非编码小RNA MicA调控鼠伤寒沙门氏菌生物被膜形成的分子机制

生物被膜是沙门氏菌持续污染食品生产过程的主要因素，探明食品加工环境中生物被膜的形成机制非常必要。非编码小RNA MicA在沙门氏菌生物被膜形成中发挥重要调控作用，MicA缺失导致生物被膜无法形成，但目前尚未阐明MicA对生物被膜形成的调控机制。本研究以鼠伤寒沙门氏菌为对象，以食品级不锈钢为粘附载体，以肉汁液为生长基质，利用RNA-seq技术结合生物信息学比较MicA缺失株、MicA过表达株及野生株浮游态细胞和生物被膜态细胞的转录组差异，试图阐明MicA如何在转录后水平对基因表达进行调控，并筛选两到三种与生物被膜形成密切相关的差异显著基因作为候选靶标基因。在此基础上，通过双质粒荧光报告系统、凝胶阻滞、定点突变等技术深入研究MicA调控靶标基因的作用位点及调控作用机制。本项目的开展将揭示MicA对鼠伤寒沙门氏菌生物被膜的精密调控网络机制，为研发新型沙门氏菌生物被膜防控技术提供理论基础。

Biofilm formation is the leading cause for the persistence of Salmonella contamination in food production process, it is essential to reveal the mechanism of Salmonella biofilm formation in food processing environment. The non-coding small RNA MicA plays a vital role in the regulation of Salmonella biofilm formation, MicA deletion strain can not form a biofilm, but it is not clear for the molecular regulation mechanism of MicA on Salmonella biofilm formation to date. In this project, Salmonella Typhimurium was utilized as the representative bacteria for biofilm formation on the food-grade stainless steel surface in the meat juice. After constructing MicA deletion and overexpression strains, we attempt to analyze the genome transcriptional profiles of the planktonic and biofilm cells of wild-type strain and the constructed mutants with RNA-seq and bioinformatics technologies, to clarify how sRNA MicA regulate gene expression after transcription and screen the differential mRNAs (2-3) associated with biofilm formation as the target mRNAs. Upon the findings of the transcriptomics, the target sites and regulation mechanism of MicA on target mRNAs was further studied by using luciferase reporter gene system, gel shift, and single-nucleotide mutation techniques. This project will reveal the molecular mechanism of Salmonella Typhimurium biofilm formation regulated by sRNA MicA, and provide a theoretical basis for novel technologies in control of the Salmonella biofilm formation.