**Figure 2.** (**A**) Venn diagram showing the numbers of operational taxonomic units (OTUs) between NCG and OG. (**B**–**E**) Alpha diversity of samples from the NCG and OG groups. (**B**) Rarefaction curves with Chao1 index. (**C**) Rarefaction curves with Good’s coverage index. (**D**) Violin plot of Shannon index. (**E**) Violin plot of Simpson index. Data are represented as mean ± standard error of mean. n = 7; ^{*}P < 0.05, ^{**}P < 0.01, ^{***}P < 0.001, and ^{****}P < 0.0001; ns, non-significant.