NANOFILTRATION MEMBRANE BIOREACTOR FOR CONTINUOUS ASYMMETRIC REDUCTION OF 2-KETOGLUTARATE TO PRODUCE L-GLUTAMATE WITH NADH REGENERATION

A nanofiltration membrane, UTC-20, was found to have a high rejection ratio to dissociable coenzymes such as NAD, NADP, and ATP irrespective to the ionic strength of the solution, By using UTC-20, a nanofiltrat ion membrane bioreactor (NFMBR) was constructed for the continuous ste reospecific reduction of 2-ketoglutarate to L-glutamate with NADH rege neration, In die NFMBR a conjugated system of glutamate dehydrogenase and glucose dehydrogenese were coimmobilized and the substrate solutio n containing a low concentration of NAD was supplied continuonsly, Bec ause of rejection by the membrane, NAD was partially immobilized and c oncentrated in the reactor so that a high regeneration number of NAD ( similar to 10000) was obtained with a good conversion (similar to 0.9) and productivity (similar to 120 g/l/d). NFMBR is expected to be appl icable to a bioreactor involving dissociable coenzymes in general.