August, Leiden, Downstream surface water
n average amount of 1 g DNA per sample was used as input material to prepare libraries that were generated using the NEBNext Ultra DNA Library Prep kit for Illumina (NEB, USA) following manufacturer s instructions: index code was added to attribute sequences to each sample. In short, the DNA sample was fragmented by sonication intro fragment sizes of 350 bp; the DNA fragments were end-polished, A-tailed, and ligated with full-length adaptor for Illumina sequencing with further PCR amplification to add the sequence adapters. The PCR products were purified on AMPure XP magnetic beads (Beckman Coulter, USA). The library preparations were sequenced with an Illumina HiSEQ PE150 system. Ten raw sequencing files with 150 bp paired-reads were obtained, with an average of 10 Gb per sample.