Comparison on the Growth Heterogeneity of Vibrio parahaemolyticus Coupled with Strain Source and Genotype Analyses in Different Oligotrophic Conditions

Abstract

Vibrio parahaemolyticus is an important foodborne pathogen in aquatic products that can survive long term in an oligotrophic environment and maintain pathogenicity. In this study, the growth curves of 38 strains of V. parahaemolyticus (pathogenic and environmental strains) under different oligotrophic conditions (tryptone soy broth [TSB] and TSB medium diluted 2, 4, and 6 times) were simulated and their growth heterogeneities were compared. The growth kinetic parameters (maximum specific growth rate and lag time) were calculated by the modified Gompertz model. The results showed that oligotrophic conditions affected the growth variability of strains, and the coefficient of variation of all strains reached the maximum in the 4-fold dilution of TSB. Under different oligotrophic conditions, the lag time of the pathogenic strains was shorter than that of the environmental strains, whereas the maximum specific growth rate of the environmental strains was greater. This indicated that pathogenic strains were more adaptable to the nutrient-deficient environment. The analysis of different genotypes revealed that the strains with genotype tlh+/tdh+/trh- showed greater growth variability in oligotrophic environments. These results provided theoretical support for the accuracy of the risk assessment of aquatic products.