SurA通过调控鞭毛表达影响伤寒沙门菌生物膜的形成

SurA influences biofilm formation ability by regulating flagellar expression in Salmonella enterica serovar Typhi

目的:研究周质伴侣蛋白SurA对伤寒沙门菌生物膜形成能力的影响及其潜在机制。方法:用前期构建的surA基因缺陷株、缺陷空载体株及缺陷回补株的生物膜实验,观察surA基因缺失对细菌生物膜形成能力的影响。通过实时定量聚合酶链式反应(quantitative real-time polymerase chain reaction,qRT-PCR)检测影响生物膜形成的几个关键基因在surA缺陷株及野生株中的表达差异,探索surA影响细菌生物膜形成的可能通路。通过电镜实验观察surA缺陷株及野生株的鞭毛表达情况。最后通过生物膜实验观察鞭毛缺失对生物膜形成的影响。结果:与野生株相比,surA缺陷株的生物膜形成能力显著下调,缺陷株里回补surA后,细菌的生物膜形成能力恢复到与野生株相当。与野生株相比,surA缺陷株中鞭毛相关基因的mRNA水平显著下调。电镜结果显示,与野生株相比,surA缺陷株的鞭毛表达数量显著减少。鞭毛缺失株(△flhD)几乎不形成生物膜。结论:伤寒沙门菌surA基因缺陷可能通过下调鞭毛基因表达来影响生物膜形成。

Objective:To investigate the effect of periplasmic chaperonin SurA on biofilm formation ability of Salmonella enterica serovar Typhi and its potential mechanism.Methods:The biofilm formation capacity of the surA deletion mutant,the defective empty vector strain and the complement strain was observed by biofilm assay.The quantitative real-time polymerase chain reaction(qRT-PCR)assay was used to detect the expression differences of several key genes affecting biofilm formation in surA deletion mutant and wild type strain,and to explore the possible pathways for surA to affect the biofilm formation ability of bacteria.Observation of flagellar expression of surA deletion mutant and wild type strain by electron microscopy.Finally,the biofilm formation ability of flagellar deletion strain was observed by biofilm assay.Results:The biofilm formation ability of the surA deletion mutant was significantly lower than the level of the wild type strain.Complementation of surA restored bacterial biofilm formation ability to the level of the wild type strain.The mRNA level of the flagellar related genes in the surA deletion mutant was significantly lower than the level of wild type strain.Electron microscopy results showed that the number of flagellar of the surA deletion mutant was significantly reduced than the wild type strain.The flagellar deletion strain(ΔflhD)hardly forms the biofilm.Conclusion:The deficiency of the surA gene may affect biofilm formation through reducing flagellar expression in Salmonella enterica serovar Typhi.