FIG 5.

Surface attachment of E. coli wild-type and phosphodiesterase mutant strains. (a) Relative surface attachment of E. coli csrA and csrA ΔdgcZ mutant strains harboring individual pde suppressor mutations, as indicated. Levels of c-di-GMP (cdG) in both mutant backgrounds are indicated (n.d., not detectable). A schematic of the regulatory network of PGA control is shown above the graph. Gray bars and white bars indicate relative levels of biofilm formation in the csrA and csrA ΔdgcZ strain backgrounds, respectively. Biofilm formation was examined at 30°C (b) and 37°C (c) for strains carrying wild-type pdeI and the pdeI(G412S) suppressor allele. Temperature-dependent expression of pdeI as measured by immunoblot analysis is shown in the inset of panel c. (d) Relative attachment of pdeL suppressor alleles (G299S, F206S, and F249L) in a cellulose-producing bcsQ⁺ ΔpdeH background. Black bars indicate strains harboring a single nucleotide polymorphism (SNP) in the bcsQ gene, and gray bars represent a “repaired” bcsQ gene (bcsQ⁺). Attachment is shown relative to that of the cellulose-deficient lab-adapted strain E. coli K-12 MG1655 of Blattner et al. (31). The assay was performed at room temperature.