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Slagter S, Konhauser KO, Briggs DEG, Tarhan LG. Controls on authigenic mineralization in experimental Ediacara-style preservation. GEOBIOLOGY 2024; 22:e12615. [PMID: 39149974 DOI: 10.1111/gbi.12615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 06/20/2024] [Accepted: 07/26/2024] [Indexed: 08/17/2024]
Abstract
The earliest evidence of complex macroscopic life on Earth is preserved in Ediacaran-aged siliciclastic deposits as three-dimensional casts and molds, known as Ediacara-style preservation. The mechanisms that led to this extraordinary preservation of soft-bodied organisms in fine- to medium-grained sandstones have been extensively debated. Ediacara-style fossilization is recorded in a variety of sedimentary facies characterized by clean quartzose sandstones (as in the eponymous Ediacara Member) as well as less compositionally mature, clay-rich sandstones and heterolithic siliciclastic deposits. To investigate this preservational process, we conducted experiments using different mineral substrates (quartzose sand, kaolinite, and iron oxides), a variety of soft-bodied organisms (microalgae, cyanobacteria, marine invertebrates), and a range of estimates for Ediacaran seawater dissolved silica (DSi) levels (0.5-2.0 mM). These experiments collectively yielded extensive amorphous silica and authigenic clay coatings on the surfaces of organisms and in intergranular pore spaces surrounding organic substrates. This was accompanied by a progressive drawdown of the DSi concentration of the experimental solutions. These results provide evidence that soft tissues can be rapidly preserved by silicate minerals precipitated under variable substrate compositions and a wide range of predicted scenarios for Ediacaran seawater DSi concentrations. These observations suggest plausible mechanisms explaining how interactions between sediments, organic substrates, and seawater DSi played a significant role in the fossilization of the first complex ecosystems on Earth.
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Affiliation(s)
- Silvina Slagter
- Department of Earth & Planetary Sciences, Yale University, New Haven, Connecticut, USA
- Instituto de Ciencias de la Ingeniería, Universidad de O'Higgins, Rancagua, Chile
| | - Kurt O Konhauser
- Department of Earth & Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Derek E G Briggs
- Department of Earth & Planetary Sciences, Yale University, New Haven, Connecticut, USA
| | - Lidya G Tarhan
- Department of Earth & Planetary Sciences, Yale University, New Haven, Connecticut, USA
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2
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Ramkissoon NK, Macey MC, Kucukkilic-Stephens E, Barton T, Steele A, Johnson DN, Stephens BP, Schwenzer SP, Pearson VK, Olsson-Francis K. Experimental Identification of Potential Martian Biosignatures in Open and Closed Systems. ASTROBIOLOGY 2024; 24:538-558. [PMID: 38648554 DOI: 10.1089/ast.2023.0013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
NASA's Perseverance and ESA's Rosalind Franklin rovers have the scientific goal of searching for evidence of ancient life on Mars. Geochemical biosignatures that form because of microbe-mineral interactions could play a key role in achieving this, as they can be preserved for millions of years on Earth, and the same could be true for Mars. Previous laboratory experiments have explored the formation of biosignatures under closed systems, but these do not represent the open systems that are found in natural martian environments, such as channels and lakes. In this study, we have conducted environmental simulation experiments using a global regolith simulant (OUCM-1), a thermochemically modelled groundwater, and an anaerobic microbial community to explore the formation of geochemical biosignatures within plausible open and closed systems on Mars. This initial investigation showed differences in the diversity of the microbial community developed after 28 days. In an open-system simulation (flow-through experiment), the acetogenic Acetobacterium (49% relative abundance) and the sulfate reducer Desulfosporomusa (43% relative abundance) were the dominant genera. Whereas in the batch experiment, the sulfate reducers Desulfovibrio, Desulfomicrobium, and Desulfuromonas (95% relative abundance in total) were dominant. We also found evidence of enhanced mineral dissolution within the flow-through experiment, but there was little evidence of secondary deposits in the presence of biota. In contrast, SiO2 and Fe deposits formed within the batch experiment with biota but not under abiotic conditions. The results from these initial experiments indicate that different geochemical biosignatures can be generated between open and closed systems, and therefore, biosignature formation in open systems warrants further investigation.
