Study of antimicrobial activity of Bacillus safensis on human and plant pathogens

Abstract

In the recent decades, pathogenic microorganisms with resistance to common drugs have become increasingly wide spread. These developments lead to significant complications in treating infections and pose a serious challenge to modern medicine. The search for new natural antibiotics that overcome drug resistance of pathogenic microflora is a viable solution to this problem. Objective The aim of this study investigating the ability of Bacillus safensis and Bacillus subtilis to produce antimicrobial agent. Materials and Methods In this study, bacterial extract of Bacillus safensis and Bacillus subtilis were prepared. The antimicrobial effects of the extracts were determined by methods Agar well diffusion, macro dilution broth and micro dilution broth on bacterial and fungal pathogens of humans and herbs. Results The extract of Bacillus safensis showed no inhibitory action on bacteria and fungi studied. The extract of Bacillus subtilis showed significant antagonistic effect against Rhizobium radiobacter, Erwinia amylovora, Botrytis cinerea, Neurospora crassa, Fusarium oxysporum, Aspergillus flavus and candida albicans. While showed no inhibitory action on the Escherichia coli, Pseudomonas syringae, klebsiella pneumonia, Shigella flexneri, Xanthomonas camoestris, Streptococcus mutans and Bacillus cereus. The highest inhibition zone was observed against Erwinia amylovora which reached 30mm and MIC and MBC for this bacterium were equivalent to 1 Mg/mL . Discussion Considering the results obtained and increasing the resistance of bacteria to chemical antibiotics is suggested with further studies on Bacillus subtilis, can be used antimicrobial and antifungal combinations of this bacterium to treat bacterial and fungal infections.