Impact of competence in the stationary phase type microtiter biofilm model. In this model, biofilm formation was evaluated by both crystal violet staining and analysis at the spectrophotometer. The FP23 strain (non-capsulated TIGR4) was compared with its isogenic mutants in comD (FP231) and comC (FP259). The comC mutant FP259 was also assayed with addition of synthetic CSP to the medium (striped bars). The experiment was performed in BHI and read after 24 (panel A) or 48 hours (panel B) of incubation at 37°C. The differences in biofilm formations between the wt and the comC and comD mutants and between FP259 with and without CSP were statistically significant (p < 0.005). Data are from triplicate experiments.