AcrR1, a novel TetR/AcrR family repressor, mediates acid and antibiotic resistance and nisin biosynthesis in Lactococcus lactis F44

• Published in: Journal of dairy science Vol. 107; no. 9; pp. 6576 - 6591
• Main Authors: Jian, Pingqiu, Liu, Jiaheng, Li, Li, Song, Qianqian, Zhang, Di, Zhang, Shenyi, Chai, Chaofan, Zhao, Hui, Zhao, Guangrong, Zhu, Hongji, Qiao, Jianjun
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.09.2024; Elsevier
• Subjects: environmental stresses; Lactococcus lactis; nisin biosynthesis; TetR family regulator; Lactococcus lactis; TetR family regulator; nisin biosynthesis; environmental stresses
• ISSN: 0022-0302; 1525-3198; 1525-3198
• DOI: 10.3168/jds.2024-24754

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. Lactococcus lactis, widely used in the manufacture of dairy products, encounters various environmental stresses both in natural habitats and during industrial processes. It has evolved intricate machinery of stress sensing and defense to survive harsh stress conditions. Here, we identified a novel TetR/AcrR family transcription regulator, designated AcrR1, to be a repressor for acid and antibiotic tolerance that was derepressed in the presence of vancomycin or under acid stress. The survival rates of acrR1 deletion strain ΔAcrR1 under acid and vancomycin stresses were about 28.7-fold (pH 3.0, HCl), 8.57-fold (pH 4.0, lactic acid) and 2.73-fold (300 ng/mL vancomycin) greater than that of original strain F44. We also demonstrated that ΔAcrR1 was better able to maintain intracellular pH homeostasis and had a lower affinity to vancomycin. No evident effects of AcrR1 deletion on the growth and morphology of strain F44 were observed. Subsequently, we characterized that the transcription level of genes associated with amino acids biosynthesis, carbohydrate transport and metabolism, multidrug resistance, and DNA repair proteins significantly upregulated in ΔAcrR1 using transcriptome analysis and quantitative reverse transcription-PCR assays. Additionally, AcrR1 could repress the transcription of the nisin post-translational modification gene, nisC, leading to a 16.3% increase in nisin yield after AcrR1 deletion. Our results not only refined the knowledge of the regulatory mechanism of TetR/AcrR family regulator in L. lactis, but presented a potential strategy to enhance industrial production of nisin.