D-Hexosaminate production by oxidative fermentation

Microbial production of D-hexosaminate was examined by means of oxidative fermentation with acetic acid bacteria. In most strains of acetic acid bacteria, membrane-bound D-glucosamine dehydrogenase (synonymous with an alternative D-glucose dehydrogenase distinct from quinoprotein D-glucose dehydrogenase) oxidized D-hexosamines to the corresponding D-hexosaminates in a stoichiometric manner. Conversion of D-hexosamines to the corresponding D-hexosaminates was observed with growing cells of acetic acid bacteria, and D-hexosaminate was stably accumulated in the culture medium even though D-hexosamine was exhausted. Since the enzyme responsible is located on the outer surface of the cytoplasmic membrane, and the enzyme activity is linked to the respiratory chain of the organisms, resting cells, dried cells, and immobilized cells of acetic acid bacteria were effective catalysts for D-hexosaminate production. D-Mannosaminate and D-galactosaminate were also prepared for the first time by means of oxidative fermentation, and three different D-hexosaminates were isolated from unreacted substrate by a chromatographic separation. In this paper, D-hexosaminate production by oxidative fermentation carried out mainly with Gluconobacter frateurii IFO 3264 is exemplified as a typical example.