A 31P-NMR study of Propionibacterium acnes, including effects caused by near-ultraviolet irradiation

161.8 MHz 31P-NMR spectra were recorded from the light sensitive skin bacterium Propionibacterium acnes. The cells were grown anaerobically on synthetic phosphate-buffered Eagle's medium or on a complex yeast extract medium. The spectra showed a large accumulation of polyphosphates when grown on Eagles medium. A splitting of the inorganic phosphate peak indicated a difference between internal and external pH of the cells. Addition of glucose to the cell suspension gave rise to a change in the pH gradient across the cell membrane, as reported for other Gram-positive bacteria. A decrease in the polyphosphate peak was observed after addition of glucose. A lethal dose of broad-band near-ultraviolet light (corresponding to a 10% survival in a survival test), increased the amount of polyphosphates visible in the NMR-spectra. The addition of glucose to irradiated cells decreased the pH in the external solution, but no splitting of the inorganic phosphate peak could however be observed. 31P-NMR can, therefore, be used to study immediate near-ultraviolet-induced effects at the cellular level, at least in the case of P. acnes.