interactionchromatographyCommercial nisin was previously diluted in phosphate-buffered saline (0.1 M, pH 7.2, PBS) or Milli-Q water (100 mg/mL,4 log10AU/mL), whereas nisin produced in-house (4982 g/mLof total protein; 4 log10AU/mL) was not diluted. To guaran-tee the hydrophobic interaction, ammonium sulphate wasadded to the samples in sufficient amount to achieve 2 M offinal concentration. From these solutions, a sample (3 mL) wasloaded onto the column. A column (10-mm diameter, 10-cmlength) was packed with butyl sepharose CL 4B matrix (5 mL;GE Healthcare, Uppsala, Sweden). It was equilibrated using3–4 column volumes (1 mL/min) of ammonium sulphate (2 M)in PBS (first profile) or water (second profile). Diluted sam-ples were sequentially eluted with 3 column volumes of (a)2 M ammonium sulphate, (b) 1 M ammonium sulphate and (c)solvent (PBS or water).Elution was performed at a 1 mL/min flow rate and eachcollected fraction contained 1 mL. Fractions were monitoredby absorbance (280 nm), protein content, and nisin activity.