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  • 1.
    Cataldi, Gianni
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Brandeker, Alexis
    Stockholm University, Faculty of Science, Department of Astronomy.
    Thébault, Philippe
    Singer, Kelsi
    Ahmed, Engy
    Stockholm University, Faculty of Science, Department of Geological Sciences. Royal Institute of Technology (KTH), Sweden.
    de Vries, Bernard L.
    Stockholm University, Faculty of Science, Department of Astronomy. European Space Research and Technology Centre (ESA/ESTEC), The Netherlands.
    Neubeck, Anna
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Olofsson, Göran
    Stockholm University, Faculty of Science, Department of Astronomy.
    Searching for Biosignatures in Exoplanetary Impact Ejecta2017In: Astrobiology, ISSN 1531-1074, E-ISSN 1557-8070, Vol. 17, no 8, p. 721-746Article in journal (Refereed)
    Abstract [en]

    With the number of confirmed rocky exoplanets increasing steadily, their characterization and the search for exoplanetary biospheres are becoming increasingly urgent issues in astrobiology. To date, most efforts have concentrated on the study of exoplanetary atmospheres. Instead, we aim to investigate the possibility of characterizing an exoplanet (in terms of habitability, geology, presence of life, etc.) by studying material ejected from the surface during an impact event. For a number of impact scenarios, we estimate the escaping mass and assess its subsequent collisional evolution in a circumstellar orbit, assuming a Sun-like host star. We calculate the fractional luminosity of the dust as a function of time after the impact event and study its detectability with current and future instrumentation. We consider the possibility to constrain the dust composition, giving information on the geology or the presence of a biosphere. As examples, we investigate whether calcite, silica, or ejected microorganisms could be detected. For a 20km diameter impactor, we find that the dust mass escaping the exoplanet is roughly comparable to the zodiacal dust, depending on the exoplanet's size. The collisional evolution is best modeled by considering two independent dust populations, a spalled population consisting of nonmelted ejecta evolving on timescales of millions of years, and dust recondensed from melt or vapor evolving on much shorter timescales. While the presence of dust can potentially be inferred with current telescopes, studying its composition requires advanced instrumentation not yet available. The direct detection of biological matter turns out to be extremely challenging. Despite considerable difficulties (small dust masses, noise such as exozodiacal dust, etc.), studying dusty material ejected from an exoplanetary surface might become an interesting complement to atmospheric studies in the future.

  • 2. de Souza, Claudio M. D.
    et al.
    Carneiro, Cristine E. A.
    Bau, Joao Paulo T.
    da Costa, Antonio C. S.
    Ivashita, Flavio F.
    Paesano, Andrea, Jr.
    di Mauro, Eduardo
    de Santana, Henrique
    Holm, Nils G.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Neubeck, Anna
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Zaia, Cassia T. B. V.
    Zaia, Dimas A. M.
    Interaction of forsterite-91 with distilled water and artificial seawater: a prebiotic chemistry experiment2013In: International Journal of Astrobiology, ISSN 1473-5504, E-ISSN 1475-3006, Vol. 12, no 2, p. 135-143Article in journal (Refereed)
    Abstract [en]

    In the present work, the interactions between forsterite-91 with distilled water and forsterite-91 with artificial seawater were studied at two pHs (2.0 and 8.0) using different techniques. A large increase in pH was observed for samples incubated at an initially acidic pH (2.0) due to the dissolution of forsterite-91 in distilled water and artificial seawater. Thus, in acidic hydrothermal vents, an increase in the amount of hydrocarbons and magnetite should be expected due to the release of Fe(II). The pH(PZC) decreased and the pH(IEP) increased when forsterite-91 was treated with distilled water and artificial seawater. The ions from the artificial seawater had an effect on zeta potential. Scanning electron microscopy (SEM) images and X-ray diffractograms showed halite in the samples of forsterite-91 mixed with artificial seawater. The presence of halite or adsorption of ions on the surface of forsterite-91 could affect the synthesis of magnetite and hydrocarbons in hydrothermal vents, due to a decrease in the dissolution rates of forsterite-91. The dissolution of forsterite-91 yields low concentrations of Fe(III) and Mn(II) as detected by electron paramagnetic resonance (EPR) spectroscopy. Microanalysis of forsterite-91 showed a higher amount of Mn, with an oxidation that was likely not + II, as Mn in supernatant solutions was only detected by EPR spectroscopy after mixing with artificial seawater at pH 2.0. As Fe(III) and Mn(II) are catalyst constituents of magnetite and manganese oxide, respectively, their presence is important for synthesis in hydrothermal vents. Etch pits were observed only in the forsterite-91 sample mixed with distilled water at pH 8.0. Na, Cl, S, Ca and K were detected in the samples mixed with artificial seawater by SEM-EDS. Si, Mg, Fe and Al were detected in almost all supernatant samples due to forsterite-91 dissolution. Cr was not dissolved in the experiments, thus Cr in the mineral could serve as an effective catalyst for Fischer Tropsch Types (FTT) reactions in hydrothermal vent systems. X-ray diffractograms of the original forsterite-91 also showed peaks arising from zeolites and clinochlore. After the samples were treated with artificial seawater, X-ray diffractograms showed the dissolution of zeolite. Experiments should be performed in the natural environment to verify the potential for zeolites to act as a catalyst in hydrothermal vents.

