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  • 1.
    Ahmed, Engy
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Holmström, Sara
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Brüchert, Volker
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Holm, Nils G.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    The Role of Microorganisms in the diversity and distribution of siderophores in Podzolic Forest Soil2013In: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 77, no 2, p. 161--208(48)Article in journal (Other academic)
    Abstract [en]

    Iron is a key component of the chemical architecture of the biosphere. Due to the low bioavailability of iron in the environment, microorganisms have developed specific uptake strategies. The most important one is the production of siderophores, which are operationally defined as low-molecular-mass biogenic Fe (III)-binding compounds which may greatly increase bioavailability of Fe [1]. One of the primary biogeochemical functions of siderophores is therefore to increase Fe bioavailability by promoting the dissolution of iron-bearing minerals [2]. This study aims to understand the role of microorganisms in the chemical diversity and distribution of siderophores in podzol soil and how this diversity can contribute to the bioavailability of Fe in forest soil.Soil samples were collected from an experimental site in the area of Bispgården in central Sweden (63°07′N, 16°70′E) from the O (organic), E (eluvial), B1 (upper illuvial), and C (mineral) horizons. Concentration and chemical composition of dissolved and adsorbed siderophores in the soil samples were determined using colorimetric assays and high-performance liquid chromatography.The highest siderophore concentrations were found in the O layer and thereafter decreased by depth. Concentrations of dissolved hydroxamate, catecholate and carboxylate siderophores were up to 84, 17 and 0.2 nmol/ g soil, respectively. In contrast, concentrations of adsorbed hydroxamates, catecholates and carboxylates were only up to 1.8, 3 and 0.2 nmol/ g soil, respectively.Siderophore-producing microorganisms were isolated from the same soil samples. Viable fungi, bacteria and actinomycete counts ranged from 7 to 300, from 300 to 1800, and from 0 to 5 cfu/gm, respectively. The highest counts were found in the O and E layers. Only the E layer contained the three types of siderophore-producing microorganisms investigated in this study. Siderophores were extracted from culture filtrates of the isolated microorganisms when grown under iron-limited conditions. These extracts varied considerably in siderophore composition. Fungal isolates produced up to 183 μM of hydroxamates, especially those isolated from the O layer, whereas bacteria and actinomycete isolated from the O and E layers of the soil produced high amounts of carboxylate, catecholate and hydroxamate siderophores. Actinomycete produced up to 93 μM of hydroxamates and 47 μM of catecholates, while bacteria produced up to 34 μM of carboxylates and up to 14 μM of catecholates.The depth variability in concentration and chemical composition and the good correlation between abundance of siderophore-producing microorganisms and siderophore soil concentrations strongly suggest that these siderophore-producing microorganisms play an important role in the mobilization of iron in the podzol soil that may be important in iron availability to plants in forest environment.

    [1] Clay et al. (1981) Biochemistry 20, 2432-2436. [2] Duckworth et al. (2009) ChemGeol 260, 149-158.

  • 2.
    Al-Hanbali, Hakam
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Evidence for fossilized microbial communities beneath the TAG hydrothermal mound, mid-Atlantic Ocean2002In: Geomicrobiology Journal, Vol. 19, p. 429-438Article in journal (Refereed)
  • 3.
    Al-Hanbali, Hakam
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Sowerby, Stephen
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Biogenicity of silicified microbes from a hydrothermal system: Relevance to the search for life on Earth and other planets2001In: Earth and Planetary Science Letters, Vol. 191, p. 213-218Article in journal (Refereed)
  • 4.
    Andersson, Eva
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    The stability of some selected amino acids under attempted redox constrained conditions2000In: Origins Life Evol. Biosphere, Vol. 30, p. 9-23Article in journal (Refereed)
  • 5.
    Andersson, Eva
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Simoneit, B.R.T.
    Holm, Nils
    Amino acid abundances and stereochemistry in hydrothermally altered sediments from the Juan de Fuca Ridge, northeastern Pacific Ocean2000In: Applied Geochemistry, Vol. 15, p. 1169-1190Article in journal (Refereed)
  • 6.
    Bohlin, Hanna
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Mörth, Carl-Magnus
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Point source influences on the carbon and nitrogen geochemistry of sediments in the Stockholm archipelago, Sweden2006In: The Science of the Total Environment, Vol. 366, p. 337-349Article in journal (Refereed)
  • 7.
    Bohlin, Hanna
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Mörth, Carl-Magnus
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Holm, Nils G.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Point source influences on the carbon and nitrogen geochemistry of sediments in the Stockholm inner archipelago, Sweden2006In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 366, no 1, p. 337-349Article in journal (Refereed)
    Abstract [en]

    This study reports analyses of carbon and nitrogen content, and δ15N and δ13C in sediments of the Höggarnsfjärden Bay near Stockholm. Samples have been taken upstream, near, and downstream of a point source of processed leach water from a garbage dump. The surface sediment at the upstream and downstream sites has δ15N and δ13C close to the expected background of the area, even though a contribution from the leach water can be observed downstream of the point source. The sediment close to the outflow is strongly influenced by the carbon and nitrogen in the leach water.

