Abstract: In this study, we analyzed the minimum inhibitory concentrations (MICs) of four kinds of food preservatives (chitosan, potassium sorbate, sodium dehydroacetate and ε-polylysine) for Vibro parahaemolyticus, and we then investigated their inhibitory effects on biofilm formation by V. parahaemolyticus. The crystal violet straining method was conducted to determine the amount of biofilm, and XTT reduction assay and phenol-sufuric acid method were used to detect the changes of metabolic activities and extracellular polysaccharide of biofilm, respectively. The results showed that the MIC of chitosan was the lowest, which was 1.25 mg/mL. At both MIC and sub-MIC, these four food preservatives could not only demonstrate a remarkable inhibitory effect on biofilm formation by V. parahaemolyticus, but also reduce the metabolic activity and the secretion of extracellular polysaccharides of cells in biofilms. Among these preservatives, the inhibitory effect of chitosan was the  strongest.

Key words: Vibrio parahaemolyticus, biofilm, food preservatives, inhibition