ADVANTAGES IN USING IMMOBILIZED THERMOPHILIC BETA-GLYCOSIDASE IN NONISOTHERMAL BIOREACTORS

Catalytic membranes, obtained by immobilizing thermophilic beta-glycos idase onto nylon supports, were used in a nonisothermal bioreactor to study the effect of temperature gradients on the rate of enzyme reacti on. Two experimental approaches were carried out to explain the molecu lar mechanisms by which the temperature gradients affect enzyme activi ty. The results showed that the thermophilic enzyme behaved as the mes ophilic beta-galactosidase, exhibiting an activity increase which was linearly proportional to the transmembrane temperature difference. The efficiency of the system proposed was determined by calculating two c onstants, alpha and beta, which represent respectively the percentage increase of enzyme activity when a temperature difference of 1 degrees C or a temperature gradient of 1 degrees C cm(-1) were applied across the catalytic membrane. The increase of enzyme activity in nonisother mal bioreactors entailed a proportional reduction of production times. The advantages in using thermophilic enzymes immobilized in nonisothe rmal bioreactors are also discussed. (C) 1998 John Wiley & Sons, Inc.