CzcR is required for virulence factor production and biofilm formation.

<p>Rhamnolipids, elastase production and biofilm formation in the wt and the Δ<i>czcRS</i> complemented strains. pMMB66EH: empty vector; pSWT: <i>czcS</i> gene; pRWT: <i>czcR</i> gene A) Rhamnolipid production on SW blue plate assay. The blue halo is due to the presence of rhamnolipids produced by the colony. Diameters of these halos are indicated below the figure. B) Elastase production determined by the Elastine-Congo Red assay. The determination was performed three times independently and standard deviations (errors bars) are indicated. C) Biofilm formation in M9 minimal medium on polypropylene tubes after 8 h of static growth. Biofilms were stained with cristal violet and quantified at OD₅₉₀ after solubilization in acetic acid. Quantification was performed in three independent experiments and standard deviations (errors bars) are indicated.