Sustainable Disruption of Microbial Biofilms: Functional and Antimicrobial Assessment of a Lipopeptide Biosurfactant

Biofilm-associated infections pose significant challenges due to the increased antibiotic resistance of microorganisms within these structures. This study involved isolating and characterizing the biosurfactant produced by Bacillus subtilis RSL-2 using molasses to develop a sustainable antibiofilm agent. The biosurfactant was identified as a surfactin-like lipopeptide (molecular weight: 1037 g/mol) based on FTIR, ¹H NMR, and HRMS analyses. It demonstrated a low critical micelle concentration (CMC) of 70 mg/L and markedly decreased surface and interfacial tensions to 24.46 and 0.46 mN/m, respectively. Functional experiments revealed significant surface activity, as evidenced by a 2.2 cm oil-displacement zone and an emulsification index of 91% in toluene. The surfactin demonstrated concentration-dependent antibacterial and antibiofilm efficacy against Staphylococcus aureus, Enterococcus hirae, Bacillus subtilis, Escherichia coli, Agrobacterium, Pseudomonas aeruginosa, Aspergillus, and Candida at their respective IC₉₀ values. The producer strains exhibited high IC₉₀ values, likely reflecting their inherent tolerance to surfactants. Surfactin's eco-friendliness, antibiofilm activity, and functional adaptability make it a promising agent for managing biofilms in both medicinal and industrial applications. This work highlights the strategic potential of molasses-derived biosurfactants as environmentally friendly and sustainable options for antibacterial and antifungal applications, particularly for addressing biofilm-associated infections.