THE OXIDATION OF ETHANOL AND TRICARBOXYLIC ACID CYCLE INTERMEDIATES BY ACETOBACTER PEROXYDANS

The main taxonomic characteristic of the genus Acetobacter as presently described is the ability to oxidize ethanol to acetic acid (Breed et al., 1948), although some species carry the oxidation further. Of particular interest is the demonstration that Acetobacter aceti produces citrate when supplied acetate and intermediates of the TCA2 cycle (Antoniani et al., 1950). This species thus appears to possess at least some enzymes of the cycle. On the other hand, Acetobacter suboydans has been reported not to utilize the TCA cycle (King and Cheldelin, 1952). Acetobater peroxydans has received little attention since the extensive work of Wieland and Pistor (1936, 1938). The currently available strain of this species has been found to be similar in hydrogen and peroxide metabolism to that used by Wieland, notably in the absence of catalase and the presence of a hydrogen-linked peroxidase (Atkinson, 1956). This paper reports observations on the oxidative metabolism of A. peroxydans which differ both from the earlier reports on this organis and from those on other Acetobacter. In particular, ethanol is oxidized to carbon dioxide and water, in contrast to Wieland's finding that acetaldehyde was the main product with a smaller amount of acetic acid being produced. The presence of most of the enzymes of the TCA cycle is indicated.