Harnessing Gluconobacter oxydans DSM2003 for enantioselective diol oxidation: Substrate scope, stereochemical...

The substrate specificity and synthetic applicability of Gluconobacter oxydans DSM2003 were systematically examined. G. oxydans DSM2003 catalyzed the oxidation of both aromatic and aliphatic primary alcohols to the corresponding carboxylic acids in high yields. The catalytic process proceeded through sequential action of membrane-bound alcohol dehydrogenase (mADH), which is pyrroloquinoline quinone (PQQ)-dependent, and membrane-bound aldehyde dehydrogenase (mALDH), which is molybdopterin-dependent; both enzymes are membrane-bound with their active sites facing the periplasmic space. Electrons are transferred via the ubiquinone pool to a terminal oxidase, driving the incomplete but highly selective oxidation reactions. Furthermore, stereoselective oxidation of phenyl 1,2-ethanediols to (R)-mandelic acids with excellent enantiomeric excess (up to 95% e.e.) and selective oxidation of α,ω-diols with four or fewer methylene groups to ω-hydroxy carboxylic acids were achieved. This biocatalytic approach offered mild reaction conditions, excellent enantioselectivity, and environmentally friendly processing, making it highly attractive for sustainable synthesis.