Differences in treponeme phylogroup composition and detection frequency within the periodontitis and periodontitis-free subject groups. Panel A. Plot showing the mean clonal abundance of treponeme taxa corresponding to oral treponeme phylogroups 1–7, within the periodontitis (n = 10, shaded dark gray) and periodontitis-free (n = 10, shaded light gray) subject groups. Y-axis: mean number of TOPO plasmids obtained per subject, whose cloned 16S rRNA inserts corresponded to taxa belonging to the respective oral treponeme phylogroups. X-axis: Phylogroups 1–7 = oral treponeme phylogroups 1–7. Panel B. Plot showing the mean number of OTUs detected within each oral treponeme phylogroup (Y-axis), in the periodontitis and periodontitis-free subject groups. Mean values are plotted with error bars indicating standard deviation. Significance: * = p < 0.05, ** = p < 0.01, *** = p < 0.001).