【摘要】 提升菌株酸耐受能力在工业生产中有重要经济价值。研究发现，乳酸乳球菌F44中一种功能未知的DeoR/GlpR家族转录因子RdrA与菌株酸耐受能力相关。为研究RdrA对F44菌株耐酸性能的影响，比较rdrA缺陷型、过表达菌株和F44原始菌株的生长曲线、pH曲线、酸耐受、Nisin耐受和Nisin效价，对RdrA的功能进行表征。此外，对rdrA缺陷突变型菌株和F44原始菌株进行转录组学测序，进一步研究RdrA影响F44菌株酸耐受的靶标基因和代谢通路。转录组测序和qPCR结果表明，RdrA主要通过抑制细胞被膜的流动性和韧性，降低胞内蛋氨酸水平，以及抑制DNA分子修复和蛋白修饰过程，降低F44酸耐受能力。研究首次揭示未知功能的转录因子RdrA，为提高乳酸乳球菌耐酸性能提供了新的研究方向和分子靶点，在工业生产中具有重要意义。更多还原

【Abstract】 Boosting the acid resistance of microbial strains is of considerable economic importance in the industrial fermentation. Recent findings have shed light on an unexplored DeoR/GlpR family transcription factor, RdrA, which plays a pivotal role in enhancing the acid tolerance of Lactococcus lactis F44. To assess the impact of RdrA on the acid resistance of the L. lactis F44, a comparative analysis was conducted. This involved examining the growth and pH curves, as well as the acid and nisin resistance, and the nisin yield of both the rdrA knockout and overexpression strains in comparison to the wild-type F44 strains. Subsequently, transcriptomic sequencing was carried out on the rdrA knockout and wild-type F44 strains to identify differentially expressed genes and analyze acid resistance regula-tory mechanisms of RdrA. The transcriptomic data, corroborated by qPCR, indicated that RdrA’s influence on the F44 strain’s environmental tolerance was primarily due to its role in diminishing the fluidity and integrity of the cell envelope. Additionally, it was found that RdrA reduces intracellular methionine levels and impedes DNA repair and protein modification processes. This study unveils the unknown transcription factor RdrA and provides new insights and molecular targets for enhancing the acid tolerance of L. lactis, which could have significant implications for industrial applications.更多还原