•Members: Mycoplasma, Spiroplasma
•Despite the absence of cell wall, they are more resistant to osmotic lysisand are able to survive conditions under which protoplast lyses.
•They require sterol or lipoglycanwhich embedded in the cytoplasmic membrane. These help stabilize the cytoplasmic membrane.
•Colonies show a characteristic “fried-egg” appearance consisting of a dense central core that penetrates downward into the agar, surrounded by a circular spreading area that is lighter in color.