Fig. 1

Principal component analysis (PCA) of faecal and salivary microbiota composition (a) and summary of major bacterial families identified (b). The PCA sample scatterplot is displayed on the first two axes summarizing most of the species variation, which is based on the OTU count data for each sample. The distance between the sample symbols (rounds for saliva and squares for faecal) approximates the dissimilarity of their species composition as measured by their Euclidean distance. Mean relative abundances (± SD) are summarized at the family level (“_f_”) for taxa > 1% and summarized in the heat map (red–yellow–green color scheme indicating high to low relative abundance). Abbreviations used for bacterial phylum levels: Acti actinobacteria, Bact bacteroidetes, Firm firmicutes, Prot proteobacteria, Verr verrucomicrobia