Microbial communities in humic lakes and ponds

The study goal was to obtain metagenomes from environmental water samples with high abundance of Polynucleobacter paneuropaeus to enable population genomic analyses of this bacterial species. Sampling sites were selected based on high observed relative abundances of Polynucleobacter paneuropaeus in an amplicon dataset of a protein-encoding gene (https://doi.org/10.1111/1755-0998.13444) and detection based on isolated genomes (https://doi.org/10.1093/gbe/evab019). One sampling campaign from 2018 (14 samples) focused at covering geographically distant populations (Austrian Alps and Northern Lapland), and another from 2020 (20 samples) on generating a time-series from one specific site (Pond EnzMain in the Austrian Alps). Samples (400 - 700 ml each) were sequentially vacuum filtered through 0.8 micrometer and 0.2 micrometer filters to enrich for the relatively small Polynucleobacter paneuropaeus bacteria on the latter filters. Metagenomes were sequenced from only the 0.2 micrometer filters for the 2018 samples, but from both 0.8 and 0.2 micrometer filters for the 2020 samples. Metagenomes from 2018 were obtained from PCR-free library preparation, while two metagenomes relating to PCR-free and PCR-amplified libraries are available for most samples from 2020.