Isolation, production and characterization of bacteriocins produced by strains from indigenous environments

摘要

About 300 bacterial strains (belonging to different genera) were isolated from different indigenous ecological niches. The sources include food (milk and yogurt), water (drinking water and waste water), soil (garden), stool (healthy infants) and clinical samples. The isolates were screened for their bacteriocin production where 54.3% were found as bacteriocin producers. Among them, Lactobacilli, Pseudomonas, Proteus and Staphylococci displayed good potential of bacteriocin production. Pseudomonas aeruginosa SA 188 (a garden soil isolate) was grown in Brain Heart infusion broth of pH 6-7 at 290C overnight (optimum conditions for bacteriocin production). The possibility of bacteriophage activity was also excluded. Partial purification of this pyocin SA188 was achieved after 70% ammonium sulphate precipitation. The bacteriocin titer was calculated to be 640AU/ml.This pyocin did not respond to proteolytic and lipolytic enzymes. It retained its activity at 1000C for 15 minutes and pH range of 4 to 10. Surfactants such as SDS could enhance the production of bacteriocin while organic solvents and metal salts had no effect on its production profile.