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Affiliation(s)
| | - Michael C Macey
- AstrobiologyOU, STEM Faculty, The Open University, Milton Keynes, UK
| | | | - Timothy Barton
- AstrobiologyOU, STEM Faculty, The Open University, Milton Keynes, UK
| | - Andrew Steele
- Earth and Planetary Laboratory, Carnegie Institution of Washington, Washington, DC, USA
| | - David N Johnson
- AstrobiologyOU, STEM Faculty, The Open University, Milton Keynes, UK
| | - Ben P Stephens
- AstrobiologyOU, STEM Faculty, The Open University, Milton Keynes, UK
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3
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Moore KR, Daye M, Gong J, Williford K, Konhauser K, Bosak T. A review of microbial-environmental interactions recorded in Proterozoic carbonate-hosted chert. GEOBIOLOGY 2023; 21:3-27. [PMID: 36268586 PMCID: PMC10092529 DOI: 10.1111/gbi.12527] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 09/14/2022] [Accepted: 09/19/2022] [Indexed: 06/16/2023]
Abstract
The record of life during the Proterozoic is preserved by several different lithologies, but two in particular are linked both spatially and temporally: chert and carbonate. These lithologies capture a snapshot of dominantly peritidal environments during the Proterozoic. Early diagenetic chert preserves some of the most exceptional Proterozoic biosignatures in the form of microbial body fossils and mat textures. This fossiliferous and kerogenous chert formed in shallow marine environments, where chert nodules, layers, and lenses are often surrounded by and encased within carbonate deposits that themselves often contain kerogen and evidence of former microbial mats. Here, we review the record of biosignatures preserved in peritidal Proterozoic chert and chert-hosting carbonate and discuss this record in the context of experimental and environmental studies that have begun to shed light on the roles that microbes and organic compounds may have played in the formation of these deposits. Insights gained from these studies suggest temporal trends in microbial-environmental interactions and place new constraints on past environmental conditions, such as the concentration of silica in Proterozoic seawater, interactions among organic compounds and cations in seawater, and the influence of microbial physiology and biochemistry on selective preservation by silicification.
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Affiliation(s)
- Kelsey R. Moore
- Division of Geological and Planetary SciencesCalifornia Institute of TechnologyPasadenaCaliforniaUSA
| | - Mirna Daye
- Department of Earth, Atmospheric and Planetary SciencesMassachusetts Institute of TechnologyCambridgeMassachusettsUSA
| | - Jian Gong
- Department of Earth, Atmospheric and Planetary SciencesMassachusetts Institute of TechnologyCambridgeMassachusettsUSA
| | | | - Kurt Konhauser
- Department of Earth and Atmospheric SciencesUniversity of AlbertaEdmontonAlbertaCanada
| | - Tanja Bosak
- Department of Earth, Atmospheric and Planetary SciencesMassachusetts Institute of TechnologyCambridgeMassachusettsUSA
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4
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Biomimetic mineralization: An emerging organism engineering strategy for biomedical applications. J Inorg Biochem 2022; 232:111815. [DOI: 10.1016/j.jinorgbio.2022.111815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 03/03/2022] [Accepted: 04/02/2022] [Indexed: 11/21/2022]
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5
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Anglés A, He Q, Sánchez García L, Carrizo D, Rodriguez N, Huang T, Shen Y, Amils R, Fernández-Remolar DC. Biospeleothems Formed by Fungal Activity During the Early Holocene in the “Salar de Uyuni”. Front Microbiol 2022; 13:913452. [PMID: 35814676 PMCID: PMC9260512 DOI: 10.3389/fmicb.2022.913452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 04/28/2022] [Indexed: 11/28/2022] Open
Abstract
The Chiquini and Galaxias caves contain speleothems that are templated by long fungal structures. They have been associated with the carbonate lacustrine deposits in the margins of the Coipasa and Uyuni Salar basins. During a wetter episode, such carbonates formed at the end of the last glaciation raising the lake level to more than 100 m in the Tauca events (15–12 ky). Such an event flooded the caves that eventually became a cryptic habitat in the lake. The caves show bizarre speleothems framed by large (>1 m) fungal buildings covering the older algal mineralized structures. Although the origin of the caves is not fully understood, the occurrence of two carbonatic units with very distinctive fabric suggests that they formed in two separated humid events. In this regard, the mineralized algal structures, showing the same features as the lacustrine carbonates, likely formed during the Tauca flooding events in the terminal Pleistocene that inundated older caves. The different caves were exposed to the atmosphere after a drop in the lake level that promoted alluvial erosion by <12–10 ky (Ticaña episode) under arid conditions. A last humid episode rising the lake surface 10 m above the Salar level, which was not enough to inundate the caves a second time, drove the formation of the biospeleothems by fungi biomineralization. The abundance and size of the preserved fungal structures suggest that they were sustained by a stable hydrological activity plus a constant organic supply. While nutrients could have been primarily sourced from the vegetal communities that occupied the exhumated lake margins, they might have also been released from the lacustrine carbonatic unit. The combination of hydrology and biological activities were likely determinants for a fast rock dissolution and mineralization ending in the construction of the fungal biospeleothems.
