[Coccoid cells and spheroplasts in cultures of the genus Thermus]

The formation of capable of self-reproduction coccoid cells, and of spheroplasts, was studied in the cultures of Thermus ruber and pigmentless Thermus sp. by light and electron microscopy. The primary origination of cocci might be due to non-uniform or multiple cell division. Spheroplasts can be produced either from coccoid or from rod-like cells as a result of autolysis of the glycopeptide layer of the cell wall. The spheroplasts of the cultures belonging to the Thermus genus are characterized by osmotic stability and a peculiar appearance due to a strongly developed periplasmic space and the eccentric arrangement of the protoplast in it.