Isolation of bacteriocin producing lactic acid bacteria from fish gut and probiotic activity against common fresh water fish pathogen Aeromonas hydrophila

Abstract

Lactic acid bacteria (LAB) produce many kinds of metabolites, which might affect the other microbes in the fish mid gut. Lactic acid produced by both homolactic acid and heterolaetic strains, which will reduce pH in the luminal contents in the stomach of neonatal piglets of fish. Isolated LAB was used as a probiotic in fresh water fish tilapia (Oreochromis mossambicus) against the most common fish pathogen Aeromonas hydrophila. Higher antagonistic activity recorded from extra cellular protein (ECP) or bacteriocin compared to the intra cellular protein (ICP) against A. hydrophila. After feeding with the potential probiotics for 25 days, challenge by immersion indicated effectiveness at reducing disease caused by A. hydrophila in fishes. Tilapia exhibited no significant difference in growth, survival nor external appearance between the probiotic fed combine probiotic treatments, but significant differences (p<0.05) occurred between probiotic and control groups. The use of LAB also enhances the production rate of rotifers, which act as biocarriers of probiotics and when fed to fish they showed increased growth rate and weight of the animal. LAB is highly appreciated as a biological enhancers-probiotics, because of beneficial effector live microorganisms © 2008 Asian Network for Scientific Information.