Viscoelasticity of the bacterial cell envelope

Bacterial cell envelopes are remarkable biological structures that allow cells to adapt to and survive changes in their external environment while maintaining their mechanical integrity as the cells grow and divide. We review efforts to characterize the mechanical properties of the bacterial cell envelope, and we highlight recent advances in measurement techniques for individual bacterial cells that have led to a more complete understanding. In addition to their elastic behavior, bacterial cell walls also demonstrate a time dependent response to externally applied forces such that their mechanical properties are more properly described as viscoelastic. These measurements provide important information that is needed to understand the complex relationship between their structure and function.