Lactic acid bacteria are the most promising microorganisms to act as live vaccines as well as microbial cell factory which can produce various chemicals. During fermentation processing, they suffer from various stress conditions, especially acid and cold stress. Therefore, we aim to develop an ideal food-safe grade microorganism with enhanced acid and cold tolerance.
Genome mutagenesis combined with high-throughput technologies was performed on Lactococcus lactis NZ9000 to screen acid tolerance strain. Next, comparative transcriptomics analysis was performed on mutant and parent strain to investigate the response mechanisms of microbial cells during acid stress. Based on the proposed acid tolerance mechanisms, one new anti-acid component—msmK was discovered. Also, an anti-cold gene cspD2 was selected. The constructed recombinant strain Lactococcus lactis NZ3900/pNZ 8149-msmK-cspD2 shows a significant survival advantage compared with Lactococcus lactis NZ3900/pNZ 8149, which means our product exhibited enhanced acid and cold tolerance.
This study provides valuable insight into the development of robust industrial strains.
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