Superoxide dismutase VPA1514 in Vibrio parahaemolyticus protects against environmental stresses

Vibrio parahaemolyticus is a foodborne enteropathogen that has become a global concern since the emergence of the pandemic O3:K6 strain in 1996. Three putative superoxide dismutases (SODs), namely FeSOD (VP2118), MnSOD (VP2860) and CuZnSOD (VPA1514), are found in V. parahaemolyticus. In this study, the VPA1514 mutant and gene complementary strains of V. parahaemolyticus were constructed to investigate the function of VPA1514 against environmental stresses. The growth of the VPA1514 mutant strain in broth medium under sublethal stress of H2O2 was significantly slowed relative to that of the wild-type strain. The survival rate of this VPA1514 mutant strain, when challenged by lethal acetic acid for two hours, was significantly lower than that of the wild-type strain. Moreover, the presence of the complementary VPA1514 gene significantly ameliorated the survival of this V. parahaemolyticus mutant strain. VPA1514 also showed the effect on the survival of a SOD mutant strain of Escherichia coli against acetic acid. In summary, this study demonstrated that VPA1514 protects against exogenous H2O2 and the lethal concentrations of acetic acid in V. parahaemolyticus.