Regulation of Gluconeogenesis in Acetobacter xylinum

Gluconeogenesis in the form of cellulose synthesis from succinate and pyruvate has been studied in resting cells of Acetobacter xylinum. Substrate utilization and cellulose formation occurred at linear rates. At saturating levels of substrate the rate of cellulose formation from succinate was two to three times that from pyruvate. The cellulose formed accounted for 5% of the pyruvate utilized and for 33% of the succinate utilized. Acetate which alone was not gluconeogenic increased the rates of succinate and pyruvate conversion to cellulose several‐fold without significantly affecting their over‐all utilization. Acetate oxidation was strongly stimulated by both gluconeogenic substrates. A “crossing over” of carbon atoms from acetate to cellulose was observed in the presence of succinate but not in the presence of pyruvate. Succinate and pyruvate when added together yielded more cellulose than expected on the basis of mere additive effects, owing to an increase rate of cellulose formation from pyruvate. Possible mechanisms correlating these observations with the properties of the enzyme systems involved in the interconversion of the various substrates are discussed.