FIG. 1.

Epifluorescence and scanning confocal photomicrographs of the surface-attached communities formed by P. aeruginosa wild type and an isogenic alginate-overproducing mutant. The strains are engineered to contain a gfp expression cassette inserted into the chromosome. The biofilms are grown in once flow-through continuous-culture reaction vessels. (Top) Epifluorescence photomicrographs of the wild type (PAO1) and the mucA22 mutant (PDO300); images were acquired 8 h postinoculation of the biofilm reactor. (Middle) Epifluorescence photomicrographs acquired 24 h postinoculation. (Bottom) Scanning confocal photomicrographs of 5-day-old wild-type and mucA22 mutant biofilms. The larger central plots are simulated fluorescent projections, in which a long shadow indicates a large, high microcolony. Shown in the right and lower frames are vertical sections through the biofilms collected at the positions indicated by the white triangles. Bar, 20 μm.