[Purification and identification of surfactin isoforms produced by Bacillus subtilis B2 strain]

Crude lipopeptide was extracted with methanol from the pellet which was precipitated with 6 mol/L HCl from the culture medium of Bacillus subtilis B2 strain. The crude lipopeptide was purified by gel filtration on Sephadex LH-20 column, the obtained product was referred to as sub-pure lipopeptide. The MALDI-TOF mass spectrum showed that B2 produced only lipopeptide surfactin. Sub-pure lipopeptide was run on muRPC C2/C18 column by HPLC SMART SYSTEM with aim at separation of surfactin isoforms. The surfactin isoforms fractions was detected by MALDI-TOF-PSD mass spectrometry, results indicated that the surfactin isoforms of B2 strain was cyclic lipodecapeptide L-Glu-L-Leu-D-Leu-L-Val-L-Asp-D-Leu-L-Leu containing fatty acid with a side chain length of 13, 14 and 15 carbon atoms.