A new member of the surfactin family produced by Bacillus subtilis with low toxicity on erythrocyte

Abstract

A new member of the surfactin family of microbial lipopeptides has been isolated from the cell broth of Bacillus subtilis TD 7 by reverse phase high performance liquid chromatography (RP-HPLC), and identified by FT-IR, GC–MS, LC–MS/MS, 1H-NMR and 13C-NMR. The surfactin-C11 consists of a heptapeptide with the sequence of N - Glu - Leu - Leu - Val - Asp - Leu - Leu - C, and a β-hydroxy fatty acid chain with 11 carbons, which is a new member with the shortest hydrophobic chain among the surfactin family produced by B. subtilis. The critical micelle concentration (CMC) of the surfactin-C11 is 5.59 × 10−5 mol/L in 10 mmol/L phosphate buffer solution (PBS, pH 7.4) at 25 °C, and the surface tension at CMC (γCMC) is 34.42 mN/m. The hemolytic activities of the surfactin-C11 on 2 % defibrinated sheep blood showed a HC50 of 448.51 μmol/L. Surfactin with short fatty acid chain has low toxicity on erythrocyte, which implies potential applications in biotechnological and pharmaceutical fields.