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Affiliation(s)
- Angélica Anglés
- State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology, Macau, China
- China National Space Administration (CNSA) Macau Center for Space Exploration and Science, Macau, China
- Blue Marble Space Institute of Science, Seattle, WA, United States
- *Correspondence: Angélica Anglés
| | - Qitao He
- State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology, Macau, China
- China National Space Administration (CNSA) Macau Center for Space Exploration and Science, Macau, China
| | - Laura Sánchez García
- Centro de Astrobiología Instituto Nacional de Tecnica Aeroespacial - Consejo Superior de Investigaciones Científicas (INTA-CSIC), Madrid, Spain
| | - Daniel Carrizo
- Centro de Astrobiología Instituto Nacional de Tecnica Aeroespacial - Consejo Superior de Investigaciones Científicas (INTA-CSIC), Madrid, Spain
| | - Nuria Rodriguez
- Centro de Astrobiología Instituto Nacional de Tecnica Aeroespacial - Consejo Superior de Investigaciones Científicas (INTA-CSIC), Madrid, Spain
| | - Ting Huang
- State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology, Macau, China
- China National Space Administration (CNSA) Macau Center for Space Exploration and Science, Macau, China
| | - Yan Shen
- State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology, Macau, China
- China National Space Administration (CNSA) Macau Center for Space Exploration and Science, Macau, China
| | - Ricardo Amils
- Centro de Astrobiología Instituto Nacional de Tecnica Aeroespacial - Consejo Superior de Investigaciones Científicas (INTA-CSIC), Madrid, Spain
| | - David C. Fernández-Remolar
- State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology, Macau, China
- China National Space Administration (CNSA) Macau Center for Space Exploration and Science, Macau, China
- Carl Sagan Center, The SETI Institute, Mountain View, CA, United States
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6
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Moore KR, Gong J, Pajusalu M, Skoog EJ, Xu M, Feliz Soto T, Sojo V, Matreux T, Baldes MJ, Braun D, Williford K, Bosak T. A new model for silicification of cyanobacteria in Proterozoic tidal flats. GEOBIOLOGY 2021; 19:438-449. [PMID: 33979014 DOI: 10.1111/gbi.12447] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 04/02/2021] [Accepted: 04/10/2021] [Indexed: 06/12/2023]
Abstract
Microbial fossils preserved by early diagenetic chert provide a window into the Proterozoic biosphere, but seawater chemistry, microbial processes, and the interactions between microbes and the environment that contributed to this preservation are not well constrained. Here, we use fossilization experiments to explore the processes that preserve marine cyanobacterial biofilms by the precipitation of amorphous silica in a seawater medium that is analogous to Proterozoic seawater. These experiments demonstrate that the exceptional silicification of benthic marine cyanobacteria analogous to the oldest diagnostic cyanobacterial fossils requires interactions among extracellular polymeric substances (EPS), photosynthetically induced pH changes, magnesium cations (Mg2+ ), and >70 ppm silica.
