Figure 9.

Ratio of surface and bulk cells for in silico wild-type and ΔpilT cells. Initially 1200 individual cells are randomly distributed on a substrate and will form microcolonies within minutes. We mixed 600 wild-type and 600 ΔpilT mutants with non-retracting pili and studied the amount of cells on the surface and within the bulk for both species. (A) Ratio of in silico wild-type (WT) cells at the surface (orange) and inside of the colony (green). Surface cells are identified by computation of the alpha shape, see section S5.5 in the supplementary information. The colonies form such that within 10 minutes, the wild-type cells can be found preferentially inside of the colonies. (B) Ratio of mutant cells identified as surface (orange) and bulk (green) cells. A larger fraction of ΔpilT mutants can be found on the surface of the colonies.