Nisin production of Lactococcus lactis N8 with hemin-stimulated cell respiration in fed-batch fermentation system

Abstract

In this study, nisin production of Lactococcus lactis N8 was optimized by independent variables of glucose, hemin and oxygen concentrations in fed-batch fermentation in which respiration of cells was stimulated with hemin. Response surface model was able to explain the changes of the nisin production of L. lactis N8 in fed-batch fermentation system with high fidelity (R2 98%) and insignificant lack of fit. Accordingly, the equation developed indicated the optimum parameters for glucose, hemin, and dissolved oxygen were 8 g L-1 h-1, 3 µg mL-1 and 40%, respectively. While 1711 IU mL-1 nisin was produced by L. lactis N8 in control fed-batch fermentation, 5410 IU mL-1 nisin production was achieved within the relevant optimum parameters where the respiration of cell was stimulated with hemin. Accordingly, nisin production was enhanced 3.1 fold in fed-batch fermentation using hemin. In conclusion the nisin production of L. lactis N8 was enhanced extensively as a result of increasing the biomass by stimulating the cell respiration with adding the hemin in the fed-batch fermentation. © 2015 American Institute of Chemical Engineers.