How Bacteria Pop

Membrane lysis, or rupture, is a cell death pathway in bacteria frequently caused by cell wall-targeting antibiotics. Although several studies have clarified some biochemical mechanisms of antibiotic action, a physical understanding of the processes leading to lysis remains lacking. Here, we model the dynamics of membrane bulging and lysis in Escherichia coli, where it has been observed that membrane bulging after cell wall digestion occurred on a characteristic timescale as fast as 100 ms. We show that bulging can be energetically favorable due to the relaxation of the combined stretching energies of the inner membrane, cell wall, and outer membrane and that experimentally observed bulge shapes, along with coarse-grained Monte Carlo simulations of pressurized fluid membranes, are consistent with model predictions. Our results elucidate the physics of cell envelope organization and may have implications for cellular morphogenesis and antibiotic discovery.