PURIFICATION AND CHARACTERIZATION OF BACTERIOCIN PRODUCED BY DIFFERENT Lactobacillus SPECIES ISOLATED FROM FERMENTED FOODS

The aim of the study was to isolate and characterize bacteriocin producing Lactic acid bacteria (LAB) from fermented foods products and to exploit their potential as biopreservatives. The two Lactobacillus strains namely L. plantarum and L. fermentum exhibiting wide spectrum of activity against closely related strain were selected and screened for their bacteriocin producing ability. Cell free supernatant fluid collected from both the isolates and several gram positive and gram negative pathogens such as S.aureus, E.coli, P.aeruginosa, S.pneumoniae, Klebisella, and proteus were inhibited by the inhibitory action of bacteriocins in study. The bacteriocinogenic potential in these strains appeared non-inducible and increase in their titer was observed after exposure to different concentrations of UV light. The concentrated crude bacteriocin samples subjected to ammonium sulphate precipitation resulted in an increased activity and high protein yield. By non-denaturing gel a band of approximately 8 KDa for L. fermentum and band corresponding to 37KDa in L. plantarum was seen. Physio-chemical characterization of the partially purified bacteriocin samples indicated heat (121°C for 60 min) and acidic pH stability (pH 2-6) of bacteriocin. Exposure to different carbon and other substations also resulted in increased bacteriocin titer. The high performance liquid chromatography was performed for L. plantarum.