رضا معصومی جهاندیزی

Background and Aim:Lactic acid bacteria (LAB) are important in foods as potential probiotics. Bacteriocins produced by LAB have received special attention in recent years due to their potential application in the food industry as natural biopreservatives. In this work, the bacteriocin produced by the dairy isolate Lactobacillus plantarum El3 was partially purified and characterized. Methods:The bacteriocin was extracted and percipitated by ammonium sulphate. Its antibacterial effect was assayed against foodborne pathogens including Escherichia coli(ATCC 1399), Bacillus cereus(ATCC 1431), Staphylococcus aureus(ATCC 29213), Yersinia enterocolitica(ATCC 35669), Shigella flexneri(PTCC 1234) by disk diffusion method. Also, effect of proteolytic enzymes (α-chymotrypsin and proteinase K) and heat (70, 100 and 121°C) was investigated. Bactericon was purified by Lammlie method. Molecular weight of bacteriocin was estimated by SDS-PAGE technique. Results:The produced bacteriocin could inhibite the growth of all used pathogens. Which the maximum zone of inhibition was attributed against E.coli (ATCC 1399) (15 mm) and minimum was against B. cereus (ATCC 1431) (10 mm).Also this compound was stable to heat. Bacteriocin was sensitive to proteolytic enzymes. Finally molecular weight was estimated approximally 6kDa. Conclusion:Consequentlly, the molecular weight confirm that produced bacteriocin of L.plantarum El3 belong the class II bacteriocins which are defined as group of small, heat-stable non lantibiotics bacteriocins.Heat stability of this bacteriocin prevent its denaturetion during food perservation methods. The bacteriocin can be easily degraded by proteolytic enzymes which makes them safe for human consumption.