Beta-Galactosidase Retention by Hollow Fiber Membranes

The method of loading Aspergillus oryzae /3-galactosidase in a hollow fiber membrane unit influenced both enzyme retention and loss of activity during operation. Operated in the normal ultrafiltration mode with enzyme in the recirculating retentate, there was about 5% leakage across the membrane and approximately 50% loss of enzymatic activity after 2 h. Loading enzyme in the sponge layer of the membrane markedly increased leakage across the membrane, but there was minimal loss of activity (< 10%) of the enzyme retained. Average leakage was 30, 40, and 7% when the membrane reactors were run in the recycle, backflush, and static modes. Leakage of enzyme across the membrane was not related to a change in molecular weight (100,000 daltons) of the enzyme nor to defects in the membrane.