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Affiliation(s)
- Kelsey R Moore
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Jian Gong
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Mihkel Pajusalu
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
- Tartu Observatory, University of Tartu, Tõravere, Estonia
| | - Emilie J Skoog
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Megan Xu
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | - Victor Sojo
- American Museum of Natural History, New York, NY, USA
- Department of Physics, Ludwig Maximilian University, München, Germany
| | - Thomas Matreux
- Department of Physics, Ludwig Maximilian University, München, Germany
| | - Matthew J Baldes
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Dieter Braun
- Department of Physics, Ludwig Maximilian University, München, Germany
| | - Kenneth Williford
- Jet Propulsion Laboratory, California Institute ofTechnology, Pasadena, CA, USA
| | - Tanja Bosak
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
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7
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Sánchez-García L, Carrizo D, Molina A, Muñoz-Iglesias V, Lezcano MÁ, Fernández-Sampedro M, Parro V, Prieto-Ballesteros O. Fingerprinting molecular and isotopic biosignatures on different hydrothermal scenarios of Iceland, an acidic and sulfur-rich Mars analog. Sci Rep 2020; 10:21196. [PMID: 33273669 PMCID: PMC7712778 DOI: 10.1038/s41598-020-78240-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 11/23/2020] [Indexed: 11/09/2022] Open
Abstract
Detecting signs of potential extant/extinct life on Mars is challenging because the presence of organics on that planet is expected to be very low and most likely linked to radiation-protected refugia and/or preservative strategies (e.g., organo-mineral complexes). With scarcity of organics, accounting for biomineralization and potential relationships between biomarkers, mineralogy, and geochemistry is key in the search for extraterrestrial life. Here we explored microbial fingerprints and their associated mineralogy in Icelandic hydrothermal systems analog to Mars (i.e., high sulfur content, or amorphous silica), to identify potentially habitable locations on that planet. The mineralogical assemblage of four hydrothermal substrates (hot springs biofilms, mud pots, and steaming and inactive fumaroles) was analyzed concerning the distribution of biomarkers. Molecular and isotopic composition of lipids revealed quantitative and compositional differences apparently impacted by surface geothermal alteration and environmental factors. pH and water showed an influence (i.e., greatest biomass in circumneutral settings with highest supply and turnover of water), whereas temperature conditioned the mineralogy that supported specific microbial metabolisms related with sulfur. Raman spectra suggested the possible coexistence of abiotic and biomediated sources of minerals (i.e., sulfur or hematite). These findings may help to interpret future Raman or GC-MS signals in forthcoming Martian missions.
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Affiliation(s)
| | - Daniel Carrizo
- Centro de Astrobiología (CSIC-INTA), Carretera de Ajalvir km 4, Madrid, Spain
| | - Antonio Molina
- Centro de Astrobiología (CSIC-INTA), Carretera de Ajalvir km 4, Madrid, Spain
| | | | | | | | - Victor Parro
- Centro de Astrobiología (CSIC-INTA), Carretera de Ajalvir km 4, Madrid, Spain
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8
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McMahon S, Ivarsson M. A New Frontier for Palaeobiology: Earth's Vast Deep Biosphere. Bioessays 2019; 41:e1900052. [PMID: 31241200 DOI: 10.1002/bies.201900052] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2019] [Revised: 04/29/2019] [Indexed: 11/11/2022]
Abstract
Diverse micro-organisms populate a global deep biosphere hosted by rocks and sediments beneath land and sea, containing more biomass than any other biome except forests. This paper reviews an emerging palaeobiological archive of these dark habitats: microfossils preserved in ancient pores and fractures in the crust. This archive, seemingly dominated by mineralized filaments (although rods and coccoids are also reported), is presently far too sparsely sampled and poorly understood to reveal trends in the abundance, distribution, or diversity of deep life through time. New research is called for to establish the nature and extent of the fossil record of Earth's deep biosphere by combining systematic exploration, rigorous microanalysis, and experimental studies of both microbial preservation and the formation of abiotic pseudofossils within the crust. It is concluded that the fossil record of Earth's largest microbial habitat may still have much to tell us about the history of life, the evolution of biogeochemical cycles, and the search for life on Mars.
