Modeling of nisin production by Lactococcus lactis

Nisin, the only FDA approved bacteriocin, is widely used as a natural food preservative against Gram-positive bacteria. It is produced by lactic acid bacteria Lactococcus lactis subsp. lactis during fermentation. Mathematical models of biomass and nisin production during fermentation not only provide information about the kinetic-metabolic nature of nisin, but also facilitate the control and optimization of nisin production. In this study, several models were developed to describe biomass, nisin, and lactic acid production as well as sucrose consumption during nisin fermentation by L. lactis in suspended-cell batch culture. All models were designed so that they contained biologically relevant parameters. The re-modified logistic and Gompertz models proposed in this study adequately described the growth and the validation showed that they could be used for the prediction accurately (slope = 1.01, R-square = 0.99). For nisin production, the Luedeking-Piret model fit considerably well and could be successfully use to predict nisin production from the value of biomass (slope = 1.04, R-square = 0.98).