Isolation of Lactobacillus spp. in African Catfish Clarias gariepinus as probable probiotics in aquaculture

Abstract

This research sought to isolate probiotic bacteria from cultured African Catfish Clarias gariepinus to be used against bacterial fish pathogens. Lactobacillus spp. were successfully isolated from the intestine of C. gariepinus, identified using biochemical characters. Pathogenic bacteria were also isolated from the same species such as Escherichia coli, Vibrio parahaemolyticus and Aeromonas hydrophila. The isolated Lactobacillus spp. was assessed in vitro for its antagonistic activity against isolated bacterial pathogens using disc diffusion method. Two impregnated paper discs of Lactobacillus spp., one antibiotic (Amoxicillin), and one blank disc were placed in each plate of cultured pathogenic bacteria. Results showed that Lactobacillus spp. is comparable to the antibiotic (Amoxicillin) on their antagonistic activity, quantified by measuring the zone of inhibition against E. coli, V. parahaemolyticus and A. hydrophila. The highest zone of inhibition of Lactobacillus spp. was shown against A. hydrophilla (8.5 mm) and lowest zone (7.25 mm) against E. coli. Antagonistic activity of antibiotic (Amoxicillin) showed highest zone of inhibition against E. coli 14 mm and the lowest was V. parahaemolyticus 7 mm. Based on the results of the study, Lactobacillus spp. was successfully isolated from the intestine of catfish. The present work highlights the isolated candidate can be a promising probiotic to be used in aquaculture feeding, because of its high potential activity against aquatic pathogenic bacteria in vitro.