In-vitro Characterization and Purification of Bacteriocins Isolated from Probiotic Curd Culture

Introduction: Bacteriocins, the polypeptides secreted from probiotics proves to be a better choice of antimicrobials than that of synthetic antibiotics due to their negligible side effects and low cost. The present research focusses on the isolation of bacteriocin producing probiotic strains from homemade curd having good antagonistic properties against acne causing bacteria, Propniobacterium acnes. Bacteriocins are isolated, purified and dried. Morphological and general phenotypic tests are performed for identification of microorganisms. Effect of temperature, pH and bile salts on efficacy of bacteriocins is studied. Antimicrobial activity of bacteriocins is tested against the indicator strain by disc diffusion method. Normal sterile saline is used as a negative control and clindamycin is taken as a positive control. MRS media is used for culturing of microorganisms. Antimicrobial activity is recorded in terms of zone of inhibition in mm. Results: The isolates obtained from curd belongs to the lactobacillus family is proved by the usual phenotypic tests. Among the seven isolates obtained from curd, bacteriocins produced from isolate 6 shows maximum antimicrobial activity. Bacteriocins are most stable at pH range of 5-6 and temperature of 25-40°C. Activity decreases with increase in concentration of bile salts and completely diminishes at 11% bile salt concentration.