One-step Removal of Proteases in a Commercial Lactase Preparation from Kluyveromyces lactis Using an Anion-exchange Membrane

Abstract

To reduce proteases in a commercial lactase preparation from K. lactis, enzyme preparations were diluted by a buffer with KCl and the dilutions were flushed through a weak anion-exchange membrane. For KCl concentration in the range of 0.20 to 0.25 M, more than 90% of lactase was recovered and protease level was decreased to less than 20%. Purified and pre-purified lactase solutions added in excess to milk and incubated for 3 months at 30 °C showed degraded milk protein bands on SDS-PAGE by treatment with the pre-purified lactase but not purified lactase. A one-step purification method for protease removal from the K. lactis lactase preparation was performed only by flushing the solution through an anion-exchange membrane.