Protects from environment
Provides staining characteristics to the bacterium
Contains receptor sites for phages/complements
Site of action of antibody and colicin
Contains toxic components to host
Bacteria with defective cell walls Bacteria with out cell wall can be induced by growth in the presence of antibiotics and a hypertonic environment to prevent lysis. They are of three types:
Protoplasts: Derived from Gram-positive bacteria and totally lacking cell walls; unstable and osmotically fragile; produced artificially by lysozyme and hypertonic medium: require hypertonic conditions for maintenance.
Spheroplast: Derived from Gram-negative bacteria; retain some residual but non-functional cellwall material; osmotically fragile;produced by growth with penicillin and must be maintained in hypertonic medium.
L- forms: Cell wall-deficient forms of bacteria usually produced in the laboratory but sometimes spontaneously formed in the body of patients treated with penicillin; more stable than protoplasts or spheroplasts , they can replicate in ordinary media.