  • 8. Bäckström, M.
    et al.
    Bohlin, Hanna
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Karlsson, S.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Element (Ag, Cd, Cu, Pb, Sb, Tl and Zn), element ratio and lead isotope profiles in a sediment affected by a mining operation episode during the late 19th century2006In: Water, Air and Soil Pollution, Vol. 177, p. 285-311Article in journal (Refereed)
  • 9. Charlou, J.L.
    et al.
    Donval, J.P
    Jean-Baptiste, P.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Geochemistry of high H2 and CH4 vent fluids issuing from ultramafic rocks at the Rainbow hydrothermal field2002In: Chemical Geology, Vol. 191, p. 345-359Article in journal (Refereed)
  • 10.
    Cohn, Corey
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Hansson, Thomas
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Larsson, Håkan
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Sowerby, Stephen
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Fate of prebiotic adenine2001In: Astrobiology, Vol. 1, p. 477-480Article in journal (Refereed)
  • 11. 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.

  • 12.
    Demina, Ludmila
    et al.
    P.P Shirshov Institute of Oceanology, Russian Academy of Sciences.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Galkin, Sergey
    P.P Shirshov Institute of Oceanology, Russian Academy of Sciences.
    Lein, Alla
    P.P. Shirshov Institute of Oceanology, Russian Academy of Sciences.
    Some features of the trace metal biogeochemistry in the deep-sea hydrothermal vent fields (Menez Gwen, Rainbow, Broken Spur at the MAR and 9°50'N at the EPR): A synthesis2013In: Journal of Marine Systems, ISSN 0924-7963, E-ISSN 1879-1573, Vol. 126, no SI, p. 94-105Article in journal (Refereed)
    Abstract [en]

    Along with summarizing the published literature and our own data some new results on properties of the trace metal biogeochemistry in the deep-sea hydrothermal ecosystems at the Mid-Atlantic Ridge (MAR) and East Pacific Rise (EPR) are shown. Differences in mean concentrations of big group of trace metals (Fe, Mn, Zn, Cu, Ni, Cr, Co, As, Pb, Cd, Ag, Hg) between the biotope water of the low- and high-temperature hydrothermal vent fields were firstly revealed. The same trace metals were studied in different groups of organisms within different temperature zones at one and the same vent field (9°50′N EPR), as well as in fauna inhabiting geochemically different vent sites. Distribution patterns of Fe, Mn, Zn, Cu, Cd, Pb, Ag, Ni, Cr, Co, As, Se, Sb, and Hg in different taxa gave an evidence of the influence of environmental and biological parameters on their bioaccumulation in organisms. Among the animals a particular “champion” with respect to the trace metal content was found to be a polychaeta Alvinella pompejana that inhabits the hottest places of the vent sulfide chimneys of the 9°50′N field, EPR. New data on the trace metal distribution between soft tissues and carbonate shell let us estimate a role of biomineralization in the accumulation of metals in the Bathimodiolus mussels. Contrasting geochemical behavior was revealed for Cu that is enriched in soft tissues of mussels and depleted in shells, on the one hand, and Mn that is accumulated almost totally in mussel shells, on the other hand.

    Deep-sea hydrothermal biological communities demonstrate a strong concentration function, and bioconcentration factors (BCF) of trace metals estimated for Bathimodiolus mussels collected at the four hydrothermal fields vary within the limits of n102–n105 and are similar to that of the littoral mussels. Due to this and to the high values of biomasses per square meter, the hydrothermal fauna may be considered as a newly discovered biological filter of the oceans.

  • 13. D'Hondt, S.
    et al.
    Jorgensen, B.B.
    Miller, D.J.
    Batzke, A.
    Blake, R.
    Cragg, B.A.
    Cypionka, H.
    Dickens, G.R.
    Ferdelman, T.
    Hinrichs, K.-U.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Mitterer, R.
    Spivack, A.
    Wang, G.
    Bekins, B.
    Engelen, B.
    Ford, K.
    Gettemy, G.
    Rutherford, S.D.
    Sass, H.
    Skilbeck, C.G.
    Aiello, I.W.
    Guèrin, G.
    House, C.H.
    Inagaki, F.
    Meister, P.
    Naehr, T.
    Niitsuma, S.
    Parkes, R.J.
    Schippers, A.
    Smith, D.C.
    Teske, A.
    Wiegel, J.
    Naranjo Padilla, C.
    Solis Acosta, J.L.
    Distributions of microbial activities in deep subseafloor sediments2004In: Science, Vol. 306, p. 2216-2221Article in journal (Refereed)
  • 14. Ehrenfreund, Pascale
    et al.
    Spaans, Marco
    Holm, Nils G.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    The evolution of organic matter in space2011In: Philosophical Transactions. Series A: Mathematical, physical, and engineering science, ISSN 1364-503X, E-ISSN 1471-2962, Vol. 369, no 1936, p. 538-554Article in journal (Refereed)
    Abstract [en]

