FIG. 7.

Biofilm formation on polystyrene plates. The indicated strains were grown in 96-well polystyrene plates for 18 h. Plates were then washed and stained with crystal violet (see Materials and Methods). Biofilm formation was quantitated by measuring the A₅₇₀ after solubilization of the stained bacteria. Data are means ± standard deviations (n = 24) (***, P < 0.005 by Student's unpaired, two-tailed t test [relative to the respective negative control]).