TY  - JOUR
A1  - Frank-Fahle, Beatrice A.
A1  - Yergeau, Etienne
A1  - Greer, Charles W.
A1  - Lantuit, Hugues
A1  - Wagner, Dirk
T1  - Microbial functional potential and community composition in permafrost-affected soils of the NW canadian arctic
JF  - PLoS one
N2  - Permafrost-affected soils are among the most obvious ecosystems in which current microbial controls on organic matter decomposition are changing as a result of global warming. Warmer conditions in polygonal tundra will lead to a deepening of the seasonal active layer, provoking changes in microbial processes and possibly resulting in exacerbated carbon degradation under increasing anoxic conditions. To identify current microbial assemblages in carbon rich, water saturated permafrost environments, four polygonal tundra sites were investigated on Herschel Island and the Yukon Coast, Western Canadian Arctic. Ion Torrent sequencing of bacterial and archaeal 16S rRNA amplicons revealed the presence of all major microbial soil groups and indicated a local, vertical heterogeneity of the polygonal tundra soil community with increasing depth. Microbial diversity was found to be highest in the surface layers, decreasing towards the permafrost table. Quantitative PCR analysis of functional genes involved in carbon and nitrogen-cycling revealed a high functional potential in the surface layers, decreasing with increasing active layer depth. We observed that soil properties driving microbial diversity and functional potential varied in each study site. These results highlight the small-scale heterogeneity of geomorphologically comparable sites, greatly restricting generalizations about the fate of permafrost-affected environments in a warming Arctic.
Y1  - 2014
U6  - https://doi.org/10.1371/journal.pone.0084761
SN  - 1932-6203
VL  - 9
IS  - 1
PB  - PLoS
CY  - San Fransisco
ER  - 
TY  - JOUR
A1  - Schirmack, Janosch
A1  - Boehm, Michael
A1  - Brauer, Chris
A1  - Löhmannsröben, Hans-Gerd
A1  - de Vera, Jean-Pierre Paul
A1  - Moehlmann, Diedrich
A1  - Wagner, Dirk
T1  - Laser spectroscopic real time measurements of methanogenic activity under simulated Martian subsurface analog conditions
JF  - Planetary and space science
N2  - On Earth, chemolithoautothrophic and anaerobic microorganisms such as methanogenic archaea are regarded as model organisms for possible subsurface life on Mars. For this reason, the methanogenic strain Methanosarcina soligelidi (formerly called Methanosarcina spec. SMA-21), isolated from permafrost-affected soil in northeast Siberia, has been tested under Martian thermo-physical conditions. In previous studies under simulated Martian conditions, high survival rates of these microorganisms were observed. In our study we present a method to measure methane production as a first attempt to study metabolic activity of methanogenic archaea during simulated conditions approaching conditions of Mars-like environments. To determine methanogenic activity, a measurement technique which is capable to measure the produced methane concentration with high precision and with high temporal resolution is needed. Although there are several methods to detect methane, only a few fulfill all the needed requirements to work within simulated extraterrestrial environments. We have chosen laser spectroscopy, which is a non-destructive technique that measures the methane concentration without sample taking and also can be run continuously. In our simulation, we detected methane production at temperatures down to -5 degrees C, which would be found on Mars either temporarily in the shallow subsurface or continually in the deep subsurface. The pressure of 50 kPa which we used in our experiments, corresponds to the expected pressure in the Martian near subsurface. Our new device proved to be fully functional and the results indicate that the possible existence of methanogenic archaea in Martian subsurface habitats cannot be ruled out. (C) 2013 Published by Elsevier Ltd.
KW  - Mars
KW  - Methanogens
KW  - Methane
KW  - Sub-zero temperature (Celsius)
KW  - Wavelength modulation spectroscopy (laser spectroscopy)
Y1  - 2014
U6  - https://doi.org/10.1016/j.pss.2013.08.019
SN  - 0032-0633
VL  - 98
SP  - 198
EP  - 204
PB  - Elsevier
CY  - Oxford
ER  -