非编码RNA AsrH对伤寒沙门菌表型的影响

Effect of non-coding RNA asrH on phenotype of Salmonella enterica serovar Typhi

目的:研究非编码RNA Asr H在伤寒沙门菌(Salmonella enterica serovar Typhi,S.Typhi)中的作用,观察其对应激条件下的生存能力、动力以及生物膜形成等表型的影响。方法:用自杀质粒p GMB151介导的同源重组法,制备asr H基因启动子缺失变异株;绘制生长曲线,观察S.Typhi在酸、氧和高渗应激条件下的生长;用半固体平板培养观察S.Typhi的动力;用结晶紫染色法观察S.Typhi生物膜形成情况。结果:序列分析表明,在变异株asr H基因启动子区域缺失了120 bp;生长曲线显示,与野生株相比,asr H缺陷株在酸性和高渗应激下的生存能力明显降低,而在氧应激下一定时间内升高;asr H缺陷株动力几乎完全消失,而生物膜形成能力强于野生株。结论:Asr H有助于S.Typhi在酸性和高渗应应激环境下生长,对S.Typhi的动力至关重要,且能抑制生物膜的形成。

Objective： To investigate the function of a novel non-coding RNA AsrH in Salmonella enteri- ca serovar Typhi （ S. Typhi）, and to observe its effect on the survival ability of asrH mutant in stress condi- tions, motility and biofilm formation. Methods： The homologous recombination induced by the suicide plas- mid pGMB151 was used to generate the asrH promoter deleted mutant of S. Typhi. The bacterial growth in acidic, oxidative and hyper osmotic stress conditions was investigated with detection of growth curve in rela- tive conditions. The bacterial motility was shown with incubating bacteria on semi-sold agar plate. Further- more, the bacterial biofilm formation were investigated with the crystal violet dyeing test. Results： A 120 bp of promoter region of asrH gene was lost in the mutant, which was confirmed by sequencing analysis. The growth of the asrH mutant was slower under the acidic and hyperosmotic stress conditions, but was fas- ter under oxidative stress condition than the wild-type strain. The asrH mutant almost lost the motility com- pletely. The biofilm formation ability of the asrH mutant was significantly increased compared with the wild-type strain. Conclusion： The non-coding RNA AsrH was beneficial to bacterial growth in the acidic and hyperosmotie stress conditions, may be essential to bacterial motile and has inhibition to biofilm formation in S. Typhi.