RealTime-PCR analysis of selected genes. RealTime-PCR for specific genes was carried out in triplicate and repeated at least once. Data presented here were generated from at least four independent sets of experiments. These data were normalized and further analyzed using a non-parametric Kruskal-Wallis Test and student t-test. The bar graphs represent the average (± standard deviation in error bars) of copy numbers × (μg S. mutans total RNA)-1, with *, # and @ illustrating statistical differences at P < 0.05, 0.01, and 0.001, respectively, when compared to the respective genes in mono-species biofilms.