Metabolic Pathway for 2-Keto-l-gulonic Acid Formation inGluconohacter melanogenusIFO 3293

l-Sorbose Dissimilation in 2-Keto-l-gulonic Acid-producing Mutant UVIO Derived fromGluconobacter melanogenusIFO 3293

“…2KGA high producers derived from G. melanogenus IFO 3293 show high membrane-bound L-sorbose dehydrogenase activity, but have L-sorbosone dehydrogenase mainly in the cytosol. 13) We found membrane-bound L-sorbosone dehydrogenase in Acetobacter liquefacience IFO 12258, which converted L-sorbosone to 2KGA almost stoichiometrically (will be published elsewhere). Construction of recombinant microorganisms with both of the membrane-bound enzymes will produce 2KGA at a higher yield with less CO 2 evolution.…”

“…In fact, the mutant El, which was obtained as a higher 2KGA producer than the strain UVlO in our subsequent strain improvement studies, had higher L-sorbose dehydrogenase, L-sorbosone dehydrogenase, and Lidonate dehydrogenase activities than UVlO, as reported previously. 13) When L-sorbose dehydrogenase activity increases, dissimilation of L-sorbose via D-sorbitol decreases and COz evolution decreases. Actually, another 2KGA high producer, the strain A28-1O, evolved less 14COZ from D-[U-14 C]sorbitol than the strain U:VlO (data not shown).…”

Isolation and Characterization of a New Vitamin C Producing Enzyme (L-Gulono-γ-lactone Dehydrogenase) of Bacterial Origin

“…After the addition of enzyme solution to the basal reaction mixture as described in Materials and Methods, each metal solution was stirred in and the reaction was started with the addition of L-gulono-y-Iactone. As shown in Table VII 4.46mM) on the activity were investigated, but no compound was inhibitory. In addition, carbonyl reagents such as hydroxyl ammonium sulfate, hydroxylamine, hydrazine monohydrate, hydrazinium dichloride, and l,4-benzoquinone, which are commonly inhibitors for quinoproteins,i 1) did not inhibit the enzyme activity.…”