Bacterial Community Structures in Freshwater Polar Environments of Svalbard.

Two thirds of Svalbard archipelago islands in the High Arctic are permanently covered with glacial ice and snow. Polar bacterial communities in the southern part of Svalbard were characterized using an amplicon sequencing approach. A total of 52,928 pyrosequencing reads were analyzed in order to reveal bacterial community structures in stream and lake surface water samples from the Fuglebekken and Revvatnet basins of southern Svalbard. Depending on the samples examined, bacterial communities at a higher taxonomic level mainly consisted either of Bacteroidetes, Betaproteobacteria, and Microgenomates (OP11) or Planctomycetes, Betaproteobacteria, and Bacteroidetes members, whereas a population of Microgenomates was prominent in 2 samples. At the lower taxonomic level, bacterial communities mostly comprised Microgenomates, Comamonadaceae, Flavobacteriaceae, Legionellales, SM2F11, Parcubacteria (OD1), and TM7 members at different proportions in each sample. The abundance of OTUs shared in common among samples was greater than 70%, with the exception of samples in which the proliferation of Planctomycetaceae, Phycisphaeraceae, and Candidatus Methylacidiphilum spp. lowered their relative abundance. A multi-variable analysis indicated that As, Pb, and Sb were the main environmental factors influencing bacterial profiles. We concluded that the bacterial communities in the polar aquatic ecosystems examined mainly consisted of freshwater and marine microorganisms involved in detritus mineralization, with a high proportion of zooplankton-associated taxa also being identified.