Development of a lacticin 3147-enriched whey powder with inhibitory activity against foodborne pathogens

The broad-spectrum bacteriocin lacticin 3147, produced by Lactococcus lacti s DPC3147, is inhibitory to a wide range of gram-positive food spoilage and pathogenic organisms. A 10% solution of demineralized whey powder was ferm ented with DPC3147 at a constant pH of 6.5. The fermentate was spray dried, and the resulting powder exhibited inhibitory activity. The ability of the lacticin 3147-enriched powder to inhibit Listeria monocytogenes Scott A an d Staphylococcus aureus 10 was assessed in buffer at both acidic (pH 5) and neutral (pH 7) pH. In addition, the ability of the powder to inhibit L. mo nocytogenes Scott A in an infant milk formulation was assessed. Resuspensio n of approximately 10(8) midexponential phase L. monocytogenes Scott A cell s in a 10% solution of the lacticin 3147-enriched powder resulted in a 1,00 0-fold reduction in viable cells at pH 5 and pH 7 after 3 h at 30 degrees C . In the case of S. aureus 10, resuspension of 2.5 X 10(7) midexponential p hase cells in a 15% solution of the lacticin 3147-enriched powder at pH 5 r esulted in only a 10-fold reduction in viable cell counts, compared with a 1,000-fold reduction at pH 7, following incubation for 3 h at 30 degrees C. The use of the lacticin 3147 powder in an infant milk formulation resulted in greater than a 99% kill of L. monocytogenes within 3 h at 30 degrees C. These results suggest that this bioactive lacticin 3147 food ingredient ma y find applications in many different foods, including those with pH close to neutrality.