假结核耶尔森氏菌rpoS基因的抗胁迫功能

为探讨食源性病原微生物假结核耶尔森氏菌的抗逆机制,采用同源重组原理进行双交换以获得rpoS基因突变株。分别在5mmol/L H_2O_2和pH 3.5两种胁迫下测定野生型菌株、rpoS基因突变株和互补菌株的存活率,并以2′,7′-二氯荧光黄双乙酸盐(DCFH-DA)为荧光探针,测定两种胁迫下细菌胞内活性氧水平。结果显示,在5mmol/L H_2O_2和pH3.5胁迫下,假结核耶尔森氏菌rpoS基因突变株存活率明显降低,这种降低能够在互补菌株中得到恢复;突变株中胞内活性氧自由基水平明显高于野生型菌株和互补菌株。说明:rpoS基因具有帮助假结核耶尔森氏菌抗氧化胁迫和酸胁迫的功能,且这一功能的发挥是通过调节胞内活性氧水平实现的。

Role of rpoS Gene in Stress Resistance in Yersinia pseudotuberculosis

Mechanism of resistance to stress conditions in food-borne pathogenic microorganism Yersinia pseudotuberculosis was studied in this research. To obtain rpoS mutant strain, double crossing over method was used in this study. The survival ratios of three strains (wild type, rpoS mutant and the complementation strain) were detected under 5 mmol/L H₂O₂ and pH 3.5 conditions. And DCFH-DA reagent was used to determine the ROS levels of these three strains.the results showed that survival ratios of rpoS mutant strain were significantly lower than the wild type under H₂O₂ and pH 3.5 conditions in Yersinia pseudotuberculosis, and this decrease could be restored in the complementation strain. Furthermore, ROS levels of the mutant strain were higher than the wild type and the complementation strain. In conclusion, rpoS plays role in helping Yersinia pseudotuberculosis survive under H₂O₂ and acid stress conditions through regulating ROS levels .