PROBIOTIC EFFECT OF LACTOBACILLUS ISOLATES AGAINST BACTERIAL PATHOGENS IN CLARIAS ORIENTALIS

Abstract

Summary. About 59 Lactobacillus isolates were isolated from 5 different fresh water sites such as Cat fish (Clarias orientalis), Hari fish (Anguilla sp), Rohu fish (Labeo rohita), Jillabe fish (Oreochromis sp) and Gende fish (Punitus carnaticus). Among the 59 isolates only 4 Lactobacillus isolates were selected for further study. Based on morphological, biochemical characteristics, the isolates were identified as Lactobacillus sp. The pathogens were isolated, characterized and identified as Vibrio parahaemolyticus, Aeromonas sp and Aeromonas salmonicida. The Lactobacillus isolates were screened for antagonistic activity against Aeromonas, Vibrio sp. by agar diffusion assay. Among the 4 isolates, Lactobacilli RLD2 showed significant antagonistic activity against Aeromonas and Vibrio sp alone. This isolate was further evaluated by standard plate count assay for the viability of pathogen. The isolate was multiplied and the fish feed was supplemented with Lactobacillus isolates. The results reveal that the size and weight of the fish statically increased in comparison to that of control fish. The present study concluded that the Lactobacillus isolates will be used as probiotic bacteria in aquaculture, to manage aeromonasis.