title: Microbial 16S rRNA gene amplicon sequencing: human stool samples
design: Bacterial DNA was extracted from fecal samples of the twin cohort using the Power Soil DNA Isolation Kit (MoBio). 16S rRNA-targeted gene amplicon library preparation and sequencing were performed at the Environmental Sample Preparation and Sequencing Facility at Argonne National Laboratory (DuPage, Illinois). The V4 region of the 16S rRNA gene was amplified by PCR with region-specific primers (515F-806R) that include sequencer adapter sequences used in the Illumina flowcell. 151bp paired-end (PE) reads with 12 bp barcodes were generated following previously described protocols on an Illumina MiSeq instrument. The samples were demultiplexed using QIIME.