  From multicellular tissues to bacterial colonies, three dimensional cellular
structures arise through the interaction of cellular activities and mechanical
forces. Simple bacterial communities provide model systems for analyzing such
interaction. Biofilms are bacterial aggregates attached to wet surfaces and
encased in a self-produced polymeric matrix. Biofilms in flows form filamentary
structures that contrast with the wrinkled layers observed on air/solid
interfaces. We are able to reproduce both types of shapes through elastic rod
and plate models that incorporate information from the biomass production and
differentiations process, such as growth rates, growth tensors or inner
stresses, as well as constraints imposed by the interaction with environment. A
more precise study of biofilm dynamics requires tackling water absorption from
its surroundings and fluid transport within the biological system. This process
alters the material properties of the biofilm and the overall stresses. We
analyze whether poroelastic approaches can provide a suitable combined
description of fluid-like and solid-like biofilm behavior.
