Isolation and characterization of a surfactin-like biosurfactant produced by <i>Bacillus subtilis</i> 3KP isolated from oil-contaminated soil in Indonesia

Biosurfactants are surface-active compounds that have many benefits. This research aims to isolate and identify biosurfactants produced by B. subtilis 3KP when cultured on a molasses substrate. The isolation and purification procedure included gradual ammonium sulfate precipitation, ion exchange and adsorption chromatography. Identification and characterization using high-pressure liquid chromatography, gas chromatography-mass spectrometry, amino acid analyzer, UV-V is spectroscopy, and infrared spectroscopy confirmed that B. subtilis 3KP biosurfactant is a lipopeptide. The biosurfactant produced by B. subtilis 3KP was determined to be a surfactin isoform, characterized by a 16-carbon fatty acid chain. The purified biosurfactant successfully decreased the surface tension from 72 mN/m to 27 mN/m and reached the critical micelle concentration at a precise value of 20.01 mg/L. This biosurfactant product is stable at 30°C-65°C, pH 4-8, and salinity 0-4 M. Therefore, the presented isolate has tremendous potential to produce surfactin-type biosurfactants which can be developed and utilized for various industrial fields.