FIG. 6.

Proposed biofilm development and maturation for a natural conjugative F-plasmid-containing E. coli strain. The diagram shows the following steps: (i) an initial microcolony biofilm is formed by stationary-growth-phase-like sessile bacteria expressing conjugative F pili, which promote only cell-cell contact; (ii) the cells simultaneously produce capsular colanic acid to support clonal growth of the newly generated populations; and (iii) after completion of the initial step, the stationary-growth-phase-like bacterial cells generate the meshwork of curli fibers to expand complex 3D biofilm structures, which promote adherence of cells to the surface and later reinforce cell-cell interactions.