Biochemical Characterization and Antimicrobial Potential of Soil-Derived Bacillus Isolates

Background: There is an increasing need for the exploration of alternative sources of antimicrobial agents as a result of the increasing prevalence of multi-drug resistant (MDR) pathogens. Bacillus species from diverse soil samples were isolated within Dutse, Jigawa State, Nigeria. Methods: Six different Bacillus isolates were identified based on cultural, morphological, and biochemical characteristics: P. polymyxa, B. subtilis, B. cereus, B. pumilus, B. megaterium, and B. licheniformis. Antibacterial activities of these isolates were assessed using agar well diffusion against clinically isolated pathogens: Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Results: Results showed that B. licheniformis showed the broadest spectrum with zones of inhibition of (23.0 ± 0.8 mm) against S. aureus and (14.0 ± 0.6 mm) against P. aeruginosa. B. subtilis likewise displayed extremely potent inhibitory action against S. aureus (19.0 ± 1.0 mm) and P. aeruginosa (21.0 ± 0.7 mm). On the other hand, B. cereus and P. polymyxa displayed moderate activity while B. megaterium and B. pumilus showed little to no zone of inhibition against some of the pathogens. Conclusion: These findings highlight soil-borne Bacillus species as promising candidates for novel antimicrobial drug discovery with potential contributions to addressing the global challenge of antibiotic resistance.