Mouse fecal sample SPF-3 (specific pathogen-free control)
16S rRNA gene sequencing methods were adapted from the methods developed for the NIH-Human Microbiome Project (https://hmpdacc.org/). Briefly, bacterial genomic DNA was extracted using MO BIO PowerSoil DNA Isolation Kit (MO BIO Laboratories). The 16S rDNA V4 region was amplified by PCR and sequenced in the MiSeq platform (Illumina) using the 2x250 bp paired-end protocol