Isolation, Partial Purification, and Characterization of Antimicrobial Peptide from Bacillus amyloliquefaciens

Antimicrobial peptides are getting an increased interest in the pharmaceutical world due to emerging antibiotic resistance rates. In this study, Bacillus strains isolated from soil of Kahramanmaras province, Turkiye and screened for antibacterial activity. Among 480 isolates, 22 (4.5%) exhibited inhibitory effects, and strain G1 demonstrated the highest activity against S. aureus and E. coli. Based on the 16S rDNA sequence analyses, the strain G1 revealed close phylogenetic affiliation with Bacillus amyloliquefaciens. Antibacterial compound production was evaluated in different growth media and Nutrient Broth was the best medium for antimicrobial compounds production. Co-culture experiments with S.aureus and E.coli indicated that no microbial competition is required for antimicrobial peptide production. Antimicrobial peptide was partially purified using Ammonium sulfate precipitation method and the highest antimicrobial activity was detected with 60% saturation. The antimicrobial activity was retained after dialysis and lyophilization, indicating notable stability of the compound. According to the gradient SDS-PAGE analysis, a protein band of approximately 8.16 kDa was detected showing antibacterial activity. The results showed that Bacillus sp. G1 produces an extracellular, low molecular weight antimicrobial peptide acting on both Staphylococcus aureus and Escherichia coli. These findings indicate potentially promising antimicrobial peptides from Bacillus strain for biotechnological and pharmaceutical applications. Further studies focusing on purification, structural characterization, and mechanism of action are required to fully elucidate its potential.