FIG. 4.

Biofilm formation by mutants in the presence or absence of capsule. Biofilm formation by isogenic cbpA and srtA mutants in the parental encapsulated (c+, filled bars) or acapsular (c−, open bars) strain background during sessile (A and C to F) or planktonic (B) growth. Bacteria were inoculated and incubated for 14 h (A) or 10 h (B to F), at which times supernatants were removed and attached biofilms were washed with PBS and quantified by staining with CV (A, D, and F) or by plating for CFU (C and E). Planktonic cells in the supernantants were enumerated by plating for CFU (B). Bacteria were grown in 12-well polystyrene plates in THY plus 0.3% glucose in a 5% CO₂ incubator at 37°C. Results are representative of three experiments. Error bars show standard deviations. WT, wild type; OD570, absorbance at 570 nm.