title: Structural characterization of a biosurfactant produced by Bacillus subtilis at 45°C creator: Makkar, R S creator: Cameotra, Swaranjit Singh subject: QR Microbiology description: 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 chromatographic reagents showed it to be identical to surfactin. Also, the infrared, 1H nuclear magnetic resonance, and mass spectroscopy analysis confirmed it to be identical to surfactin. Biochemically, the surfactant was a lipopeptide-containing lipid (17.05%) and protein (13.2%). The surfactant yielded a minimal aqueous surface-tension value of 28 dyne/cm and an interfacial tension value at 0.1% concentration of 0.2 dyne/cm against diesel oil. The critical micelle concentration of the surfactant was 35 mg/L. The biosurfactant exhibited an emulsification value (E 24) of 90 against diesel oil and a sand-pack oil recovery of 62%. It has potential application in microbial-enhanced oil recovery in thermophilic, alkaline, acidic, and halophilic environments publisher: Springer Science date: 1999 type: Article type: PeerReviewed format: application/pdf identifier: http://crdd.osdd.net/open/821/1/swaranjit1999.1.pdf relation: http://dx.doi.org/10.1007/s11743-999-0091-6 identifier: Makkar, R S and Cameotra, Swaranjit Singh (1999) Structural characterization of a biosurfactant produced by Bacillus subtilis at 45°C. Journal of Surfactants and Detergents, 2 (3). pp. 367-372. ISSN 1097-3958 relation: http://crdd.osdd.net/open/821/