Bacillus spp. for suppression of eggplant bacterial wilt pathogen in Andaman Islands: Isolation and characterization

Bacillus spp. isolated from different soils of Andaman Islands was characterized for antimicrobial potential by different methods. Among 65 strains tested, six Bacillus strains showed best in vitro antagonistic potential against solanaceous bacterial wilt pathogen Ralstonia solanacearum. The identity of the Bacillus strains were confirmed using 16S rRNA gene sequencing and biolog based phenotypic fingerprinting. The functional analysis revealed that most of the strains were positive for the production of IAA, siderophore and phosphate solubilization. In glass house and field studies, Bacillus amyloliquifaceans strain (Bs_Abi) showed significant biocontrol efficacy (92.1 and 73.7%, respectively) against brinjal bacterial wilt disease. The antimicrobial potential of Bs_Abi were further ascertained by presence of nine antimicrobial peptide (AMP) gene biosynthesis in PCR amplifications which confirmed the presence of peptide genes for six antibiotics (iturin, bacillomycin D, mycosubtilin, surfactin, bacilysin and subtilin). Our study revealed that the utilization of such antagonistic Bacillus spp. with multi antimicrobial peptide genes and more functional traits from tropical/ extreme soils would play a vital role in management of eggplant bacterial wilt disease and in formulation of new bioinoculants for improving the cropping system in Andaman and Nicobar Islands