Institution: | a International Institute of Genetics and Biophysics of CNR, via Guglielmo Marconi, 12, 80125 Naples, Italy b Department of Human Physiology and Integrated Biological Functions of the Second University of Naples, via S.M. di Costantinopoli, 16, 80138 Naples, Italy |
Abstract: | Lactose hydrolysis by β-galactosidase immobilized on two nylon membranes, differently grafted, has been studied in a bioreactor operating under isothermal and non-isothermal conditions. One membrane (M1) was obtained by chemical grafting of methylmethacrylate (MAA); the other one (M2) by a double chemical grafting: styrene (Sty) and MAA. Hexamethylenediamine was used as a spacer between the grafted membranes and the enzyme. Both membranes have been physically characterized studying their permeabilities in presence of pressure or temperature gradients. Under non-isothermal conditions, the increase in activity of membrane M2 was higher than that of membrane M1. The and β coefficients, giving the percentage of activity increase when a temperature difference of 1°C is applied across the catalytic membranes, have been calculated. Results have been discussed with reference to the greater hydrophobicity of membrane M2 with respect to membrane M1, the hydrophobicity being a prerequisite for the occurrence of the process of thermodialysis. |