METABOLIC PATHWAY FOR 2-KETO-L-GULONIC ACID FORMATION IN GLUCONOBACTER-MELANOGENUS IFO-3293

The l-sorbosone pathway for 2-keto-l-gulonic acid (2KGA) formation from l-sorbose in Gluconobacter melanogenus IFO 3293 was confirmed. l-Sorbose dehydrogenase, which catalyzes the conversion of l-sorbose to l-sorbosone, was found in the membrane fraction of the microorganism, and l-sorbosone dehydrogenase in the cytosol fraction. The latter enzyme requires NAD or NADP as a cofactor. 2KGA was reduced to l-idonic acid by 2KGA reductase, but l -idonic acid was re-oxidized to 2KGA by membrane-bound l-idonate dehydrogenase. © 1990 by the Japan Society for Bioscience, Biotechnology, and Agrochemistry. All rights reserved.