MiSeq library preparation and quality control.

Amplicons were visualized on a 1.2% agarose gel. Gel extraction was performed using the MinElute gel extraction kit (Qiagen) according to the manufacturer’s instructions. Purified DNA was eluted in 10 μl of buffer EB (Qiagen) and quantified using the Qubit double-stranded-DNA broad-range assay (Thermo Fisher). Samples were pooled in equimolar concentrations, and the final library was purified using AmpureXP beads at a bead-to-DNA ratio of 0.7:1. Libraries were submitted to the UNC High Throughput Sequencing Facility for Illumina MiSeq 2 × 300-base paired-end sequencing.