A lipoic acid auxotroph of Escherichia coil K-12, strain W1485lip2 (ATCC25645), produced pyruvic acid aerobically from glucose under the lipoic acid-deficient conditions, while the prototrophic parent strain, W1485 (ATCC12435), produced 2-oxoglutaric acid as the main product. The mechanism of the pyruvic acid production by strain W1485lip2 was found to be the impaired oxidative decarboxylation of pyruvic acid caused by the decrease in the activity of pyruvate dehydrogenase complex under the conditions of lipoic acid deficiency. Under the optimum culture conditions using the pH-controlled jar fermentor, 25.5 g/l pyruvic acid was obtained from 50 g/l glucose after the culture for 32-40 h at pH 6.0. The relationship between the pyruvic acid productivity and the pyruvate dehydrogenase complex activity in jar-fermenter culture was discussed.