  • 3.
    Duc, Nguyen Thanh
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Neubeck, Anna
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    The potential for abiotic methane formation fueled by olivine dissolutionIn: Nature Geoscience, ISSN 1752-0894, E-ISSN 1752-0908Article in journal (Refereed)
  • 4.
    Holm, Nils
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Neubeck, Anna
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Nitrogen dynamics in oceanic basement and its implications for HCN and abiotic organic synthesis2009In: Geochimica Cosmochimica Acta: Goldschmidt 2009, New York, NY: Elsevier , 2009, p. A547-A547Conference paper (Other (popular science, discussion, etc.))
  • 5.
    Holm, Nils
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Neubeck, Anna
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Reduction of nitrogen compounds i oceanic basemet and its implications for HCN formation and abiotic organic synthesis2009In: Geochemical Transactions, ISSN 1467-4866, E-ISSN 1467-4866, Vol. 10, no 9Article in journal (Refereed)
    Abstract [en]

    Hydrogen cyanide is an excellent organic reagent and is central to most of the reaction pathways leading to abiotic formation of simple organic compounds containing nitrogen, such as amino acids, purines and pyrimidines. Reduced carbon and nitrogen precursor compounds for the synthesis of HCN may be formed under off-axis hydrothermal conditions in oceanic lithosphere in the presence of native Fe and Ni and are adsorbed on authigenic layer silicates and zeolites. The native metals as well as the molecular hydrogen reducing CO2 to CO/CH4 and NO3-/NO2- to NH3/NH4+ are a result of serpentinization of mafic rocks. Oceanic plates are conveyor belts of reduced carbon and nitrogen compounds from the off-axis hydrothermal environments to the subduction zones, where compaction, dehydration, desiccation and diagenetic reactions affect the organic precursors. CO/CH4 and NH3/NH4+ in fluids distilled out of layer silicates and zeolites in the subducting plate at an early stage of subduction will react upon heating and form HCN, which is then available for further organic reactions to, for instance, carbohydrates, nucleosides or even nucleotides, under alkaline conditions in hydrated mantle rocks of the overriding plate. Convergent margins in the initial phase of subduction must, therefore, be considered the most potent sites for prebiotic reactions on Earth. This means that origin of life processes are, perhaps, only possible on planets where some kind of plate tectonics occur.

  • 6. Ivarsson, M.
    et al.
    Bach, W.
    Broman, Curt
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Neubeck, Anna
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Bengtson, S.
    Fossilized Life in Subseafloor Ultramafic Rocks2018In: Geomicrobiology Journal, ISSN 0149-0451, E-ISSN 1521-0529, Vol. 35, no 6, p. 460-467Article in journal (Refereed)
    Abstract [en]

    Ultramafic rocks are hypothesized to support a subseafloor hydrogen-driven biosphere because of extensive production of bioavailable energy sources like H-2 or CH4 from fluid-rock interactions. Hence, the apparent lack of microbial remains in subseafloor ultramafic rocks, in contrast to their frequent observation in subseafloor basalts, is somewhat of a paradox. Here we report fossilized microbial remains in aragonite veins in ultramafic rocks from the 15 degrees 20N Fracture Zone area on the Mid-Atlantic Ridge (MAR), collected during Ocean Drilling Program (ODP) Leg 209. The microbial remains consist of filamentous structures associated with biofilms. The young age (<1 Myr) and absence of diagenesis result in fossilized microbial communities with a pristine composition characterized by carbonaceous matter (CM) and the enrichment in trace elements such as Ni, Co, Mo and Mn. Our study confirms the presence of the hypothesized deep subseafloor biosphere hosted in ultramafic rocks. We further show that host rock composition may influence the microbial elemental composition, which is recorded during the fossilization.

