Fig 4.

Dispersion by wild-type P. aeruginosa biofilms correlates with increased expression of dipA and requires protein synthesis. (A) Fold change in dipA, rbdA, and bdlA RNA levels in wild-type P. aeruginosa planktonic cells, the remaining biofilms following dispersion, and dispersed cells compared to biofilm growth conditions was assessed by qRT-PCR analysis. (B) P. aeruginosa biofilms following 4 days of growth under flowing conditions were treated for 30 min with tetracycline (arrow 1) prior to the induction of dispersion (arrow 2). Control biofilms were not treated. Dispersion was induced by a sudden increase in the medium glutamate concentration. The biofilm effluent was collected in 0.2-ml aliquots into microtiter plates, and the absorbance was read at 600 nm. All experiments were carried out in triplicate. Error bars indicate standard deviations. *, significantly different from biofilms (P < 0.05), as determined by ANOVA and SigmaStat.