Influence of combinations of sublethal stresses on the control of Vibrio parahaemolyticus and its cellular oxidative response

Vibrio parahaemolyticus is one of the most prevalent marine foodborne pathogens in some oriental countries and is a pathogen of global concern since the emergence of the pandemic O3:K6 strain in 1996. In this study, V. parahaemolyticus KX-V231 in the exponential phase was treated by single or combinations of sublethal stresses, including low salinity, starvation and low temperature, for 24 h. Its survival, cell membrane permeability and cellular oxidative response were examined. Low salinity/low temperature and low salinity/starvation/low temperature combinations efficiently induced a 3 to 4 log reduction of the V. parahaemolyticus population. The numbers of survivors in the treated samples were strongly correlated with the level of cellular reactive oxygen species, but not with the change in cell membrane permeability. Some antioxidative factors and related regulators, including rpoS, rpoE, oxyR, ahpC1, ahpC2, catalase VPA0453 and glutathione synthetase VP2611, were expressed in the exponential phase control and all of the stressed samples, while other factors examined (peroxiredoxins VPA1681 and VPA1293, catalases VPA0768 and VPA1418) were expressed under particular stress conditions. The data obtained in this study facilitate the selection of preservative factors in the control of V. parahaemolyticus and the gentle processing of seafood.