  • 7. Ivarsson, M.
    et al.
    Bengtson, S.
    Neubeck, Anna
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    The igneous oceanic crust - Earth's largest fungal habitat?2016In: Fungal ecology, ISSN 1754-5048, E-ISSN 1878-0083, Vol. 20, p. 249-255Article, review/survey (Refereed)
    Abstract [en]

    In recent years the igneous oceanic crust has been recognized as a substantial microbial habitat and a scientific frontier within Geology, Biology, and Oceanography. A few successful metagenomic investigations have indicated the presence of Archaea and Bacteria, but also fungi in the subseafloor igneous crust. A comprehensive fossil record supports the presence of fungi in these deep environments and provides means of investigating the fungal presence that complements metagenomic methods. Considering the vast volume of the oceanic crust and that it is the largest aquifer on Earth, we put forward that it is the largest fungal habitat on the planet. This review aims to introduce a yet unexplored fungal habitat in an environment considered extreme from a biological perspective. We present the current knowledge of fungal abundance and diversity and discuss the ecological role of fungi in the igneous oceanic crust.

  • 8. Ivarsson, Magnus
    et al.
    Schnürer, Anna
    Bengtson, Stefan
    Neubeck, Anna
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Anaerobic Fungi: A Potential Source of Biological H-2 in the Oceanic Crust2016In: Frontiers in Microbiology, ISSN 1664-302X, E-ISSN 1664-302X, Vol. 7, article id 674Article in journal (Refereed)
    Abstract [en]

    The recent recognition of fungi in the oceanic igneous crust challenges the understanding of this environment as being exclusively prokaryotic and forces reconsiderations of the ecology of the deep biosphere. Anoxic provinces in the igneous crust are abundant and increase with age and depth of the crust. The presence of anaerobic fungi in deep-sea sediments and on the seafloor introduces a type of organism with attributes of geobiological significance not previously accounted for. Anaerobic fungi are best known from the rumen of herbivores where they produce molecular hydrogen, which in turn stimulates the growth of methanogens. The symbiotic cooperation between anaerobic fungi and methanogens in the rumen enhance the metabolic rate and growth of both. Methanogens and other hydrogen-consuming anaerobic archaea are known from subseafloor basalt; however, the abiotic production of hydrogen is questioned to be sufficient to support such communities. Alternatively, biologically produced hydrogen could serve as a continuous source. Here, we propose anaerobic fungi as a source of bioavailable hydrogen in the oceanic crust, and a close interplay between anaerobic fungi and hydrogen-driven prokaryotes.

  • 9.
    Lindgren, Paula
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Ivarsson, Magnus
    Naturhistoriska riksmuséet.
    Neubeck, Anna
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Broman, Curt
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Henkel, Herbert
    Kungliga tekniska högskolan.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Putative fossil life in a hydrothermal system of the Dellen impact structure, Sweden2010In: International Journal of Astrobiology, ISSN 1473-5504, E-ISSN 1475-3006, Vol. 9, no 3, p. 137-146Article in journal (Refereed)
    Abstract [en]

    The role of muscarinic acetylcholine receptors (mAChRs) in regulating glucose uptake in L6 skeletal muscle cells was investigated. [H-3]-2-Deoxyglucose uptake was increased in differentiated L6 cells by insulin, acetylcholine, oxotremorine-M and carbachol. mAChR-mediated glucose uptake was inhibited by the AMPK inhibitor Compound C. Whole cell radioligand binding using [H-3]-N-methyl scopolamine chloride identified mAChRs in differentiated but not undifferentiated L6 cells and M-3 mAChR mRNA was detected only in differentiated cells. M-3 mAChRs are Gq-coupled, and cholinergic stimulation by the rnAChR agonists acetylcholine, oxotremorine-M and carbachol increased Ca2+ in differentiated but not undifferentiated L6 cells. This was due to muscarinic but not nicotinic activation as responses were antagonised by the muscarinic antagonist atropine but not the nicotinic antagonist tubocurarine. Western blotting showed that both carbachol and the AMPK activator AICAR increased phosphorylation of the AMPK alpha subunit at Thr172, with responses to carbachol blocked by Compound C and the CaMKK inhibitor STO609 but not by the PI3K inhibitor wortmannin. AICAR-stimulated AMPK phosphorylation was not sensitive to STO-609, confirming that this compound inhibits CaMKK but not the classical AMPK kinase LKB1. The TAK1 inhibitor (5Z)-7-oxozeaenol and the G(i) inhibitor pertussis toxin both failed to block AMPK phosphorylation in response to carbachol. Using CHO-K1 cells stably expressing each of the mAChR subtypes (M-1-M-4), it was determined that only the M-1 and M-3 mAChRs phosphorylate AMPK, confirming a G(q)-dependent mechanism. This study demonstrates that activation of M-3 mAChRs in L6 skeletal muscle cells stimulates glucose uptake via a CaMKK-AMPK-dependent mechanism, independent of the insulin-stimulated pathway.

