title: Circumferential gap propagation in an anisotropic elastic bacterial sacculus.
abstract: We have modeled stress concentration around small gaps in anisotropic elastic sheets, corresponding to the peptidoglycan sacculus of bacterial cells, under loading corresponding to the effects of turgor pressure in rod-shaped bacteria. We find that under normal conditions the stress concentration is insufficient to mechanically rupture bacteria, even for gaps up to a micron in length. We then explored the effects of stress-dependent smart autolysins, as hypothesized by A. L. Koch [ Adv. Microb. Physiol. 24 301 (1983); Res. Microbiol. 141 529 (1990)]. We show that the measured anisotropic elasticity of the peptidoglycan (PG) sacculus can lead to stable circumferential propagation of small gaps in the sacculus. This is consistent with the recent observation of circumferential propagation of PG-associated MreB patches in rod-shaped bacteria. We also find a bistable regime of both circumferential and axial gap propagation, which agrees with behavior reported in cytoskeletal mutants of B. subtilis. We conclude that the elastic anisotropies of a bacterial sacculus, as characterized experimentally, may be relevant for maintaining rod-shaped bacterial growth.
authors.affiliation: Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4R2.
authors.forename: Swadhin
authors.initials: S
authors.lastname: Taneja
authors.affiliation: Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4R2.
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Levitan
authors.affiliation: Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4R2.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Rutenberg
mesh_terms: D016880:Anisotropy; D049108:Cell Enlargement; D048429:Cell Size; D002473:Cell Wall / Q000502:physiology*; D003198:Computer Simulation; D055119:Elastic Modulus / Q000502:physiology; D004926:Escherichia coli / Q000166:cytology* / Q000502:physiology*; D008560:Membrane Fluidity / Q000502:physiology*; D008954:Models, Biological; D009024:Morphogenesis / Q000502:physiology*; D010457:Peptidoglycan / Q000378:metabolism*; D013314:Stress, Mechanical
chemical_list: D010457:Peptidoglycan