TY  - JOUR
A1  - Wen, Xi
A1  - Unger, Viktoria
A1  - Jurasinski, Gerald
A1  - Koebsch, Franziska
A1  - Horn, Fabian
A1  - Rehder, Gregor
A1  - Sachs, Torsten
A1  - Zak, Dominik
A1  - Lischeid, Gunnar
A1  - Knorr, Klaus-Holger
A1  - Boettcher, Michael E.
A1  - Winkel, Matthias
A1  - Bodelier, Paul L. E.
A1  - Liebner, Susanne
T1  - Predominance of methanogens over methanotrophs in rewetted fens characterized by high methane emissions
JF  - Biogeosciences
N2  - The rewetting of drained peatlands alters peat geochemistry and often leads to sustained elevated methane emission. Although this methane is produced entirely by microbial activity, the distribution and abundance of methane-cycling microbes in rewetted peatlands, especially in fens, is rarely described. In this study, we compare the community composition and abundance of methane-cycling microbes in relation to peat porewater geochemistry in two rewetted fens in northeastern Germany, a coastal brackish fen and a freshwater riparian fen, with known high methane fluxes. We utilized 16S rRNA high-throughput sequencing and quantitative polymerase chain reaction (qPCR) on 16S rRNA, mcrA, and pmoA genes to determine microbial community composition and the abundance of total bacteria, methanogens, and methanotrophs. Electrical conductivity (EC) was more than 3 times higher in the coastal fen than in the riparian fen, averaging 5.3 and 1.5 mS cm(-1), respectively. Porewater concentrations of terminal electron acceptors (TEAs) varied within and among the fens. This was also reflected in similarly high intra- and inter-site variations of microbial community composition. Despite these differences in environmental conditions and electron acceptor availability, we found a low abundance of methanotrophs and a high abundance of methanogens, represented in particular by Methanosaetaceae, in both fens. This suggests that rapid (re) establishment of methanogens and slow (re) establishment of methanotrophs contributes to prolonged increased methane emissions following rewetting.
Y1  - 2018
U6  - https://doi.org/10.5194/bg-15-6519-2018
SN  - 1726-4170
SN  - 1726-4189
VL  - 15
IS  - 21
SP  - 6519
EP  - 6536
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Vuillemin, Aurele
A1  - Horn, Fabian
A1  - Friese, Andre
A1  - Winkel, Matthias
A1  - Alawi, Mashal
A1  - Wagner, Dirk
A1  - Henny, Cynthia
A1  - Orsi, William D.
A1  - Crowe, Sean A.
A1  - Kallmeyer, Jens
T1  - Metabolic potential of microbial communities from ferruginous sediments
JF  - Environmental microbiology
N2  - Ferruginous (Fe-rich, SO4-poor) conditions are generally restricted to freshwater sediments on Earth today, but were likely widespread during the Archean and Proterozoic Eons. Lake Towuti, Indonesia, is a large ferruginous lake that likely hosts geochemical processes analogous to those that operated in the ferruginous Archean ocean. The metabolic potential of microbial communities and related biogeochemical cycling under such conditions remain largely unknown. We combined geochemical measurements (pore water chemistry, sulfate reduction rates) with metagenomics to link metabolic potential with geochemical processes in the upper 50 cm of sediment. Microbial diversity and quantities of genes for dissimilatory sulfate reduction (dsrAB) and methanogenesis (mcrA) decrease with increasing depth, as do rates of potential sulfate reduction. The presence of taxa affiliated with known iron- and sulfate-reducers implies potential use of ferric iron and sulfate as electron acceptors. Pore-water concentrations of acetate imply active production through fermentation. Fermentation likely provides substrates for respiration with iron and sulfate as electron donors and for methanogens that were detected throughout the core. The presence of ANME-1 16S and mcrA genes suggests potential for anaerobic methane oxidation. Overall our data suggest that microbial community metabolism in anoxic ferruginous sediments support coupled Fe, S and C biogeochemical cycling.
Y1  - 2018
U6  - https://doi.org/10.1111/1462-2920.14343
SN  - 1462-2912
SN  - 1462-2920
VL  - 20
IS  - 12
SP  - 4297
EP  - 4313
PB  - Wiley
CY  - Hoboken
ER  -