STUDIES ON THE METABOLISM OF THE AUTOTROPHIC BACTERIA* IlL TI~ NATURE OF THE ENERGY STORAGE MATERIAL ACTIVE IN THE CHEMOSYNTHETIC PROCESS BY K. G. VOGLER AND W. W. UMBREIT

The most striking result of a study of the process of chemosynthesis (synthesis of all materials from CO2 using chemical energy obtained by oxidation) in the autotrophic bacterium, Thiobacillus thiooxidans, was the ability of the cell to store up the energy derived from sulfur oxidation in an available form which could be used for COs fixation under conditions in which sulfur oxidation was impossible (Vogler, 1942). This ability to store the energy of sulfur oxidation in the cell seems to differentiate the process of chemosynthesis from that of photosynthesis except that definitive experiments in photosynthesis are not yet available. It was of considerable interest to determine the nature of this readily available storage product. The data contained in this paper show that the oxidation of sulfur is directly coupled to transfers of inorganic phosphorus from the medium to the cells. They also show that CO2 uptake is coupled to transfers of inorganic phosphate from the cell to the medium and that CO~ fixation is dependent, in the absence of concomitant sulfur oxidation, upon the amount of phosphate previously taken up during sulfur oxidation. These relationships strongly suggest that the energy storage product is a phosphorylated compound and that the energy is stored in the cell as phosphate bond energy (cf. Lipmann, 1941). Such a finding relates the process of energy storage and transfer in the autotrophic bacterium to that of heterotrophic organisms (cf. Kalckar, 1941; Lipmann, 1941).