Statistical analysis.
The sequencing data were processed and analyzed using the software VSEARCH version 2.7.1 (Statistical analysis was performed in R version 3.6.1 via the Rstudio interface. To identify the contaminating DNA coming from experiment operation, the decontam package was used. The feature table covering all samples and the concentration of DNA in each eligible library as measured by fluorescent intensity were input to the function. The species richness, Shannon index, unweighted UniFrac distance, and weighted UniFrac distance were computed, and ordination analyses were conducted using the vegan, ape, ggplot2, and GUniFrac packages with all ZOTUs. Principal coordinates analysis and permutational analysis of variance (PERMANOVA) was performed based on both unweighted UniFrac distance and weighted UniFrac distance. Multivariable PERMANOVA was performed using weighted UniFrac distance. The diversity comparations between the same group were calculated by paired 