Figure 1. Phenotypic characterization of pili-deficient mutant (pilB, pilA and pilA-E5A) biofilms.

(a) Relative cytochrome content in biofilm extracts of the pili-deficient mutants in reference to WT (average and s.e. of two biological replicates for each). Significant differences in cytochrome content (*P<0.01) relative to the WT were identified in t-test pairwise comparisons. (b) Biofilm biomass on plastic surfaces estimated from the OD₅₈₀ of the biofilm-associated crystal violet solubilized with acetic acid (shown are averages and s.d. of six biofilm replicates of the WT, pili-deficient mutants and the genetic complemented pilB+ strain). (c) OmcZ_S band among haem-stained proteins isolated from the biofilm matrix of the WT and pili-deficient strains (full gels are shown in Supplementary Fig. 2c). Lanes were loaded with 20 μg of protein. Numbers at left are relative molecular masses of protein standards in kDa.