Fig 9.

Cellulose localization and the generation of ridges in macrocolonies. (A) Schematic summary of cellulose location and two-layer architecture in AR3110 macrocolonies. Red and orange layers illustrate zones of stationary and post-exponential-phase-like physiology, respectively. Blue lines indicate zones rich in cellulose. (B) Schematic representation of radial expansion of a colony. Circle lines of a radius of r, 2r, and 3r represent the border of hypothetical colonies. Red and blue lines in colonies with a radio of r and 2r, respectively, have the same length but different curvature angles, i.e., bacteria positioned at these outer rim lines of an expanding colony can grow into successively smaller areas (illustrated by the hatched red and blue areas). Due to “tissue-like” cohesion and elasticity of a colony that generates both curli fibers and cellulose, this results in the colony buckling up into radially oriented ridges.