Abstract:In order to study the main antimicrobial substances in the fermentation liquid of Bacillus subtilis SC-2, clinical strains of pathogenic methicillin-resistant Staphylococcus aureus (MRSA), Propionibacterium acnes, and Candida albicans were used as indicator strains, antimicrobial activity was measured using the agar diffusion method, and the crude extracts of SC-2 fermentation liquid were separated and purified. The crude extract containing antimicrobial substances was separated by silica gel column chromatography, Sephadex LH-20 gel column chromatography, and high performance liquid chromatography (HPLC) to yield a monomeric compound, GNH-2, with antibacterial activity. This substance showed broad-spectrum antimicrobial activity. At a concentration of 1.0 mg/mL, the GNH-2 inhibition zone diameters against Candida albicans, Escherichia coli, and E. coli 251 were 34±0.30 mm, 18±0.15 mm, and 19±0.10 mm, respectively. The GNH-2 inhibition zone diameters against S. aureus, MRSA, and Propionibacterium acnes were 28±0.10 mm, 30±0.10 mm, and 56±0.35 mm, respectively, which were better than those of vancomycin at the same concentration. The results of ninhydrin coloration preliminarily suggested that GNH-2 was a straight-chain peptide. This work provides the basis for subsequent structure confirmation and new drug development.
