2-KETOGLUCONIC ACID PRODUCTION BY ACETOBACTER-PASTEURIANUS

Production of 2-ketogluconic acid in batch fermentation was investigat ed. Acetobacter pasteurianus ATCC 6438, which produces selectively 2-k etogluconic acid only, was used. The optimal pH for glucose dehydrogen ation to gluconate by resting cells was 5.0 and for gluconate dehydrog enation to 2-ketogluconate 4.25. When glucose medium was used, the 89% yield was achieved after 90 h. For the optimal productivity, medium c ontaining glucose and gluconate with the molar glucose:gluconate ratio 7.4 was proposed, and the yield of 92% after 56 h was achieved. This composition of medium led to the elevation of dissolved oxygen concent ration during fermentation. It consequently resulted in elevated gluco nate dehydrogenase activity being discussed as the rate-limiting activ ity of the batch production.