Fig. 1

Alpha diversity of salivary microbiome. Saliva samples were collected from 10 astronauts at various time points before flying to the ISS (pre-flight), while on the ISS (Flight) and upon return to Earth (post-flight). Diversity was measured using Shannon’s diversity index (left panel) and Faith’s phylogenetic diversity (right panel). Richness was measured by counting the number of unique amplicon sequence variants (ASV) within each sample (middle panel). Reads were rarified to different counts (x-axis) and the values for each rarefied read count plotted (y-axis). For all 3 metrics tested, alpha diversity was the highest in-flight, with post-flight samples decreasing to pre-flight values. Kruskal-Wallis one-way analysis of variance followed by the Benjamini-Hochberg multiple comparison post-hoc test (Significance threshold P < 0.05).