IN VITRO AND IN SILICO CHARACTERIZATION OF SURFACTIN PRODUCED BY PAENIBACILLUS AQUISTAGNI OP288247 ISOLATED FROM BALIOSPERMUM MONTANUM

Abstract

Novel antimicrobial agents are urgently needed due to the rising incidence of antibiotic-resistant infections. Although medicinal plants like Baliospermum montanum are endangered and scarce, plant-associated bacteria offer a promising source of bioactive compounds. The antibacterial capability of B. montanum plant-associated bacteria was assessed in this investigation. A total of 17 bacterial isolates have been examined for antibacterial activity against 6 pathogenic bacteria: Proteus vulgaris, Staphylococcus aureus, Streptococcus pyogenes, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae.  The isolate with most potent antibacterial activity was S4S2, which was identified as Paenibacillus aquistagni OP288247 by 16S ribosomal RNA gene sequencing. Four fractions were obtained by column chromatography; the second fraction exhibited strong antibacterial activity. Thin-layer chromatography (TLC) and bioautography have been utilised to localize active ingredient, which was identified as surfactin by liquid chromatography-mass spectrometry (LC–MS) analysis. The TLC-purified active fraction demonstrated dose–dependent inhibition of S. aureus biofilm formation, with maximum inhibition of 33.33% at 1.0 mg/mL. Molecular docking demonstrated that surfactin exhibited a favorable interaction with the S. aureus virulence protein CifB, with a binding affinity of -6.4kcal/mol. This study identifies surfactin as a promising candidate and demonstrates, for the first time, that plant-associated bacteria from B. montanum contribute to the antimicrobial potential of this medicinal plant.