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Affiliation(s)
- Sean McMahon
- School of Geosciences, University of Edinburgh, Edinburgh, EH8 9XP, UK.,UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, EH9 3FD, UK
| | - Magnus Ivarsson
- Department of Biology, University of Southern Denmark, DK-5230, Odense, Denmark.,Department of Palaeobiology, Swedish Museum of Natural History, Stockholm, SE-104 05, Sweden
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9
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The Taphonomy of Proterozoic Microbial Mats and Implications for Early Diagenetic Silicification. GEOSCIENCES 2019. [DOI: 10.3390/geosciences9010040] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The complex nature of growth and decomposition in microbial mats results in a broad range of microbial preservation. Such taphonomic variability complicates both the description of microbial elements preserved within geologic materials and the potential interpretation of microbial biomarkers. This study uses a taphonomic assessment to explore the preservation of different microbial components within silicified microbial mats of the late Mesoproterozoic (~1.0 Ga) Angmaat Formation, Bylot Supergroup, Baffin Island. The Angmaat Formation consists of unmetamorphosed and essentially undeformed strata that represent intertidal to supratidal deposition within an evaporative microbial flat. Early diagenetic silicification preserved microbial communities across a range of environments, from those episodically exposed to persistently submerged. Here, we present the development of a new methodology involving the use of high-resolution image mosaics to investigate the taphonomy of microfossils preserved in these mats. A taphonomic grade is assigned using a modified classification that accounts for both the taphonomic preservation state (good, fair, poor) of individual microfossils, as well as the degree of compaction of the overall mat. We show that although various taphonomic states occur within each of the silicified mats, the overall taphonomic assessment differentiates between well-preserved mats that are interpreted to have been silicified during active growth, to highly degraded and compacted mats that are interpreted to represent preservation during later stages of biological decomposition. These data indicate that even small changes in the timing of silicification may have substantial implications on our identification of microbial biomarkers and, therefore, our interpretation of early Earth ecosystems.
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10
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Igisu M, Yokoyama T, Ueno Y, Nakashima S, Shimojima M, Ohta H, Maruyama S. Changes of aliphatic C-H bonds in cyanobacteria during experimental thermal maturation in the presence or absence of silica as evaluated by FTIR microspectroscopy. GEOBIOLOGY 2018; 16:412-428. [PMID: 29869829 DOI: 10.1111/gbi.12294] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2017] [Accepted: 03/16/2018] [Indexed: 06/08/2023]
Abstract
Aliphatic C-H bonds are one of the major organic signatures detected in Proterozoic organic microfossils, and their origin is a topic of interest. To investigate the influence of the presence of silica on the thermal alteration of aliphatic C-H bonds in prokaryotic cells during diagenesis, cyanobacteria Synechocystis sp. PCC6803 were heated at temperatures of 250-450°C. Changes in the infrared (IR) signals were monitored by micro-Fourier transform infrared (FTIR) spectroscopy. Micro-FTIR shows that absorbances at 2,925 cm-1 band (aliphatic CH2 ) and 2,960 cm-1 band (aliphatic CH3 ) decrease during heating, indicating loss of the C-H bonds, which was delayed by the presence of silica. A theoretical approach using solid-state kinetics indicates that the most probable process for the aliphatic C-H decrease is three-dimensional diffusion of alteration products under both non-embedded and silica-embedded conditions. The extrapolation of the experimental results obtained at 250-450°C to lower temperatures implies that the rate constant for CH3 (kCH3 ) is similar to or lower than that for CH2 (kCH2 ; i.e., CH3 decreases at a similar rate or more slowly than CH2 ). The peak height ratio of 2,960 cm-1 band (CH3 )/2,925 cm-1 band (CH2 ; R3/2 values) either increased or remained constant during the heating. These results reveal that the presence of silica does affect the decreasing rate of the aliphatic C-H bonds in cyanobacteria during thermal maturation, but that it does not significantly decrease the R3/2 values. Meanwhile, studies of microfossils suggest that the R3/2 values of Proterozoic prokaryotic fossils from the Bitter Springs Group and Gunflint Formation have decreased during fossilization, which is inconsistent with the prediction from our experimental results that R3/2 values did not decrease after silicification. Some process other than thermal degradation, possibly preservation of specific classes of biomolecules with low R3/2 values, might have occurred during fossilization.
