The effect of nisin concentration and nutrient depletion on nisin production of Lactococcus lactis.

The kinetics of nisin production was studied in batch cultures using a construct of Lactococcus lactis subsp. lactis C2SmPrt-, containing a transposon (TnNip) that encodes nisin production. The introduction of TnNip into C2SmPrt- significantly lowered the specific growth rate and the maximum A620 reached was reduced from 15.2 to 11.0. The effect of nisin concentration and nutrient depletion on nisin production of the construct, C2SmPrt-(TnNip), was examined. Nisin production was found to be inhibited by high concentrations of nisin, when grown in excess nutrient, even though growth of the culture continued because nutrient limitation was not operating. However, in low nutrient concentrations nisin production was limited by nutrient depletion. The specific growth rate of C2SmPrt-(TnNip) was altered, by using different nutrient concentrations and different sugars, in order to examine the relationship between nisin production and growth. Nisin production was shown to be growth-associated for most of growth, but near the end of growth, when the specific growth rate was 0.05 h-1 or less, the production ceased.