Role of Carbon Dioxide in Catabolism of Propane by “ Nocardia paraffinicum ” ( Rhodococcus rhodochrous )

Abstract

The catabolism of propane by “ Nocardia paraffinicum ” ( Rhodococcus rhodochrous ) has been shown to involve CO 2 fixation after its oxidation to propionic acid. “ N. paraffinicum ” failed to grow on either propane or 1-propanol in the absence of CO 2 . The rate of propane utilization was directly related to the initial CO 2 concentration, and Warburg respirometry suggested that CO 2 was required for the catabolism of 1-propanol, propionaldehyde, and propionate but not for 2-propanol. These data also suggested that the predominant pathway for the utilization of propane by “ N. paraffinicum ” was through 1-propanol. The use of [2- 14 C]propane and 14 CO 2 confirmed the catabolism of propane and the fixation of CO 2 . Through the use of these isotopes and the pyruvate carboxylase inhibitor sodium arsenite, the labeled 2,4-dinitrophenylhydrazine derivative of pyruvate was trapped and isolated via thin-layer chromatography. The trapping of [ 14 C]pyruvate in this manner was considered to be indicative of the presence of the methylmalonyl coenzyme A pathway for CO 2 fixation.