Enzymatic and biosurfactant production with antimicrobial activity by Bacillus subtilis group.

Biosurfactants are valuable microbial metabolites with broad industrial and environmental applications. In this study, we investigated biosurfactant production by Bacillus subtilis group strains using residual glycerol as the sole carbon source, while also evaluating their enzymatic activity and antimicrobial properties. PCR-based gene detection confirmed the presence of genes encoding surfactin, fengycin, and iturin peptide biosynthesis. Crude glycerol, a byproduct of biodiesel production, supported biosurfactant synthesis by the tested strains. Strains CCMA 0087, 0658, and 2031 exhibited diesel oil emulsification rates ranging from approximately 53 to 61%, while also reducing water surface tension to around 30 mN/m. Notably, the crude biosurfactant produced by Bacillus velezensis CCMA 0087 inhibited Escherichia coli growth, whereas Bacillus subtilis CCMA 2031 partially inhibited Fusarium paranaense (~ 38%), representing the first report of biosurfactant activity against this phytopathogen. Ligninolytic enzyme assays revealed that strain 2031 exhibited the highest manganese peroxidase (MnP) activity, while 0087 showed the greatest lignin peroxidase (LiP) activity. These findings highlight the potential of biosurfactants and ligninolytic enzymes from Bacillus subtilis group strains for biocontrol and bioremediation applications.