  • 10.
    Neubeck, Anna
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Low temperature olivine alteration ; an experimental approach2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Water reacting with minerals to alter or dissolve them is a common phenomenon on Earth, leading to a unique chemical composition of the oceans and continents. The continuous circulation of elements and the chemical reactions between them creates the extraordinary environment prevailing on our Earth today and was probably an important requirement for the onset of life on our planet. Olivine is a mineral with the special property of being unstable at atmospheric pressures and temperatures due to its crystal structure and chemical composition. Hydrous alteration of olivine has the capacity to form molecular hydrogen (H2) and hydrated secondary products concurrent with the release of heat. H2 is considered to be crucial for the deep subsurface biosphere and is capable of reducing oxidized carbon species to CH4 and other hydrocarbons through the so-called Sabatier reaction or Fischer-Tropsch Type reactions which are important when studying the large scale CH4 outgassing on Mars or the CH4 seeps coupled to contemporary terrestrial ophiolites.

    This thesis investigates the potential abiotic formation of H2 and CH4 at low temperatures and pressures as well as under anoxic conditions but also looks at the potential for sustaining the growth of methanogenic archaea with olivine and water. The results suggest that olivine has the potential to form H2 and fuel the abiotic formation of CH4 at low temperatures and low concentrations of dissolved bicarbonate. At higher bicarbonate concentrations, precipitation of silica and carbonate are suggested to cover the reactive catalytic sites on the olivine surface.

  • 11.
    Neubeck, Anna
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    The effect of DIC on low temperature olivine alteration and H2 formationManuscript (preprint) (Other academic)
  • 12.
    Neubeck, Anna
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Duc, Nguyen Thanh
    Hellevang, Helge
    Oze, Christopher
    Bastviken, David
    Bacsik, Zoltan
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Holm, Nils G.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Olivine alteration and H-2 production in carbonate-rich, low temperature aqueous environments2014In: Planetary and Space Science, ISSN 0032-0633, E-ISSN 1873-5088, Vol. 96, p. 51-61Article in journal (Refereed)
    Abstract [en]

    Hydrous alteration of olivine is capable of producing molecular hydrogen (H-2) under a wide variety of hydrothermal conditions. Although olivine hydrolysis (i.e., serpentinization) has commonly been assessed at elevated temperatures ( > 100 degrees C), the nature of these reactions in relation to H-2 production at lower temperatures has not been systematically evaluated, especially with regard to carbonate-rich fluids. Specifically, carbonate formation may kinetically infringe on geochemical routes related to serpentinization and H-2 production at lower temperatures. Here time-dependent interactions of solid, liquid, and gaseous phases with respect to olivine hydrolysis in a carbonate-rich solution (20 mM HCO3-) at 30, 50 and 70 degrees C for 315 days is investigated experimentally. Within the first two months, amorphous Si-rich (i.e., talc-like) and carbonate phases precipitated; however, no inhibition of olivine dissolution is observed at any temperature based on surface chemistry analyses. High-resolution surface analyses confirm that precipitates grew as spheroids or vertically to form topographic highs allowing further dissolution of the free olivine surfaces and exposing potential catalysts. Despite no magnetite (Fe3O4) being detected, H-2 increased with time in experiments carried out at 70 degrees C, indicating an alternative coupled route for Fe oxidation and H-2 production. Spectrophotometry analyses show that aqueous Fe(II) is largely converted to Fe(III) potentially integrating into other phases such as serpentine and talc, thus providing a viable pathway for H-2 production. No increase in H-2 production was observed in experiments carried out at 30 and 50 degrees C supporting observations that incorporation of Fe(II) into carbonates occurred faster than the intertwined processes of olivine hydrolysis and Fe(III) oxidation. Overall, carbonate formation is confirmed to be a major influence related to H-2 production in low-temperature serpentinization systems.

