Bacterial community profiling was performed by amplification of the V3V4 hypervariable regions of the 16S rRNA gene using primers V3_35F (CCTACGGGAGGCAGCAG) and V4_806R (GGACTACHVGGGTWTCTAAT). Libraries were prepared using a dual-indexed PCR approach consisting of an initial amplification followed by an indexing PCR. Purified and normalized libraries were pooled and sequenced on the Illumina MiSeq platform using 2  300 bp paired-end v3 chemistry with a 1525% PhiX spike-in.