    Carbon, and molecules made from it, have already been observed in the early Universe. During cosmic time, many galaxies undergo intense periods of star formation, during which heavy elements like carbon, oxygen, nitrogen, silicon and iron are produced. Also, many complex molecules, from carbon monoxide to polycyclic aromatic hydrocarbons, are detected in these systems, like they are for our own Galaxy. Interstellar molecular clouds and circumstellar envelopes are factories of complex molecular synthesis. A surprisingly high number of molecules that are used in contemporary biochemistry on the Earth are found in the interstellar medium, planetary atmospheres and surfaces, comets, asteroids and meteorites and interplanetary dust particles. Large quantities of extra-terrestrial material were delivered via comets and asteroids to young planetary surfaces during the heavy bombardment phase. Monitoring the formation and evolution of organic matter in space is crucial in order to determine the prebiotic reservoirs available to the early Earth. It is equally important to reveal abiotic routes to prebiotic molecules in the Earth environments. Materials from both carbon sources (extra-terrestrial and endogenous) may have contributed to biochemical pathways on the Earth leading to life’s origin. The research avenues discussed also guide us to extend our knowledge to other habitable worlds.

  • 15. Hinrichs, K.-U.
    et al.
    Hayes, J.M.
    Bach, W.
    Spivack, A.J.
    Hmelo, L.R.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Johnson, C.G.
    Sylva, S.P.
    Biological formation of ethane and propane in the deep marine subsurface2006In: Proc. Natl. Acad. Sci. USA, Vol. 103, p. 14684-14689Article in journal (Refereed)
  • 16.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Abiotic organic synthesis underneath the ocean floor2007In: 7th European Workshop on Astrobiology, 2007Conference paper (Other academic)
  • 17.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry. geokemi.
    Abiotic phosphorylation2008Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    Much uncertainty exists with regard to the possibility of abiotic formation of nucleotide constituents in geological environments and the combination of them into larger entities. The components that would probably be most easily formed are the purine nitrogen bases, i.e. primarily adenine. The ribose and deoxyribose could, in principle, be formed by the formose (Butlerow) reaction from formaldehyde, but so far it has been very difficult to produce pure pentoses via that pathway. The addition of the phosphodiester backbone is also difficult to achieve. Phosphorylation has, however, been carried out experimentally using pyrophosphate. The potential of pyrophosphate formation upon heating of hydrogenated orthophosphates like whitlockite ((Ca18Mg2H2(PO4)14) to a few hundred ºC has probably been underestimated. This reaction requires low water to rock ratio, conditions that are met at subduction of an oceanic plate. Once pyrophosphate is available, phosphorylation of pentoses, ribose in particular, may occur. Experiments involving heating of sodium dihydrogen phosphate have even shown high yields of trimetaphosphate. This compound is an even better phosphorylating agent than pyrophosphate and has been identified in volcanic fumaroles, but not yet in other geological settings. Ribose may be formed from formaldehyde and glycolaldehyde, because the ribose molecule is stabilized by borate of interstitial fluids. Borate binds to the 2’ and 3’ positions of the ribose molecule. Mechanistically, aldehydes can be formed directly from elemental carbon in the presence of water. The initial reaction of elemental carbon with water gives hydroxymethylene, which can rearrange to formaldehyde. A new hydroxymethylene molecule can then add onto the formaldehyde (and larger aldehyde molecules) and form glycolaldehyde. In this way, the known lag in the formation of glycolaldehyde from formaldehyde is avoided. This lag has previously been a drawback and a reason that the formose reaction was for a while outdated as a possible mechanism for abiotic synthesis of carbohydrates. The reason why pentoses are stabilized by borate is that it forms trigonal and tetrahedral complexes with oxygen groups and, therefore, has a strong affinity for organic material. Boric acid and borate readily form complexes with a wide variety of sugars, particularly the furanose form of pentoses, and other compounds containing cis-hydroxyl groups like humic substances. Borate is continuously scavenged from seawater by secondary layer minerals of oceanic lithosphere and is released again at moderate heating of the subducting plate at convergent margins. The Mariana back-arc is a good example of this process. The fact that ribose is stabilized by borate may change our opinion of the formose reaction as a seemingly random and nonselective reaction into a very precise geochemical abiotic pre-RNA process.

  • 18.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry. geokemi.
    Abiotic synthesis underneath the ocean floor2008In: XV International Conference on the Origin of Life: Book of Abstracts, 2008, p. 19-20Conference paper (Other (popular science, discussion, etc.))
  • 19.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry. geokemi.
    Mineral-fluid interaction at convergent margins: the initiation of genetic information?2008In: International Workshop on Geobiology, 2008, p. 3-3Conference paper (Other (popular science, discussion, etc.))
  • 20.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Oceanic lithosphere, Mg(II), Na(I), PPi and life's origin2012In: Serpentine days: 3rd edition / [ed] M. Andreani, A.-L. Auzende, I. Daniel, A. Delacour, Deep Carbon Observatory , 2012Conference paper (Other academic)
    Abstract [en]

