Abstract

Bacillus subtilis was isolated from milk samples. Antibiotic resistance and the antimicrobial activity of B. subtilis were studied. All the four isolates of B. subtilis were sensitive to antibiotics such as streptomycin (25 μg/ml), ampicillin (10 μg/ml), penicillin (10 μg/ml), erythromycin (15 μg/ml), amoxycillin (10 μg/ml).But they were resistant to bacitracin (10 μg/ml). B. subtilis shown antibacterial activity against the selected human pathogens such as Salmonella spp, Streptococcus spp, Klebsiellaspp and E. coli. The antimicrobial substance from B. subtilis extracted with organic solvent such as ethyl actetate have also shown antibacterial activity against the human pathogens. The proteineceaous nature of the B. subtilis exerted antimicrobial activity. The amount of protein varied between 0.05 - 0.55 mg/ml and the protein was qualitatively analyzed by SDS-PAGE. The entire samples have shown peptide < 62 kDa.

Key words: Bacillus subtilis, antibiotics, Salmonella spp, human pathogens, ethyl acetate, SDS PAGE.