The production of nisin by batch culture of Lactococcus lactis ATCC 11454 in MRS broth (pH 6.5), as treated in 30 assays, that were set up by a fractional factorial design of two levels (2([4similar to1])), was improved. The minimum and maximum concentrations of sucrose (5.0-12.5 g/L), asparagine (7.5-75 g/L), potassium phosphate (6.0-18.0 g/L), and Tween-80 (1.0-6.6 g/L) were added to MRS broth. The best nisin activities ranged from 1.5 x 10(4) to 1.8 x 10(4) arbitrary units (AU) /mL for the maximum levels of sucrose, asparagine, and monobasic potassium phosphate, and for the minimum concentration of Tween-80. The best following proportions between nutrients were adopted as optimum for maximum specific nisin productivity of about 6.0 mg/ mg of dry cell weight (related to 2.5 mg of pure nisin preparation with a specific activity of 1.0 x 10(5) AU/mL): C /N = 0.17, C /P = 0.69, N/P = 4.17 (C = sucrose, N = asparagine, P = phosphate, T = Tween-80).