ISOLATION AND PURIFICATION OF LOW MOLECULAR WEIGHT PEPTIDE FROM MARINE B.cereus AND IT’S ANTIMICROBIAL ACTIVITY

Many marine sponges contain dense, highly diverse microbial communities. In the present study, totally eight associated bacterial strains were isolated from sponge namely Hyattella cribriformis. Isolated associated bacterial strains were tested for the antibacterial activity against human bacterial pathogens such as Staphylococcus aureus, Vibrio cholerae, Salmonella paratyphi, Klebsiella pneumoniae, Salmonella typhi, Proteus mirabilis, Klebsiella oxytoca, E.coli, Pseudomonas aeruginosa and Lactobacillus bulgaricus on Muller Hinton agar plates. The most potential strain was selected based on their antibacterial activity and it was characterized by biochemical tests and 16S rDNA sequencing. Phylogenetic analysis indicated that the strain has high sequence similarity with Bacillus cereus. It was designated as Bacillus cereus SBS02. An antagonistic low molecular weight protein was purified from the culture supernatant using centrifugation filters, having cut-off value of 10 kDa and gel filtration chromatography. A low molecular weight antibiotic peptide of 8KDa was obtained and analyzed by 15% SDS-PAGE. It was inhibitory to human pathogens and food-spoilage bacteria, such as C. albicans, Listeria monocytogenes and Pseudomonas aeruginosa, B. cereus, B.subtilis and other LABs viz, L. bulgaricus and L. vulgaris. The purified protein was thermostable as well as tolerant to wide range of pH. Based on the properties (inhibition of closely related spp. and stability) it was confirmed as class II bacteriocin produced by B.cereus and designated as Cerein SBS02. © 2013 Universal Research Publications. All rights reserved