FIG 5.

Contribution of cellular c-di-GMP levels to the biofilm dispersion response. (A) Cellular c-di-GMP level of planktonic cells harboring the empty vector pMJT1 or overexpressing PA2133 and dipA encoding phosphodiesterases. c-di-GMP levels were determined by high-pressure liquid chromatography (HPLC). “pmol/mg” refers to c-di-GMP levels (pmol) per total cell protein (in mg). *, Significantly different from PAO1 vector control (P < 0.01 as determined by ANOVA and SigmaStat). (B to D) Detection of dispersion after induction of PA2133, dipA, bdlA, and bdlA-G31A gene expression. Dispersion experiments were carried out in tube reactor-grown biofilms. Dispersion was indicated by an increase in the turbidity of biofilm tube reactor effluents. (B) Detection of dispersion after induction of PA2133 and dipA gene expression by the addition of 0.1% arabinose to the growth medium. P. aeruginosa PAO1 harboring the empty vector pMJT1 was used as a control. (C and D) Detection of dispersion after the induction of bdlA (C) and bdlA-G31A (D) gene expression upon addition of arabinose to the growth medium. The graphs are representative of two independent biofilm replicates indicated by dashed and solid lines. Dispersion was detected upon the addition of arabinose to the ΔbdlA strain carrying pJN-bdlA-G31A (D), but not to the PAO1/pMJT-1, PAO1/pMJT-PA2133, and PAO1/pMJT-dipA strains (B) or to the ΔbdlA strain carrying pJN-bdlA (C).