摘要：Lactic Acid Bacteria (LAB) predominates the micro flora of fermented products. They produce metabolites that inhibit the growth of food-borne pathogens and spoilage microorganisms. The objectives of the present study were isolation, identification of LAB from traditional Indian fermented foods and study of physical and cultural parameters on the bacteriocins produced by them. Seven isolates of bacteriocin producing LAB were isolated from curd, dosa batter and idli batter and were identified as species of Lactobacillus . The culture supernatants of the seven isolates were evaluated for their antimicrobial activity against pathogens like Staphylococcus aureus and Pseudomonas sp. The stability of the bacteriocins was tested at different temperatures, pH, presence of bile salt like sodium deoxycholate and storage period at 4°C. The diameters of the inhibitory zones ranged between 9 and 12 mm for Staphylococcus aureus , with no effect on Pseudomonas . The bacteriocins produced by the isolates were stable at temperatures ranging between 30 to 80°C and over a wide range of pH from 2 to10, with the highest activity at pH 6. It was also found that the bacteriocins were stable at different concentrations of the bile salt used and remained active even after a storage period of 30 days at 4°C. Sodium Dodecyl Sulphate polyacrylamide gel electrophoretic analysis of the partially purified bacteriocins suggested their apparent molecular weights between 16.5 to 48 kDa. These bacteriocins may have a potential use as food biopreservatives and may help in improving the gut environment by combating several pathogenic microorganisms.
