16S (515f and 926R) DNA meta-barcoding of soil prokaryotes under widespread trees across Europe
All PCR products were size checked by running 2 l of DNA on a 1% agarose gel for 15 to 20 min. The duplicate PCR amplicons were then pooled and cleaned using Sera-Mag bead purification (Cytiva Life Sciences, Marlborough, MA, USA) according to the manufacturer's instructions, then all samples with unique 8-10 bp indentifiers were pooled into an equimolar mix of 100 to 105 samples and cleaned with the E.Z.N.A. Cycle Pure Kit (Omega Bio-Tek, Norcross, GA, USA), followed by a quality check on an Agilent Bioanalyzer (Agilent, Santa Clara, CA). Pools were finally shipped for library preparation and 250 PE sequencing on the Illumina NovaSeq 6000 Sequencing System (Illumina, San Diego, CA, USA) at the service providers (Novogene Europe) laboratory.