Fig. 1

The alternative sigma-factor sigX of S. mutans is induced by A. act. when both species are co-cultured in a biofilm. a sigX expression determined by fluorescence intensity of S. mutans SMP _sigX GFP, a gfp-reporter for sigX expression. b sigX expression determined by q-RT-PCR. The data were normalized to sigX expression in a S. mutans biofilm after 4 h. c Growth of S. mutans and A. act. in single- and dual-species biofilms determined by crystal violet staining. d Cell numbers of S. mutans and (e) A. act in single- and dual-species biofilms determined by q-PCR of the 16S rRNA gene. Mean and standard deviation of three independent experiments are shown for a–c, and of four independent experiments with two technical replicates for d–e