TY - GEN A1 - de Vera, Jean-Pierre Paul A1 - Alawi, Mashal A1 - Backhaus, Theresa A1 - Baque, Mickael A1 - Billi, Daniela A1 - Boettger, Ute A1 - Berger, Thomas A1 - Bohmeier, Maria A1 - Cockell, Charles A1 - Demets, Rene A1 - de la Torre Noetzel, Rosa A1 - Edwards, Howell A1 - Elsaesser, Andreas A1 - Fagliarone, Claudia A1 - Fiedler, Annelie A1 - Foing, Bernard A1 - Foucher, Frederic A1 - Fritz, Jörg A1 - Hanke, Franziska A1 - Herzog, Thomas A1 - Horneck, Gerda A1 - Hübers, Heinz-Wilhelm A1 - Huwe, Björn A1 - Joshi, Jasmin Radha A1 - Kozyrovska, Natalia A1 - Kruchten, Martha A1 - Lasch, Peter A1 - Lee, Natuschka A1 - Leuko, Stefan A1 - Leya, Thomas A1 - Lorek, Andreas A1 - Martinez-Frias, Jesus A1 - Meessen, Joachim A1 - Moritz, Sophie A1 - Moeller, Ralf A1 - Olsson-Francis, Karen A1 - Onofri, Silvano A1 - Ott, Sieglinde A1 - Pacelli, Claudia A1 - Podolich, Olga A1 - Rabbow, Elke A1 - Reitz, Günther A1 - Rettberg, Petra A1 - Reva, Oleg A1 - Rothschild, Lynn A1 - Garcia Sancho, Leo A1 - Schulze-Makuch, Dirk A1 - Selbmann, Laura A1 - Serrano, Paloma A1 - Szewzyk, Ulrich A1 - Verseux, Cyprien A1 - Wadsworth, Jennifer A1 - Wagner, Dirk A1 - Westall, Frances A1 - Wolter, David A1 - Zucconi, Laura T1 - Limits of life and the habitability of Mars BT - the ESA space experiment BIOMEX on the ISS T2 - Astrobiology N2 - BIOMEX (BIOlogy and Mars EXperiment) is an ESA/Roscosmos space exposure experiment housed within the exposure facility EXPOSE-R2 outside the Zvezda module on the International Space Station (ISS). The design of the multiuser facility supports-among others-the BIOMEX investigations into the stability and level of degradation of space-exposed biosignatures such as pigments, secondary metabolites, and cell surfaces in contact with a terrestrial and Mars analog mineral environment. In parallel, analysis on the viability of the investigated organisms has provided relevant data for evaluation of the habitability of Mars, for the limits of life, and for the likelihood of an interplanetary transfer of life (theory of lithopanspermia). In this project, lichens, archaea, bacteria, cyanobacteria, snow/permafrost algae, meristematic black fungi, and bryophytes from alpine and polar habitats were embedded, grown, and cultured on a mixture of martian and lunar regolith analogs or other terrestrial minerals. The organisms and regolith analogs and terrestrial mineral mixtures were then exposed to space and to simulated Mars-like conditions by way of the EXPOSE-R2 facility. In this special issue, we present the first set of data obtained in reference to our investigation into the habitability of Mars and limits of life. This project was initiated and implemented by the BIOMEX group, an international and interdisciplinary consortium of 30 institutes in 12 countries on 3 continents. Preflight tests for sample selection, results from ground-based simulation experiments, and the space experiments themselves are presented and include a complete overview of the scientific processes required for this space experiment and postflight analysis. The presented BIOMEX concept could be scaled up to future exposure experiments on the Moon and will serve as a pretest in low Earth orbit. KW - EXPOSE-R2 KW - BIOMEX KW - Habitability KW - Limits of life KW - Extremophiles KW - Mars Y1 - 2019 U6 - https://doi.org/10.1089/ast.2018.1897 SN - 1531-1074 SN - 1557-8070 VL - 19 IS - 2 SP - 145 EP - 157 PB - Liebert CY - New Rochelle ER - TY - JOUR A1 - Schulze-Makuch, Dirk A1 - Wagner, Dirk A1 - Kounaves, Samuel P. A1 - Mangelsdorf, Kai A1 - Devine, Kevin G. A1 - de Vera, Jean-Pierre A1 - Schmitt-Kopplin, Philippe A1 - Grossart, Hans-Peter A1 - Parro, Victor A1 - Kaupenjohann, Martin A1 - Galy, Albert A1 - Schneider, Beate A1 - Airo, Alessandro A1 - Froesler, Jan A1 - Davila, Alfonso F. A1 - Arens, Felix L. A1 - Caceres, Luis A1 - Cornejo, Francisco Solis A1 - Carrizo, Daniel A1 - Dartnell, Lewis A1 - DiRuggiero, Jocelyne A1 - Flury, Markus A1 - Ganzert, Lars A1 - Gessner, Mark O. A1 - Grathwohl, Peter A1 - Guan, Lisa A1 - Heinz, Jacob A1 - Hess, Matthias A1 - Keppler, Frank A1 - Maus, Deborah A1 - McKay, Christopher P. A1 - Meckenstock, Rainer U. A1 - Montgomery, Wren A1 - Oberlin, Elizabeth A. A1 - Probst, Alexander J. A1 - Saenz, Johan S. A1 - Sattler, Tobias A1 - Schirmack, Janosch A1 - Sephton, Mark A. A1 - Schloter, Michael A1 - Uhl, Jenny A1 - Valenzuela, Bernardita A1 - Vestergaard, Gisle A1 - Woermer, Lars A1 - Zamorano, Pedro T1 - Transitory microbial habitat in the hyperarid Atacama Desert JF - Proceedings of the National Academy of Sciences of the United States of America KW - habitat KW - aridity KW - microbial activity KW - biomarker KW - Mars Y1 - 2018 U6 - https://doi.org/10.1073/pnas.1714341115 SN - 0027-8424 VL - 115 IS - 11 SP - 2670 EP - 2675 PB - National Acad. of Sciences CY - Washington ER - TY - JOUR A1 - Gefen-Treves, Shany A1 - Kedem, Isaac A1 - Weiss, Gad A1 - Wagner, Dirk A1 - Tchernov, Dan A1 - Kaplan, Aaron T1 - Acclimation of a rocky shore algal reef builder Neogoniolithon sp. to changing illuminations JF - Limnology and oceanography e-lectures / Association for the Sciences of Limnology and Oceanography N2 - Vermetid reefs and rocky shores are hot spots of biodiversity, often referred to as the subtropical equivalent of coral reefs. The development of the ecosystem depends on the activity of several reef builders, including red crustose coralline algae (CCA) such as Neogoniolithon brassica-florida. Despite its importance, little is known about Neogoniolithon sp. acclimation to rapid changes in light intensity and corresponding photosynthetic activity. To overcome the large spatial variability in the light field (due to location and the porous nature of the rocks) we grew Neogoniolithon sp. on glass slides and characterized its photosynthetic performance in response to various light intensities by following O-2 exchange and fluorescence parameters. This was also performed on rock-inhabiting thalli collected from the east Mediterranean basin. Generally, maximal photosynthetic rate was reached when Neogoniolithon sp. thalli grown under low illumination (such as in protected niches where the light intensity can be as low as 1% of surface illumination) were examined. When exposed to light intensities higher than those experienced during growth, Neogoniolithon sp. activates adaptive/protective mechanisms such as state transition and nonphotochemical fluorescence quenching and increases the dark respiration thereafter. We find that the Fv/Fm parameter (variable/maximal fluorescence) is not suitable to assess photosynthetic performance in Neogoniolithon sp. and propose using instead an alternative parameter recently developed. Our findings help to clarify why Neogoniolithon sp. is usually observed in shaded niches along the reef surfaces. Y1 - 2019 U6 - https://doi.org/10.1002/lno.11245 SN - 0024-3590 SN - 1939-5590 VL - 65 IS - 1 SP - 27 EP - 36 PB - Wiley CY - Hoboken 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 - TY - THES A1 - Wagner, Dirk T1 - Microbial perspectives of the methane cycle in permafrost ecosystems in the Eastern Siberian Arctic : implications for the global methane budget N2 - The Arctic plays a key role in Earth’s climate system as global warming is predicted to be most pronounced at high latitudes and because one third of the global carbon pool is stored in ecosystems of the northern latitudes. In order to improve our understanding of the present and future carbon dynamics in climate sensitive permafrost ecosystems, the present study concentrates on investigations of microbial controls of methane fluxes, on the activity and structure of the involved microbial communities, and on their response to changing environmental conditions. For this purpose an integrated research strategy was applied, which connects trace gas flux measurements to soil ecological characterisation of permafrost habitats and molecular ecological analyses of microbial populations. Furthermore, methanogenic archaea isolated from Siberian permafrost have been used as potential keystone organisms for studying and assessing life under extreme living conditions. Long-term studies on methane fluxes were carried out since 1998. These studies revealed considerable seasonal and spatial variations of methane emissions for the different landscape units ranging from 0 to 362 mg m-2 d-1. For the overall balance of methane emissions from the entire delta, the first land cover classification based on Landsat images was performed and applied for an upscaling of the methane flux data sets. The regionally weighted mean daily methane emissions of the Lena Delta (10 mg m-2 d-1) are only one fifth of the values calculated for other Arctic tundra environments. The calculated annual methane emission of the Lena Delta