Influence of the spacer length on the activity of enzymes immobilised on nylon/polyGMA membranes. Part 2. Non-isothermal conditions.

beta-Galactosidase has been immobilised through spacers of different length on nylon membranes grafted with glycidyl methacrylate. Hexamethylendiamine, Ethylendiamine 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 ?T. Comparison of the enzyme reaction rates under isothermal and non-isothermal conditions resulted in percentage activity increases (P.A.I.) and reduction of the production times (tr) proportional to the size of the applied ?T. 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.