    Life may have started in connection with early plate tectonic processes coupled to alkaline hydrothermal activity. Pyrophosphate (PPi) and Na+ transport may have preceded ATP and H+ transport through primitive membranes in association with the dominant geochemistry of the Earth at the time of the origin and early evolution of life. A hydrothermal environment in which Na+ is abundant and H+ is rare exists in sediment-starved subduction zones, like the Mariana forearc in the W Pacific Ocean. It is considered to mimic the Archean Earth (Pons et al., 2011). There, the forearc pore fluids have a pH up to 12.6 and a Na+-concentration of 0.7 mol/kg seawater. PPi could have been formed during early subduction of oceanic lithosphere by dehydration of protonated orthophosphates.  A key to PPi formation in these geological environments is a low local activity of water. Magnesium, on the other hand, is a common element on Earth, particularly in oceanic crust and the upper mantle (as well as on the other terrestrial planets) and plays a special role in biochemistry due to its ability to coordinate six oxygen atoms efficiently in its first coordination shell. Such oxygen atoms may be part of one or two charged oxyanions, which means that Mg2+can, for instance, tie together two different phosphate groups that are located at distance from each other in a macromolecule, and in this way be responsible for the folding of large molecules like RNA. This property of Mg2+ also helps the stabilization of diphosphate and triphosphate groups of nucleotides, as well as promoting the condensation of orthophosphate to oligophosphates, like PPi and trimetaphosphate. According to the ‘RNA World’ hypothesis the first enzymes – the ribozymes – consisted of RNA, which depended on Mg2+ for its self-cleavage (Gilbert, 1986). Mg2+ is also present in all DNA and RNA activation processes. The central role of Mg2+ in the function of ribozymes and its ‘archaic’ position in ribosomes (the protein making machinery in all cells), and the fact that magnesium generally has coordination properties different from other cations, suggests that the inorganic chemistry of magnesium, together with that of sodium and phosphate, had a key position in the first chemical processes leading to the origin and early evolution of life.

  • 21.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Phosphorylation at Convergent Margins2009In: Origins of Life and Evolution of the Biospheres: ISSOL 2008 / [ed] A. Schwartz, Dordrecht: Springer , 2009, p. 194-194Conference paper (Other (popular science, discussion, etc.))
  • 22.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry. geokemi.
    Phosphorylation underneath the ocean floor?2008In: Geochimica et Cosmochimica Acta, 2008Conference paper (Other (popular science, discussion, etc.))
  • 23.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    The Geobiology of Magnesium2011In: Comets, Rocks and Life / [ed] Kirsi Lehto & Harry Lehto, Turku, 2011Conference paper (Other academic)
    Abstract [en]

    Magnesium (Mg) is one of the eight main elements of Earth’s crust and one of the four major elements making up the mass of the whole Earth. Mg is one of the main constituents of silicate minerals that build up Earth, like olivine, pyroxenes, serpentine, talc, phyllosilicates (clay minerals), etc. The concentration of divalent magnesium (Mg2+) in ocean water is 52.8 mmol/kg. The intra- and extracellular concentration in organisms, on the other hand, is about 1 mmol/kg. The coordination geometry of magnesium is strictly octahedral, i.e. the Mg atom coordinates six atoms – almost always oxygen – around itself in its first coordination shell. In the marine geochemical environment magnesium is particularly important since the tri-octahedral layer of the common phyllosilicates in sediments consist primarily of brucite, the mineral name of magnesium hydroxide (Mg(OH)2). The ocean floor beneath the sediment layers consists of basalts and ultramafic rocks that have relatively low silica contents (45-52% and <45%, respectively) but have a high content of primary ferromagnesian silicate minerals (olivine and pyroxenes). Alteration of these minerals in contact with water leads to ‘serpentinization’, a process in which olivine and pyroxenes are transformed to serpentine. The serpentine cannot accommodate all of the magnesium of the primary minerals, so dissolved magnesium is abundant in serpentinization environments and the mineral brucite is formed as a separate mineral phase at temperatures below about 315°C. Brucite may be transformed into double-layer hydroxides (DLH) if a fraction of the divalent Mg2+ is replaced by common trivalent cations such as Al3+, Fe3+, and Cr3+. Polyphosphate generation often has an absolute requirement for divalent metal ions, typically Mg(II). It has been shown by several investigators that magnesium pyrophosphate (MgPPi) is easily formed under mild abiotic hydrothermal conditions (165-180°C) from magnesium salts and orthophosphate (Pi). The Mg2+ is an essential catalyst for many biochemical reactions. It is well known that Mg2+ is required for the stabilization of the diphosphate group of ADP and the triphosphate group of ATP. The reason is that Mg2+ forms six-membered rings with the oxygen and phosphorus atoms of ADP and ATP.

