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  - 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  - 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  - 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  - 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  - 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  - 
TY  - JOUR
A1  - Nwosu, Ebuka Canisius
A1  - Roeser, Patricia Angelika
A1  - Yang, Sizhong
A1  - Ganzert, Lars
A1  - Dellwig, Olaf
A1  - Pinkerneil, Sylvia
A1  - Brauer, Achim
A1  - Dittmann, Elke
A1  - Wagner, Dirk
A1  - Liebner, Susanne
T1  - From water into sediment-tracing freshwater cyanobacteria via DNA analyses
JF  - Microorganisms : open access journal
N2  - Sedimentary ancient DNA-based studies have been used to probe centuries of climate and environmental changes and how they affected cyanobacterial assemblages in temperate lakes. Due to cyanobacteria containing potential bloom-forming and toxin-producing taxa, their approximate reconstruction from sediments is crucial, especially in lakes lacking long-term monitoring data. To extend the resolution of sediment record interpretation, we used high-throughput sequencing, amplicon sequence variant (ASV) analysis, and quantitative PCR to compare pelagic cyanobacterial composition to that in sediment traps (collected monthly) and surface sediments in Lake Tiefer See. Cyanobacterial composition, species richness, and evenness was not significantly different among the pelagic depths, sediment traps and surface sediments (p > 0.05), indicating that the cyanobacteria in the sediments reflected the cyanobacterial assemblage in the water column. However, total cyanobacterial abundances (qPCR) decreased from the metalimnion down the water column. The aggregate-forming (Aphanizomenon) and colony-forming taxa (Snowella) showed pronounced sedimentation. In contrast, Planktothrix was only very poorly represented in sediment traps (meta- and hypolimnion) and surface sediments, despite its highest relative abundance at the thermocline (10 m water depth) during periods of lake stratification (May-October). We conclude that this skewed representation in taxonomic abundances reflects taphonomic processes, which should be considered in future DNA-based paleolimnological investigations.
KW  - Aphanizomenon
KW  - Planktothrix
KW  - Snowella
KW  - cyanobacteria sedimentation
KW  - lake monitoring
KW  - sedimentary ancient DNA
KW  - sediment traps
KW  - environmental reconstruction
Y1  - 2021
U6  - https://doi.org/10.3390/microorganisms9081778
SN  - 2076-2607
VL  - 9
IS  - 8
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Rodriguez, Victoria
A1  - Moskwa, Lisa-Marie
A1  - Oses, Romulo
A1  - Kühn, Peter
A1  - Riveras-Muñoz, Nicolás
A1  - Seguel, Oscar
A1  - Scholten, Thomas
A1  - Wagner, Dirk
T1  - Impact of climate and slope aspects on the composition of soil bacterial communities involved in pedogenetic processes along the chilean coastal cordillera
JF  - Microorganisms
N2  - Soil bacteria play a fundamental role in pedogenesis. However, knowledge about both the impact of climate and slope aspects on microbial communities and the consequences of these items in pedogenesis is lacking. Therefore, soil-bacterial communities from four sites and two different aspects along the climate gradient of the Chilean Coastal Cordillera were investigated. Using a combination of microbiological and physicochemical methods, soils that developed in arid, semi-arid, mediterranean, and humid climates were analyzed. Proteobacteria, Acidobacteria, Chloroflexi, Verrucomicrobia, and Planctomycetes were found to increase in abundance from arid to humid climates, while Actinobacteria and Gemmatimonadetes decreased along the transect. Bacterial-community structure varied with climate and aspect and was influenced by pH, bulk density, plant-available phosphorus, clay, and total organic-matter content. Higher bacterial specialization was found in arid and humid climates and on the south-facing slope and was likely promoted by stable microclimatic conditions. The presence of specialists was associated with ecosystem-functional traits, which shifted from pioneers that accumulated organic matter in arid climates to organic decomposers in humid climates. These findings provide new perspectives on how climate and slope aspects influence the composition and functional capabilities of bacteria, with most of these capabilities being involved in pedogenetic processes.
KW  - bacterial-community structure
KW  - bacterial diversity
KW  - climate gradient
KW  - slope aspect
KW  - Chilean Coastal Cordillera
KW  - soil formation
Y1  - 2022
U6  - https://doi.org/10.3390/microorganisms10050847
SN  - 2076-2607
VL  - 10
IS  - 5
PB  - MDPI
CY  - Basel
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  - 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  - 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  - 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  - 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  - Genderjahn, Steffi
A1  - Lewin, Simon
A1  - Horn, Fabian
A1  - Schleicher, Anja M.
A1  - Mangelsdorf, Kai
A1  - Wagner, Dirk
T1  - Living lithic and sublithic bacterial communities in Namibian drylands
JF  - Microorganisms : open access journal
N2  - Dryland xeric conditions exert a deterministic effect on microbial communities, forcing life into refuge niches. Deposited rocks can form a lithic niche for microorganisms in desert regions. Mineral weathering is a key process in soil formation and the importance of microbial-driven mineral weathering for nutrient extraction is increasingly accepted. Advances in geobiology provide insight into the interactions between microorganisms and minerals that play an important role in weathering processes. In this study, we present the examination of the microbial diversity in dryland rocks from the Tsauchab River banks in Namibia. We paired culture-independent 16S rRNA gene amplicon sequencing with culture-dependent (isolation of bacteria) techniques to assess the community structure and diversity patterns. Bacteria isolated from dryland rocks are typical of xeric environments and are described as being involved in rock weathering processes. For the first time, we extracted extra- and intracellular DNA from rocks to enhance our understanding of potentially rock-weathering microorganisms. We compared the microbial community structure in different rock types (limestone, quartz-rich sandstone and quartz-rich shale) with adjacent soils below the rocks. Our results indicate differences in the living lithic and sublithic microbial communities.
KW  - lithobiont
KW  - intracellular DNA
KW  - extracellular DNA
KW  - weathering
KW  - dryland
KW  - rock
Y1  - 2021
U6  - https://doi.org/10.3390/microorganisms9020235
SN  - 2076-2607
VL  - 9
IS  - 2
PB  - MDPI
CY  - Basel
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  - 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  - 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  - 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  - 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  - 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  -