design: Extracted DNA was normalized to 20 ng/l and sent to Genewiz (South Plainfield, NJ, USA) for sequencing. 16S-EZ library preparation and next generation sequencing were performed by Genewiz (South Plainfield, NJ, USA). Briefly, sequencing libraries were prepared using a MetaVX 16S rDNA Library Preparation Kit (Genewiz) and analyzed with an Illumina MiSeq instrument (Illumina, San Diego CA, US) according to manufacturer protocol. Sequencing was conducted using a 2x250 paired-end configuration. Base calls were made by internal Illumina software and sequence data was demultiplexed and converted to FASTQ format with Illuminas bcl2fastq 2.17 software. Raw digital data was processed using Qiime (version 1.9.1). Pair-end reads were joined, and barcode and primer sequences were removed. Chimeric sequences were removed and the remaining sequences were clustered into operational taxonomic units (OTUs) and assigned taxonomy based on comparison to the Greengenes database