Effects of starvation and osmotic stress on viability and heat resistance of Pseudomonas fluorescens AH9
- F Jørgensen, S. Knøchel N
- Journal of Applied Microbiology
Vibrio parahaemolyticus is an emerging enteric pathogen often associated with the consumption of improperly cooked seafood. The major virulence factor of this pathogen is represented by the termostable direct hemolysin (TDH). When entering the host organism, the vibrion has to face a series of environmental changes (such as temperature and osmolarity) which determine various cellular responses among which the heat shock response has an important role. The purpose of this study was to analyze the survival profiles, the morphological changes and the TDH production in V. parahaemolyticus strains grown under sub-lethal heat and osmotic stress. Our study has demonstrated the thermolotolerance in V. parahaemolyticus strains and the absence of cross-protection between the osmotic and heat stress. We have also observed that the osmotic stress induced important changes to the bacterial cell morphology. The production of the thermostable direct hemolysin, the major virulence factor in V. parahaemolyticus, was increased in cells remained viable after thermal inactivation at 47C, these results demonstrating the risk of virulence conservation in insufficiently heat treated food.