Comprehensive preparation of uronic and aldaric acids by bacteria possessing aldose C-6 alcohol dehydrogenase...

Sixteen types of uronic acids are derived from aldohexoses. Except for a few examples, uronic acids are difficult to prepare and are not commercially available as reagents. Our previous study reported that C-6 oxidation of aldose (d-glucose) and aldonic acid (d-gluconic acid) by alcohol dehydrogenases from Pseudogluconobacter saccharoketogenes Rh47-3 produced the uronic acids (d-glucuronic acid and l-guluronic acid, respectively). Aldaric acid (d-glucaric acid) was also produced by further oxidation with aldehyde dehydrogenase from the same bacterium. The present study demonstrates that alcohol dehydrogenase widely oxidizes aldoses and aldonic acids, while aldehyde dehydrogenase extensively oxidizes aldoses and uronic acids; the alcohol dehydrogenase was named "aldose C-6 alcohol dehydrogenase" Except for commercially available d- and l-gulonic acid, all aldonic acids (14 types), uronic acids (16 types), and aldaric acids (10 types) derived from aldohexoses could be prepared using the alcohol dehydrogenase and resting cells. These sugar acids were obtained by oxidizing various aldoses and aldonic acids through either aldose C-1/C-6-inverting oxidation or aldose C-1/C-6-retaining oxidation, although the production of d-iduronic acid and d-idaric acid was low. The same reaction was also performed with Youhaiella spp., a registered strain in the Japan Collection of Microorganisms. The results provide comprehensive and simple methods for preparing sugar acids.