Figure 3.

Representation of the main microbial taxa characterizing the different anatomical regions of HRT. Panel a indicates the most abundant bacterial species for each compartment of the human respiratory tract. Panel b reports the taxa showing a possible abundance gradient in relation to the distance from oral, lung and nasal compartments, respectively. Panel c shows an heatmap of the specific multivariate analysis through MaAslin2 software based on sampling methods as well as HRT-CSTs as well as bioproject, and geographical origin. Only the top 50 species with significant associations are reported. Significant positive correlations are reported in red, while Significant negative correlations are reported in blu.