PRODUCTIVITY OF IMMOBILIZED DEXTRANSUCRASE FOR LEUCROSE FORMATION

Continuous leucrose formation with dextransucrase entrapped in calcium alginate beads was investigated A plug-flow packed bed reactor was us ed as the reaction vessel and the conversion of sucrose as a function of residence time was measured at different initial sucrose concentrat ions. Leucrose productivity by the immobilized enzyme at different rea ction conditions was determined and compared to the productivity of a discontinuous operation process. Productivities of the continuous proc ess were in a range of 0.7-3.6 g U-1, whereas only 0.7 g U-1 could be reached in the discontinuous process; moreover, inactivation constants of the immobilized enzyme in the continuous operation mode were deter mined. The enzyme was continually inactivated with increasing reaction time. This was due to transport limitations inside the enzyme particl es that could be confirmed by investigation of the swelling behavior o f the enzyme beads due to the formation of dextran. (C) 1996 by Elsevi er Science Inc.