amounts to about 0.03 Tg. The low methane emission rates obtained in this study are the result of the used remotely sensed high-resolution data basis, which provides a more realistic estimation of the real methane emissions on a regional scale. Soil temperature and near soil surface atmospheric turbulence were identified as the driving parameters of methane emissions. A flux model based on these variables explained variations of the methane budget corresponding to continuous processes of microbial methane production and oxidation, and gas diffusion through soil and plants reasonably well. The results show that the Lena Delta contributes significantly to the global methane balance because of its extensive wetland areas. The microbiological investigations showed that permafrost soils are colonized by high numbers of microorganisms. The total biomass is comparable to temperate soil ecosystems. Activities of methanogens and methanotrophs differed significantly in their rates and distribution patterns along both the vertical profiles and the different investigated soils. The methane production rates varied between 0.3 and 38.9 nmol h-1 g-1, while the methane oxidation ranged from 0.2 to 7.0 nmol h-1 g-1. Phylogenetic analyses of methanogenic communities revealed a distinct diversity of methanogens affiliated to Methanomicrobiaceae, Methanosarcinaceae and Methanosaetaceae, which partly form four specific permafrost clusters. The results demonstrate the close relationship between methane fluxes and the fundamental microbiological processes in permafrost soils. The microorganisms do not only survive in their extreme habitat but also can be metabolic active under in situ conditions. It was shown that a slight increase of the temperature can lead to a substantial increase in methanogenic activity within perennially frozen deposits. In case of degradation, this would lead to an extensive expansion of the methane deposits with their subsequent impacts on total methane budget. Further studies on the stress response of methanogenic archaea, especially Methanosarcina SMA-21, isolated from Siberian permafrost, revealed an unexpected resistance of the microorganisms against unfavourable living conditions. A better adaptation to environmental stress was observed at 4 °C compared to 28 °C. For the first time it could be demonstrated that methanogenic archaea from terrestrial permafrost even survived simulated Martian conditions. The results show that permafrost methanogens are more resistant than methanogens from non-permafrost environments under Mars-like climate conditions. Microorganisms comparable to methanogens from terrestrial permafrost can be seen as one of the most likely candidates for life on Mars due to their physiological potential and metabolic specificity. N2 - Die Arktis spielt eine Schlüsselrolle im Klimasystem unserer Erde aus zweierlei Gründen. Zum einen wird vorausgesagt, dass die globale Erwärmung in den hohen Breiten am ausgeprägtesten sein wird. Zum anderen ist ein Drittel des globalen Kohlenstoffs in Ökosystemen der nördlichen Breiten gespeichert. Um ein besseres Verständnis der gegenwärtigen und zukünftigen Entwicklung der Kohlenstoffdynamik in klimaempfindlichen Permafrostökosystemen zu erlangen, konzentriert sich die vorliegende Arbeit auf Untersuchungen zur Kontrolle der Methanflüsse durch Mikroorganismen, auf die Aktivität und Struktur der beteiligten Mikroorganismen-gemeinschaften und auf ihre Reaktion auf sich ändernde Umweltbedingungen. Zu diesem Zweck wurde eine integrierte Forschungsstrategie entwickelt, die Spurengasmessungen mit boden- und molekularökologischen Untersuchungen der Mikroorganismengemeinschaften verknüpft. Langzeitmessungen zu den Methanflüssen werden seit 1998 durchgeführt. Diese Untersuchungen zeigten beträchtliche saisonale und räumliche Schwankungen der Methanemissionen auf, die zwischen 0 und 362 mg m-2 d-1 für die untersuchten Landschaftseinheiten schwankten. Für die Bilanzierung der Methanemissionen für das gesamte Delta wurde erstmals eine Klassifikation der unterschiedlichen Landschaftseinheiten anhand von Landsat-Aufnahmen durchgeführt und für eine Hochrechnung der Methandaten genutzt. Die Mittelwerte der regional gewichteten täglichen Methanemissionen des Lenadeltas (10 mg m-2 d-1) sind nur ein Fünftel so hoch wie die berechneten Werte für andere arktische Tundren. Die errechnete jährliche Methanemission des Lenadeltas beträgt demnach ungefähr 0,03 Tg. Die geringen Methanemissionsraten dieser Studie können durch den bisher noch nicht realisierten integrativen Ansatz, der Langzeitmessungen und Landschafts-klassifizierungen beinhaltet, erklärt werden. Bodentemperatur und oberflächennahe atmosphärische Turbulenzen wurden als die antreibenden Größen der Methanfreisetzung identifiziert. Ein Modell, das auf diesen Variablen basiert, erklärt die Veränderungen der Methanflüsse gemäß der dynamischen mikrobiellen Prozesse und der Diffusion von Methan durch den Boden und die Pflanzen zutreffend. Die Ergebnisse zeigen, dass das Lenadelta erheblich zur globalen Methanemission aufgrund seiner weitreichenden Feuchtgebiete beiträgt. Die mikrobiologischen Untersuchungen zeigten, dass Permafrostböden durch eine hohe Anzahl von Mikroorganismen besiedelt wird. Die Gesamtbiomasse ist dabei mit Bodenökosystemen gemäßigter Klimate vergleichbar. Die Stoffwechselaktivitäten von methanogenen Archaeen und methanotrophen Bakterien unterschieden sich erheblich in ihrer Rate und Verteilung im Tiefenprofil sowie zwischen den verschiedenen untersuchten Böden. Die Methanbildungsrate schwankte dabei zwischen 0,3 und 38,9 nmol h-1 g-1, während die Methanoxidation eine Rate von 0,2 bis 7,0 nmol h-1 g-1 aufwies. Phylogenetische Analysen der methanogenen Mikro-organismengemeinschaften zeigten eine ausgeprägte Diversität der methanogenen Archaeen auf. Die Umweltsequenzen bildeten vier spezifische Permafrostcluster aus, die den Gruppen Methanomicrobiaceae, Methanosarcinaceae und Methano-saetaceae zugeordnet werden konnten. Die Ergebnisse zeigen, dass die Methanfreisetzung durch die zugrunde liegenden mikrobiologischen Prozesse im Permafrostboden gesteuert wird. Die beteiligten Mikroorganismen überleben nicht nur in ihrem extremen Habitat, sondern zeigten auch Stoffwechselaktivität unter in-situ-Bedingungen. Ferner konnte gezeigt werden, dass eine geringfügige Zunahme der Temperatur zu einer erheblichen Zunahme der Methanbildungsaktivität in den ständig gefrorenen Permafrostablagerungen führen kann. Im Falle der Permafrostdegradation würde dieses zu einer gesteigerten Freisetzung von Methan führen mit bisher unbekannten Auswirkungen auf das Gesamtbudget der Methanfreistzung aus arktischen Gebieten. Weitere Untersuchungen zur Stresstoleranz von methanogenen Archaeen – insbesondere des neuen Permafrostisolates Methanosarcina SMA-21 - weisen eine unerwartete Widerstandsfähigkeit der Mikroorganismen gegenüber ungünstigen Lebensbedingungen auf. Eine bessere Anpassung an Umweltstress wurde bei 4°C im Vergleich zu 28°C beobachtet. Zum ersten Mal konnte gezeigt werden, dass methanogene Archaeen aus terrestrischem Permafrost unter simulierten Marsbedingungen unbeschadet überleben. Die Ergebnisse zeigen, dass methanogene Archaeen aus Permafrostböden resistenter gegenüber Umweltstress und Marsbedingungen sind als entsprechende Mikroorganismen aus Habitaten, die nicht durch Permafrost gekennzeichnet sind. Mikroorganismen, die den Archaeen aus terrestrischen Permafrosthabitaten ähneln, können als die wahrscheinlichsten Kandidaten für mögliches Leben auf dem Mars angesehen werden. KW - Methankreislauf KW - mikrobielle Prozesse KW - Diversität KW - Spurengasflüsse KW - Permafrostökosysteme KW - methane cycle KW - microbial processes KW - diversity KW - trace gas fluxes KW - permafrost ecosystems Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-15434 ER - TY - JOUR A1 - Wojcik, Robin A1 - Donhauser, Johanna A1 - Frey, Beat W. A1 - Holm, Stine A1 - Holland, Alexandra A1 - Anesio, Alexandre M. A1 - Pearce, David A. A1 - Malard, Lucie A1 - Wagner, Dirk A1 - Benning, Liane G. T1 - Linkages between geochemistry and microbiology in a proglacial terrain in the High Arctic JF - Annals of glaciology N2 - Proglacial environments are ideal for studying the development of soils through the changes of rocks exposed by glacier retreat to weathering and microbial processes. Carbon (C) and nitrogen (N) contents as well as soil pH and soil elemental compositions are thought to be dominant factors structuring the bacterial, archaeal and fungal communities in the early stages of soil ecosystem formation. However, the functional linkages between C and N contents, soil composition and microbial community structures remain poorly understood. Here, we describe a multivariate analysis of geochemical properties and