  • 24.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    THE POTENTIAL OF ABIOTIC ORGANIC SYNTHESIS IN ALKALINE ENVIRONMENTS OF SUBDUCTION ZONES2010Conference paper (Other academic)
    Abstract [en]

    Reduced carbon and nitrogen precursor compounds 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. Once the reduced carbon and nitrogen compounds have been formed the synthesis of hydrogen cyanide is, in principle, possible [1]. HCN 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. 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 the HCN, which is then available for further organic reactions. Since the released fluids will rise through hydrated ultramafic mantle rocks of the lower part of the overriding plate, they will experience a strong pH increase. The reason for this increase is that the serpentinization of ferromagnesian minerals in ultramafic rocks in contact with the water leads to the formation of the secondary magnesium hydroxide mineral brucite, which causes high pH. The high pH may promote abiotic formation of carbohydrates like pentose sugars, particularly ribose, as well as nucleosides and even nucleotides, since pyrophosphate is stable under alkaline conditions at low water-rocks ratios [2]. Convergent margins in the initial phase of subduction must, therefore, be considered the most potent sites for prebiotic organic reactions on terrestrial planets, provided that some type of plate tectonics occurs.

  • 25.
    Holm, Nils
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Andersson, Eva
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Hydrothermal simulation experiments as a tool for studies of the origin of life on Earth and other terrestrial planets: A review2005In: Astrobiology, Vol. 5, p. 444-460Article in journal (Refereed)
  • 26.
    Holm, Nils
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Baltscheffsky, Herrick
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Early plate tectonics, pyrophosphate, Na+, and the origin of life2011In: Origins2011 International Conference / [ed] Muriel Gargaud & Robert Pascal, Montpellier, 2011Conference paper (Other academic)
    Abstract [en]

    Life may have started in association with early plate tectonic processes. Considerable geological evidence supports an initiation of plate tectonics on Earth shortly after the end of the Hadean about 4 Ga ago. The salinity of the young ocean was probably high, since sodium is rapidly mobilized from rocks by hydrothermal processes. Such processes also lead to the continuous release of Mg2+ and precipitation of brucite, Mg(OH)2, during serpentinization of olivine in mafic rocks of the ocean floor. The serpentinization processes are now recognized as probably the most important metamorphic hydration reactions that may contribute to our understanding of the origin of life, since they are coupled to the formation of source molecules like H2, thought to have been required for the origin of life. The transformation of olivine at relatively low temperature (50-300°C) to the serpentine mineral lizardite as the prevalent phase is particularly associated with reduction of water to hydrogen and oxidation of Fe(II) to Fe(III). During weathering of olivine and pyroxene in mafic rocks Fe(OH)2 may be formed as an intermediate phase (in solid solution with Mg(OH)2)during the partial oxidation of Fe(II). Fe(OH)2 is metastable with respect to magnetite and will convert to this mineral via a spontaneous reaction. However, the conversion also creates a small amount of native iron, which means that the ocean floor is quite reducing. The oceanic crust is hydrated to a depth of a kilometer or more and can therefore provide a substantial flux of water for serpentinization of upper mantle rocks when it is subducted. A modern hydrothermal environment in which Na+ and Mg2+ are abundant exists in sediment-starved alkaline subduction zones, like the Mariana forearc in the western Pacific Ocean. It is considered to mimic the Archean Earth. Pyrophosphate could have been formed during early subduction of oceanic lithosphere by dehydration of protonated orthophosphates. The key to pyrophosphate formation in these geological environments is low water to rock ratio, i.e. low local activity of water. The difference in complexity between the inorganic pyrophosphate and ATP also supports the possible role of PPi as early energy donor for the origin of life.

  • 27.
    Holm, Nils
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Baltscheffsky, Herrick
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Links between hydrothermal environments, pyrophosphate, Na+, and early evolution2011In: Origins of life and evolution of the biosphere, ISSN 0169-6149, E-ISSN 1573-0875, Vol. 41, no 5, p. 483-493Article in journal (Refereed)
    Abstract [en]

    The discovery that photosynthetic bacterial membrane-bound inorganic pyrophosphatase (PPase) catalyzed light-induced phosphorylation of orthophosphate (Pi) to pyrophosphate (PPi) and the capability of PPi to drive energy requiring dark reactions supported PPi as a possible early alternative to ATP. Like the proton-pumping ATPase, the corresponding membrane-bound PPase also is a H+-pump, and like the Na+-pumping ATPase, it can be a Na+-pump, both in archaeal and bacterial membranes. We suggest that PPi and Na+ transport preceded ATP and H+ transport in association with geochemistry of the Earth at the time of the origin and early evolution of life. Life may have started in connection with early plate tectonic processes coupled to alkaline hydrothermal activity. A hydrothermal environment in which Na+ is abundant exists in sediment-starved subduction zones, like the Mariana forearc in the W Pacific Ocean. It is considered to mimic the Archean Earth. The forearc pore fluids have a pH up to 12.6, a Na+-concentration of 0.7 mol/kg seawater. PPi could have been formed during early subduction of oceanic lithosphere by dehydration of protonated orthophosphates. A key to PPi formation in these geological environments is a low local activity of water.

