FIG. 3.

Biofilm formation under continuous flow. Biofilm formation after 3 days (A and B) and 6 days (C and D) of growth is shown for minimal medium-grown bacteria in a flow cell. Phase-contrast micrographs at a magnification of ×1,000 obtained after 3 days of growth (maturation-1 stage) are shown for P. aeruginosa PAO1 (A) and a representative mutant, ΔPA1553::Tet^r (B). Confocal scanning laser microscopy images of maturation-2 stage biofilms at a magnification of ×400 of the P. aeruginosa PAO1 (C) and the ΔPA1553::Tet^r mutant (D) after 6 days of growth (maturation-2 stage), showing the xy and xz planes. Flow cell experiments were performed in triplicate as described in Materials and Methods.