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 - Krauze, Patryk A1 - Kämpf, Horst A1 - Horn, Fabian A1 - Liu, Qi A1 - Voropaev, Andrey A1 - Wagner, Dirk A1 - Alawi, Mashal T1 - Microbiological and Geochemical Survey of CO2-Dominated Mofette and Mineral Waters of the Cheb Basin, Czech Republic JF - Frontiers in microbiology N2 - The Cheb Basin (NW Bohemia, Czech Republic) is a shallow, neogene intracontinental basin. It is a non-volcanic region which features frequent earthquake swarms and large-scale diffuse degassing of mantle-derived CO2 at the surface that occurs in the form of CO2-rich mineral springs and wet and dry mofettes. So far, the influence of CO2 degassing onto the microbial communities has been studied for soil environments, but not for aquatic systems. We hypothesized, that deep-trenching CO2 conduits interconnect the subsurface with the surface. This admixture of deep thermal fluids should be reflected in geochemical parameters and in the microbial community compositions. In the present study four mineral water springs and two wet mofettes were investigated through an interdisciplinary survey. The waters were acidic and differed in terms of organic carbon and anion/cation concentrations. Element geochemical and isotope analyses of fluid components were used to verify the origin of the fluids. Prokaryotic communities were characterized through quantitative PCR and Illumina 16S rRNA gene sequencing. Putative chemolithotrophic, anaerobic and microaerophilic organisms connected to sulfur (e.g., Sulfuricurvum, Sulfurimonas) and iron (e.g., Gallionella, Sideroxydans) cycling shaped the core community. Additionally, CO2-influenced waters form an ecosystem containing many taxa that are usually found in marine or terrestrial subsurface ecosystems. Multivariate statistics highlighted the influence of environmental parameters such as pH, Fe2+ concentration and conductivity on species distribution. The hydrochemical and microbiological survey introduces a new perspective on mofettes. Our results support that mofettes are either analogs or rather windows into the deep biosphere and furthermore enable access to deeply buried paleo-sediments. KW - elevated CO2 concentration KW - microbial ecology KW - deep biosphere KW - Eger Rift KW - paleo-sediment KW - Sulfuricurvum KW - Gallionella KW - Sideroxydans Y1 - 2017 U6 - https://doi.org/10.3389/fmicb.2017.02446 SN - 1664-302X VL - 8 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Nwosu, Ebuka Canisius A1 - Brauer, Achim A1 - Kaiser, Jérôme A1 - Horn, Fabian A1 - Wagner, Dirk A1 - Liebner, Susanne T1 - Evaluating sedimentary DNA for tracing changes in cyanobacteria dynamics from sediments spanning the last 350 years of Lake Tiefer See, NE Germany JF - Journal of paleolimnology N2 - Since the beginning of the Anthropocene, lacustrine biodiversity has been influenced by climate change and human activities. These factors advance the spread of harmful cyanobacteria in lakes around the world, which affects water quality and impairs the aquatic food chain. In this study, we assessed changes in cyanobacterial community dynamics via sedimentary DNA (sedaDNA) from well-dated lake sediments of Lake Tiefer See, which is part of the Klocksin Lake Chain spanning the last 350 years. Our diversity and community analysis revealed that cyanobacterial communities form clusters according to the presence or absence of varves. Based on distance-based redundancy and variation partitioning analyses (dbRDA and VPA) we identified that intensified lake circulation inferred from vegetation openness reconstructions, delta C-13 data (a proxy for varve preservation) and total nitrogen content were abiotic factors that significantly explained the variation in the reconstructed cyanobacterial community from Lake Tiefer See sediments. Operational taxonomic units (OTUs) assigned to Microcystis sp. and Aphanizomenon sp. were identified as potential eutrophication-driven taxa of growing importance since circa common era (ca. CE) 1920 till present. This result is corroborated by a cyanobacteria lipid biomarker analysis. Furthermore, we suggest that stronger lake circulation as indicated by non-varved sediments favoured the deposition of the non-photosynthetic cyanobacteria sister clade Sericytochromatia, whereas lake bottom anoxia as indicated by subrecent- and recent varves favoured the Melainabacteria in sediments. Our findings highlight the potential of high-resolution amplicon sequencing in investigating the dynamics of past cyanobacterial communities in lake sediments and show that lake circulation, anoxic conditions, and human-induced eutrophication are main factors explaining variations in the cyanobacteria community in Lake Tiefer See during the last 350 years. KW - Late Holocene KW - Methylheptadecanes KW - Varves KW - Anthropocene KW - Sericytochromatia KW - Melainabacteria Y1 - 2021 U6 - https://doi.org/10.1007/s10933-021-00206-9 SN - 0921-2728 SN - 1573-0417 VL - 66 IS - 3 SP - 279 EP - 296 PB - Springer CY - Dordrecht ER -