The production of a highly concentrated probiotic preparation of Lactococcus lactis CECT 539 was studied in both batch and realkalized fed-batch fermentations in diluted whey (DW) media (DW25, DW50, DW75, DW100, and DW125) supplemented with MRS broth nutrients (except glucose and Tween 80) at 25, 50, 75, 100, and 125% of their standard concentrations in the complex medium. The fed-batch culture using DW100 medium provided the highest concentrations of probiotic biomass (5.98 g/L) and nisin (258.47 BU/mL), which were obtained at lower production costs than those estimated for the fed-batch culture in DW medium. The batch and fed-batch cultures reduced the initial chemical oxygen demand (COD) of the media by 29.1-41.7% and 31.2-54.2%, respectively. Graphical abstract.
Keywords: Batch fermentation; Fed-batch fermentation; Nisin; Probiotic biomass; Whey.