associated microbial community structures between a moraine and a glaciofluvial outwash in the proglacial area of a High Arctic glacier (Longyearbreen, Svalbard). Our results reveal distinct differences in developmental stages and heterogeneity between the moraine and the glaciofluvial outwash. We observed significant relationships between C and N contents, delta C-13(org) and delta N-15 isotopic ratios, weathering and microbial abundance and community structures. We suggest that the observed differences in microbial and geochemical parameters between the moraine and the glaciofluvial outwash are primarily a result of geomorphological variations of the proglacial terrain. KW - biogeochemistry KW - glacial geomorphology KW - glacier chemistry KW - microbiology KW - processes and landforms of glacial erosion Y1 - 2018 U6 - https://doi.org/10.1017/aog.2019.1 SN - 0260-3055 SN - 1727-5644 VL - 59 IS - 77 SP - 95 EP - 110 PB - Cambridge Univ. Press CY - Cambridge ER - TY - JOUR A1 - Meier, Lars A. A1 - Krauze, Patryk A1 - Prater, Isabel A1 - Horn, Fabian A1 - Schaefer, Carlos Ernesto Reynaud A1 - Scholten, Thomas A1 - Wagner, Dirk A1 - Müller, Carsten Werner A1 - Kühn, Peter T1 - Pedogenic and microbial interrelation in initial soils under semiarid climate on James Ross Island, Antarctic Peninsula region JF - Biogeosciences N2 - James Ross Island (JRI) offers the exceptional opportunity to study microbial-driven pedogenesis without the influence of vascular plants or faunal activities (e.g., penguin rookeries). In this study, two soil profiles from JRI (one at Santa Martha Cove - SMC, and another at Brandy Bay BB) were investigated, in order to gain information about the initial state of soil formation and its interplay with prokaryotic activity, by combining pedological, geochemical and microbiological methods. The soil profiles are similar with respect to topographic position and parent material but are spatially separated by an orographic barrier and therefore represent windward and leeward locations towards the mainly southwesterly winds. These different positions result in differences in electric conductivity of the soils caused by additional input of bases by sea spray at the windward site and opposing trends in the depth functions of soil pH and electric conductivity. Both soils are classified as Cryosols, dominated by bacterial taxa such as Actinobacteria, Proteobacteria, Acidobacteria, Gemmatimonadetes and Chloroflexi. A shift in the dominant taxa was observed below 20 cm in both soils as well as an increased abundance of multiple operational taxonomic units (OTUs) related to potential chemolithoautotrophic Acidiferrobacteraceae. This shift is coupled by a change in microstructure. While single/pellicular grain microstructure (SMC) and platy microstructure (BB) are dominant above 20 cm, lenticular microstructure is dominant below 20 cm in both soils. The change in microstructure is caused by frequent freeze-thaw cycles and a relative high water content, and it goes along with a development of the pore spacing and is accompanied by a change in nutrient content. Multivariate statistics revealed the influence of soil parameters such as chloride, sulfate, calcium and organic carbon contents, grain size distribution and pedogenic oxide ratios on the overall microbial community structure and explained 49.9% of its variation. The correlation of the pedogenic oxide ratios with the compositional distribution of microorganisms as well as the relative abundance certain microorganisms such as potentially chemolithotrophic Acidiferrobacteraceae-related OTUs could hint at an interplay between soil-forming processes and microorganisms. Y1 - 2019 U6 - https://doi.org/10.5194/bg-16-2481-2019 SN - 1726-4170 SN - 1726-4189 VL - 16 IS - 12 SP - 2481 EP - 2499 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Masyagina, Oxana. V. A1 - Evgrafova, S. Yu A1 - Bugaenko, T. N. A1 - Kholodilova, V. V. A1 - Krivobokov, L. A1 - Korets, M. A. A1 - Wagner, Dirk T1 - Permafrost landslides promote soil CO2 emission and hinder C accumulation JF - The science of the total environment : an international journal for scientific research into the environment and its relationship with man N2 - Landslides arc common in high-latitude forest ecosystems that have developed on permafrost. The most vulnerable areas in the permafrost territories of Siberia occur on the south-facing slopes of northern rivers, where they arc observed on about 20% of the total area of river slopes. Landslide disturbances will likely increase with climate change especially due to increasing summer-autumn precipitation. These processes are the most destructive natural disturbance agent and lead to the complete removal of pre-slide forest ecosystems (vegetation cover and soil). To evaluate postsliding ecosystem succession, we undertook integrated ecological research at landslides of different age classes along the Nizhnyaya Tunguska River and the Kochechum River (Tura, Krasnoyarsk region, Russia). Just after the event (at the one-year-old site), we registered a drop in soil respiration, a threefold lower microbial respiration rate, and a fourfold smaller mineral soil carbon and nitrogen stock at bare soil (melkozem) plots at the middle location of the site as compared with the non affected control site. The recovery of disturbed areas began with the re-establishment of plant cover and the following accumulation of an organic soil layer. During the 35-year succession (L1972), the accumulated layer (0 layer)at the oldest site contained similar C- and N stocks to those found at the control sites. However, the mineral soil C- and N stocks and the microbial biomass even of the oldest landslide area- did not reach the value of these parameters in control plots. Later, the soil respiration level and the eco-physiological status of soil microbiota also recovered due to these changes. This study demonstrates that the recovery after landslides in permafrost forests takes several decades. In addition, the degradation of permafrost due to landslides clearly hinders the accumulation of soil organic matter in the mineral soil. (C) 2018 Elsevier B.v. All rights reserved. KW - Landslides KW - Soil microorganisms KW - Permafrost KW - Soil C- and N stocks KW - Boreal ecosystems KW - Soil respiration Y1 - 2018 U6 - https://doi.org/10.1016/j.scitotenv.2018.11.468 SN - 0048-9697 SN - 1879-1026 VL - 657 SP - 351 EP - 364 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Serrano, Paloma A1 - Alawi, Mashal A1 - de Vera, Jean-Pierre Paul A1 - Wagner, Dirk T1 - Response of Methanogenic Archaea from Siberian Permafrost and Non-permafrost Environments to Simulated Mars-like Desiccation and the Presence of Perchlorate JF - Astrobiology N2 - Numerous preflight investigations were necessary prior to the exposure experiment BIOMEX on the International Space Station to test the basic potential of selected microorganisms to resist or even to be active under Mars-like conditions. In this study, methanogenic archaea, which are anaerobic chemolithotrophic microorganisms whose lifestyle would allow metabolism under the conditions on early and recent Mars, were analyzed. Some strains from Siberian permafrost environments have shown a particular resistance. In this investigation, we analyzed the response of three permafrost strains (Methanosarcina soligelidi SMA-21, Candidatus Methanosarcina SMA-17, Candidatus Methanobacterium SMA-27) and two related strains from non-permafrost environments (Methanosarcina mazei, Methanosarcina barkeri) to desiccation conditions (-80 degrees C for 315 days, martian regolith analog simulants S-MRS and P-MRS, a 128-day period of simulated Mars-like atmosphere). Exposure of the different methanogenic strains to increasing concentrations of magnesium perchlorate allowed for the study of their metabolic shutdown in a Mars-relevant perchlorate environment. Survival and metabolic recovery were analyzed by quantitative PCR, gas chromatography, and a new DNA-extraction method from viable cells embedded in S-MRS and P-MRS. All strains survived the two Mars-like desiccating scenarios and recovered to different extents. The permafrost strain SMA-27 showed an increased methanogenic activity by at least 10-fold after deep-freezing conditions. The methanogenic rates of all strains did not decrease significantly after 128 days S-MRS exposure, except for SMA-27, which decreased 10-fold. The activity of strains SMA-17 and SMA-27 decreased after 16 and 60 days P-MRS exposure. Non-permafrost strains showed constant survival and methane production when exposed to both desiccating scenarios. All strains showed unaltered methane production when exposed to the perchlorate concentration reported at the Phoenix landing site (2.4 mM) or even higher concentrations. We