Improved acid-stress tolerance of Lactococcus lactis NZ9000 and Escherichia coli BL21 by overexpression of the anti-acid component recT

• Published in: Journal of industrial microbiology & biotechnology 2018-12, Vol.45 (12), p.1091-1101
• Main Authors: Zhu, Zhengming, Ji, Xiaomei, Wu, Zhimeng, Zhang, Juan, Du, Guocheng
• Format: Article
• Language: English
• Subjects: Acids; Bacteria; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Biochemistry; Bioinformatics; Biomedical and Life Sciences; Biotechnology; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; E coli; Escherichia coli; Escherichia coli - physiology; Escherichia coli Proteins - genetics; Escherichia coli Proteins - metabolism; Ethanol; Fermentation; Gene Expression Regulation, Bacterial; Genetic Engineering; Genetics and Molecular Biology of Industrial Organisms - Original Paper; Homologous recombination; Homology; Hydrogen-Ion Concentration; Inorganic Chemistry; Lactic acid; Lactic Acid - metabolism; Lactococcus lactis; Lactococcus lactis - physiology; Life Sciences; Metabolism; Microbiology; Microorganisms; pH effects; Plasmids - genetics; Plasmids - metabolism; Salinity tolerance; Sodium Chloride - metabolism; Stress, Physiological; Stresses; Survival; Tolerances
• ISSN: 1367-5435; 1476-5535
• DOI: 10.1007/s10295-018-2075-8

Acid accumulation caused by carbon metabolism severely affects the fermentation performance of microbial cells. Here, different sources of the recT gene involved in homologous recombination were functionally overexpressed in Lactococcus lactis NZ9000 and Escherichia coli BL21, and their acid-stress tolerances were investigated. Our results showed that L. lactis NZ9000 (ERecT and LRecT) strains showed 1.4- and 10.4-fold higher survival rates against lactic acid (pH 4.0), respectively, and that E. coli BL21 (ERecT) showed 16.7- and 9.4-fold higher survival rates than the control strain against lactic acid (pH 3.8) for 40 and 60 min, respectively. Additionally, we found that recT overexpression in L. lactis NZ9000 improved their growth under acid-stress conditions, as well as increased salt- and ethanol-stress tolerance and intracellular ATP concentrations in L. lactis NZ9000. These findings demonstrated the efficacy of recT overexpression for enhancing acid-stress tolerance and provided a promising strategy for insertion of anti-acid components in different hosts.