  • 13.
    Neubeck, Anna
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Ivarsson, Magnus
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Boron influence on biochemical reactions in natural zeolites2007Conference paper (Other (popular science, discussion, etc.))
  • 14.
    Neubeck, Anna
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Nguyen, Duc
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Bastviken, David
    Crill, Patrick
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Formation of H2 and CH4 by weathering of olivine at temperatures between 30 and 70°C2011In: Geochemical Transactions, ISSN 1467-4866, E-ISSN 1467-4866, Vol. 12, no 6Article in journal (Refereed)
    Abstract [en]

    Hydrocarbons such as CH4 are known to be formed through the Fischer-Tropsch or Sabatier type reactions in hydrothermal systems usually at temperatures   above 100°C. Weathering of olivine is sometimes suggested to account for abiotic formation of CH4 through its redox lowering and water splitting properties. Knowledge about the CH4 and H2 formation processes at low temperatures is important for the research about the origin and cause of early Earth and Martian   CH4 and for CO2 sequestration. We have conducted a series of low temperature, long-term weathering experiments in which we have tested the   CH4 and H2 formation potential of forsteritic olivine.

    The results show low temperature CH4 production that is probably influenced by chromite and magnetite as catalysts. Extensive analyses of a potential CH4 source trapped in the crystal structure of the olivine showed no signs of incorporated CH4. Also, the available sources of organic carbon were not enough to support the total amount of CH4 detected in our experiments. There was also a linear relationship between silica release into solution and the net CH4 accumulation into the incubation bottle headspaces suggesting that CH4 formation under these conditions could be a qualitative indicator of olivine dissolution.

    It is likely that minerals such as magnetite, chromite and other metal-rich minerals found on the olivine surface catalyze   the formation of CH4, because of the low temperature of the system. This may expand the range of environments plausible for abiotic CH4 formation both on Earth and on other terrestrial bodies.

  • 15.
    Neubeck, Anna
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Nguyen Thanh, Duc
    Etiope, Giuseppe
    Low-temperature dunite hydration: evaluating CH4 and H2 production from H2O and CO22016In: Geofluids, ISSN 1468-8115, E-ISSN 1468-8123, Vol. 16, no 3, p. 408-420Article in journal (Refereed)
    Abstract [en]

    Abiotic methane (CH4) and hydrogen (H2) produced after hydration of mafic/ultramafic rocks represent energy sources for microbes that may thrive in the deep subsurface regions of Earth and possibly on other planets. While H2 is a direct product of serpentinization, CH4 can form via Fischer–Tropsch Type (FTT) reactions (carbon reduction) that, due to potential H2 migration, can be spatially and temporally detached from serpentinization. We tested an alternative process hypothesized by some scholars, in which CO2 can be reduced through dunite hydration without initially added H2, implying that CH4 can form in the same serpentinized fluid–rock system. The experiment used natural dunite sand (Forsterite 92), CO2 with δ13C ~ −25‰ (VPDB), and a 1 mm dissolved SiO2 solution mixed in 30 glass bottles (118 mL) stored for up to 8 months at low temperature (50°C) to simulate land-based serpentinization systems. In addition, 30 control bottles without olivine were used as blanks. Trivial amounts of CH4 (orders of 0.2–0.9 ppmv) were detected in both samples and blanks, likely representing analytical noise; essentially, no significant amount of CH4 formed under the experimental conditions used in this work. Low amounts of H2 (~2.55 ± 1.39 ppmv) were generated, with production yields that were one order of magnitude lower than in previously published experiments. Moderate concentrations of SiO2 appeared to hinder low-temperature H2 production. Our experiment confirms that the low-temperature reduction of CO2 into CH4 through direct olivine hydration, without initial H2, is sluggish and not straightforward, which is consistent with previous studies. The presence of substantial amounts of H2, as well as suitable metal catalysts, appears to be essential in the low-temperature production of abiotic CH4, as observed in published FTT experiments.

