Production of nisin‐like bacteriocins by Lactococcus lactis strains isolated from vegetables

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Abstract
Four bacteriocin producing lactic acid bacteria isolated from vegetables were identified as Lactococcus lactis strains on the basis of physiological and biochemical characteristics, carbohydrate fermentation patterns and analysis of total soluble protein pattern by SDS PAGE. The bacteriocins had a wide spectrum of activity as antagonism was detected not only towards a variety of lactic acid bacteria, but also to Staphylococcus aureus and Listeria monocytogenes. These bacteriocins were resistant to heating at 121 °C for 15 minutes and showed highest activity at low pH (Lactococcus strains were all immune to the bacteriocins produced as well as to commerical nisin. Bacteriocin producer culture supernatants showed a high degree (70 or 100%) of cross‐reactivity in the nisin ELISA, suggesting similarity of the produced bacteriocins to nisin. The potential application of bacteriocin producing lactococci of vegetable origin for safety assurance of vegetable foods and controlling vegetable fermentations is discussed.