title: 16S rRNA-seq of human gut microbiome
design: DNA from CRCs and their corresponding normal specimens was extracted using Qiagen DNA isolation kits according to the manufacturers instructions (Qiagen, USA). Amplification of V4 variable regions of the 16S rRNA gene was performed by using amplification primers. Another round of PCR was performed to add Illumina adaptor sequences and indexes to the amplicons. The Illumina MiSeq platform was used for sequencing at the UAB Genomic Core. The 16S rRNA sequence coverage for our sample set ranged between 18,298 and 92,844 reads/sample, with mean sequence coverage of 50,594 reads/sample.