Metabolite profiling and molecular characterization of NBAIR BSWG1: A potential strain of Bacillus subtilis against Fusarium oxysporium f. sp. udum

To address the fungal wilt of pigeon pea caused by <i>Fusarium oxysporium</i> f. sp. <i>udum</i>, farmers currently rely on chemical fungicides, despite their harmful effects. However, there is a growing need for safer alternatives like green pesticides. Bacterial biocontrol agents and their derivatives serve as potential green pesticides in the management of plant pathogens. In the present study, we aimed to identify indigenous <i>Bacillus subtilis</i> strains effective against <i>F</i>. <i>oxysporium</i> f. sp. <i>udum</i>. We used PCR and MALDI-TOF analysis to identify the active components responsible for the efficiency of efficient strain. Biochemical studies of cell-free extracts extracted from <i>B</i>. <i>subtilis</i> strains demonstrated the highest biosurfactant activity in NBAIR BSWG1, with an oil displacement of 2 cm and an emulsification index of 60 %. Molecular characterization confirmed the presence of surfactin, fengycin, and iturin coding genes in the <i>B. subtilis</i> strains, among them, NBAIR BSWG1 showed the highest number of lipopeptide-producing genes. Meanwhile, NBAIR BSWG1 showed inhibition of 79.84 % against <i>F</i>. <i>oxysporium</i> f. sp. <i>udum</i> using cell-free extract. Further metabolite profiling of NBAIR BSWG1 using MALDI-TOF analysis further confirmed surfactin, fengycin, and iturin in the purified cell-free extract of NBAIR BSWG1. Two peaks with <i>m</i>/<i>z</i> of 923.77 and 1149.92 were identified as novel lipopeptide compounds which need further characterization. The present study identified NBAIR BSWG1 as an efficient bacterial strain for the inhibition of <i>F</i>. <i>oxysporium</i> f. sp. <i>udum</i> and its antifungal properties are mainly due to the production of cyclic lipopeptides.