Nisin Production in a Two Liters Bioreactor Using Lactococcus lactis NCIM 2114

Abstract

The facultative anaerobe, Lactococcus lactis was grown in batch fermentation (1.5 L working volume) at 30°C, using 5% inoculums to initiate growth for the production of the antimicrobial food additive nisin. L. lactis strain NCIM 2114 produced a maximal nisin concentration of 50,400 IU/mL and 8,830 IU/mg biomass in MRS growth medium using a 2 L bioreactor with optimal conditions of 25 rpm and 0.2 vvm determined by a Box Behnken design statistical package. Nisin was obtained from cell-free extracts and quantified using ultra-fast liquid chromatography (UFLC). Maximum bioactive nisin concentration was found at 4 h and harvested. Increasing aeration, agitation or time until harvest had negative impact on bioactive product yield. In a repeated trial under the same conditions, cell-free extracts of nisin were measured by well diffusion assay at 240 IU/mL (antimicrobial activity). Bioactive nisin was confirmed. The optimal specific growth rate for L. lactis was measured to be 0.25 h-1. This study shows that active biomass production can be increased using conditions determined by standard statistical methods.