Study on use of Nisinto to control Streptococcus iniae and Lactococcusgarvieae in rainbow trout fillet

In this study، effect of different concentrations of nisin (0، 0. 25، 0. 5 and 0. 75 µg/ ml) were conducted against zoonotic bacteria Streptococcus iniae and Lactococcusgarvieae in fish fillet of rainbow trout (Oncorhynchusmykiss) in refrigerator storage. Lyophilized cultured of S. iniae (GQ850377) and L. garvieae (Ir-170A856bp) were obtained from Department of Aquatic Health and Diseases، Faculty of Veterinary Medicine، University of Tehran، Tehran، Iran، and were used in this study. After determination of incubation dose of two bacteria (1. 4×108 and 9. 2×107 CFU/ ml) and preparation of nisin solution، incubation of bacterial was done in fish fillets. The results revealed that different concentrations of nisin were statistically different in reduction of bacteria comparing with control group (P<0. 05). The highest inhibitory effect was observed in 0. 75 µg/ ml 65. 77% on L. garvieae and 60. 88 % on S. iniae. Thatresults showed that nisin، as a preservative، can be effective in control of food-borne bacteria in foodstuff.