Fig. 2

Principal coordinate analysis (PCoA) plots of genus-level Bray–Curtis distances along the first two principal coordinatess across all samples. Within subplots, each point represents a single sample (N = 4536). Beta-diversity was significantly associated with disease status (A), URT sampling site (B), geographic region (C), disease type (D), sequencing method (E), and 16S rRNA hypervariable region used for amplicon sequencing (F). Significant differences in beta-diversity were observed for all six parameters, as determined by PERMANOVA, p < 0.001 in all cases