in the whey medium after protein hydrolysis with neutrase, and supplementation (per liter) with 2.5 g yeast extract and 0.03 and also lactose to give a final sugar concentration of 40 g The immobilization procedure was slightly modified; after inoculation the cells were first allowed to grow in the reactor for 8 h, using a stirrer speed of 250 rev.:min, until a cell density of 1.7 g l was reached, and then the medium was continuously