conclude that methanogens from (non-)permafrost environments are suitable candidates for potential life in the martian subsurface and therefore are worthy of study after space exposure experiments that approach Mars-like surface conditions. KW - Methanogenic archaea KW - Simulated Mars-like conditions KW - Subfreezing temperatures KW - Martian regolith analogs KW - Perchlorate KW - Permafrost Y1 - 2019 U6 - https://doi.org/10.1089/ast.2018.1877 SN - 1531-1074 SN - 1557-8070 VL - 19 IS - 2 SP - 197 EP - 208 PB - Liebert CY - New Rochelle ER - TY - JOUR A1 - Söll, Änne A1 - Köstler, Andreas A1 - Krause, Regina A1 - Ludwig, Joachim A1 - Pohlenz, Philipp A1 - Rößler, Dirk A1 - Kirf, Marcel A1 - Klein, Armin A1 - Wagner, Nelli A1 - Angelow, Jürgen T1 - Portal = Pläne vorgelegt: Maßnahmen zur Studienreform BT - Das Potsdamer Universitätsmagazin N2 - Aus dem Inhalt: - Pläne vorgelegt: Maßnahmen zur Studienreform - Fische lügen beim Sex - Käfersammlerin des 21. Jahrhunderts T3 - Portal: Das Potsdamer Universitätsmagazin - 10-12/2008 Y1 - 2008 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-440162 SN - 1618-6893 IS - 10-12/2008 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 - TY - JOUR A1 - de Vera, Jean-Pierre Paul A1 - Böttger, Ute A1 - de la Torre Nötzel, Rosa A1 - Sanchez, Francisco J. A1 - Grunow, Dana A1 - Schmitz, Nicole A1 - Lange, Caroline A1 - Hübers, Heinz-Wilhelm A1 - Billi, Daniela A1 - Baque, Mickael A1 - Rettberg, Petra A1 - Rabbow, Elke A1 - Reitz, Günther A1 - Berger, Thomas A1 - Möller, Ralf A1 - Bohmeier, Maria A1 - Horneck, Gerda A1 - Westall, Frances A1 - Jänchen, Jochen A1 - Fritz, Jörg A1 - Meyer, Cornelia A1 - Onofri, Silvano A1 - Selbmann, Laura A1 - Zucconi, Laura A1 - Kozyrovska, Natalia A1 - Leya, Thomas A1 - Foing, Bernard A1 - Demets, Rene A1 - Cockell, Charles S. A1 - Bryce, Casey A1 - Wagner, Dirk A1 - Serrano, Paloma A1 - Edwards, Howell G. M. A1 - Joshi, Jasmin Radha A1 - Huwe, Björn A1 - Ehrenfreund, Pascale A1 - Elsaesser, Andreas A1 - Ott, Sieglinde A1 - Meessen, Joachim A1 - Feyh, Nina A1 - Szewzyk, Ulrich A1 - Jaumann, Ralf A1 - Spohn, Tilman T1 - Supporting Mars exploration BIOMEX in Low Earth Orbit and further astrobiological studies on the Moon using Raman and PanCam technology JF - Planetary and space science N2 - The Low Earth Orbit (LEO) experiment Biology and Mars Experiment (BIOMEX) is an interdisciplinary and international space research project selected by ESA. The experiment will be accommodated on the space exposure facility EXPOSE-R2 on the International Space Station (ISS) and is foreseen to be launched in 2013. The prime objective of BIOMEX is to measure to what extent biomolecules, such as pigments and cellular components, are resistant to and able to maintain their stability under space and Mars-like conditions. The results of BIOMEX will be relevant for space proven biosignature definition and for building a biosignature data base (e.g. the proposed creation of an international Raman library). The library will be highly relevant for future space missions such as the search for life on Mars. The secondary scientific objective is to analyze to what extent terrestrial extremophiles are able to survive in space and to determine which interactions between biological samples and selected minerals (including terrestrial, Moon- and Mars analogs) can be observed under space and Mars-like conditions. In this context, the Moon will be an additional platform for performing similar experiments with negligible magnetic shielding and higher solar and galactic irradiation compared to LEO. Using the Moon as an additional astrobiological exposure platform to complement ongoing astrobiological LEO investigations could thus enhance the chances of detecting organic traces of life on Mars. We present a lunar lander mission with two related objectives: a lunar lander equipped with Raman and PanCam instruments which can analyze the lunar surface and survey an astrobiological exposure platform. This dual use of testing mission technology together with geo- and astrobiological analyses will significantly increase the science return, and support the human preparation objectives. It will provide knowledge about the Moon's surface itself and, in addition, monitor the stability of life-markers, such as cells, cell components and pigments, in an extraterrestrial environment with much closer radiation properties to the surface of Mars. The combination of a Raman data base of these data together with data from LEO and space simulation experiments, will lead to further progress on the analysis and interpretation of data that we will obtain from future Moon and Mars exploration missions. KW - Moon KW - Mars KW - Low Earth Orbit KW - Astrobiology KW - Instrumentation KW - Spectroscopy KW - Biosignature Y1 - 2012 U6 - https://doi.org/10.1016/j.pss.2012.06.010 SN - 0032-0633 VL - 74 IS - 1 SP - 103 EP - 110 PB - Elsevier CY - Oxford ER - TY - GEN A1 - Vuillemin, Aurèle A1 - Friese, André A1 - Alawi, Mashal A1 - Henny, Cynthia A1 - Nomosatryo, Sulung A1 - Wagner, Dirk A1 - Crowe, Sean A. A1 - Kallmeyer, Jens T1 - Geomicrobiological features of ferruginous sediments from Lake Towuti, Indonesia T2 - Frontiers in microbiology N2 - Lake Towuti is a tectonic basin, surrounded by ultramafic rocks. Lateritic soils form through weathering and deliver abundant iron (oxy)hydroxides but very little sulfate to the lake and its sediment. To characterize the sediment biogeochemistry, we collected cores at three sites with increasing water depth and decreasing bottom water oxygen concentrations. Microbial cell densities were highest at the shallow site a feature we attribute to the availability of labile organic matter (OM) and the higher abundance of electron acceptors due to oxic bottom water conditions. At the two other sites, OM degradation and reduction processes below the oxycline led to partial electron acceptor depletion. Genetic information preserved in the sediment as extracellular DNA (eDNA) provided information on aerobic and anaerobic heterotrophs related to Nitrospirae. Chloroflexi, and Therrnoplasmatales. These taxa apparently played a significant role in the degradation of sinking OM. However, eDNA concentrations rapidly decreased with core depth. Despite very low sulfate concentrations, sulfate-reducing bacteria were present and viable in sediments at all three sites, as confirmed by measurement of potential sulfate reduction rates. Microbial community fingerprinting supported the presence of taxa related to Deltaproteobacteria and Firmicutes with demonstrated capacity for iron and sulfate reduction. Concomitantly, sequences of Ruminococcaceae, Clostridiales, and Methanornicrobiales indicated potential for fermentative hydrogen and methane production. Such first insights into ferruginous sediments showed that microbial populations perform successive metabolisms related to sulfur, iron, and methane. In theory, iron reduction could reoxidize reduced sulfur compounds and desorb OM from iron minerals to allow remineralization to methane. Overall, we found that biogeochemical processes in the sediments can be linked to redox differences in the bottom waters of the three sites, like oxidant concentrations and the supply of labile OM. At the scale of the lacustrine record, our geomicrobiological study should provide a means to link the extant subsurface biosphere to past environments. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 440 KW - bottom waters KW - iron-rich sediment KW - sedimentary microbes KW - extracellular DNA KW - sulfate reduction KW - iron reduction KW - Lake Towuti Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-407312 ER - TY - JOUR A1 - Mogrovejo Arias, Diana Carolina A1 - Brill, Florian H. H. A1 - Wagner, Dirk T1 - Potentially pathogenic bacteria isolated from diverse habitats in Spitsbergen, Svalbard JF - Environmental earth sciences N2 - The Arctic ecosystem, a reservoir of genetic microbial diversity, represents a virtually unlimited source of microorganisms that could interact with human beings. Despite continuous exploration of Arctic habitats and description of their microbial communities, bacterial phenotypes commonly associated with pathogenicity, such as hemolytic activity, have rarely been reported. In this study, samples of snow, fresh and marine water, soil, and sediment from several habitats in the Arctic archipelago of Svalbard were collected during Summer, 2017. Bacterial isolates were obtained after incubation on oligotrophic media at different temperatures and their hemolytic potential was assessed on sheep blood agar plates. Partial (alpha) or true (beta) hemolysis was observed in 32 out of 78 bacterial species. Genes expressing cytolytic compounds, such as hemolysins, likely increase the general fitness of the producing