Use of Bacteriocin Producing Lactococcus lactis subsp. lactis LABW4 to Prevent Listeria monocytogenes Induced Spoilage of Meat

Abstract

A bacteriocin producing strain of Lactococcus lactis subsp. lactis LABW4 was isolated from natu-rally fermented milk product which exhibited strong antibacterial activity against Listeria mono-cytogenes MTCC657, a food spoilage psychrophilic organism. Both cell free and heat killed super-natants of LABW4 were effective to produce zones of inhibition against L. monocytogenes in vitro. The antibacterial metabolite(s) of LABW4 showed strong cidal effect on the growth of L. monocy-togenes. Meat samples, mixed with heat killed supernatant of LABW4 when inoculated with Lis-teria, remain fresh up to 25 days in refrigerated condition whereas spoilage started immediately after 24 hours of inoculation for control sets. Enhancement of Lactate dehydrogenase of L. mono-cytogenes upon treatment with LABW4 cell free supernatant suggested its lytic mode of action. Cell lysis or degradations were also supported by scanning electron micrograph of treated cells.