Mechanism of alanine hyperproduction by arthrobacter oxydans HAP-1: metabolic shift to fermentation under nongrowth aerobic conditions

Arthrobacter oxydans HAP-1 hyperproduces DL-alanine in a non-growth-associated manner. We found that decreased activities of pyruvate dehydrogenase and of the enzyme catalyzing NADH oxidation in the stationary phase are paralleled by a shift of pyruvate metabolism to alanine synthesis by L-alanine dehydrogenase. We propose that this enzyme functions as an electron sink even under aerobic conditions.