title: 16S amplicon NGS _Woodchip_EE
design: DNA extraction was performed from the inoculum and the cathodic biofilms from all BESs experiments. DNA was extracted from each sample in technical triplicate using the DNeasy PowerSoil Kit (Qiagen, Germany) according to manufacturer instructions after an initial step of thermal treatment (5 cycles of 10 min at -20C and 10 min at 65C). The yield and purity (A260/A280 and A260/A230) of the extracted DNA was quantified on a Nanodrop 1000 spectrophotometer (Thermo Fisher Scientific) while eventual fragmentation was determined through gel electrophoresis 0.8% (w/v) 1TAE agarose gels. DNA was stored at -80C until analyses. Replicates were then pooled together to minimize extraction bias. The NGS was performed at Stab Vida Lda (Lisbon, Portugal). Sequencing targeted the V3 and V4 regions of the bacterial 16S rRNA gene using primers 341F (CCTACGGGNGGCWGCAG) and 785R (GACTACHVGGGTATCTAATCC) (Klindworth et al., 2013). The generated DNA libraries were sequenced with MiSeq Reagent Kit Nano in the lllumina MiSeq platform, using 300bp paired-end sequencing reads. The nucleotide sequences generated and analyzed are available at the NCBI SRA repository