单增李斯特菌双元调控系统hssS/hssR缺失株的构建及其生物学特性

单增李斯特菌(Listeria monocytogenes,LM)是一种重要的食源性人畜共患病原菌,可抵抗外界多种不利因素的影响,如酸、碱、渗透压和氧化应激.双元调控系统(two-component system,TCS)是细菌适应环境的重要调控系统,为了探明双元调控系统HssS/HssR对单增李斯特菌抗应激能力及毒力...

Construction of Listeria monocytogenes Two-Component System hssS/hssR Deletion and Research on Its Biological Characteristics

Listeria monocytogenes(LM)is an important food-borne zoonotic pathogenic microorganism, which can survival under various stress conditions, such as acidic, alkalic, osmotic and oxidative stresses.Two-component systems play important roles in sensing and adaptating to the environments. In this study, we try to explore the roles of the two-component system HssS/HssR in stresses resistance and pathogenicity of Listeria monocytogenes. A hssS/hssR deleted strain was constructed based on Listeria monocytogenes 10403S, and its biological characteristics were investigated. Growth curves showed that deletion of hssS/hssR weakened the growth ability under oxidative stress (20 mmol·L^-1 H₂O₂) condition. Survival assays showed that the growth rate of deletion strain ΔhssS/hssR was significantly lower than that of the parent strain treated with 20 mmol·L^-1 H₂O₂for one hour (P<0.01). Phagocytosis and proliferation assays in macrophage RAW264.7 cells showed that deletion of hssS/hssR significantly enhanced the ability of anti-phagocytosis (P<0.01) and proliferation in macrophages (P<0.05). Virulence assays conducted on chicken embryo showed that the LD₅₀ of the parent strain and deleted strain were 10^2.2and 10^1.4, respectively. And the bacteria load in the liver of chicken embryo infected by the deletion strain was significantly higher than that of parent strain (P<0.01), indicating that deletion of hssS/hssR significantly enhanced the virulence of Listeria monocytogenes. These results indicated that the two-component system HssS/HssR mediates the oxidative stress resistance and virulence of Listeria monocytogenes.