design: Genomic DNA was isolated from ~200 mg of feces using ZymoBIOMICS DNA Kits following the manufacturers standardized protocol. We amplified the V3-V4 hypervariable regions of the 16S rRNA genes using universal primers 341F (5-CCTACGGGNGGCWGCAG-3) and 805R (5-GGACTACHVGGGTWTCTAAT -3), generating 465 bp amplicons. PCR ingredients and PCR cycling conditions were optimized to minimize bias and ensure consistent amplification across all samples as described previously. After amplifying the library, high-throughput sequencing was performed on the Illumina NovaSeq platform using 2 x 250 bp paired end reads mode (LC Sciences, Houston, Texas).