Nickel sequestering by polyphosphate bodies in Staphylococcus aureus

Metal incorporation and possible cellular compartmentalization of nickel by Staphylococcus aureus was investigated. Cells grown on nutrient agar were removed, washed and exposed to 10, 20, 50 or 100 ppm of nickel in distilled water. The cells were air-dried on Formvar coated grids and then examined in a transmission electron microscope operating in the scanning transmission mode. The spot setting was used in conjunction with an energy dispersive X-ray spectrometer to determine the location and relative amount of the nickel in different parts of the cells. The study showed that polyphosphate bodies bind large amounts of the metal. The peak height for nickel increased in the higher exposure amounts of nickel. No nickel was detected in the cell wall or cytoplasmic areas. The results are discussed in relation to nickel transport in cells and staphylococcal infections in humans.