FIG. 1.

(A) Formation of a bacterial ring (indicated by the arrow) at the air-liquid interface of polystyrene culture tubes rotating in a roller drum by the wt strain and the Bvg⁻ phase-locked strain of B. bronchiseptica. (B) Microtiter assay of biofilm formation at 24 h by wt and mutant strains of B. bronchiseptica. (C) Kinetics of biofilm formation for B. bronchiseptica strains showing the OD₅₄₀s of solubilized crystal violet from surface-attached cells grown in microtiter plates and assayed at specified time intervals. Each data point is the average for six wells, and error bars indicate the standard errors. Representative data from one of at least five independent experiments are shown. The wt and different mutant strains were grown in SS medium under Bvg⁺ phase conditions. (D) Complementation of the BvgAS locus restores biofilm formation. Microtiter assays were performed as described for panel C. (E) Conditions were the same as for panel C, except that the wt strain was grown in SS medium in the presence of modulator MgSO₄ or nicotinic acid (Nic).