FIG 6 .

PruR negatively regulates biofilm formation. (A) Biofilms grown for 48 h on PVC coverslips were quantified as described in the legend to Fig. 1C. A ΔpruR mutant with no plasmid inserted is indicated (-). The error bars show 1 SD. (B) UPP production visualized by staining with afWGA, as described in the legend to Fig. 3C. Bars, 5 µm. (C) Adherent biomass grown for 48 h was quantified as described above for panel A, with IPTG omitted. The Δcel background was utilized to reduce excess clumping. (D) Quantification of c-di-GMP levels in the indicated E. coli strains. The E. coli strains were grown to late exponential phase, and nucleotides were extracted and quantified as described in Text S1 in the supplemental material. Values are results of two independent biological replicates each with three technical replicates. The error bars show 1 SD.