Isolation and Characterization of Bacteria from the Intestine of Clarias batrachus for Probiotic Organism

Abstract

Clarias batrachus (Linn.) in India is at a deteriorating state. The use of probiotic organism is one of the alternatives to promote fish nutrition in worldwide aquaculture. An extensive study was performed to isolate and identify probiotic bacteria from the gut of the C. batrachus. Quantitative and qualitative analysis of bacterial flora associated with the intestine of C. batrachus were carried out. Total viable bacterial count in the intestine of catfish was 1.61 × 1010cfu/g. Thirty-two different bacterial isolates were selected from the intestinal microflora of C. batrachus. Gram-positive rod-shaped bacteria dominated (81%) the populations in catfish. The five intestinal isolates (PKA1, PKA2, PKA17, PKA18 and PKA19) showed antagonistic properties against common fish pathogens - Vibrio harveyi, Vibrio vulnificus and Vibrio parahaemolyticus. The strain PKA17, PKA18 and PKA19 were identified as Lysinibacillus sphaericus, Bacillus cereus and Bacillus thuringiensis respectively by the 16S rDNA sequencing.