microorganisms and confer a competitive advantage over the availability of nutrients in natural habitats. In environmental species, the nutrient-acquisition function of these compounds presumably precedes their function as toxins for mammalian erythrocytes. However, in the light of global warming, the presence of hemolytic bacteria in Arctic environments highlights the possible risks associated with these microorganisms in the event of habitat melting/destruction, ecosystem transition, and re-colonization. KW - Arctic KW - Svalbard KW - hemolysins KW - climate change KW - pathogens KW - virulence Y1 - 2020 U6 - https://doi.org/10.1007/s12665-020-8853-4 SN - 1866-6280 SN - 1866-6299 VL - 79 IS - 5 PB - Springer CY - Berlin ; Heidelberg ER - 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 - Tanski, Georg A1 - Wagner, Dirk A1 - Knoblauch, Christian A1 - Fritz, Michael A1 - Sachs, Torsten A1 - Lantuit, Hugues T1 - Rapid CO2 Release From Eroding Permafrost in Seawater JF - Geophysical research letters Y1 - 2019 U6 - https://doi.org/10.1029/2019GL084303 SN - 0094-8276 SN - 1944-8007 VL - 46 IS - 20 SP - 11244 EP - 11252 PB - American Geophysical Union CY - Washington 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 - GEN A1 - Liu, Qi A1 - Kämpf, Horst A1 - Bussert, Robert A1 - Krauze, Patryk A1 - Horn, Fabian A1 - Nickschick, Tobias A1 - Plessen, Birgit A1 - Wagner, Dirk A1 - Alawi, Mashal T1 - Influence of CO2 degassing on the microbial community in a dry mofette field in Hartoušov, Czech Republic (Western Eger Rift) T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - The Cheb Basin (CZ) is a shallow Neogene intracontinental basin filled with fluvial and lacustrine sediments that is located in the western part of the Eger Rift. The basin is situated in a seismically active area and is characterized by diffuse degassing of mantle-derived CO2 in mofette fields. The Hartousov mofette field shows a daily CO2 flux of 23-97 tons of CO2 released over an area of 0.35 km(2) and a soil gas concentration of up to 100% CO2. The present study aims to explore the geo-bio interactions provoked by the influence of elevated CO2 concentrations on the geochemistry and microbial community of soils and sediments. To sample the strata, two 3-m cores were recovered. One core stems from the center of the degassing structure, whereas the other core was taken 8 m from the ENE and served as an undisturbed reference site. The sites were compared regarding their geochemical features, microbial abundances, and microbial community structures. The mofette site is characterized by a low pH and high TOC/sulfate contents. Striking differences in the microbial community highlight the substantial impact of elevated CO2 concentrations and their associated side effects on microbial processes. The abundance of microbes did not show a typical decrease with depth, indicating that the uprising CO2-rich fluid provides sufficient substrate for chemolithoautotrophic anaerobic microorganisms. Illumine MiSeq sequencing of the 16S rRNA genes and multivariate statistics reveals that the pH strongly influences microbial composition and explains around 38.7% of the variance at the mofette site and 22.4% of the variance between the mofette site and the undisturbed reference site. Accordingly, acidophilic microorganisms (e.g., OTUs assigned to Acidobacteriaceae and Acidithiobacillus) displayed a much higher relative abundance at the mofette site than at the reference site. The microbial community at the mofette site is characterized by a high relative abundance of methanogens and taxa involved in sulfur cycling. The present study provides intriguing insights into microbial life and geo-bio interactions in an active seismic region dominated by emanating mantle-derived CO2-rich fluids, and thereby builds the basis for further studies, e.g., focusing on the functional repertoire of the communities. However, it remains open if the observed patterns can be generalized for different time-points or sites. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1100 KW - geo-bio interaction KW - elevated CO2 concentration KW - paleo-sediment KW - deep biosphere KW - acidophilic microorganisms KW - Acidobactetiaceae KW - Acidithiobacillus KW - Acidothermus Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-471153 SN - 1866-8372 IS - 1100 ER - TY - JOUR A1 - Liu, Qi A1 - Kämpf, Horst A1 - Bussert, Robert A1 - Krauze, Patryk A1 - Horn, Fabian A1 - Nickschick, Tobias A1 - Plessen, Birgit A1 - Wagner, Dirk A1 - Alawi, Mashal T1 - Influence of CO2 degassing on the microbial community in a dry mofette field in Hartoušov, Czech Republic (Western Eger Rift) JF - Frontiers in Microbiology N2 - The Cheb Basin (CZ) is a shallow Neogene intracontinental basin filled with fluvial and lacustrine sediments that is located in the western part of the Eger Rift. The basin is situated in a seismically active area and is characterized by diffuse degassing of mantle-derived CO2 in mofette fields. The Hartousov mofette field shows a daily CO2 flux of 23-97 tons of CO2 released over an area of 0.35 km(2) and a soil gas concentration of up to 100% CO2. The present study aims to explore the geo-bio interactions provoked by the influence of elevated CO2 concentrations on the geochemistry and microbial community of soils and sediments. To sample the strata, two 3-m cores were recovered. One core stems from the center of the degassing structure, whereas the other core was taken 8 m from the ENE and served as an undisturbed reference site. The sites were compared regarding their geochemical features, microbial abundances, and microbial community structures. The mofette site is characterized by a low pH and high TOC/sulfate contents. Striking differences in the microbial community highlight the substantial impact of elevated CO2 concentrations and their associated side effects on microbial processes. The abundance of microbes did not show a typical decrease with depth, indicating that the uprising CO2-rich fluid provides sufficient substrate for chemolithoautotrophic anaerobic microorganisms. Illumine MiSeq sequencing of the 16S rRNA genes and multivariate statistics reveals that the pH strongly influences microbial composition and explains around 38.7% of the variance at the mofette site and 22.4% of the variance between the mofette site and the undisturbed reference site. Accordingly, acidophilic microorganisms (e.g., OTUs assigned to Acidobacteriaceae and Acidithiobacillus) displayed a much higher relative abundance at the mofette site than at the reference site. The microbial community at the mofette site is characterized by a high relative abundance of methanogens and taxa involved in sulfur cycling. The present study provides intriguing insights into microbial life and geo-bio interactions in an active seismic region dominated by emanating mantle-derived CO2-rich fluids, and thereby builds the basis for further studies, e.g., focusing on the functional repertoire of the communities. However, it remains open if the observed patterns can be generalized for different time-points or sites. KW - geo–bio interaction KW - elevated CO2 KW - concentration KW - paleo-sediment KW - deep biosphere KW - acidophilic microorganisms KW - Acidobacteriaceae KW - Acidithiobacillus KW - Acidothermus Y1 - 2018 U6 - https://doi.org/10.3389/fmicb.2018.02787 SN - 1664-302X VL - 9 PB - Frontiers Media CY - Lausanne ER - TY - JOUR A1 - Nagakura, Toshiki A1 - Schubert, Florian A1 - Wagner, Dirk A1 - Kallmeyer, Jens T1 - Biological sulfate reduction in deep subseafloor sediment of Guaymas Basin JF - Frontiers in microbiology N2 - Sulfate reduction is the quantitatively most important process to degrade organic matter in anoxic marine sediment and has been studied intensively in a variety of settings. Guaymas Basin, a young marginal ocean basin, offers the unique opportunity to study sulfate reduction in an environment characterized by organic-rich sediment, high sedimentation rates, and high geothermal gradients (100-958 degrees C km(-1)). We measured sulfate reduction rates (SRR) in samples taken during the International Ocean Discovery Program (IODP) Expedition 385 using incubation experiments with radiolabeled (SO42-)-S-35 carried out at in situ pressure and temperature. The highest SRR (387 nmol cm(-3) d(-1)) was recorded in near-surface sediments from Site U1548C, which had the steepest geothermal gradient (958 degrees C km(-1)). At this site, SRR were generally over an order of magnitude higher than at similar depths at other sites (e.g., 387-157 nmol cm(-3) d(-1) at 1.9 mbsf from Site U1548C vs. 46-1.0 nmol cm(-3) d(-1) at 2.1 mbsf from Site U1552B). Site U1546D is characterized by a sill intrusion, but it had already reached thermal equilibrium and SRR were in the same range