Broad Antimicrobial-spectrum of Plantaricin LR14 against Gram-positive and Gram-negative Bacteria

Bacteriocin, plantaricin LR14 was purified from a natural isolate of Lactobacillus plantarum LR/14 and showed bactericidal mode of action when treated with cells of target bacteria as described in our previous study. Here, antimicrobial activity of purified plantaricin LR14 was monitored in terms of loss of viable count of sensitive strains after treatment. Both time-bound and concentration-based response of plantaricin LR14 on the loss of viable count of target bacteria was observed. While it was active against indicator strain Micrococcus luteus, some other Gram-positive as well as Gram-negative bacteria were also affected. Pathogenic strains including strictly food-borne pathogens such as Listeria monocytogenes, Salmonella, Yersinia enterocolitica, and Bacillus licheniformis were inhibited by plantaricin LR14. The inhibition could also be demonstrated of a clinical urogenic strain of Escherichia coli. Inhibition of Gram-positive as well as Gram-negative bacteria implies that plantaricin LR14 has a broad host-range inhibitory spectrum, which may have applications not only in food safety but in some clinical settings as well.