INHIBITION OF LISTERIA-MONOCYTOGENES BY PLANTARICIN NA, AN ANTIBACTERIAL SUBSTANCE FROM LACTOBACILLUS-PLANTARUM

A Lactobacillus plantarum of vegetable origin produced a bacteriocin i nhibitory to Listeria monocytogenes. The antimicrobial agent was inact ivated by proteolytic enzymes, was resistant to heat (100 degrees C fo r 30 min) and stable over a wide pH range (pH 2-10), and displayed a b actericidal mode of action. Growth inhibition of L. monocytogenes depe nd on bacteriocin concentration. The antilisterial efficiency depended on the strain of L. monocytogenes used but was not influenced by the growth phase of this strain. A decrease in absorbance overtime, indica tive of cell lysis, was also observed. The significance of the results is discussed in relation to the potential of the bacteriocin in contr olling Listeria-associated food-borne hazards in foods.