NITROGENOUS SUBSTRATES OF ENDOGENOUS RESPIRATION IN PSEUDOMONAS AERUGINOSA.

Gronlund, Audrey F. (University of British Columbia, Vancouver, Canada) and J. J. R. Campbell. Nitrogenous substrates of endogenous respiration in Pseudomonas aeruginosa. J. Bacteriol. 86:58-66. 1963.-The nature of the nitrogenous reserves of Pseudomonas aeruginosa that are oxidized during endogenous respiration was studied by following the changes in the chemical constituents and in the distribution of radioactivity of starving cells that had been grown on C(14)-labeled substrates. The total protein and nucleic acid of Warburg vessel contents decreased during starvation. Deoxyribonucleic acid increased slightly, whereas ribonucleic acid (RNA) decreased. C(14)O(2) was evolved from endogenously respiring cells specifically labeled in the nucleic acid fraction and from cells specifically labeled in the protein fraction. Chemical fractionation of C(14)-labeled cells showed a decrease in hot trichloroacetic acid-soluble and -insoluble compounds, indicating that the C(14)O(2) arose from the degradation of RNA and protein and not free pool compounds. A decrease in ribosomal RNA and protein was evident from physical fractionations of starved, labeled cells. An enzyme responsible for the initiation of ribosomal degradation was found to be associated with the ribosome fraction. It was concluded that oxidation of the ribonucleo-protein during endogenous respiration may be a general phenomenon in microorganisms.