Probiotic Potential of Gut Associated Bacteria from Indigenous Fresh Water Ornamental Fishes of Kerala, South India

Abstract

Probiotic potential of gut associated aerobic and facultative anaerobic bacterial flora of indigenous freshwater fishes such as Puntius filamentosus and Barilius bakeri, were analysed in this study. Total viable count (TVC) of heterotrophic bacteria ranged between 0.64 x 10 7 to 1.31 x 10 7 and 0.59 x 10 7 to 1.92 x 10 7 per gram in gut of Barilius bakeri and P. filamentosus respectively. While bacteria belonging to the genus Corynebacterium dominated the gut of P. filamentosus, Bacillus was found to be dominant genus in the gut of B. bakeri. More than 50% of bacterial isolates from both these fishes were capable of producing various exoenzymes such as amylase, gelatinase and lipase, with 15% of them showing excellent amylolytic and gelatinolytic activity. Selected bacterial isolates were tested for antagonistic activity against fish, shrimp and human pathogens, which revealed 15% of isolates having antagonistic activity against at least one pathogenic Vibrio species tested. These isolates were further tested for their ability to grow under different temperature, pH and salinity conditions in order to evaluate their suitability for application under different filed conditions. The result of the present study offer scope for further research to evaluate probiotic potential of these gut associated bacteria in the larval rearing system and hatchery operations.