Effect of several organic acids and sodium chloride on the viability of Vibrio parahaemolyticus

In order to elucidate the mechanism of food poisoning outbreaks caused by Vibrio parahaemolyticus, the viability of this bacterium was examined after a one-hour incubation in acidic media (pH 5.0, 5.5 and 6.0) with several organic acids and sodium chloride at 37°C. The viability hardly decreased even at pH 5.0 in the medium without any organic acid in the presence of 0.5% sodium chloride solution. In the medium with 0.1M acetate, lactate or succinate the viability decreased markedly, but citrate, malate, tartrate or oxalate had almost no effect. The effects of acetate and lactate decreased with increasing sodium chloride concentration (3%). Among Kanagawa-phenomenon-positive strains, negative strains of V. parahaemolyticus and V. alginolyticus, almost no difference was observed in the behavior in acidic media with the various organic acids mentioned above.