Abstract:

Bacillus subtilis JA produces a broad spectrum of bioactive lipopeptides with great potential applications
in agriculture and industry. Crude lipopeptides were extracted with 100% methanol from the precipitate which was
obtained by adding 6 mol/L HCl to the cell-free culture broth. The crude extract was separated on a Diamonsil C18
column (5 μm, 250 mm×4.6 mm) in reversed-phase high performance liquid chromatography （HPLC） system to separate
the lipopeptide homologues. Five peaks were eluted from HPLC. Electrospray ionization mass spectrometry (ESI-MS) was
used to analyze each HPLC fraction. The results showed three series of ion peaks. According to the values of m/z,
the three series of ions were classified into surfactin, iturin and fengycin homologues, which were well-known
biosurfactants produced by B. subtilis strains. The major ions were structurally characterized using tandem mass
spectrometry. This study suggested a reasonable method for the isolation and identification of lipopeptides produced
by B. subtilis strains.

Key words: Bacillus
subtilis, lipopeptides , high performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESI-MS)