β-d-Glucosidase stabilization in a polarized ultrafiltration membrane reactor

Cellobiose hydrolysis by β-d-glucosidase (β-d-glucoside glucohydrolase EC 3.2.1.21) can become the rate-limiting step in the hydrolysis of cellulosic wastes because of inhibition phenomena involving other enzymes of the cellulase complex. Enhancement of the overall rate can therefore be obtained by increasing the amount of β-d-glucosidase present in the reactor. Unfortunately, the thermal stability of β-d-glucosidase is rather poor compared to $\text{endo}\text{-(1 → 4)-β-}\text{d}\text{-}\text{glucanase}$ and cellobiohydrolase. A novel stabilization method is proposed that exploits the polarization phenomena that take place in an unstirred ultrafiltration membrane enzymatic reactor. As much as a 20-fold increase in half-life compared to the native enzyme is obtained by injecting small amounts of hydroxyethyl cellulose into the system. No reduction in enzyme activity levels is observed.