Fig 2. CiaRH is required for biofilm formation by the ΔsdbA mutant.

(a) Crystal violet staining of 24 h biofilms grown in 24-well plates. Biofilms were grown with the parent, ΔsdbA, sdbA-complemented mutant (+SdbA), ΔciaRH, ΔsdbAΔciaRH double mutant, and ΔsdbA ciaRH-complemented mutant (ΔsdbA + CiaRH). Results are means ± SD of at least three experiments. The lower panel shows representative wells after staining. (b) In parallel to the biofilm formation assay, three additional wells for each strain were tested for total growth. The optical density was measured for the combined biofilm and planktonic cells for each mutant. (c) Biofilm formation of single deletion mutants for ciaRH and degP in the parent strain. Biofilms were grown for 24 h in 24-well plates prior to staining. Data were analyzed by one-way ANOVA and asterisks indicate a significant difference from the parent (***P ≤ 0.001, ****P ≤ 0.0001).