Isolation and characterization of a C12-lipopeptide produced by Bacillus subtilis HSO 121

A new lipopeptide with C-12 fatty acid has been isolated from the cell broth of Bacillus subtilis HSO121 by chromatographic methods, which is believed to be the homologue of lipopeptides. The fatty acid portion was methylated and analyzed by GC/MS, ESI Q-TOF MS and H-1-NMR. The peptide portion, of which the amino acid composition was obtained by HPLC combined with a phenyl isothiocyanate (PITC) derivatization methods, was analyzed by ESI Q-TOF MS. Comparing the obtained results with surfactin C-13 showed that the new lipopeptide has a peptide moiety similar to that of surfactin and the difference exists in the fatty acid portion, which is an iso-C-12 beta-hydroxy fatty acid. The critical micelle concentration (CMC) of this new homologue is estimated to be 6.27 x 10(-5) mol/l in 10 mmol/l phosphate buffer solution (PBS, pH 8.0) at 30 degrees C, and the surface tension at CMC (gamma(CMC)) achieved is as little as 27.71 mN/m. The hemolytic activities of the C-12-lipopeptide on 2% human erythrocytes showed a HC50 of 26.5 mu mol/l. Copyright (C) 2008 European Peptide Society and John Wiley & Sons, Ltd.