者： Tian, Kairen

作者： Tian, Kairen;Li, Yanni;Wang, Binbin;Wu, Hao;Qiao, Jianjun;Tian, Kairen;Li, Yanni;Wang, Binbin;Wu, Hao;Caiyin, Qinggele;Qiao, Jianjun;Zhang, Zhijun;Qiao, Jianjun

作者机构：

关键词： genome shuffling; acid tolerance; nisin production; genome comparison; transcriptome

期刊名称：JOURNAL OF DAIRY SCIENCE （ 影响因子：4.034； 五年影响因子：4.354 ）

ISSN： 0022-0302

年卷期： 2019 年 102 卷 2 期

页码：

收录情况： SCI

摘要： Nisin, as a common green (environmentally friendly), nontoxic antibacterial peptide secreted by Lactococcus lactis, is widely used to prevent the decomposition of meat and dairy products and maintains relatively high stability at low pH. However, the growth of Lc. lactis is frequently inhibited by high lactic acid concentrations produced during fermentation. This phenomenon has become a great challenge in enhancing the nisin yield for this strain. Here, the shuffled strain G423 that could survive on a solid plate at pH 3.7 was generated through protoplast fusion-mediated genorne shuffling. The nisin titer of G423 peaked at 4,543 IU/mL, which was 59.9% higher than that of the same batch of the initial strain Lc. lactis F44. The whole genome comparisons between G423 and F44 indicated that 6 large fragments (86,725 bp) were inserted in G423 compared with that of Lc. lactis F44. Transcriptome data revealed that 4 novel noncoding transcripts, and the significantly upregulated genes were involved in multiple processes in 6423. In particular, the expression of genes involved in cell wall and membrane biosynthesis was obviously perturbed under acidic stress. Quantitative real-time PCR analysis showed that the transcription of noncoding small RNA NC-1 increased by 2.35-fold at pH 3.0 compared with that of the control (pH 7.0). Overexpression assays indicated that small RNA NC-1 could significantly enhance the acid tolerance and nisin production of G423 and F44. Our work provided new insights into the sophisticated genetic mechanisms involved in Lc. lactis in an acidic environment, which might elucidate its potential application in food and dairy industries.

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