  • 16.
    Neubeck, Anna
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Sjöberg, Susanne
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Price, Alex
    Callac, Nolwenn
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Schnürer, Anna
    Effect of Nickel Levels on Hydrogen Partial Pressure and Methane Production in Methanogens2016In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 12, article id e0168357Article in journal (Refereed)
    Abstract [en]

    Hydrogen (H-2) consumption and methane (CH4) production in pure cultures of three different methanogens were investigated during cultivation with 0, 0.2 and 4.21 mu M added nickel (Ni). The results showed that the level of dissolved Ni in the anaerobic growth medium did not notably affect CH4 production in the cytochrome-free methanogenic species Methanobacterium bryantii and Methanoculleus bourgensis MAB1, but affected CH4 formation rate in the cytochrome-containing Methanosarcina barkeri grown on H-2 and CO2. Methanosarcina barkeri also had the highest amounts of Ni in its cells, indicating that more Ni is needed by cytochrome-containing than by cytochrome-free methanogenic species. The concentration of Ni affected threshold values of H-2 partial pressure (pH(2)) for all three methanogen species studied, with M. bourgensis MAB1 reaching pH(2) values as low as 0.1 Pa when Ni was available in amounts used in normal anaerobic growth medium. To our knowledge, this is the lowest pH(2) threshold recorded to date in pure methanogen culture, which suggests that M. bourgensis MAB1 have a competitive advantage over other species through its ability to grow at low H-2 concentrations. Our study has implications for research on the H-2-driven deep subsurface biosphere and biogas reactor performance.

  • 17.
    Neubeck, Anna
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Sun, Li
    Müller, Bettina
    Ivarsson, Magnus
    Hosgörmez, Hakan
    Özcan, Dogacan
    Broman, Curt
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Schnürer, Anna
    Microbial Community Structure in a Serpentine-Hosted Abiotic Gas Seepage at the Chimaera Ophiolite, Turkey2017In: Applied and Environmental Microbiology, ISSN 0099-2240, E-ISSN 1098-5336, Vol. 83, no 12, article id UNSP e03430Article in journal (Refereed)
    Abstract [en]

    The surface waters at the ultramafic ophiolitic outcrop in Chimaera, Turkey, are characterized by high pH values and high metal levels due to the percolation of fluids through areas of active serpentinization. We describe the influence of the liquid chemistry, mineralogy, and H-2 and CH4 levels on the bacterial community structure in a semidry, exposed, ultramafic environment. The bacterial and archaeal community structures were monitored using Illumina sequencing targeting the 16S rRNA gene. At all sampling points, four phyla, Proteobacteria, Actinobacteria, Chloroflexi, and Acidobacteria, accounted for the majority of taxa. Members of the Chloroflexi phylum dominated low-diversity sites, whereas Proteobacteria dominated high-diversity sites. Methane, nitrogen, iron, and hydrogen oxidizers were detected as well as archaea and metal-resistant bacteria. IMPORTANCE Our study is a comprehensive microbial investigation of the Chimaera ophiolite. DNA has been extracted from 16 sites in the area and has been studied from microbial and geochemical points of view. We describe a microbial community structure that is dependent on terrestrial, serpentinization-driven abiotic H-2, which is poorly studied due to the rarity of these environments on Earth.

  • 18.
    Neubeck, Anna
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Tulej, Marek
    Ivarsson, Magnus
    Broman, Curt
    Riedo, Andreas
    McMahon, Sean
    Wurz, Peter
    Bengtson, Stefan
    Mineralogical determination in situ of a highly heterogeneous material using a miniaturized laser ablation mass spectrometer with high spatial resolution2016In: International Journal of Astrobiology, ISSN 1473-5504, E-ISSN 1475-3006, Vol. 15, no 2, p. 133-146Article in journal (Refereed)
    Abstract [en]

    Techniques enabling in situ elemental and mineralogical analysis on extraterrestrial planets are strongly required for upcoming missions and are being continuously developed. There is ample need for quantitative and high-sensitivity analysis of elemental as well as isotopic composition of heterogeneous materials. Here we present in situ spatial and depth elemental profiles of a heterogeneous rock sample on a depth-scale of nanometres using a miniaturized laser ablation mass spectrometer (LMS) designed for planetary space missions. We show that the LMS spectra alone could provide highly detailed compositional, three-dimensional information and oxidation properties of a natural, heterogeneous rock sample. We also show that a combination of the LMS and Raman spectroscopy provide comprehensive mineralogical details of the investigated sample. These findings are of great importance for future space missions where quick, in situ determination of the mineralogy could play a role in the process of selecting a suitable spot for drilling.

