Antimicrobial Effect of B. subtilis, against Aeromonas hydrophila and Pseudomonas fluorescens

BACKGROUND AND OBJECTIVESThis research was conducted with the aim of using gamma radiation to generate mutant strains of Bacillus subtilis ATCC ۶۶۳۳ to study probiotic performance under in vitro conditions.MATERIALS AND METHODSStrain B. subtilis ATCC ۶۶۳۳ was irradiated with gamma irradiation (۶.۲۵ KGy). Subsequently, the mutant strains were evaluated for their bacterial growth performance and antibacterial activity against some aquaculture pathogenic strains, Aeromonas hydrophila and Pseudomonas fluorescens.RESULTS AND DISCUSSIONThe results of this study showed that strains number ۴۵, ۵۱ and ۸۸ had a higher growth rate than the other sub-strains. The strongest antagonistic activity against the pathogens A. hydrophila and P. fluorescens was associated with number ۴۵, while numbers ۳۲ and ۴۴ showed the least antagonistic activity compared to the others.CONCLUSIONIn the present study, the generation of the mutant strain ATCC ۶۶۳۳ by gamma irradiation increased the antagonistic activity against the important pathogenic bacteria in fish culture against A. hydrophila and P. fluorescens. According to the results, substrain No. ۴۵ should be evaluated for further studies in fish aquaculture systems.