FIG 2 .

Biofilm size and live cell number are decreased in VRE strains harboring mutant relA alleles. (A) Biofilms of the VRE WT and relA mutant were formed in 24-well plates coated with bovine fibronectin. Quantification of biofilm was performed with crystal violet staining. Absorbance at 595 nm was measured for each sample. Three independent experiments were performed and combined to determine the mean average (with error bars). *, P = 0.0074 by two-tailed t test. The relA WT consistently grew to 10⁹ CFU/ml, while the relA mutant grew to 10⁸ CFU/ml per 24-h biofilm. (B and C) Biofilms were formed on multichambered glass slides. After 48 h, biofilms were stained with the Live/Dead BacLight bacterial viability kit and analyzed by confocal microscopy. (B) Representative images of a single segment. (C) The ratio of green to red (fluorescein isothiocyanate [FITC] to tetramethyl rhodamine isothiocyanate [TRITC]) signal was calculated from the average of each section, and ratios were combined for the final average (n = 8). **, P = 0.002.