Isolation, Screening and Molecular Identification of Bacteriocin producing Lactic Acid Bacteria possessing wide spectrum Antibacterial Activity

The advent of health issues due to the presence of chemical preservatives in food items has caught the attention of majority of consumers. More recently, biopreservatives like bacteriocins produced from lactic acid bacteria (LAB) have been observed to hold potential in preservation of food as these have no harmful effect on human health. The present research is focused on the isolation and identification of bacteriocin producing lactic acid bacteria from milk samples. A total of 25 LAB isolated from milk were used to determine their antibacterial activity against potent food pathogenic indicator organisms. Both cell free supernatant and partially purified bacteriocins extracted from selected isolates were compared for their antibacterial spectrum. A total of 12 isolates exhibiting good antibacterial potential against food spoiling bacteria (Escherichia coli, Pseudomonas aeruginosa, Listeria monocytogenes, Bacillus cereus, Staphylococcus aureus and Shigella flexnen) were further subjected to molecular identification using 16S rRNA gene amplification. The isolates followed by sequencing were identified as belonging to five different species of Lactobacillus; however, a majority of them were of Lactobacillus plantarum species. One bacteriocin producing strain identified in the present study as Lactobacillus herbarum has been reported by very few researchers till date, hence it may have the potential to produce novel bacteriocin.