Identification of antifungal compound produced by Bacillus subtilis LB5 with ability to control anthracnose disease caused by Colletotrichum gloeosporioides

Abstract

Bacillus subtilis strain LB5 showed inhibitory activity on conidial germination ofColletotrichum gloesporioides causal agent of mango and wax apple anthracnose disease. The antifungal metabolites produced by B. subtilis strain LB5 were highly stable to heat, pH ranging from 3 to 11, and ultraviolet (UV) light. Cell-free supernatant of LB5 culture broth was extracted by using n-butanol to give the n-butanol soluble fraction, which was purified by reversed phase high-performance liquid chromatography (RP-HPLC) to obtain the major antifungal compound. The structure of antifungal compound was identified as iturin A-2, a cyclic lipopeptide antibiotic, based on the analysis of 1H and 13C nuclear magnetic resonance (NMR) and fast atom bombardment mass spectrometry (FAB-MS) spectra. Key words: Bacillus subtilis LB5, Colletotrichum gloeosporioides, reversed phase high-performance liquid chromatography (RP-HPLC), nuclear magnetic resonance (NMR), fast atom bombardment mass spectrometry (FAB-MS), antifungal compound, iturin A-2.