Effect of membrane-bound aldehyde dehydrogenase-encoding gene disruption on glyceric acid production in Gluconobacter oxydans.

Gluconobacter oxydans IFO12528 is able to produce glyceric acid (GA) from glycerol through the action of a membrane-bound alcohol dehydrogenase (mADH), which is required for GA production. To determine whether membrane-bound aldehyde dehydrogenase (mALDH) also plays a role in GA production in G. oxydans, we constructed an aldH-disrupted mutant of G. oxydans (ΔaldH). ΔaldH was unable to produce acetic acid from ethanol, but was able to produce GA at a level approximately half that of the wildtype strain, suggesting the involvement of another ALDH in GA production. We also investigated the enantiomeric composition of GA produced by the IFO12528 and ΔaldH strains. No difference in GA composition was evident in the ΔaldH mutant, with ~73% D-GA enantiomeric excess observed in both strains.