FIG. 1.
The sadC gene (PA4332) is involved in the transition to irreversible attachment during biofilm formation. (A) Biofilm formation of the WT and ΔPA4332 mutant in a microtiter plate assay. Image of CV-stained wells (top) and quantification of staining by OD550 readings of the ethanol-solubilized dye (bottom). The graph depicts averages of four replicates with the standard deviation indicated by error bars. (B) Biofilm assay as described above comparing the addition of a vector control (pMQ72) or a sadC-containing plasmid (psadC) to either the WT or ΔsadC mutant strains. (C) Static attachment assay in minimal medium containing glucose and Casamino Acids. Surface-attached bacteria were quantified from 10 fields of view using phase-contrast microscopy. Average numbers of attached cells per field of view are shown. (D) Reversible attachment under static conditions. Bacteria associated with the substratum were observed and scored as to whether they were reversibly or irreversibly attached defined on the basis of whether movement was observed. The average percentage of reversibly attached cells is represented comparing the WT to the ΔsadC mutant (n = 10 fields of view; *, P = 0.00069).