Structural characterization of a biosurfactant produced by Bacillus subtilis at 45 degrees C

Structural and biochemical characterization of a biosurfactant produced by Bacillus subtilis under thermophilic conditions was performed. Preliminary structural determination of CHCl3/CH3OH (65:15) extracts by thin-layer chro matographic reagents showed it to be identical to surfactin. Also, the infr ared, H-1 nuclear magnetic resonance, and mass spectroscopy analysis confir med it to be identical to surfactin. Biochemically, the surfactant was a li popeptide-containing lipid (17.05%) and protein (13.2%). The surfactant yie lded a minimal aqueous surface-tension Value of 28 dyne/cm and an interfaci al tension Value at 0.1% concentration of 0.2 dyne/cm against diesel oil. T he critical micelle concentration of the surfactant was 35 mg/L. The biosur factant exhibited an emulsification value (E-24) Of 90 against diesel oil a nd a sand-pack oil recovery of 62%. It has potential application in microbi al-enhanced oil recovery in thermophilic, alkaline, acidic, and halophilic environments.