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Affiliation(s)
- Motoko Igisu
- School of Life Science and Technology, Tokyo Institute of Technology, Kanagawa, Japan
| | - Tadashi Yokoyama
- Graduate School of Integrated Arts and Sciences, Hiroshima University, Hiroshima, Japan
| | - Yuichiro Ueno
- Department of Subsurface Geobiology Analysis and Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Kanagawa, Japan
- Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo, Japan
- Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan
| | - Satoru Nakashima
- Department of Earth and Space Science, Osaka University, Osaka, Japan
| | - Mie Shimojima
- School of Life Science and Technology, Tokyo Institute of Technology, Kanagawa, Japan
| | - Hiroyuki Ohta
- Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan
- School of Life Science and Technology, Tokyo Institute of Technology, Kanagawa, Japan
| | - Shigenori Maruyama
- Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan
- Novosibirsk State University, Novosibirsk, Russia
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11
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McMahon S, Bosak T, Grotzinger JP, Milliken RE, Summons RE, Daye M, Newman SA, Fraeman A, Williford KH, Briggs DEG. A Field Guide to Finding Fossils on Mars. JOURNAL OF GEOPHYSICAL RESEARCH. PLANETS 2018; 123:1012-1040. [PMID: 30034979 PMCID: PMC6049883 DOI: 10.1029/2017je005478] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 03/28/2018] [Accepted: 04/23/2018] [Indexed: 05/05/2023]
Abstract
The Martian surface is cold, dry, exposed to biologically harmful radiation and apparently barren today. Nevertheless, there is clear geological evidence for warmer, wetter intervals in the past that could have supported life at or near the surface. This evidence has motivated National Aeronautics and Space Administration and European Space Agency to prioritize the search for any remains or traces of organisms from early Mars in forthcoming missions. Informed by (1) stratigraphic, mineralogical and geochemical data collected by previous and current missions, (2) Earth's fossil record, and (3) experimental studies of organic decay and preservation, we here consider whether, how, and where fossils and isotopic biosignatures could have been preserved in the depositional environments and mineralizing media thought to have been present in habitable settings on early Mars. We conclude that Noachian-Hesperian Fe-bearing clay-rich fluvio-lacustrine siliciclastic deposits, especially where enriched in silica, currently represent the most promising and best understood astropaleontological targets. Siliceous sinters would also be an excellent target, but their presence on Mars awaits confirmation. More work is needed to improve our understanding of fossil preservation in the context of other environments specific to Mars, particularly within evaporative salts and pore/fracture-filling subsurface minerals.
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Affiliation(s)
- S. McMahon
- Department of Geology and GeophysicsYale UniversityNew HavenCTUSA
- UK Centre for Astrobiology, School of Physics and AstronomyUniversity of EdinburghEdinburghUK
| | - T. Bosak
- Department of Earth, Atmospheric and Planetary SciencesMassachusetts Institute of TechnologyCambridgeMAUSA
| | - J. P. Grotzinger
- Division of Geological and Planetary SciencesCalifornia Institute of TechnologyPasadenaCAUSA
| | - R. E. Milliken
- Department of Earth, Environmental and Planetary SciencesBrown UniversityProvidenceRIUSA
| | - R. E. Summons
- Department of Earth, Atmospheric and Planetary SciencesMassachusetts Institute of TechnologyCambridgeMAUSA
| | - M. Daye
- Department of Earth, Atmospheric and Planetary SciencesMassachusetts Institute of TechnologyCambridgeMAUSA
| | - S. A. Newman
- Department of Earth, Atmospheric and Planetary SciencesMassachusetts Institute of TechnologyCambridgeMAUSA
| | - A. Fraeman
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - K. H. Williford
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - D. E. G. Briggs
- Department of Geology and GeophysicsYale UniversityNew HavenCTUSA
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12
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Price A, Pearson VK, Schwenzer SP, Miot J, Olsson-Francis K. Nitrate-Dependent Iron Oxidation: A Potential Mars Metabolism. Front Microbiol 2018; 9:513. [PMID: 29616015 PMCID: PMC5869265 DOI: 10.3389/fmicb.2018.00513] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 03/06/2018] [Indexed: 11/13/2022] Open
Abstract
