P20_post-treatment
DNA was extracted from the whole swabs and its concentration measured with a Nanodrop 2000c Spectrophotometers (Fisher Scientific, Hampton, NH, USA). The quality of the extracted DNA was evaluated on a 1% agarose gel. Libraries were prepared by amplifying the V3 hypervariable region of the 16S rRNA gene based on a modified version of the libraries described by Bartram et al25. Primers used were GC-341F (5- CCTACGGGAGGCAGCAG-3) and 518R (5-ATTACCGCGGCTGCTG-3). Amplicons were amplified by PCR and normalised according to the obtained concentrations prior to sequencing.