FIG. 1.

Transposon insertions in the pga locus of E. coli K-12 and their effects on biofilm formation. (A) Insertions are numbered relative to the first nucleotide (+1) of the coding region of the corresponding gene. The coordinates of this locus on the E. coli K-12 genome (6) are shown. (B) Biofilm formation in polystyrene microtiter plates. Isogenic strains are represented by bars numbered as follows: 1, MG1655; 2, XWC880 (pgaC880::cam); 3, XWA672 (pgaA672::cam); 4, XWC880(pUC19); 5, XWC880(pPGA372)(pgaABCD), 6, XWA672(pUC19); and 7, XWA672 (pPGA372). (C) Strains were as in panel B, except that they were csrA mutants. All biofilms were grown in LB medium at 26°C for 24 h. The asterisks denote significant differences relative to the corresponding parent strain (P < 0.001 [Tukey multigroup analysis]).