High-quality sequences were clustered into OTUs defined at 97% similarity. These OTUs were applied for diversity, richness and rarefaction curve analyses using MOTHUR. Taxonomic assignments of OTUs that reached the 97% similarity level were made using the QIIME (quantitative insights into microbial ecology) software package through comparison with the SILVA, Greengene, and RDP databases. Venn diagrams were generated to identify the mutual and specific taxons between groups using R software (http://www.r-project.org/).