DNA was extracted from samples using Zymo BIOMICS kit. The primer sequences used to amplify an approximately 450 pb fragment of the bacterial 16S rRNA gene were Bakt_314F 5'- CCTACGGGNGGCWGCAG '3 and Bakt_805R 3'- GACTACHVGGGTATCTAATCC -5' (Herlemann et al., 2011). The pooled final DNA library was sequenced using paired 300-bp reads that overlap in their ends, generating high quality, full-length reads for the targeted V3 and V4 regions.