FIG. 7.

Quantitative assay of biofilm formation in cocultures containing both wild-type B. bronchiseptica (RB50) and the ΔcyaA mutant in the Bvg⁺ phase (0 mM nicotinic acid) and Bvgⁱ phase (0.4 mM nicotinic acid). Bacteria were grown in 96-well polystyrene plates, and biofilm formation was quantified by absorbance of solubilized crystal violet stains, as described in Materials and Methods. Coculture of RB50 with the ΔcyaA mutant results in a low level of biofilm (comparable to that of RB50 alone) in the Bvg⁺ phase, but no significant reduction of biofilm formation in the coculture was observed in the Bvgⁱ phase. OD₅₉₅, optical density at 595 nm.