Microbiome statistical analysis

To obtain the relative abundance of bacteria, the abundance of the different bacterial species was divided by the total bacterial count in each sample. Principal coordinates analysis (PCoA) based on the Bray–Curtis distance and permutational multivariate analysis of variance (PERMANOVA) were used to compare the microbial profiles of the three groups (i.e., the before group, the control group, and the after group). The Bray–Curtis distance is a distance metric used to calculate community similarity, which considers the feature abundance data in the calculation. To determine the differentially abundant species between two groups, the Wilcoxon rank-sum test and the false discovery rate (FDR) were calculated, and an adjusted p-value <0.05 was used as the standard. Only those microbial species with a relative abundance value above 0.001% in at least 10% of the samples were considered.