Effects of Zataria multiflora Boiss. Essential Oil and Acetic Acid on Thermostable Direct Haemolysin production of Vibrio parahaemolyticus

Consumption of contaminated seafood with Vibrio parahaemolyticus results in gastroenteritis in consumer. Thermostabledirecthaemolysin is one of the major virulence factors of this emerging pathogen which has an important role in its pathogenicity. The objective of this study was to evaluate the effect of Zataria multiflora Boiss. essential oil and acetic acid on the production of TDH toxin of Vibrio parahaemolyticus in subinhibitory concentrations of these preservatives. The toxin production under specific condition including the combination of different concentrations of the essential oil (0، 0. 005، 0. 015، 0. 03 and 0. 045%)، pH values (5. 5، 6. 5 and 7. 5) modified with acetic acid and 3 incubation temperatures (8، 25 and 35°C) in BHI broth medium was studied and the number of the bacteria have been counted and the toxin production has been evaluated after the growth of the organism and subsequent turbidity in the medium using the KAP-Rpla commercial kit. Toxin titerproduced in a broth with pH value of 7. 5 and 35°Cand in the absence of essential oil was 1/256 while it was 1/32 in the same condition and with the presence of 0. 015% essential oil. Also the titer of this toxin in 25°Cand pH of 6. 5 equals 1/256 while with adding the 0. 015% ofZataria multiflora Boiss. essential oil، It reduced to 1/8. According to the results the essential oil in combination with different pH values and incubation temperatures has a decreasing effect on the toxin production of Vibrio parahaemolyticus. It suggests that further studies with the same conditions as current study in a food model is needed to confirm the positive effect of these natural preservatives.