Studies on Nisin Production by Isolated Lactobacillus Species in Aqueous Two-phase System

Isolated lactobacillus sp.(from cheese whey) was examined for its ability to produce bacteriocin like nisin in submerged fermentation and aqueous two-phase system(ATPS) at pH 6.5, 30.C for 18 h fermentation using M17S medium with 5%(v/v) inoculum and the nisin yields were obtained 4500 IU/ml and 20216 IU/ml where as biomass yield obtained 19.55 mg/ml and 31.88 mg/ml respectively.The maximum yield of nisin (24800 IU/ml) and biomass (22.49 mg/ml) were obtained in ATPS (28% PEG 6000 and 4% MgSO4.7H20 with 5-times concentrated M17 medium containing 0.5% lactose as carbon source) under similar conditions.