Figure 6
From: Benchmarking laboratory processes to characterise low-biomass respiratory microbiota
Microbiota profiles of nasopharyngeal (NP) samples (n = 140) and DNA blanks (n = 8). (a) Two-dimensional nonmetric multidimensional scaling (NMDS) plot, based on the Bray–Curtis dissimilarity matrix, visualizes the microbial community composition (each point) of the NP samples and DNA blanks (cross). Samples are stratified by DNA concentration based on 16S rRNA gene qPCR quantification (concentration pg/µl: < 0.1; 0.1–0.2; 0.2–0.5; 0.5–1.0). The stress value illustrates how well the high-dimensional data are captured in the two-dimensional space; a value of around 0.2 indicates an acceptable representation. (b) Dendrogram visualizes an average linkage hierarchical clustering of NP samples and DNA blanks based on the Bray–Curtis dissimilarity index. The length of the branches represents the similarities between samples and DNA blanks. Stacked bar charts show the relative abundance of the top 20 OTUs and the residuals. Based on the clustering indices, 8 clusters were identified, 7 clusters solely consisted of NP samples (grey) and one separate cluster contained all DNA blanks and 2 NP samples (in green). Bacterial density colours correspond with colours used in the NMDS plot.
