Biocontrol potential and molecular characterization of lipopeptides producing Bacillus subtilis against Sclerotinia sclerotiorum

Bacillus subtilis is a Gram-positive and endospore producing bacterium. Limited studies have shown that lipopeptides produced by B. subtilis can be inhibitory to phytopathogens. Sclerotinia sclerotiorum is a plant pathogenic fungus which causes various diseases like cotton rot, watery soft rot, stem rot, crown rot and blossom blight in vegetable crops. The objective of the study was to isolate lipopeptides from B. subtilis and study their inhibitory potential against S. sclerotiorum. So, the B. subtilis isolates were extracted from the collected soils of Western Ghats of India. They were initially characterized through morphological parameters followed by PCR amplification of the 16S rDNA gene and confirmation through BLAST algorithm in NCBI database. The lipopeptides produced by these isolates were tested against S. sclerotiorum. B. subtilis strains were effective against S. sclerotiorum and exhibited 18.33 to 29.5 % inhibition under dual culture bio-assay. The antagonistic activity of lipopeptides extracted from B. subtilis strains showed 21.56 to 88.89 % inhibition of S. sclerotiorum in the lowest to highest concentration of lipopeptide tested and was found to be significantly higher than the control. The present study has shown that B. subtilis strains vary in the production of lipopeptides and some of them could produce lipopeptides that are highly inhibitory to S. sclerotiorum. B. subtilis strain NBAIR BSWG1 showed the highest inhibition for S. sclerotiorum. Lipopeptide based poison food technique and the dual culture bioassay results showed that B. subtilis strain NBAIR BSWG1 has immense potential for use in the biological control of S. sclerotiorum. Further studies are being carried out in formulating the lipopeptides for field application.