Synthesis of enhanced biosurfactant by Bacillus subtilis MTCC 2423 at 45°C by foam fractionation

Production of a lipopeptide surfactant in a 6.5-L batch fermentor was carried out using Bacillus subtilis MTCC 2423 at 45 degreesC. A good yield was obtained from sucrose (2%) substrate fermentation by continuous removal of the product by foam fractionation. The biosurfactant was recovered from collapsed foam by acid precipitation. The biosurfactant yield (4.5 g/L was about 4.5 times higher than the yield (ca. 1 g/L obtained by shake-flask fermentation. Surface activity of the collapsed foam was very high, and total surface activity was observed in the collapsed foam. The structural characterization of this biosurfactant produced at 45 degreesC by the strain used in this study was recently reported. The biosurfactant was analyzed by thin-layer chromatography, infrared, H-1 nuclear magnetic resonance, and mass spectroscopy and was found to be identical to surfactin, a lipopeptide surfactant.