Comparative effectiveness of nisin and bacteriocin J46 at different pH values

A comparative study of the inhibitory activity of nisin, the well-known lantibiotic produced by certain strains of Lactococcus lactis subsp. lactis, and of the bacteriocin produced by L. lactis subsp. cremoris J46, a strain previously isolated from fermented milk, was conducted. For both bacteriocins, the activity against L. lactis subsp. cremoris decreased with increasing pH. In addition, the bacteriocin preparations were more stable at 4 degrees than at 20 degrees C. The influence of the storage temperature was more crucial for nisin. Essentially the same activity was observed for bacteriocin J46 stored for 3 h at 4 degrees or 20 degrees C. More interesting was the observed stability of bacteriocin J46 at pH values between 5.8 and 6.8. For example, about 23% of nisin activity was lost at pH 6.4 whereas no loss of bacteriocin J46 activity was observed.