16S rRNA amplicon sequencing of a blank sample
DNA concentration was measured using Qubit dsDNA HS/BR Assay Kit. Sequencing libraries for the bacterial 16S rRNA gene variable regions 1-3 (bV13-A) were prepared according to a custom protocol based on the Illumina protocol using the primers: [27F] AGAGTTTGATCCTGGCTCAG and [534R] ATTACCGCGGCTGCTGG (Ward et al., 2012). The samples were paired-end sequenced using an Illumina MiSeq reagent kit v3.