This work considers the hypothetical viability of microbial nitrate-dependent Fe2+ oxidation (NDFO) for supporting simple life in the context of the early Mars environment. This draws on knowledge built up over several decades of remote and in situ observation, as well as recent discoveries that have shaped current understanding of early Mars. Our current understanding is that certain early martian environments fulfill several of the key requirements for microbes with NDFO metabolism. First, abundant Fe2+ has been identified on Mars and provides evidence of an accessible electron donor; evidence of anoxia suggests that abiotic Fe2+ oxidation by molecular oxygen would not have interfered and competed with microbial iron metabolism in these environments. Second, nitrate, which can be used by some iron oxidizing microorganisms as an electron acceptor, has also been confirmed in modern aeolian and ancient sediment deposits on Mars. In addition to redox substrates, reservoirs of both organic and inorganic carbon are available for biosynthesis, and geochemical evidence suggests that lacustrine systems during the hydrologically active Noachian period (4.1-3.7 Ga) match the circumneutral pH requirements of nitrate-dependent iron-oxidizing microorganisms. As well as potentially acting as a primary producer in early martian lakes and fluvial systems, the light-independent nature of NDFO suggests that such microbes could have persisted in sub-surface aquifers long after the desiccation of the surface, provided that adequate carbon and nitrates sources were prevalent. Traces of NDFO microorganisms may be preserved in the rock record by biomineralization and cellular encrustation in zones of high Fe2+ concentrations. These processes could produce morphological biosignatures, preserve distinctive Fe-isotope variation patterns, and enhance preservation of biological organic compounds. Such biosignatures could be detectable by future missions to Mars with appropriate instrumentation.
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Affiliation(s)
- Alex Price
- Faculty of Science, Technology, Engineering and Mathematics, The Open University, Milton Keynes, United Kingdom
| | - Victoria K. Pearson
- Faculty of Science, Technology, Engineering and Mathematics, The Open University, Milton Keynes, United Kingdom
| | - Susanne P. Schwenzer
- Faculty of Science, Technology, Engineering and Mathematics, The Open University, Milton Keynes, United Kingdom
| | - Jennyfer Miot
- CNRS, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Muséum National d’Histoire Naturelle, Université Pierre et Marie Curie – Sorbonne Universités, UMR 7590, Paris, France
| | - Karen Olsson-Francis
- Faculty of Science, Technology, Engineering and Mathematics, The Open University, Milton Keynes, United Kingdom
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Gaboyer F, Le Milbeau C, Bohmeier M, Schwendner P, Vannier P, Beblo-Vranesevic K, Rabbow E, Foucher F, Gautret P, Guégan R, Richard A, Sauldubois A, Richmann P, Perras AK, Moissl-Eichinger C, Cockell CS, Rettberg P, Marteinsson, Monaghan E, Ehrenfreund P, Garcia-Descalzo L, Gomez F, Malki M, Amils R, Cabezas P, Walter N, Westall F. Mineralization and Preservation of an extremotolerant Bacterium Isolated from an Early Mars Analog Environment. Sci Rep 2017; 7:8775. [PMID: 28821776 PMCID: PMC5562696 DOI: 10.1038/s41598-017-08929-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 07/14/2017] [Indexed: 11/09/2022] Open
Abstract
The artificial mineralization of a polyresistant bacterial strain isolated from an acidic, oligotrophic lake was carried out to better understand microbial (i) early mineralization and (ii) potential for further fossilisation. Mineralization was conducted in mineral matrixes commonly found on Mars and Early-Earth, silica and gypsum, for 6 months. Samples were analyzed using microbiological (survival rates), morphological (electron microscopy), biochemical (GC-MS, Microarray immunoassay, Rock-Eval) and spectroscopic (EDX, FTIR, RAMAN spectroscopy) methods. We also investigated the impact of physiological status on mineralization and long-term fossilisation by exposing cells or not to Mars-related stresses (desiccation and radiation). Bacterial populations remained viable after 6 months although the kinetics of mineralization and cell-mineral interactions depended on the nature of minerals. Detection of biosignatures strongly depended on analytical methods, successful with FTIR and EDX but not with RAMAN and immunoassays. Neither influence of stress exposure, nor qualitative and quantitative changes of detected molecules were observed as a function of mineralization time and matrix. Rock-Eval analysis suggests that potential for preservation on geological times may be possible only with moderate diagenetic and metamorphic conditions. The implications of our results for microfossil preservation in the geological record of Earth as well as on Mars are discussed.