  • 28.
    Holm, Nils
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Charlou, J.L.
    Initial indications of abiotic formation of hydrocarbons in the Rainbow ultramafic hydrothermal system, Mid-Atlantic Ridge2001In: Earth and Planetary Science Letters, Vol. 191, p. 1-8Article in journal (Refereed)
  • 29.
    Holm, Nils
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Dumont, Marion
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Gislason, Sigurdur R.
    Torssander, Peter
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    HEKLA COLD SPRINGS – GROUNDWATER MIXING AND IMPACT OF CO22007In: 7th International Symposium on Applied Isotope Geochemistry, 2007Conference paper (Other academic)
  • 30.
    Holm, Nils
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Dumont, Marion
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Ivarsson, Magnus
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Konn, Cécile
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Alkaline fluid circulation in ultramafic rocks and formation of nucleotide constituents: A hypothesis2006In: Geochemical transactions, Vol. 7, no 7Article in journal (Refereed)
  • 31.
    Holm, Nils G.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Glasses as sources of condensed phosphates on the early earth2014In: Geochemical Transactions, ISSN 1467-4866, E-ISSN 1467-4866, Vol. 15, p. 8-Article, review/survey (Refereed)
    Abstract [en]

    Procedures for the analysis of phosphorus in geological material normally aims for the determination of the total amount of P expressed as orthophosphate (PO43-) or the differentiation between inorganic and organic P. This is probably due to analytical difficulties but also to the prevalent opinion that the chemistry of phosphorus in geological environments is almost entirely restricted to the mineral apatite. Because of the low solubility of apatite it is, therefore, commonly argued that little P was around for prebiotic chemistry and that pre-biological processes would essentially have had to do without this indispensable element unless it was provided by alternative sources or mechanisms (such as reduction and activation by lightning or delivery to Earth by celestial bodies). It is a paradox that the potential existence of reactive phosphorus compounds, such as the mineral schreibersite - iron phosphide, in geological material on Earth is seldom considered although we are aware of the existence of such compounds in meteorite material. The content of Al2O3 in rocks appears to be important for the speciation of phosphorus and for how strongly it binds to silicates. In general, low alumina seems to promote the existence of isolated charge-balanced phosphorus complexes.

  • 32.
    Holm, Nils G.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    The significance of Mg in prebiotic geochemistry2012In: Geobiology, ISSN 1472-4677, E-ISSN 1472-4669, Vol. 10, no 4, p. 269-279Article, review/survey (Refereed)
    Abstract [en]

    Magnesium plays a special role in biochemistry because of its ability to coordinate six oxygen atoms efficiently in its first coordination shell. Such oxygen atoms may be part of one or two charged oxyanions, which means that Mg2+ can, for instance, tie together two different phosphate groups that are located at distance from each other in a macromolecule, and in this way be responsible for the folding of molecules like RNA. This property of Mg2+ also helps the stabilization of diphosphate and triphosphate groups of nucleotides, as well as promoting the condensation of orthophosphate to oligophosphates, like pyrophosphate and trimetaphosphate. Borates, on the other hand, are known to promote the formation of nucleobases and carbohydrates, ribose in particular, which is yet another constituent of nucleotides. The oldest borate minerals that we find on Earth today are magnesium borates. Dissolved borate stabilizes pentose sugars by forming complexes with cis-hydroxyl groups. In the furanose form of ribose, the preferential binding occurs to the 2 and 3 carbon, leaving the 5 carbon free for phosphorylation. The central role of Mg2+ in the function of ribozymes and its archaic position in ribosomes, and the fact that magnesium generally has coordination properties different from other cations, suggests that the inorganic chemistry of magnesium had a key position in the first chemical processes leading to the origin and early evolution of life.

  • 33.
    Holm, Nils G.
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Gislason, Sigurour R.
    Sturkell, Erik
    Torssander, Peter
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Hekla cold springs (Iceland): groundwater mixing with magmatic gases2010In: Isotopes in environmental and health studies, ISSN 1025-6016, E-ISSN 1477-2639, Vol. 46, no 2, p. 180-189Article in journal (Refereed)
    Abstract [en]

    We have analysed the chemical and stable isotope compositions of four springwaters situated just northwest of the Hekla volcano, where cold water emerges from the base of the lava flows. The stable isotope ratios of water (H, O), dissolved inorganic carbon (C) and sulphate (S) were used to determine whether magmatic gases are mixing with the groundwater. The waters can be characterised as Na-HCO3 type. The results show that deep-seated gases mix with groundwater, substantially affecting the concentration of solutes and the isotopic composition of dissolved carbon and sulphate.

  • 34.
    Holm, Nils G.
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Oze, C.
    Mousis, O.
    Waite, J. H.
    Guilbert-Lepoutre, A.
    Serpentinization and the Formation of H-2 and CH4 on Celestial Bodies (Planets, Moons, Comets)2015In: Astrobiology, ISSN 1531-1074, E-ISSN 1557-8070, Vol. 15, no 7, p. 587-600Article, review/survey (Refereed)
    Abstract [en]

    Serpentinization involves the hydrolysis and transformation of primary ferromagnesian minerals such as olivine ((Mg,Fe)(2)SiO4) and pyroxenes ((Mg,Fe)SiO3) to produce H-2-rich fluids and a variety of secondary minerals over a wide range of environmental conditions. The continual and elevated production of H-2 is capable of reducing carbon, thus initiating an inorganic pathway to produce organic compounds. The production of H-2 and H-2-dependent CH4 in serpentinization systems has received significant interdisciplinary interest, especially with regard to the abiotic synthesis of organic compounds and the origins and maintenance of life in Earth's lithosphere and elsewhere in the Universe. Here, serpentinization with an emphasis on the formation of H-2 and CH4 are reviewed within the context of the mineralogy, temperature/pressure, and fluid/gas chemistry present in planetary environments. Whether deep in Earth's interior or in Kuiper Belt Objects in space, serpentinization is a feasible process to invoke as a means of producing astrobiologically indispensable H-2 capable of reducing carbon to organic compounds.

