FIG. 4.

Biofilm competition assay. Equal quantities of PAO1 and its isogenic mutants were grown together as a biofilm for 5 days. A section of tubing was removed daily, and the total number of cells, as well as the number of Gm^r cells, was enumerated by serial dilution and plate count. All three mutants were less fit than the wild type and were reduced to 0.0001% or less of total cells after 5 days.