Fig. 2.

Schematic representation of how depletion attraction operates in a colony of bacteria producing exopolysaccharide. Bacterial cells are large spherocylinders (magenta) and coiled polymers (EPSs) are assumed as small spheres (yellow). The dashed lines around each bacteria are zones of excluded volume as shown in A and B, which is not accessible to the center of mass of a given EPS after it has been secreted into the medium. In A, as bacterial cells are separated from each other, the area of excluded volume is large, an area that could be partially accessible for the EPS particles if the cells come closer and form aggregates, as is shown in B.