Cultivation and molecular analyses of methanotrophic enrichments from Siberian permafrost-affected soils

• Main Authors: Griess, Juliane, Mangelsdorf, K., Wagner, Dirk
• Format: Conference Object
• Language: unknown
• Published: 2009
• Subjects: Arctic; Global warming; lena delta; permafrost; Tundra; Siberia
• Online Access: https://epic.awi.de/id/eprint/20260/; https://epic.awi.de/id/eprint/20260/1/Gri2009b.pdf; https://hdl.handle.net/10013/epic.32231; https://hdl.handle.net/10013/epic.32231.d001

The Arctic plays a key role in Earths climate system as global warming is predicted to be most pronounced at high latitudes. Thawing of permafrost could release large quantities of greenhouse gases into the atmosphere, thus further increasing global warming and transforming the Arctic tundra ecosystems from a carbon sink to a carbon source. Therefore, an understanding of the aerobic methane oxidizing community, as the major sink for methane in permafrost environments, is of particular interest.Active layer samples from different horizons were taken on Samoylov Island (Lena Delta, Siberia) for cultivation and further molecular characterization of the methane oxidizing bacteria (MOB). Conditions of cultivation in mineral-salt-media with methane as the sole carbon source were different in terms of temperature, concentration of methane and presence of copper. Amplification of bacterial 16S rRNA genes was carried out using the universal primers 27F and GC_907R and 1492R, respectively, followed by DGGE or clone library analyses.DGGE fingerprints showed an effect of different cultivation conditions on the composition of the enriched communities. In addition to MOB, heterotrophic microorganisms were detected that belong to the phyla Bacteroidetes and Proteobacteria. Clone library analyses showed that cultures incubated at 28°C contained regularly Methylocella tundrae. In contrast, cultures grown at 10°C were of higher methanotrophic variety with members related to Methylobacter psychrophilus and Methylobacter tundripaludum, whose presence in permafrost-affected soils was confirmed by former clone library analyses of environmental DNA. Further studies will be conducted on an isolation of relevant methane oxidizing bacteria using optimized cultivation conditions.