FIG 1.
De novo pyrimidine biosynthesis is linked to the formation of SCV and mucoidy in P. aeruginosa. (A) PAO581 cells grown at 37°C for 48 h on PIA plates (left) and PIA plates with uracil (right). (B) The effect of disrupting the de novo pyrimidine pathway in a stable alginate-producing strain, P. aeruginosa PAO581. PAO581 carA, PAO581 carB, and PAO581 pyrD were grown on PIA plates at 37°C for 48 h. (C) The effect of adding uracil (0.1 mM) to the medium (PIA) on the growth of three pyrimidine biosynthetic mutants (carA, carB, and pyrD) at 37°C for 48 h. (D) Alginate production for PAO1, PAO581, PAO581 carA, PAO581 carB, and PAO581 pyrD when grown on PIA plates with and without uracil at 37°C for 24 h. Alginate was collected and measured using the standard carbazole assay. Values shown are mean alginate ± standard deviation from triplicate reads. (E) The β-galactosidase activity of PalgD measured using pLP170-PalgD-lacZ reporter constructs in PAO1, PAO581, PAO581 carA, PAO581 carB, and PAO581 pyrD grown on PIA plates containing carbenicillin and uracil at 37°C for 24 h. Relative expression mean values ± standard deviations from triplicate reads are shown. Two-way analysis of variance (ANOVA) was used with statistical significance at a P value of <0.01 (****, P < 0.0001).