Fig. 2

Principal components analysis and diversity analysis. Number of common and unique OTUS by Venn (Fig. 2a, b) and OUT Principal coordinate Analysis (PCoA) with Bray–Curtis algorithm (Fig. 2c, d). The Venn diagram showing shared and unique OTUs at 95% identity among the four groups of saliva (Fig. 2a) and plaque samples (Fig. 2b). Observed species, chao, ace, shannon’s diversity, simpson’s diversity and good’s coverage were used to as index of alpha diversity (Fig. 2e). The Beta diversity index (Fig. 2f) between groups was tested by the multi-sample comparison Kruskal–Wallis Test (Kruskal. Test in R). There were no significant differences among four groups (P > 0.05)