design: Genomic DNA was extracted using the ZymoBIOMICS DNA Miniprep Kit. The 16S rRNA gene was amplified using the Ion 16S Metagenomics Kit targeting V2, V3, V4, V6-7, V8 and V9 hypervariable regions through two multiplex PCR reactions (V2-V4-V8 / V3-V6-7-V9). Amplicon libraries were prepared with the Ion Plus Fragment Library Kit and Ion Xpress Barcode Adapters, quantified using the Ion Universal Library Quantitation Kit, and sequenced as ~400 bp reads on an Ion Torrent S5XL platform using 510/520/530 Kit-Chef chemistry.