Influence of cations and anions of the survival of Vibrio parahaemolyticus in freshwater

To study the effect of various cations and chloride concentration on the survival of Vibrio parahaemolyticus, 2,000,000,000-7,000,000,000 cfu per ml were added to flasks containing river water or distilled water. In river water the number of cells declined rapidly and no culturable cells were detected by day 2. In river water amended with 3 per cent (weight /volume) of sodium chloride, the population remained unchanged for the 7 d of the experiment but with 0.85 per cent sodium chloride, the population was stable for 3 d before declining rapidly. The longevity of V. parahaemolyticus in distilled water was also positively correlated with the concentration of added sodium chloride. The test organisms survived longer in solutions made up with chloride-containing compounds than in those with sodium bicarbonate. Potassium promoted the culturability of V. parahaemolyticus in distilled water, followed by magnesium, lithium and calcium.