design: Libraries were pooled prior to sequencing on the MiSeq platform (Illumina, United States), 250-cycle paired read configuration. Cluster size and amount of clustering were assessed on the Bioanalyzer 2100 (Agilent Technologies, United States) and with the Library Quantification Kit for Illumina (KAPA Biosciences, United States), respectively. The PhiX (v3) control library (Illumina, United States) was combined with the amplicon library (20 % expected). Data quality assessment was performed with the MiSeq Control Software (MCS) v2.6.2.1 instrument.