Dynamics of biofilm formation in the model based on exponentially growing cells. Biofilm formation in comC and comD mutants in different genetic backgrounds. Biofilm formation in microtiter plates was evaluated in the presence (closed symbols) and absence of CSP (open symbols). Rough wt pneumococci (squares), the mutants for comC encoding CSP (circles) and for comD encoding the CSP-receptor histidine kinase (triangles) were assayed in parallel in a time course experiment. Panel A: Biofilm formation induced by CSP2 in strains derived from strain TIGR4 (comC2, comD2). Mutants assayed were FP23 (non-capsulated TIGR4) and its derivatives FP64 (comC mutant) and FP184 (comD mutant). Panel B: Biofilm formation induced by CSP1 in strains derived from D39 (comC1, comD1). Mutants assayed were RX1 (non-capsulated mutant) and its derivatives FP5 (comC mutant) and FP48 (comD mutant). Data of the twelve time course experiments are from one representative series; repetition showed comparable results.