Figure 6. Alternative cell fates of bulging cells.
(A) Snapshots of spheroplast formation induced by cephalexin. Initial stages of spheroplast formation are identical with those of beta-lactam induced cell lysis. These remarkably stable spheroplasts lysed immediately upon Mg2+ removal, as judged by optical density drop of the liquid culture. (B) Snapshots of bulging cells reverting to rod shape cells upon drug removal. Cells with stabilized bulges escaped lysis by initiating septation near old poles and pinching off portions of the filaments. (C) Proposed model of beta-lactam induced bulges as a meta-stable state towards cell lysis, spheroplast formation, or reversion to rod-shaped cells. All scale bars represent 2 μm. See also Movie S4 and S5.