as nearby Site U1545C, which is minimally affected by sills. The wide temperature range observed at each drill site suggests major shifts in microbial community composition with very different temperature optima but awaits confirmation by molecular biological analyses. At the transition between the mesophilic and thermophilic range around 40 degrees C-60 degrees C, sulfate-reducing activity appears to be decreased, particularly in more oligotrophic settings, but shows a slight recovery at higher temperatures. KW - sulfate reduction KW - subsurface life KW - deep biosphere KW - thermophiles; KW - Guaymas Basin Y1 - 2022 U6 - https://doi.org/10.3389/fmicb.2022.845250 SN - 1664-302X VL - 13 PB - Frontiers Media CY - Lausanne ER - TY - JOUR A1 - Nomosatryo, Sulung A1 - Tjallingii, Rik A1 - Henny, Cynthia A1 - Ridwansyah, Iwan A1 - Wagner, Dirk A1 - Tomás, Sara A1 - Kallmeyer, Jens T1 - Surface sediment composition and depositional environments in tropical Lake Sentani, Papua Province, Indonesia JF - Journal of Paleolimnology N2 - Tropical Lake Sentani in the Indonesian Province Papua consists of four separate basins and is surrounded by a catchment with a very diverse geology. We characterized the surface sediment (upper 5 cm) of the lake's four sub-basins based on multivariate statistical analyses (principal component analysis, hierarchical clustering) of major element compositions obtained by X-ray fluorescence scanning. Three types of sediment are identified based on distinct compositional differences between rivers, shallow/proximal and deep/distal lake sediments. The different sediment types are mainly characterized by the correlation of elements associated with redox processes (S, Mn, Fe), carbonates (Ca), and detrital input (Ti, Al, Si, K) derived by river discharge. The relatively coarse-grained river sediments mainly derive form the mafic catchment geology and contribution of the limestone catchment geology is only limited. Correlation of redox sensitive and detrital elements are used to reveal oxidation conditions, and indicate oxic conditions in river samples and reducing conditions for lake sediments. Organic carbon (TOC) generally correlates with redox sensitive elements, although a correlation between TOC and individual elements change strongly between the three sediment types. Pyrite is the quantitatively dominant reduced sulfur mineral, monosulfides only reach appreciable concentrations in samples from rivers draining mafic and ultramafic catchments. Our study shows large spatial heterogeneity within the lake's sub-basins that is mainly caused by catchment geology and topography, river runoff as well as the bathymetry and the depth of the oxycline. We show that knowledge about lateral heterogeneity is crucial for understanding the geochemical and sedimentological variations recorded by these sediments. The highly variable conditions make Lake Sentani a natural laboratory, with its different sub-basins representing different depositional environments under identical tropical climate conditions. KW - Tropical lake KW - Lacustrine sediment KW - XRF analysis KW - Multivariate KW - statistics Y1 - 2022 U6 - https://doi.org/10.1007/s10933-022-00259-4 SN - 0921-2728 SN - 1573-0417 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Rasigraf, Olivia A1 - Wagner, Dirk T1 - Landslides BT - an emerging model for ecosystem and soil chronosequence research JF - Earth science reviews : the international geological journal bridging the gap between research articles and textbooks N2 - Erosion by landslides is a common phenomenon in mountain regions around the globe, affecting all climatic zones. Landslides facilitate bedrock weathering, pedogenesis and ecological succession, being key drivers of biodiversity. Landslide chronosequences have long been used for studies of vegetation succession in initial ecosystems, but they further offer ideal model systems for studies of soil development and microbial community succession. In this review we synthesize the state of knowledge on the role of landslides in ecosystems, their influence on element cycles and interactions with biota. Further, we discuss feedback mechanisms between global warming, landslide activity and greenhouse gas emissions. In the view of increasing anthropogenic influence and climate change, soils are becoming a critical resource. Due to their ubiquity, landslide chronosequences have the potential to provide critical insights into soil development under different climates and thereby contribute to future soil restoration efforts. KW - Landslides KW - Greenhouse gas emissions KW - Landslide chronosequences KW - Soil KW - microbial community KW - Erosion KW - Biodiversity KW - Microbial processes KW - Climate KW - change Y1 - 2022 U6 - https://doi.org/10.1016/j.earscirev.2022.104064 SN - 0012-8252 SN - 1872-6828 VL - 231 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Mitzscherling, Julia A1 - Horn, Fabian A1 - Winterfeld, Maria A1 - Mahler, Linda A1 - Kallmeyer, Jens A1 - Overduin, Pier Paul A1 - Schirrmeister, Lutz A1 - Winkel, Matthias A1 - Grigoriev, Mikhail N. A1 - Wagner, Dirk A1 - Liebner, Susanne T1 - Microbial community composition and abundance after millennia of submarine permafrost warming JF - Biogeosciences N2 - Warming of the Arctic led to an increase in permafrost temperatures by about 0.3 degrees C during the last decade. Permafrost warming is associated with increasing sediment water content, permeability, and diffusivity and could in the long term alter microbial community composition and abundance even before permafrost thaws. We studied the long-term effect (up to 2500 years) of submarine permafrost warming on microbial communities along an onshore-offshore transect on the Siberian Arctic Shelf displaying a natural temperature gradient of more than 10 degrees C. We analysed the in situ development of bacterial abundance and community composition through total cell counts (TCCs), quantitative PCR of bacterial gene abundance, and amplicon sequencing and correlated the microbial community data with temperature, pore water chemistry, and sediment physicochemical parameters. On timescales of centuries, permafrost warming coincided with an overall decreasing microbial abundance, whereas millennia after warming microbial abundance was similar to cold onshore permafrost. In addition, the dissolved organic carbon content of all cores was lowest in submarine permafrost after millennial-scale warming. Based on correlation analysis, TCC, unlike bacterial gene abundance, showed a significant rank-based negative correlation with increasing temperature, while bacterial gene copy numbers showed a strong negative correlation with salinity. Bacterial community composition correlated only weakly with temperature but strongly with the pore water stable isotopes delta O-18 and delta D, as well as with depth. The bacterial community showed substantial spatial variation and an overall dominance of Actinobacteria, Chloroflexi, Firmicutes, Gemmatimonadetes, and Proteobacteria, which are amongst the microbial taxa that were also found to be active in other frozen permafrost environments. We suggest that, millennia after permafrost warming by over 10 degrees C, microbial community composition and abundance show some indications for proliferation but mainly reflect the sedimentation history and paleoenvironment and not a direct effect through warming. Y1 - 2019 U6 - https://doi.org/10.5194/bg-16-3941-2019 SN - 1726-4170 SN - 1726-4189 VL - 16 IS - 19 SP - 3941 EP - 3958 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Genderjahn, Steffi A1 - Alawi, Mashal A1 - Mangelsdorf, Kai A1 - Horn, Fabian A1 - Wagner, Dirk T1 - Desiccation- and saline-solerant bacteria and archaea in kalahari an sediments JF - Frontiers in microbiology N2 - More than 41% of the Earth’s land area is covered by permanent or seasonally arid dryland ecosystems. Global development and human activity have led to an increase in aridity, resulting in ecosystem degradation and desertification around the world. The objective of the present work was to investigate and compare the microbial community structure and geochemical characteristics of two geographically distinct saline pan sediments in the Kalahari Desert of southern Africa. Our data suggest that these microbial communities have been shaped by geochemical drivers, including water content, salinity, and the supply of organic matter. Using Illumina 16S rRNA gene sequencing, this study provides new insights into the diversity of bacteria and archaea in semi-arid, saline, and low-carbon environments. Many of the observed taxa are halophilic and adapted to water-limiting conditions. The analysis reveals a high relative abundance of halophilic archaea (primarily Halobacteria), and the bacterial diversity