Analysis of Halophilic Phenotypic Variation and Cytotoxicity of Vibrio parahaemolyticus from Different Sources

<i>Vibrio parahaemolyticus</i> is an aquatic animal pathogen. Recently, the detection rate of <i>V. parahaemolyticus</i> in freshwater products has exceeded that in seafood products, and the strains isolated from freshwater products exhibit better growth conditions in low-salinity environments. This study is based on a food risk detection activity in Changzhou, Jiangsu Province, China, investigating the variation of halophilism and the virulence of two groups of strains under different salt concentrations. Under 0%, 0.5%, and 1% salt, the strains from the freshwater showed faster growth than those from the seawater. In comparison, the strains from the seawater group under 2% and 3% salt grew faster than the growing status under the foregoing low-salt concentration environment. The cytotoxicity produced by the two strains was approximately 1.4 times higher in the 0.5% and 1% salt concentration groups compared to the 3% corresponding experimental group. Under the 0%, 0.5%, and 1% salt, the cytotoxicity of strains in the freshwater group increased by nearly 20% compared to that in the seawater groups. The freshwater strains showed altered halophilism and adapted to the low-salt environment. This research will be helpful in establishing a local and global control strategy against the diseases resulting from <i>V. parahaemolyticus</i>.