INORGANIC POLYPHOSPHATE METABOLISM IN CHLOROBIUM THIOSULFATOPHILUM.

Hughes, D. E. (Dartmouth Medical School, Hanover, N.H.), S. F. Conti, and R. C. Fuller. Inorganic polyphosphate metabolism in Chlorobium thiosulfatophilum. J. Bacteriol. 85:577-584. 1963.-Cells of the obligate phototroph Chlorobium thiosulfatophilum, when grown on a normal concentration of inorganic phosphate, accumulated large intracellular metachromatic granules identified as polymetaphosphate. Inorganic phosphate was released from polymetaphosphate by cell-free extracts. This release was adenosine diphosphate-dependent and light-independent. When cells were subcultured through serial transfer in the absence of inorganic phosphate, the production of polymetaphosphate granules was almost completely stopped. After the serial transfer, these cells showed little or no endogenous release of inorganic phosphate or release from added polymetaphosphate. Using such polymetaphosphate-free cells, it has been possible to demonstrate photosynthetic phosphorylation by the naturally occurring photosynthetic macro-molecules isolated from this organism. These particles, of about 100 A in diameter with a molecular weight of approximately 1.5 million, are by far the simplest functional naturally occurring photosynthetic electron-transport units thus far described.