FIG. 7.

Production of biofilms by ddhC::Tn5 (A1-8) and waaG::Tn5 (A1-9) mutants. (A) Biofilm production by waaG mutants A1-9 (waaG::Tn5) and YA155 (ΔwaaG::kan) was observed as rings on the tube walls at the liquid-air interface. Strain A1-8 produced fragile biofilms which detached easily and cannot be seen here. Note the less dense medium in both A1-8 and A1-9 caused by the formation of cell clumps, which caused the cells to settle to the bottom of the tube. Bacteria were grown in LGS at 37°C with shaking at 250 rpm for 20 h. Complementation of waaG in strain YA156 eliminated the ability of cells to form biofilms under this condition. (B) The ddhC::Tn5 (A1-8) and waaG::Tn5 (A1-9) mutants were shown to exhibit higher levels of adherence to PVC surfaces compared to WT Rv. The higher level of adherence of A1-8 than of WT LT2 was similar to that of ΔwaaG::kan mutant strain YA155. Cells were grown in M63 medium supplemented with 0.2% glucose and 0.5% CAA in microtiter wells for 8 h. Attached cells were quantified by staining the biofilms with crystal violet and determining the absorbance of the solubilized dye at 595 nm.