Dissimilation of C14-labeled glucose by Serratia marcescens.

Glucose containing radioactive carbon has been utilized in the study of the metabolic distribution of the various carbon atoms during dissimilation by the following organisms: Leuconostoc mesenteroides, (Gunsalus and Gibbs, J. Biol. Chem. 194, 871, 1952); Pseudomonas saccharophila, (Entner and Doudoroff, J. Biol. Chem. 196, 853, 1952); Pseudomonas fluorescens (Lewis et al., J. Biol. Chem., 216, 273, 1955). The distribution of the radioactivity of variously labeled glucose-C'4 after oxidation by Serratia marcescens is reported herein. S. marcescens, grown on a dry milk-glucose medium (Wasserman et al., Can. J. Microbiol. 2, 447, 1956), was allowed to oxidize glucose-l-C'4, glucose-6-C'4 (obtained from the National Bureau of Standards), and glucose-2-C'4 (obtained from Tracerlab2). The experiments, conducted in the Warburg respirometer, were concluded when the rate of oxygen consumption in the presence of substrate was the same as that of the endogenous cells. Carbon dioxide, collected in 5 N NaOH in the center well, was precipitated as BaCO3. The cells were separated from the supernatant by centrifugation and both fractions converted to CO2 by the persulfate method (Calvin et al., Isotopic Carbon, J. Wiley and Sons, 1949). The precipitated BaCO3 was collected on filter paper disks using the Tracerlab precipitation apparatus and counted with an accuracy of 5 per cent. The counts were corrected to infinite thinness. Pyruvic acid was determined by the Friedemann and Haugen method (J. Biol. Chem., 147, 415, 1943), and 2-ketogluconic acid by the method of