Figure 6

S. aureus engages in colony avoidance.

(A) wildtype S. aureus colonies avoid each other (left panel) but an agr mutant (small colony) is not avoided by wildtype colonies (right panel) (B). wildtype colonies produce a halo of surfactant on the surface of the agar plate around the colony that can be observed using oblique illumination, whereas agr mutants do not (not shown). The edge of surfactant is highlighted with arrows (C). drop collapse test demonstrating that the halo is surfactant: (i) main colony, (ii) water droplet collapses due to surfactant action within the surfactant halo, (iii) the edge of the surfactant halo, (iv) a water droplet does not collapse outside the surfactant halo.