An immobilized system for the continuous production of formic acid using thylakoid membranes and carbon dioxide reductase from potato tuber chloroplasts

Carbon dioxide reductase present in the protein fraction obtained from illuminated chloroplasts exhibited requirement of light and anaerobic condition for the enzymatic reduction of CO 2 to formic acid. Addition of dithionite gave a three-fold activation of carbon dioxide reduction, while dithioerythreitol and glutathione did not have much effect. Preincubation of the enzyme with dithioerythreitol, however, showed some inhibition. Reconstitution experiments showed that supplementation of thylakoid preparation in the carbon dioxide reductase assay system increased the output of formate to 3-fold. From the studies on the immobilization of carbon dioxide reductase and thylakoid preparation in 2% and 4% agarose gel it was evident that 2% gel gave better yield of formate. Maximum formate production was maintained up to 14 days and the rate of formate production reduced considerably after 20 days. In a system where continuous production of formic acid was studied it was found that washing of the column on alternate days gave a better yield; aging of the column for 20 days stopped production of formic acid. Treatment with 3(3,4-chlorophenyl)-l,l-dimethyl urea or NADP + inhibited formate formation considerably in immobilized system.