Figure 3

BdcA disperses biofilms in static biofilm tests with 96-well plates. (A) Strains as in the Figure 2 caption. Black bars indicate mature biofilm formation (2 h after IPTG induction for each strain), and the gray bars show biofilm formation after dispersal (19 h after IPTG induction for P. aeruginosa/ pMMB206-BdcA and 21.5 h after IPTG induction for P. fluorescens/ pMMB206-BdcA and R. meliloti/ pMMB206-BdcA). For all three strains, 0.1 mM IPTG was added after 24 h incubation to induce bdcA expression. The P. aeruginosa biofilm was formed at 37°C in LB with 250 μg/mL chloramphenicol, the P. fluorescens biofilm was formed at 30°C in LB with 250 μg/mL chloramphenicol, and the R. meliloti biofilm was formed at 30°C in LB with 50 μg/mL chloramphenicol. pMMB206 indicates cells with this plasmid, and BdcA indicates cells containing pMMB206-BdcA. (B) For the dual-species biofilms, R. meliloti (30°C) and P. aeruginosa (37°C) biofilms were formed in LB for 24 h then E. coli DH5α/ pMMB206-BdcA/pRK2013 was added. The mixed biofilm was developed for 4 h, then IPTG was added for 26 h to produce BdcA. For the triple species biofilm, the R. meliloti and P. aeruginosa biofilm was formed in LB for 24 h at 30°C, then E. coli DH5α/ pMMB206-BdcA/pRK2013 was added. The mixed biofilm was developed for 11 h, then IPTG was added for another 24 h to produce BdcA. Normalized biofilm is indicated by dividing biofilm formation by cell turbidity. pMMB206 (black bars) indicates cells with this plasmid, and BdcA (gray bars) indicates cells containing pMMB206-BdcA. ** indicates statistical significant difference as determined by a Student's t-test (p < 0.05). Error bars indicate the standard deviation of two independent cultures.