FIG. 3.
Phenotypes of cells under flow conditions. Biofilms of the wild-type (WT; S. aureus 8325-4) and the hla::erm mutant (S. aureus DU1090) strains were grown in flow cell chambers. At the times indicated, biofilms were observed from a top-down perspective by using phase-contrast microscopy. In images from 4 and 8 h, light regions represent bacterial macrocolonies (indicated by the white arrows) and dark areas are the surface of the flow cell chamber. The magnification is ×675 for images from 4 and 8 h. At 24 h, the images were recorded at an original magnification of ×230. (They are shown at a magnification of ×173.) In these images from 24 h, the very dense macrocolonies formed by the wild type appear as dark regions and the light areas define macrocolony borders or channels between the macrocolonies. Small clusters of cells, but no macrocolonies, were observed for the hla mutant at all time points.