  • 19. Tulej, Marek
    et al.
    Neubeck, Anna
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Ivarsson, Magnus
    Riedo, Andreas
    Neuland, Maike B.
    Meyer, Stefan
    Wurz, Peter
    Chemical Composition of Micrometer-Sized Filaments in an Aragonite Host by a Miniature Laser Ablation/Ionization Mass Spectrometer2015In: Astrobiology, ISSN 1531-1074, E-ISSN 1557-8070, Vol. 15, no 8, p. 669-682Article in journal (Refereed)
    Abstract [en]

    Detection of extraterrestrial life is an ongoing goal in space exploration, and there is a need for advanced instruments and methods for the detection of signatures of life based on chemical and isotopic composition. Here, we present the first investigation of chemical composition of putative microfossils in natural samples using a miniature laser ablation/ionization time-of-flight mass spectrometer (LMS). The studies were conducted with high lateral (similar to 15 mu m) and vertical (similar to 20-200 nm) resolution. The primary aim of the study was to investigate the instrument performance on micrometer-sized samples both in terms of isotope abundance and element composition. The following objectives had to be achieved: (1) Consider the detection and calculation of single stable isotope ratios in natural rock samples with techniques compatible with their employment of space instrumentation for biomarker detection in future planetary missions. (2) Achieve a highly accurate chemical compositional map of rock samples with embedded structures at the micrometer scale in which the rock matrix is easily distinguished from the micrometer structures. Our results indicate that chemical mapping of strongly heterogeneous rock samples can be obtained with a high accuracy, whereas the requirements for isotope ratios need to be improved to reach sufficiently large signal-to-noise ratio (SNR). Key Words: Biogenicity-Biomarkers-Biosignatures-Filaments-Fossilization. Astrobiology 15, 669-682.

  • 20. Tulej, Marek
    et al.
    Riedo, Andreas
    Neuland, Maike B.
    Meyer, Stefan
    Wurz, Peter
    Thomas, Nicolas
    Grimaudo, Valentine
    Moreno-Garcia, Pavel
    Broekmann, Peter
    Neubeck, Anna
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Ivarsson, Magnus
    CAMAM: A Miniature Laser Ablation Ionisation Mass Spectrometer and Microscope-Camera System for In Situ Investigation of the Composition and Morphology of Extraterrestrial Materials2014In: Geostandards and Geoanalytical Research, ISSN 1639-4488, E-ISSN 1751-908X, Vol. 38, no 4, p. 441-466Article in journal (Refereed)
    Abstract [en]

    Performance studies of a microscope-camera system (MCS) and a laser ablation/ionisation mass spectrometer (LIMS) instrument (referred to here as a laser mass spectrometer or LMS) are presented. These two instruments were designed independently for in situ analysis of solids on planetary surfaces and will be combined to a single miniature instrument suite for in situ chemical and morphological analysis of surface materials on planetary bodies. LMS can perform sensitive chemical (elemental, isotope and molecular) analyses with spatial resolution close to micrometre-sized grains. It allows for studies with mass resolution (M/M) up to 800 in ablation mode (elemental composition) and up to 1500 in desorption mode (molecular analysis). With an effective dynamic range of at least eight orders of magnitude, sensitive and quantitative measurements can be conducted of almost all elements and isotopes with a concentration larger than a few ppb atoms. Hence, in addition to the major element composition, which is important for the determination of mineralogical constituents of surface materials, trace elements can also be measured to provide information on mineral formation processes. Highly accurate isotope ratio measurements can be used to determine in situ geochronology of sample material and for investigations of various isotope fractionation processes. MCS can conduct optical imagery of mm-sized objects at several wavelengths with micrometre spatial resolution for the characterisation of morphological surface details and to provide insight into surface mineralogy. Furthermore, MCS can help in the selection of sample surface areas for further mass spectrometric analysis of the chemical composition. Surface auto-fluorescence measurements and images in polarised light are additional capabilities of the MCS, to identify either fluorescing minerals or organic materials, if present on the analysed surface, for further investigation by LMS. The results obtained by investigations of NIST reference materials, amino acid films and a natural graphite sample embedded in silicate rock are presented to illustrate the performance of the instruments and their potential to deliver chemical information for mineral and organic phases in their geological context.