  • 35.
    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.))
  • 36.
    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.

  • 37. Humphris, S.E.
    et al.
    Herzig, P.M.
    Miller, D.J.
    Alt, J.C.
    Becker, K.
    Brown, D.
    Brügmann, G.
    Chiba, H.
    Fouquet, Y.
    Gemmell, J.B.
    Guèrin, G.
    Hannington, M.D.
    Holm, Nils
    Stockholm University.
    Honnorez, J.J.
    Itturino, G.J.
    Knott, R.
    Ludwig, R.
    Nakamura, K.
    Petersen, S.
    Reysenbach, A.-L.
    Rona, P.A.
    Smith, S.
    Sturz, A.A.
    Tivey, M.K.
    Zhao, X.
    The internal structure of an active seafloor massive sulphide deposit1995In: Nature, Vol. 377, p. 713-716Article in journal (Refereed)
  • 38. Ivarsson, Magnus
    et al.
    Broman, Curt
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Gustafsson, Håkan
    Holm, Nils G.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Biogenic Mn-Oxides in Subseafloor Basalts2015In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, no 6, article id e0128863Article in journal (Refereed)
    Abstract [en]

    The deep biosphere of the subseafloor basalts is recognized as a major scientific frontier in disciplines like biology, geology, and oceanography. Recently, the presence of fungi in these environments has involved a change of view regarding diversity and ecology. Here, we describe fossilized fungal communities in vugs in subseafloor basalts from a depth of 936.65 metres below seafloor at the Detroit Seamount, Pacific Ocean. These fungal communities are closely associated with botryoidal Mn oxides composed of todorokite. Analyses of the Mn oxides by Electron Paramagnetic Resonance spectroscopy (EPR) indicate a biogenic signature. We suggest, based on mineralogical, morphological and EPR data, a biological origin of the botryoidal Mn oxides. Our results show that fungi are involved in Mn cycling at great depths in the seafloor and we introduce EPR as a means to easily identify biogenic Mn oxides in these environments.

  • 39. Ivarsson, Magnus
    et al.
    Broman, Curt
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Chromite oxidation by manganee oxides in subseafloor basalts and the presence of putative fossilized microorganisms2011In: Geochemical Transactions, ISSN 1467-4866, E-ISSN 1467-4866, Vol. 12, p. 5-Article in journal (Refereed)
    Abstract [en]

    Chromite is a mineral with low solubility and is thus resistant to dissolution. The exception is when manganese oxides are available, since they are the only known naturally occurring oxidants for chromite. In the presence of Mn(IV) oxides, Cr(III) will oxidise to Cr(VI), which is more soluble than Cr(III), and thus easier to be removed. Here we report of chromite phenocrysts that are replaced by rhodochrosite (Mn(II) carbonate) in subseafloor basalts from the Koko Seamount, Pacific Ocean, that were drilled and collected during the Ocean Drilling Program (ODP) Leg 197. The mineral succession chromite-rhodochrosite-saponite in the phenocrysts is interpreted as the result of chromite oxidation by manganese oxides. Putative fossilized microorganisms are abundant in the rhodochrosite and we suggest that the oxidation of chromite has been mediated by microbial activity. It has previously been shown in soils and in laboratory experiments that chromium oxidation is indirectly mediated by microbial formation of manganese oxides. Here we suggest a similar process in subseafloor basalts.

  • 40. Ivarsson, Magnus
    et al.
    Broman, Curt
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Holmström, Sara
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Ahlbom, Marianne
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Lindblom, Sten
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Putative fossilized fungi from the lithified volcaniclastic apron of Gran Canaria, Spain2011In: Astrobiology, ISSN 1531-1074, E-ISSN 1557-8070, Vol. 11, no 7, p. 633-650Article in journal (Refereed)
    Abstract [en]

    We report the discovery of fossilized filamentous structures in samples of the lithified, volcaniclastic apron of Gran Canaria, which were obtained during Leg 157 of the Ocean Drilling Program (ODP). These filamentous structures are 2–15 μm in diameter and several hundred micrometers in length and are composed of Si, Al, Fe, Ca, Mg, Na, Ti, and C. Chitin was detected in the filamentous structures by staining with wheat germ agglutinin dye conjugated with fluorescein isothiocyanate (WGA-FITC), which suggests that they are fossilized fungal hyphae. The further elucidation of typical filamentous fungal morphological features, such as septa, hyphal bridges, and anastomosis and their respective sizes, support this interpretation. Characteristic structures that we interpreted as fossilized spores were also observed in association with the putative hyphae. The fungal hyphae were found in pyroxene phenocrysts and in siderite pseudomorphs of a basalt breccia. The fungal colonization of the basalt clasts occurred after the brecciation but prior to the final emplacement and lithification of the sediment at 16–14 Ma. The siderite appears to have been partially dissolved by the presence of fungal hyphae, and the fungi preferentially colonized Fe-rich carbonates over Fe-poor carbonates (aragonite). Our findings indicate that fungi may be an important geobiological agent in subseafloor environments and an important component of the deep subseafloor biosphere, and that hydrothermal environments associated with volcanism can support a diverse ecosystem, including eukaryotes.

