Bacterial and protozoan dynamics upon thawing and freezing of an active layer permafrost soil

• Published in: The ISME Journal
• Main Authors: Schostag, Morten, Prieme, Anders, Jacquiod, Samuel, Russel, Jakob, Ekelund, Flemming, Jacobsen, Carsten Suhr
• Other Authors: University of Copenhagen = Københavns Universitet (UCPH), Department of Biology, Northern Arizona University Flagstaff, Geological Survey of Denmark and Greenland (GEUS), Agroécologie Dijon, Institut National de la Recherche Agronomique (INRA)-Université de Bourgogne (UB)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Université Bourgogne Franche-Comté COMUE (UBFC), Aarhus University Aarhus, Danish National Research Foundation CENPERM DNRF100, Danish Geocenter; Danish Council for Independent Research DFF-4002-00274, European Project: 675546,H2020,H2020-MSCA-ITN-2015,MicroArctic(2016)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2019
• Subjects: [SDV]Life Sciences [q-bio]; [SDE]Environmental Sciences; [SDV.BV]Life Sciences [q-bio]/Vegetal Biology; Arctic; Norway; Svalbard; permafrost
• Online Access: https://hal.inrae.fr/hal-02620200; https://doi.org/10.1038/s41396-019-0351-x

International audience The active layer of soil overlaying permafrost in the Arctic is subjected to annual changes in temperature and soil chemistry, which we hypothesize to affect the overall soil microbial community. We investigated changes in soil microorganisms at different temperatures during warming and freezing of the active layer soil from Svalbard, Norway. Soil community data were obtained by direct shotgun sequencing of total extracted RNA. No changes in soil microbial communities were detected when warming from -10 to -2 degrees C or when freezing from -2 to -10 degrees C. In contrast, within a few days we observed changes when warming from -2 to +2 degrees C with a decrease in fungal rRNA and an increase in several OTUs belonging to Gemmatimonadetes, Bacteroidetes and Betaproteobacteria. Even more substantial changes occurred when incubating at 2 degrees C for 16 days, with declines in total fungal potential activity and decreases in oligotrophic members from Actinobacteria and Acidobacteria. Additionally, we detected an increase in transcriptome sequences of bacterial phyla Bacteriodetes, Firmicutes, Betaproteobacteria and Gammaproteobacteria-collectively presumed to be copiotrophic. Furthermore, we detected an increase in putative bacterivorous heterotrophic flagellates, likely due to predation upon the bacterial community via grazing. Although this grazing activity may explain relatively large changes in the bacterial community composition, no changes in total 16S rRNA gene copy number were observed and the total RNA level remained stable during the incubation. Together, these results are showing the first comprehensive ecological evaluation across prokaryotic and eukaryotic microbial communities on thawing and freezing of soil by application of the Total RNA technique.