Antimicrobial Activity of Bacillus Species Isolated from Soil against Human Pathogens

Aims: Emergence and spread of drug resistance microbial infection has become a major concern in disease control and treatment. So, it is of great priority to prevent MDR emergence and to develop new drug to cope up with this rising threat. The study was conducted to analyze the Bacillus species as a potential source of antibiotics with activity against resistant strains. Materials and Methods: 10 Soil samples from various locations were processed for the isolation of Bacillus spp. with antimicrobial activity. Identification was carried out based on the biochemical analysis according to Bergey�s Manual of Determinative Bacteriology. Antimicrobial activity of the Bacillus spp. were demonstrated by agar well diffusion method against MRSA, Staphylococcus aureus, Escherichia coli, Klebsiella spp. , Enterococcus spp. , Salmonella spp. and Streptococcus spp. Results: 13 Bacillus isolates out of 41 were found showing antimicrobial effect with majority of them being B. larvae, B. firmus and B. laterosporus. All of the Bacillus isolates demonstrated inhibitory effect against the Gram�s positive test organisms compared to 53.86 % of isolates against the Gram�s negative test organisms. Thus, majority of isolates were Gram positive inhibitors with 53.86 % isolates demonstrating broad spectrum activity. Bacillus isolates were found to show effective inhibitory effect against MRSA compared to other test strains. Conclusion: Bacillus species can be a potential source of antibiotics with inhibitory effect against both Gram�s positive and Gram�s negative organisms along with potent effect against MRSA.