Influence of the spacer length on the activity of enzymes immobilised on nylon/poly GMA membranes Part 2: Non-isothermal conditions

beta-Galactosidase has been immobilised through spacers of different length on nylon membranes grafted with glycidyl methacrylate. Hexamethylendiamine, etbylendiamine or hydrazine have been separately used as spacers. The behaviour of the catalytic membranes has been studied in a bioreactor operating under non-isothermal conditions as a function of the applied temperature difference DeltaT. Comparison of the enzyme reaction rates under isothermal and non-isothermal. conditions resulted in percentage activity increases (PAT) and reduction of the production time (tau(r)) proportional to the size of the applied DeltaT. Both these parameters increased with the increase of the spacer length. Results have been discussed in the frame of reference of the process of thermodialysis which reduces the limitations to the diffusion of substrate and reaction products across the catalytic membrane, limitations introduced by the grafting and immobilisation process. The advantages of employing non-isothermal bioreactors in biotechnological productive processes have been outlined. (C) 2002 Elsevier Science B.V. All rights reserved.