The objective of the study was to purify and characterize the antimicrobial protein produced by B.amyloliquefaciens MBL27. An antimicrobial protein isolated from Bacillus amyloliquefaciens MBL27 displays a broad inhibitory spectrum against various Gram negative and Gram positive organisms including clinical pathogens. The proteinaceous compound was isolated from cell-free culture supernatant by (NH4)2SO4 precipitation (40%, w/v saturation) and further purified by ion-exchange chromatography followed by gel filtration on Sephadex G-100 column. The entire purification protocol led to 17.8-fold increase and on SDS-PAGE gels, the protein showed a single band and it is a monomer of 34 kDa. Activity gel electrophoresis also revealed one clear zone of inhibitory activity that corresponded to the band obtained with SDS-PAGE. The inhibitory activity of antimicrobial protein was insensitive to catalase but sensitive to Trichloroacetic acid. It was found to be thermostable and maintained its activity in a wide range of pH.
Keywords: Antimicrobial protein, Bacillus amyloliquefaciens, chromatography, gel electrophoresis, purification