Distinct summer and winter bacterial communities in the active layer of Svalbard permafrost revealed by DNA- and RNA-based analyses

Morten Schostag, Marek Stibal, Carsten S. Jacobsen, Jacob Bælum, Neslihan Tas, Bo Elberling, Janet K. Jansson, Philipp Semenchuk, Anders Prieme

    Research output: Contribution to journalJournal articleResearchpeer-review

    226 Downloads (Pure)

    Abstract

    The active layer of soil overlaying permafrost in the Arctic is subjected to dramatic annual changes in temperature and soil chemistry, which likely affect bacterial activity and community structure. We studied seasonal variations in the bacterial community of active layer soil from Svalbard (78ºN) by co-extracting DNA and RNA from 12 soil cores collected monthly over a year. PCR amplicons of 16S rRNA genes (DNA) and reverse transcribed transcripts (cDNA) were quantified and sequenced to test for the effect of low winter temperature and seasonal variation in concentration of easily degradable organic matter on the bacterial communities. The copy number of 16S rRNA genes and transcripts revealed no distinct seasonal changes indicating potential bacterial activity during winter despite soil temperatures well below -10ºC. Multivariate statistical analysis of the bacterial diversity data (DNA and cDNA libraries) revealed a season-based clustering of the samples, and, e.g., the relative abundance of potentially active Cyanobacteria peaked in June and Alphaproteobacteria increased over the summer and then declined from October to November. The structure of the bulk (DNA-based) community was significantly correlated with pH and dissolved organic carbon, while the potentially active (RNA-based) community structure was not significantly correlated with any of the measured soil parameters. A large fraction of the 16S rRNA transcripts was assigned to nitrogen-fixing bacteria (up to 24% in June) and phototrophic organisms (up to 48% in June) illustrating the potential importance of nitrogen fixation in otherwise nitrogen poor Arctic ecosystems and of phototrophic bacterial activity on the soil surface.
    Original languageEnglish
    Article number399
    JournalFrontiers in Microbiology
    Volume6
    Number of pages13
    ISSN1664-302X
    DOIs
    Publication statusPublished - 2015

    Bibliographical note

    This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    Keywords

    • Permafrost active layer
    • Seasonal variation
    • Bacterial community structure
    • 16SrRNA gene
    • Arctic

    Cite this

    Schostag, M., Stibal, M., Jacobsen, C. S., Bælum, J., Tas, N., Elberling, B., Jansson, J. K., Semenchuk, P., & Prieme, A. (2015). Distinct summer and winter bacterial communities in the active layer of Svalbard permafrost revealed by DNA- and RNA-based analyses. Frontiers in Microbiology, 6, [399]. https://doi.org/10.3389/fmicb.2015.00399