is marked by an abundance of Gemmatimonadetes and spore-forming Firmicutes. In the deeper, anoxic layers, candidate division MSBL1, and acetogenic bacteria (Acetothermia) are abundant. Together, the taxonomic information and geochemical data suggest that acetogenesis could be a prevalent form of metabolism in the deep layers of a saline pan. KW - saline pan KW - Kalahari KW - Halobacteria KW - Gemmatimonadetes KW - Firmicutes Y1 - 2018 U6 - https://doi.org/10.3389/fmicb.2018.02082 SN - 1664-302X VL - 9 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Genderjahn, Steffi A1 - Alawi, Mashal A1 - Wagner, Dirk A1 - Schueller, I. A1 - Wanke, A. A1 - Mangelsdorf, Kai T1 - Microbial community responses to modern environmental and Past Climatic Conditions in Omongwa Pan, Western Kalahari BT - a paired 16S rRNA Gene profiling and lipid biomarker approach JF - Journal of geophysical research : Biogeosciences N2 - Due to a lack of well-preserved terrestrial climate archives, paleoclimate studies are sparse in southwestern Africa. Because there are no perennial lacustrine systems in this region, this study relies on a saline pan as an archive for climate information in the western Kalahari (Namibia). Molecular biological and biogeochemical analyses were combined to examine the response of indigenous microbial communities to modern and past climate-induced environmental conditions. The 16S rRNA gene high-throughput sequencing was applied to sediment samples from Omongwa pan to characterize the modern microbial diversity. Highest diversity of microorganisms, dominated by the extreme halophilic archaeon Halobacteria and by the bacterial phylum Gemmatimonadetes, was detected in the near-surface sediments of Omongwa pan. In deeper sections abundance and diversity significantly decreases and Bacillus, known to form spores, become dominant. Lipid biomarkers for living and past microbial life were analyzed to track the influence of climate variation on the abundance of microbial communities from the Last Glacial Maximum to Holocene time. Since water is an inevitable requirement for microbial life, in this dry region the abundance of past microbial biomarkers was evaluated to conclude on periods of increased paleoprecipitation in the past. The data point to a period of increased humidity in the western Kalahari during the Last Glacial to Holocene transition indicating a southward shift of the Intertropical Convergence Zone during this period. Comparison with results from a southwestern Kalahari pan suggests complex displacements of the regional atmospheric systems since the Last Glacial Maximum. Y1 - 2018 U6 - https://doi.org/10.1002/2017JG004098 SN - 2169-8953 SN - 2169-8961 VL - 123 IS - 4 SP - 1333 EP - 1351 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Liu, Qi A1 - Adler, Karsten A1 - Lipus, Daniel A1 - Kämpf, Horst A1 - Bussert, Robert A1 - Plessen, Birgit A1 - Schulz, Hans-Martin A1 - Krauze, Patryk A1 - Horn, Fabian A1 - Wagner, Dirk A1 - Mangelsdorf, Kai A1 - Alawi, Mashal T1 - Microbial signatures in deep CO2-saturated miocene sediments of the active Hartousov mofette system (NW Czech Republic) JF - Frontiers in microbiology N2 - The Hartousov mofette system is a natural CO2 degassing site in the central Cheb Basin (Eger Rift, Central Europe). In early 2016 a 108 m deep core was obtained from this system to investigate the impact of ascending mantle-derived CO2 on indigenous deep microbial communities and their surrounding life habitat. During drilling, a CO2 blow out occurred at a depth of 78.5 meter below surface (mbs) suggesting a CO2 reservoir associated with a deep low-permeable CO2-saturated saline aquifer at the transition from Early Miocene terrestrial to lacustrine sediments. Past microbial communities were investigated by hopanoids and glycerol dialkyl glycerol tetraethers (GDGTs) reflecting the environmental conditions during the time of deposition rather than showing a signal of the current deep biosphere. The composition and distribution of the deep microbial community potentially stimulated by the upward migration of CO2 starting during Mid Pleistocene time was investigated by intact polar lipids (IPLs), quantitative polymerase chain reaction (qPCR), and deoxyribonucleic acid (DNA) analysis. The deep biosphere is characterized by microorganisms that are linked to the distribution and migration of the ascending CO2-saturated groundwater and the availability of organic matter instead of being linked to single lithological units of the investigated rock profile. Our findings revealed high relative abundances of common soil and water bacteria, in particular the facultative, anaerobic and potential iron-oxidizing Acidovorax and other members of the family Comamonadaceae across the whole recovered core. The results also highlighted the frequent detection of the putative sulfate-oxidizing and CO2-fixating genus Sulfuricurvum at certain depths. A set of new IPLs are suggested to be indicative for microorganisms associated to CO2 accumulation in the mofette system. KW - geo-bio interaction KW - CO2 KW - mofette systems KW - Eger Rift KW - microbial lipid KW - biomarker KW - microbial diversity KW - deep biosphere KW - saline groundwater Y1 - 2020 U6 - https://doi.org/10.3389/fmicb.2020.543260 SN - 1664-302X VL - 11 PB - Frontiers Media CY - Lausanne ER - TY - JOUR A1 - Bartholomäus, Alexander A1 - Lipus, Daniel A1 - Mitzscherling, Julia A1 - MacLean, Joana A1 - Wagner, Dirk T1 - Draft Genome Sequence of Nocardioides alcanivorans NGK65(T), a Hexadecane-Degrading Bacterium JF - Microbiology Resource Announcements N2 - The Gram-positive bacterium Nocardioides alcanivorans NGK65(T) was isolated from plastic-polluted soil and cultivated on medium with polyethylene as the single carbon source. Nanopore sequencing revealed the presence of candidate enzymes for the biodegradation of polyethylene. Here, we report the draft genome of this newly described member of the terrestrial plastisphere. Y1 - 2022 U6 - https://doi.org/10.1128/mra.01213-21 SN - 2576-098X VL - 11 IS - 8 PB - American Society for Microbiology CY - Washington ER - TY - JOUR A1 - Mitzscherling, Julia A1 - MacLean, Joana A1 - Lipus, Daniel A1 - Bartholomäus, Alexander A1 - Mangelsdorf, Kai A1 - Lipski, André A1 - Roddatis, Vladimir A1 - Liebner, Susanne A1 - Wagner, Dirk T1 - Nocardioides alcanivorans sp. nov., a novel hexadecane-degrading species isolated from plastic waste JF - International journal of systematic and evolutionary microbiology N2 - Strain NGK65(T), a novel hexadecane degrading, non-motile, Gram-positive, rod-to-coccus shaped, aerobic bacterium, was isolated from plastic polluted soil sampled at a landfill. Strain NGK65(T) hydrolysed casein, gelatin, urea and was catalase-positive. It optimally grew at 28 degrees C. in 0-1% NaCl and at pH 7.5-8.0. Glycerol, D-glucose, arbutin, aesculin, salicin, potassium 5-ketogluconate. sucrose, acetate, pyruvate and hexadecane were used as sole carbon sources. The predominant membrane fatty acids were iso-C-16:0 followed by iso-C(17:)0 and C-18:1 omega 9c. The major polar lipids were phosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and hydroxyphosphatidylinositol. The cell-wall peptidoglycan type was A3 gamma, with LL-diaminopimelic acid and glycine as the diagnostic amino acids. MK 8 (H-4) was the predominant menaquinone. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain NGK65(T) belongs to the genus Nocardioides (phylum Actinobacteria). appearing most closely related to Nocardioides daejeonensis MJ31(T) (98.6%) and Nocardioides dubius KSL-104(T) (98.3%). The genomic DNA G+C content of strain NGK65(T) was 68.2%. Strain NGK65(T) and the type strains of species involved in the analysis had average nucleotide identity values of 78.3-71.9% as well as digital DNA-DNA hybridization values between 22.5 and 19.7%, which clearly indicated that the isolate represents a novel species within the genus Nocardioides. Based on phenotypic and molecular characterization, strain NGK65(T) can clearly be differentiated from its phylogenetic neighbours to establish a novel species, for which the name Nocardioides alcanivorans sp. nov. is proposed. The type strain is NGK65(T) (=DSM 113112(T)=NCCB 100846(T)). KW - Nocardioides alcanivorans KW - hexadecane KW - plastic degradation KW - terrestrial KW - plastisphere KW - bacteria Y1 - 2022 U6 - https://doi.org/10.1099/ijsem.0.005319 SN - 1466-5026 SN - 1466-5034 VL - 72 IS - 4 PB - Microbiology Society CY - London ER - TY - JOUR A1 - Bernhard, Nadine A1 - Moskwa, Lisa-Marie A1 - Schmidt, Karsten A1 - Oeser, Ralf Andreas A1 - Aburto, Felipe A1 - Bader, Maaike Y. A1 - Baumann, Karen A1 - von Blanckenburg, Friedhelm A1 - Boy, Jens A1 - van den Brink, Liesbeth A1 - Brucker, Emanuel A1 - Buedel, Burkhard A1 - Canessa, Rafaella A1 - Dippold, Michaela A. A1 - Ehlers, Todd A1 - Fuentes, Juan P. A1 - Godoy, Roberto A1 - Jung, Patrick A1 - Karsten, Ulf A1 - Koester, Moritz A1 - Kuzyakov, Yakov A1 - Leinweber, Peter A1 - Neidhardt, Harald A1 - Matus, Francisco A1 - Mueller, Carsten W. A1 - Oelmann, Yvonne A1 - Oses, Romulo A1 - Osses, Pablo A1 - Paulino, Leandro A1 - Samolov, Elena A1 - Schaller, Mirjam A1 - Schmid, Manuel A1 - Spielvogel, Sandra A1 - Spohn, Marie A1 - Stock, Svenja A1 - Stroncik, Nicole A1 - Tielboerger, Katja A1 - Uebernickel, Kirstin A1 - Scholten, Thomas A1 - Seguel, Oscar A1 - Wagner, Dirk A1 - Kühn, Peter T1 - Pedogenic and microbial interrelations to regional climate and local topography BT - New insights from a climate gradient (arid to humid) along the Coastal Cordillera of Chile JF - Catena : an interdisciplinary journal of soil science, hydrology, geomorphology focusing on geoecology and landscape evolution N2 - The effects of climate and topography on soil physico-chemical and microbial parameters were studied along an extensive latitudinal climate gradient in the Coastal Cordillera of Chile (26 degrees-38 degrees S). The study sites encompass arid (Pan de Azucar), semiarid (Santa Gracia), mediterranean (La Campana) and humid (Nahuelbuta) climates and vegetation, ranging from arid desert, dominated by biological soil crusts (biocrusts), semiarid shrubland and mediterranean sclerophyllous forest, where biocrusts are present but do have a seasonal pattern to temperate-mixed forest, where biocrusts only occur as an early pioneering development stage after disturbance. All soils originate from granitic parent materials and show very strong differences in pedogenesis intensity and soil depth. Most of the investigated physical, chemical and microbiological soil properties showed distinct trends along the climate gradient. Further, abrupt changes between the arid northernmost study site and the other semi-arid to humid sites can be shown, which indicate non-linearity and thresholds along the climate gradient. Clay and total organic carbon contents (TOC) as well as Ah horizons and solum depths increased from arid to humid climates, whereas bulk density (BD), pH values and base saturation (BS) decreased. These properties demonstrate the accumulation of organic matter, clay formation and element leaching as key-pedogenic processes with increasing humidity. However, the soils in the northern arid climate do not follow this overall latitudinal trend, because texture and BD are largely controlled by aeolian input of dust and sea salts spray followed by the formation of secondary evaporate minerals. Total soil DNA concentrations and TOC increased from arid to humid sites, while areal coverage by biocrusts exhibited an opposite trend. Relative bacterial and archaeal abundances were lower in the arid site, but for the other sites the local variability exceeds the variability along the climate gradient. Differences in soil properties between topographic positions were most pronounced at the study sites with the mediterranean and humid climate, whereas microbial abundances were independent on topography across all study sites. In general, the regional climate is the strongest controlling factor for pedogenesis and microbial parameters in soils developed from the same parent material. Topographic position along individual slopes of limited length augmented this effect only under humid conditions, where water erosion likely relocated particles and elements downward. The change from alkaline to neutral soil pH between the arid and the semi-arid site coincided with qualitative differences in soil formation as well as microbial habitats. This also reflects non-linear relationships of pedogenic and microbial processes in soils depending on climate with a sharp threshold between arid and semi-arid conditions. Therefore, the soils on the transition between arid and semi-arid conditions are especially sensitive and may be well used as indicators of long and medium-term climate changes. Concluding, the unique latitudinal precipitation gradient in the Coastal Cordillera of Chile is predestined to investigate the effects of the main soil forming factor - climate - on pedogenic processes. KW - Climate KW - Topography KW - Soil texture KW - Total organic carbon KW - Carbon isotope ratio (delta C-13(TOC)) KW - Microbial abundance Y1 - 2018 U6 - https://doi.org/10.1016/j.catena.2018.06.018 SN - 0341-8162 SN - 1872-6887 VL - 170 SP - 335 EP - 355 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Oeser, Ralf Andreas A1 - Stroncik, Nicole A1 - Moskwa, Lisa-Marie A1 - Bernhard, Nadine A1 - Schaller, Mirjam A1 - Canessa, Rafaella A1 - van den Brink, Liesbeth A1 - Köster, Moritz A1 - Brucker, Emanuel A1 - Stock, Svenja A1 - Pablo Fuentes, Juan A1 - Godoy, Roberto A1 - Javier Matus, Francisco A1 - Oses Pedraza, Romulo A1 - Osses McIntyre, Pablo A1 - Paulino, Leandro A1 - Seguel, Oscar A1 - Bader, Maaike Y. A1 - Boy, Jens A1 - Dippold, Michaela A. A1 - Ehlers, Todd A1 - Kühn, Peter A1 - Kuzyakov, Yakov A1 - Leinweber, Peter A1 - Scholten, Thomas A1 - Spielvogel, Sandra A1 - Spohn, Marie A1 - Ubernickel, Kirstin A1 - Tielbörger, Katja A1 - Wagner, Dirk A1 - von Blanckenburg, Friedhelm T1 - Chemistry and microbiology of the Critical Zone along a steep climate and vegetation gradient in the Chilean Coastal Cordillera JF - Catena : an interdisciplinary journal of soil science, hydrology, geomorphology focusing on geoecology and landscape evolution N2 - From north to south, denudation rates from cosmogenic nuclides are similar to 10 t km(-2) yr(-1) at the arid Pan de Aziicar site, similar to 20 t km(2) yr(-1) at the semi-arid site of Santa Gracia, -60 t km(-2) yr(-1) at the Mediterranean climate site of La Campana, and similar to 30 t km(-2) yr(-1) at the humid site of Nahuelbuta. A and B horizons increase in thickness and elemental depletion or enrichment increases from north (similar to 26 degrees S) to south (similar to 38 degrees S) in these horizons. Differences in the degree of chemical weathering, quantified by the chemical depletion fraction (CDF), are significant only between the arid and sparsely vegetated site and the other three sites. Differences in the CDF between the sites, and elemental depletion within the sites are sometimes smaller than the variations induced by the bedrock heterogeneity. Microbial abundances (bacteria and archaea) in saprolite substantially increase from the arid to the semi-arid sites. With this study, we provide a comprehensive dataset characterizing the Critical Zone geochemistry in the Chilean Coastal Cordillera. This dataset confirms climatic controls on weathering and denudation rates and provides prerequisites to quantify the role of biota in future studies. KW - Weathering KW - Denudation KW - Microbial abundance KW - Climate KW - Chile Y1 - 2018 U6 - https://doi.org/10.1016/j.catena.2018.06.002 SN - 0341-8162 SN - 1872-6887 VL - 170 SP - 183 EP - 203 PB - Elsevier CY - Amsterdam ER - TY - GEN A1 - Genderjahn, Steffi A1 - Alawi, Mashal A1 - Mangelsdorf, Kai A1 - Horn, Fabian A1 - Wagner, Dirk T1 - Desiccation- and saline-tolerant bacteria and archaea in Kalahari pan sediments T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - More than 41% of the Earth’s land area is covered by permanent or seasonally arid dryland ecosystems. Global development and human activity have led to an increase in aridity, resulting in ecosystem degradation and desertification around the world. The objective of the present work was to investigate and compare the microbial community structure and geochemical characteristics of two geographically distinct saline pan sediments in the Kalahari Desert of southern Africa. Our data suggest that these microbial communities have been shaped by geochemical drivers, including water content, salinity, and the supply of organic matter. Using Illumina 16S rRNA gene sequencing, this study provides new insights into the diversity of bacteria and archaea in semi-arid, saline, and low-carbon environments. Many of the observed taxa are halophilic and adapted to water-limiting conditions. The analysis reveals a high relative abundance of halophilic archaea (primarily Halobacteria), and the bacterial diversity is marked by an abundance of Gemmatimonadetes and spore-forming Firmicutes. In the deeper, anoxic layers, candidate division MSBL1, and acetogenic bacteria (Acetothermia) are abundant. Together, the taxonomic information and geochemical data suggest that acetogenesis could be a prevalent form of metabolism in the deep layers of a saline pan. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 993 KW - saline pan KW - Kalahari KW - Halobacteria KW - Gemmatimonadetes KW - Firmicutes Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-459154 SN - 1866-8372 IS - 993 ER -