Fig. 2

Study design and quality of shotgun sequencing. a Design and workflow of this study. b Rarefaction curves of the shotgun sequencing, x-axis represents the depth of sequencing, y-axis represents the percentage of richness. The rows of the panel are different microbial communities, and the columns of the panel represent the taxonomic or functional level richness. The black solid line is the average percentage of the richness of the 8 samples at the specific depth of subsampling. The red vertical solid lines represent the average sequencing depth 6.4 Gb, the blue horizontal dotted lines represent the threshold of 80% richness