Investigation of antibacterial, nutritive value, acid and bile tolerance properties of Bacillus sp., isolated from Indian major carp Labeo rohita (Hamilton, 1822)

Bacillus sp., generally regarded as safe, has emerged as a robust organism that can withstand adverse environmental conditions and grows easily to very high densities. Tolerance and resistance to acidic pH, high osmotic concentration of NaCl, and bile salts were tested in broth medium. A probiotic bacterium isolated from the gut of Indian major carp Labeo rohita rendered maximum antagonistic activity against Aeromonas hydrophila pathogen and nutritive value were also tested. They were B. flexus (M3) and B. megaterium (M5) and their characteristics were as given below. B. flexus (M3) showed a higher capacity to grow even at 40°C with alkaline- pH 7. It also recorded higher nutrient value in all the biochemical parameters. B. flexus (M3) showed maximum inhibitory zone of 22 mm in well diffusion method and 16 mm in disc diffusion method against B. megaterium (M5).