Elucidating the biosurfactant potential of <i>Bacillus</i> strains: a study of structure and function in food applications

Abstract This study explores the isolation and characterisation of biosurfactant-producing Bacillus strains. Four β-hemolytic isolates Bacillus velezensis (H6), Bacillus subtilis (S15 and S4), and Bacillus cereus (S32) were identified as potential biosurfactant producers. Among them, strain H6 showed the highest activity, reducing surface tension by 35 mN/m. This surface activity was further supported by FTIR analysis, which confirmed the lipopeptide nature of the compounds. In addition, thermogravimetric analysis indicated the thermal stability up to 140–190 °C. The biosurfactants also exhibited low critical micelle concentration values (0.3–0.5 g/L) outperformed sodium dodecyl sulphate and confirming their strong surface-active potential. Liquid chromatography–tandem mass spectrometry revealed diverse lipopeptide families, including surfactins, iturins, and fengycins, with strain H6 producing the highest levels. Overall, the biosurfactants displayed excellent functional properties, achieving up to 90% emulsification and foaming activity, which highlights their applicability in industrial sectors, particularly in food processing.