  • 21. Wiesendanger, Reto
    et al.
    Wacey, David
    Tulej, Marek
    Neubeck, Anna
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Ivarsson, Magnus
    Grimaudo, Valentine
    Moreno-Garcia, Pavel
    Cedeno-Lopez, Alena
    Riedo, Andreas
    Wurz, Peter
    Chemical and Optical Identification of Micrometer-Sized 1.9 Billion-Year-Old Fossils by Combining a Miniature Laser Ablation Ionization Mass Spectrometry System with an Optical Microscope2018In: Astrobiology, ISSN 1531-1074, E-ISSN 1557-8070, Vol. 18, no 8, p. 1071-1080Article in journal (Refereed)
    Abstract [en]

    The recognition of biosignatures on planetary bodies requires the analysis of the putative microfossil with a set of complementary analytical techniques. This includes localized elemental and isotopic analysis of both, the putative microfossil and its surrounding host matrix. If the analysis can be performed with spatial resolution at the micrometer level and ppm detection sensitivities, valuable information on the (bio)chemical and physical processes that influenced the sample material can be gained. Our miniaturized laser ablation ionization mass spectrometry (LIMS)-time-of-flight mass spectrometer instrument is a valid candidate for performing the required chemical analysis in situ. However, up until now it was limited by the spatial accuracy of the sampling. In this contribution, we introduce a newly developed microscope system with micrometer accuracy for Ultra High Vacuum application, which allows a significant increase in the measurement capabilities of our miniature LIMS system. The new enhancement allows identification and efficient and accurate sampling of features of micrometer-sized fossils in a host matrix. The performance of our system is demonstrated by the identification and chemical analysis of signatures of micrometer-sized fossil structures in the 1.9 billion-year-old Gunflint chert.

  • 22. Young, E. D.
    et al.
    Kohl, I. E.
    Lollar, B. Sherwood
    Etiope, G.
    Rumble, D.
    Li, S.
    Haghnegahdar, M. A.
    Schauble, E. A.
    McCain, K. A.
    Foustoukos, D. I.
    Sutclife, C.
    Warr, O.
    Ballentine, C. J.
    Onstott, T. C.
    Hosgormez, H.
    Neubeck, Anna
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Marques, J. M.
    Perez-Rodriguez, I.
    Rowe, A. R.
    LaRowe, D. E.
    Magnabosco, C.
    Yeung, L. Y.
    Ash, J. L.
    Bryndzia, L. T.
    The relative abundances of resolved (CH2D2)-C-12 and (CH3D)-C-13 and mechanisms controlling isotopic bond ordering in abiotic and biotic methane gases2017In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 203, p. 235-264Article in journal (Refereed)
    Abstract [en]

    We report measurements of resolved (CH2D2)-C-12 and (CH3D)-C-13 at natural abundances in a variety of methane gases produced naturally and in the laboratory. The ability to resolve (CH2D2)-C-12 from (CH3D)-C-13 provides unprecedented insights into the origin and evolution of CH4. The results identify conditions under which either isotopic bond order disequilibrium or equilibrium are expected. Where equilibrium obtains, concordant Delta (CH2D2)-C-12 and Delta (CH3D)-C-13 temperatures can be used reliably for thermometry. We find that concordant temperatures do not always match previous hypotheses based on indirect estimates of temperature of formation nor temperatures derived from CH4/H-2 D/H exchange, underscoring the importance of reliable thermometry based on the CH4 molecules themselves. Where Delta (CH2D2)-C-12 and Delta (CH3D)-C-13 values are inconsistent with thermodynamic equilibrium, temperatures of formation derived from these species are spurious. In such situations, while formation temperatures are unavailable, disequilibrium isotopologue ratios nonetheless provide novel information about the formation mechanism of the gas and the presence or absence of multiple sources or sinks. In particular, disequilibrium isotopologue ratios may provide the means for differentiating between methane produced by abiotic synthesis vs. biological processes. Deficits in (CH2D2)-C-12 compared with equilibrium values in CH4 gas made by surface-catalyzed abiotic reactions are so large as to point towards a quantum tunneling origin. Tunneling also accounts for the more moderate depletions in (CH3D)-C-13 that accompany the low (CH2D2)-C-12 abundances produced by abiotic reactions. The tunneling signature may prove to be an important tracer of abiotic methane formation, especially where it is preserved by dissolution of gas in cool hydrothermal systems (e.g., Mars). Isotopologue signatures of abiotic methane production can be erased by infiltration of microbial communities, and Delta (CH2D2)-C-12 values are a key tracer of microbial recycling.

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