sRNA与群体感应系统相互作用调控保加利亚乳杆菌自溶的分子机制

Autolysis of Lactic acid bacteria (LAB) plays a vital role in the process of flavour during cheese ripening while restricts the proliferation of cell in yogurt fermentation and probiotics production. Our team found in the previous study, Lactic acid bacteria quorum sensing (QS) signal peptide concentration accumulated to a certain threshold is a key factor in triggering cell autolysis, and the signal transduction pathways of autolysis process were successfully analyzed. In the study also found that the signal transduction pathway in addition to the regulation of the QS signal peptide, but also by the bacterial sRNA negative feedback regulation, but the specific mechanism is not clear. This may be the key to the precise regulation of lactic acid bacteria on cell autolysis. In order to achieve the precise control of lactic acid bacteria autolysis, to meet the dairy industry on lactic acid bacteria different autolysis needs. Based on the above research, in this project, RNA-seq technology was used to detect the transcript levels of sRNA and mRNA before and after autolysis. By studying the interaction between differential sRNAs and quorum sensing key genes, we explore the regulation of sRNA regulation of autolysis of bacteria. And clarify the precise regulation mechanism of autolysis of lactic acid bacteria. This project will lay a theoretical foundation for the precise regulation of the autolysis of lactic acid bacteria starter.

乳酸菌自溶会导致菌体的死亡和胞内酶的释放，对发酵乳制品的风味形成、品质特性及生产周期等具有重要影响。本团队前期研究发现，乳酸菌自身分泌的一种群体感应信号肽浓度累积到一定阈值是触发菌体自溶的关键因素，并且成功对自溶过程的信号传导通路进行了解析。研究同时发现，该信号传导通路除了受群体感应信号肽的调控外，还受细菌sRNA的负反馈调控，但是具体机制不清楚，这可能是乳酸菌对菌体自溶进行精细化调控的关键。为实现对乳酸菌菌株自溶度的精细化调控，满足乳品工业对乳酸菌不同自溶度的需求，本项目从保加利亚乳杆菌sRNA入手，采用RNA-seq技术对菌体发生自溶前后sRNA和mRNA的转录水平进行检测，筛选差异的sRNA与mRNA，通过研究差异sRNA与群体感应关键基因的互作关系，探索sRNA参与调控菌体自溶的规律，阐明乳酸菌菌体自溶的精细化调控机制，为实现乳品工业发酵剂菌株自溶度的精准调控奠定理论基础。

乳酸菌自溶会导致菌体的死亡和胞内酶的释放，对发酵乳制品的风味形成、品质特性及生产周期等具有重要影响。本团队前期研究发现，乳酸菌自身分泌的一种群体感应信号肽浓度累积到一定阈值是触发菌体自溶的关键因素，并且成功对自溶过程的信号传导通路进行了解析。研究同时发现，该信号传导通路除了受群体感应信号肽的调控外，还受细菌sRNA的负反馈调控，但是具体机制不清楚，这可能是乳酸菌对菌体自溶进行精细化调控的关键。.为实现对乳酸菌菌株自溶度的精细化调控，满足乳品工业对乳酸菌不同自溶度的需求，本项目从保加利亚乳杆菌sRNA入手，采用RNA-seq技术对菌体发生自溶前后sRNA和mRNA的转录水平进行检测，筛选差异的sRNA与mRNA，通过研究差异sRNA与群体感应关键基因的互作关系，探索sRNA参与调控菌体自溶的规律。结果表明保加利亚乳杆菌的自溶是受其群体感应系统所调控，但是在群体感应信号传导通路上的关键基因——反馈调节基因（RR）除了接受QS信号以外，还受到2条sRNA的负反馈调控，这是菌株实现精细化调控自溶的关键机制。.乳酸菌精细调控自溶机制的探明将对乳酸菌的筛选、分子育种及其应用提供重要理论指导。同时根据自溶机理选育不同自溶度乳酸菌用于发酵乳品或益生菌制品，对推动我国发酵乳业的快速发展，增加产品附加值，实现农业供给侧结构性调整，具有重要理论指导意义及实用价值。另外近年研究证实，乳酸菌在食品中的存活能力、在肠道中定殖能力等重要特性均受sRNA与群体感应系统组成的网络调控，本项目从乳酸菌响应环境变化并与QS相关的sRNA入手，开展乳酸菌自溶的精细化调控机制研究，阐明sRNA参与菌株自溶过程并发挥调控作用的分子机制，将为研究乳酸菌响应环境条件变化的基因表达提供参考，为今后从分子水平研究乳酸菌环境适应性、定殖能力、提高菌种发酵密度等提供了新的思路和途径。