RUQIYA, S.2023-01-162023-01-162022-12-28https://krishikosh.egranth.ac.in/handle/1/5810192440ThesisBacillus subtilis an endospore forming soil bacterium, popular for its biocontrol potential against numerous phytopathogens. In the present study we isolated several isolates of Bacillus subtilis from the soils of Western Ghats of Karnataka. They were initially characterized based on morphological parameters. The further confirmation of these Bacillus subtilis isolates were done by PCR amplification of 16S rRNAgene. The presence of lipopeptide genes i.e., surfactin (srfA) at 420 bp size, (srfAA) at 201 bp size, (sfp) at 675 size, fengycin (fenD) at 430 bp size, (fenB) at 675 bp size and bacillomycin (bmyB) at 410 bp size, confirmed through PCR using gene specific primers. Based on maximum number of gene, lipopeptides from Bacillus subtilis strain WGBS1 was chosen for characterization using MALDI TOF where surfactin and fengycin were confirmed by 1058 and 1478 m/z ratio respectively. Dual culture bio-assay of Bacillus subtilis strain WGBS1 was carried out against Fusarium oxysporum f. sp. udum, Sclerotinia sclerotiorum and Alternaria alternata that resulted in the inhibition of 42.38, 50.21 and 43.03 per cent respectively. The antagonistic activity of lipopeptides isolated from WGBS1 was tested on Fusarium oxysporum f. sp. udum, Sclerotinia sclerotiorum and Alternaria alternata at the concentration of 100 μl/ml showed the highest inhibition percentage i.e., 93.63, 98.76 and 97.98 per cent respectively. These promising bioassay results and molecular confirmation of lipopeptides producing genes describes the immense biocontrol potential of Bacillus subtilis strain WGBS1 and thus can find widespread applications in the field of agriculture as a potent bio-inoculant agent.EnglishThesis