  • 41.
    Ivarsson, Magnus
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Broman, Curt
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Lindblom, Sten
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Fluid inclusions as a tool to constrain the preservation conditions of sub-seafloor cryptoendoliths2009In: Planetary and Space Science, Vol. 57, p. 477-490Article in journal (Refereed)
  • 42.
    Ivarsson, Magnus
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Gehör, Seppo
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Micro-scale variations of iron isotopes in fossilized microorganisms2008In: International Journal of AstrobiologyArticle in journal (Refereed)
  • 43.
    Ivarsson, Magnus
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Fossilized microorganisms from Emperor Seamounts: evidence for a deep sub-seafloor biosphere2007In: 17th Annual V.M. Goldschmidt Conference, 2007Conference paper (Refereed)
  • 44.
    Ivarsson, Magnus
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Fossilized microorganisms from Emperor Seamounts: evidence for a deep sub-seafloor biosphere2007Conference paper (Other academic)
  • 45.
    Ivarsson, Magnus
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Microbial colonization of various habitable niches during alteration of oceanic crust2008In: International Geological Congress, 2008Conference paper (Refereed)
  • 46.
    Ivarsson, Magnus
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Microbial colonization of various habitable niches during alteration of oceanic crust2008In: Links Between Geological Processes, Microbial Activities and Evolution of Life, 2008Chapter in book (Refereed)
  • 47.
    Ivarsson, Magnus
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Mn as a potential energy source for subseafloor chemoautotrophs2006In: 16th Annual V.M. Goldschmidt Conference, 2006Conference paper (Refereed)
  • 48.
    Ivarsson, Magnus
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Lausmaa, Jukka
    Lindblom, Sten
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Broman, Curt
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Fossilized microorganisms from the Emperor Seamounts: implications for the search for a sub-surface fossil record on Earth and Mars2008In: AstrobiologyArticle in journal (Refereed)
  • 49.
    Ivarsson, Magnus
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Lindblom, Sten
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Broman, Curt
    Naturhistoriska riksmuseet.
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Fossilized microorganisms associated with zeolite-carbonate interfaces in sub-seafloor hydrothermal environments2008In: Geobiology, ISSN 1472-4677, E-ISSN 1472-4669, Vol. 6, no 2, p. 155-170Article in journal (Refereed)
    Abstract [en]

    In this paper we describe carbon-rich filamentous structures observed in association with the zeolite mineral phillipsite from sub-seafloor samples drilled and collected during the Ocean Drilling Program (ODP) Leg 197 at the Emperor Seamounts. The filamentous structures are ~5 µm thick and ~100–200 µm in length. They are found attached to phillipsite surfaces in veins and entombed in vein-filling carbonates. The carbon content of the filaments ranges between ~10 wt% C and 55 wt% C. They further bind to propidium iodide (PI), which is a dye that binds to damaged cell membranes and remnants of DNA.

    Carbon-rich globular microstructures, 1–2 µm in diameter, are also found associated with the phillipsite surfaces as well as within wedge-shaped cavities in phillipsite assemblages. The globules have a carbon content that range between ~5 wt% C and 55 wt% C and they bind to PI. Ordinary globular iron oxides found throughout the samples differ in that they contain no carbon and do not bind to the dye PI. The carbon-rich globules are mostly concentrated to a film-like structure that is attached to the phillipsite surfaces. This film has a carbon content that ranges between ~25 wt% C and 75 wt% C and partially binds to PI. EDS analyses show that the carbon in all structures described are not associated with calcium and therefore not bound in carbonates. The carbon content and the binding to PI may indicate that the filamentous structures could represent fossilized filamentous microorganisms, the globules could represent fossilized microbial cells and the film-like structures could represent a microbially produced biofilm.

    Our results extend the knowledge of possible habitable niches for a deep biosphere in sub-seafloor environments and suggests, as phillipsite is one of the most common zeolite mineral in volcanic rocks of the oceanic crust, that it could be a common feature in the oceanic crust elsewhere.

  • 50.
    Ivarsson, Magnus
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Lindblom, Sten
    Broman, Curt
    Holm, Nils
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Fossilized microorganisms associated with zeolites-carbonate interfaces in sub-seafloor hydrothermal environments2008In: Geobiology, Vol. 6, p. 155-170Article in journal (Refereed)
12 1 - 50 of 74
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