Functional characterization of the digestive microbiota based on metabolic pathway abundances in the buccal mucosa, supragingival plaque, tongue dorsum, and stool from metagenomic shotgun sequencing. Cladogram represents the KEGG BRITE functional hierarchy, with the outermost circles representing individual metabolic modules and the innermost very broad functional categories. Pathways coloration denotes modules showing significant differential abundances in at least one of the four body habitats. Metabolic profiling was performed with HUMAnN , revealing a much lower degree of variability among individuals and significant specifity of many pathways' relative abundance to individual body habitats. In particular, sugar transport and metabolism varies at each of the four habitats with metagenomic data, as does iron uptake and utilization.