Abbreviations

Abstract, a marine bacterium, is an opportunistic pathogen capable of causing vibriosis with high mortality to shes in the South China Sea. Stress resis-tance is very important for its survival in the natural envi-ronment and upon infection of the host. RpoS, an alternative sigma factor, is considered as an important regu-lator involved in stress response and virulence in many pathogens. In this study, the gene was cloned and characterized to evaluate the role of RpoS in. The predicted protein showed high identity with other reported gene products. The in-frame deleted mutation of in led to sensitivity of the strain to ethanol, hyperosmolarity, heat, and hydrogen peroxide challenges. Further studies showed that extracellular autoinducer 2 level, four of seven detected protease activi-ties, and cytotoxicity of extracellular products were mark-edly decreased in the mutant compared with that in the wild-type strain. The results indicated that the global regu-lator RpoS was part of the regulatory networks of virulence and LuxS quorum sensing system