Table 1.

Comparison between K. viridifaciens cell wall-deficient cells

Characteristic	Protoplast	L-form	S-cell
Origin	Osmoprotective conditions combined with lysozyme treatment	Osmoprotective conditions combined with prolonged exposure to lysozyme and penicillin G	Osmoprotective conditions
Area (µm2)	4.01 ± 1.93	7.06 ± 5.87	20.73 ± 11.53
Cell wall	Homogeneous regeneration. Wall material mostly associated with the cell surface	Not uniform, disordered assembly. Wall material often detached from the cell surface	Not uniform, disordered assembly. Wall material sometimes detached from the cell surface
Genotype	Wild type	Mutant	Wild type

Bacteria can be forced to grow without cell wall if cell wall synthesis is inhibited. Here, Ramijan et al.³⁰ show that, in filamentous actinomycetes, hyperosmotic stress induces formation of wall-deficient cells that can switch to normal mycelial growth, or mutate and proliferate indefinitely as wall-less forms.