Fig. 3.

Quantitative analysis of the suppressive effect of cyclic-di-GMP and its analogs on Staphylococcus aureus biofilm formation (a) and on Pseudomonas aeruginosa biofilm formation (b) using the crystal violet staining method. The biofilm of S. aureus MS2507 and P. aeruginosa PAO1 was formed on wells of a polystyrene microplate. The media for biofilm formation were supplemented with indicated concentrations of synthetic cyclic-di-GMP and its analogs. After the incubation, the biofilm formed on the surface of wells was stained with crystal violet. The dye staining the biofilm was then extracted and the OD_{570 nm} was measured. Relative values of each culture to the control culture containing none of the synthetic cyclic-di-GMP and its analogs are presented in the figure. ^*P<0.05; ^**P<0.01; ^***P<0.001.