Biological Activity Of Bacteriocin Produced By Lactobacillus Pentosus Isolated From Fermented Milk

Abstract

Isolated lactic acid bacteria (LAB) from a variety of foods are significant because they have the ability to suppress microorganisms, including bacteria that are resistant to drugs.The objectives of this research were to isolate and identify antibacterial substances producing LAB from fermented milk (yougrt) and to optimize the production of bacteriocin present in cell free supernatant (CFS) against bacterial strains responsible for food borne illness.For current studies Lactobacillus pentosus was isolated from yogurt by serial dilutions and grown on nutrient agar. Agar well diffusion assay was used to study antibacterial activity of bacteriocin against E.coli, Bacillus subtilis, Bacillus cerus and Staphylococcus aureus. The zone of inhibition was measured to track antibacterial activity. Different range of temperature (40⁰C, 600C, 80⁰C, 100⁰C and 120⁰C), pH (3, 5, 7, 9 and 11) and concentrations (25mg/ml, 50mg/ml, 75mg/ml, 100mg/ml) of bacteriocin were investigated in relation to cell free supernatant (CFS) activity. Bacteriocin showed maximum antibacterial effect against B. subtilis at 60⁰C which is 3±0.10 and against B. cerus at pH 5 as 4.6±2.08 and the concentration was 100mg/ml at which bacteriocin showed maximum antibacterial effect against E. coli as 2.8±0.3. On the other hand, minimum antibacterial effect was shown by bacteriocin against S. aureus at 120⁰C as 1.06±0.2 and no effect was shown by bacteriocin at pH 11. 50mg/ml showed minimum antibacterial effect which is 1.0±0.32. The action of bacteriocin was compared with antibiotic Amoxil (500mg) as a positive control. Mean values for zone of inhibition for variables under study were compared using one-way ANOVA. The outcomes of this study suggested that bacteriocin's heat stability makes it possible for the food industry to employ it as preservative of food and to prevent poisoning caused by B. cereus and other pathogenic strains.