Dobrogosz, Walter J. (North Carolina State University, Raleigh). Altered end-product patterns and catabolite repression in Escherichia coli. J. Bacteriol. 91:2263–2269. 1966.—End products formed during growth of Escherichia coli ML30 on glucose were examined under various conditions known to promote or prevent catabolite repression of the inducible β-galactosidase system in this organism. Cultures were grown under these conditions in the presence of C14-glucose or C14-pyruvate. The products formed were assayed isotopically after separation on columns of silicic acid. Under conditions known to promote catabolite repression, glucose was degraded primarily to acetate and CO2. When repression was turned off by anaerobic shock, glucose metabolism was characterized by the accumulation of ethyl alcohol in addition to acetate and CO2. The results presented in this report indicate that oxidative decarboxylation of pyruvate may markedly affect the amount of energy that can be derived from glucose catabolism. In turn, the amount of energy derived from catabolic processes may play a key role in the mechanism of catabolite repression.