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J Ind Microbiol Biotechnol. 2019 Aug 14. doi: 10.1007/s10295-019-02226-x. [Epub ahead of print]

Systemic understanding of Lactococcus lactis response to acid stress using transcriptomics approaches.

Zhu Z1,2, Yang P1,2, Wu Z3,2, Zhang J4,5, Du G3,2.

Author information

1
Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China.
2
School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China.
3
The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China.
4
Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China. zhangj@jiangnan.edu.cn.
5
School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China. zhangj@jiangnan.edu.cn.

Abstract

During fermentation, acid stress caused by the accumulation of acidic metabolites seriously affects the metabolic activity and production capacity of microbial cells. To elucidate the acid stress-tolerance mechanisms of microbial cells, we performed genome mutagenesis combined with high-throughput technologies to screen acid stress-tolerant strains. Mutant strain Lactococcus lactis WH101 showed a 16,000-fold higher survival rate than that of the parent strain after 5 h of acid shock at pH 4.0 and maintained higher ATP, NH4+, and intracellular pH (pHi) levels during acid stress. Additionally, comparative transcriptomics analysis revealed enhanced regulation of carbohydrate metabolism and sugar transport to provide additional energy, amino acid metabolism and transport to maintain pHi homeostasis and ATP generation, and fatty acid metabolism to enhance cellular acid tolerance. Moreover, overexpression of identified components resulted in 12.6- and 12.9-fold higher survival rates after acid shock for 3 h at pH 4.0 in L. lactis (ArcB) and L. lactis (MalQ) compared to the control strain, respectively. These findings provide valuable insight into the acid stress-response mechanisms of L. lactis and promote the further development of robust industrial strains.

KEYWORDS:

Acid stress; High-throughput screening; Lactococcus lactis; Metabolic engineering; Transcriptomics

PMID:
31414323
DOI:
10.1007/s10295-019-02226-x

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