METABOLISM OF CITRIC ACID IN BACTERIUM SUCCINICUM

Abstract

The resting cells of Bacterium succinicum grown aerobically in bouillon citrate medium hardly fermented citrate under anaerobic conditions. But when a small amount of glucose was added to these cells along with citric acid under anaerobic conditions, a remarkable increase in the rate of citrate breakdown was observed. This was confirmed to be typical enzymatic adaptation.
The occurrence of the splitting reaction in the adapted cells was demonstrated with the inhibition experiments by dipyridyl and with the isotopic experiments.
Soluble enzyme preparations were obtained from the adapted cells which dissimilated citrate under anaerobic conditions. One molecule of pyruvate and one molecule of carbon dioxide were formed per molecule of citrate decomposed by the extracts when further oxidation of pyruvate was blocked. Therefore, the presence of the splitting enzyme of citrate in the extracts was confirmed. The enzyme, however, was different either from the condensing enzyme or the citridesmolase in its adaptive nature and as to the requirements of cofactors.