Figure 4: Biofilm formation on microtiter plates. Biofilm production of Streptococcus constellatus strains H39 and ATCC 27823, Streptococcus intermedius ATCC 27335 and Streptococcus anginosus ATCC 33397 on a polystyrene microtiter plate: a set of microtitier plate wells (three wells for each strain) stained with 0.1% crystal violet solution after 24 h of incubation (A). The quantitative analysis of biofilm production as measuring the optical density of destained biofilms at 570 nm (B). The data are from one of three independent experiments. Bars indicate standard deviations.