Analysis of wild-type and plasmid-cured thermus spp. by X-ray photoelectron spectroscopy

The cell surface composition of a wild-type and a plasmid-cured Thermus strain was studied using X-ray photoelectron spectroscopy. The elemental composition with regard to carbon, oxygen, nitrogen, phosphorus, sodium and sulphur was measured. The most striking compositional difference was observed for the phosphorus content, which in atom fractions was equivalent to 0.13% in the wild-type and 0.37% in the cured strain. The carbon content was slightly lower (68%) in the wild-type than in the cured strain (70%); this difference was due to a significant reduction of the hydrocarbonaceous component of the carbon peak, which was 37% in the wild-type and 42% in the plasmid-cured strain. The results suggest that the presence of plasmids in Thermus may correlate with specific cell-surface properties. The significance of these findings must be further evaluated by studies of the molecular structure and physicochemical properties of the cell surface.