Research Paper Volume 16, Issue 2 pp 1336—1351

Figure 2. Calculation of alpha diversity index reflects sequencing depth. (A) The OTUs indicating the numbers of observed bacterial species. The X-axis represents the random sampling depth, and the Y-axis represents the exponential value. The curve slowly plateaus, indicating that there is enough sequencing data to represent information on the majority of microbial species in the sample. (B) Species richness and evenness. The abscissa represents the number of sequences contained in OTUs. For example, the 1000^th most abundant OTU is represented by “1000”. The ordinate represents the relative abundance of the OTU, where “0.01” stands for 0.01%. (C) Species accumulation curve. The number of samples is represented on the X-axis, and the detected OTU number of samples is represented on the Y-axis. The flattening of the curve indicates that the sample size is adequate. (D) Good’s coverage analysis. Each sample is represented by one curve. The abscissa represents the random sampling depth, and the ordinate represents the exponential value. The curves flatten early on, and the value of the Y-axis changes barely, indicating the rationality of the amount of sequencing data. (E, F) Violin diagram of Shannon and Simpson index. Different colors represent different groups, and the ordinate is the index value. (G) Venn diagram of the number of OTUs in A, B, C, and D groups. Abbreviation: OTUs: operational taxonomic units.