FIG 6.

The c-di-GMP global pool modulates swimming motility using a multilevel regulation program. Swimming motility (A and C) and c-di-GMP concentrations (B and D) of all the DGC and PDE mutant intermediates were normalized to the wild-type EC1 levels. (A) Swimming motility decreased significantly to a first level after deleting W909_14950 (bars 2 to 4) and then to an extremely lower level after deleting W909_10355 (bars 5 to 8). The nonmotile ΔfliG strain was used as a negative control. (B) c-di-GMP concentrations of all consecutive PDE mutants showed reverse results with swimming motility. (C) The maximum swimming ability was shown after deleting W909_14945 and remained unchanged despite deleting other DGC genes. (D) c-di-GMP concentrations were reduced extremely after deleting W909_14945, continuingly decreased after deleting W909_02155, and became undetectable after deleting W909_06670. Dotted lines indicate the wild-type levels of motility and c-di-GMP concentrations. Experiments were repeated three times in triplicates. Each sample was statistically compared to every other sample; the same lowercase letters indicate samples that are not significantly different, and different letters indicate significant differences (P < 0.0001 for panels A and C; P < 0.01 for panels B and D), as determined by one-way ANOVA with a multiple-comparison test.