A Characterization and Evaluation of Antibacterial Efficacy of Bacteriocin Produced by Bacillus subtilis Isolated from Raw Milk

This study presents Bacteriocin (antimicrobial compound) produced from Bacillus subtilis isolated from unpasteurized milk. The antibiotic susceptibility tests for B. subtilis isolated from raw milk against various antibiotics demonstrated high sensitivity to Tetracycline, Moderate and less sensitivity towards Streptomycin and Chloramphenicol respectively while being resistant to Penicillin. Culture filtrate containing Bacteriocin showed thermostability (up to 100 °C), expressed a pH tolerance (2.0-10.0) and emerged resistance towards trypsin and pepsin. Partial purification of bacteriocin was performed using ammonium sulphate precipitation and then purified by passing into a column of Silica gel. In SDS-PAGE analysis, purified bacteriocin isolated from Bacillus subtilis showed the molecular weight to be approximately 3.4 KDa. The isolate Bacteriocin was tested finally for antibacterial activity against E. coli, associated with food borne illnesses. The zone of inhibition clearly proved that Bacteriocin has inhibitory effect on the food pathogen E. coli, thus confirming its bactericidal action in food.