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Affiliation(s)
- F Gaboyer
- Centre de Biophysique Moléculaire, CNRS, Orléans, France.
| | - C Le Milbeau
- Institut des Sciences de la Terre d'Orléans, UMR 7327, CNRS-Université d'Orléans, 1A Rue de la Férollerie, 45071, Orléans Cedex 2, France
| | - M Bohmeier
- Institute of Aerospace Medicine, Radiation Biology Department, German Aerospace Center (DLR), Cologne, Germany
| | - P Schwendner
- UK Center for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
| | - P Vannier
- MATIS - Prokaria, Reykjavík, Iceland
| | - K Beblo-Vranesevic
- Institute of Aerospace Medicine, Radiation Biology Department, German Aerospace Center (DLR), Cologne, Germany
| | - E Rabbow
- Institute of Aerospace Medicine, Radiation Biology Department, German Aerospace Center (DLR), Cologne, Germany
| | - F Foucher
- Centre de Biophysique Moléculaire, CNRS, Orléans, France
| | - P Gautret
- Institut des Sciences de la Terre d'Orléans, UMR 7327, CNRS-Université d'Orléans, 1A Rue de la Férollerie, 45071, Orléans Cedex 2, France
| | - R Guégan
- Institut des Sciences de la Terre d'Orléans, UMR 7327, CNRS-Université d'Orléans, 1A Rue de la Férollerie, 45071, Orléans Cedex 2, France
| | - A Richard
- Centre de Microscopie Electronique, Université d'Orléans, Orléans, France
| | - A Sauldubois
- Centre de Microscopie Electronique, Université d'Orléans, Orléans, France
| | - P Richmann
- Institut des Sciences de la Terre d'Orléans, UMR 7327, CNRS-Université d'Orléans, 1A Rue de la Férollerie, 45071, Orléans Cedex 2, France
| | - A K Perras
- University Regensburg, Department of Microbiology, Regensburg, Germany.,Medical University of Graz, Department of Internal Medicine, Graz, Austria
| | | | - C S Cockell
- UK Center for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
| | - P Rettberg
- Institute of Aerospace Medicine, Radiation Biology Department, German Aerospace Center (DLR), Cologne, Germany
| | | | - E Monaghan
- Leiden Observatory, Universiteit Leiden, Leiden, Netherlands
| | - P Ehrenfreund
- Leiden Observatory, Universiteit Leiden, Leiden, Netherlands
| | - L Garcia-Descalzo
- Instituto Nacional de Técnica Aeroespacial - Centro de Astrobiología (INTA-CAB), Madrid, Spain
| | - F Gomez
- Instituto Nacional de Técnica Aeroespacial - Centro de Astrobiología (INTA-CAB), Madrid, Spain
| | - M Malki
- Universidad Autónoma de Madrid (UAM), Madrid, Spain
| | - R Amils
- Universidad Autónoma de Madrid (UAM), Madrid, Spain
| | - P Cabezas
- European Science Foundation (ESF), Strasbourg, France
| | - N Walter
- European Science Foundation (ESF), Strasbourg, France
| | - F Westall
- Centre de Biophysique Moléculaire, CNRS, Orléans, France
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14
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Manning-Berg AR, Kah LC. Proterozoic microbial mats and their constraints on environments of silicification. GEOBIOLOGY 2017; 15:469-483. [PMID: 28397335 DOI: 10.1111/gbi.12238] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Accepted: 03/09/2017] [Indexed: 06/07/2023]
Abstract
The occurrence of microfossiliferous, early diagenetic chert in Proterozoic successions is broadly restricted to peritidal marine environments. Such coastal environments are amongst the most environmentally variable of marine environments, experiencing both enhanced evaporation and potential influx of terrestrial freshwaters. To better understand potential conditions under which silicification occurs, we focus on microfossiliferous early diagenetic chert from the Mesoproterozoic Bylot Supergroup, northern Baffin Island. Spectacular preservation of silicified microbial mats, their associated mineral phases, and the petrographic fabrics of the chert itself require that silicification occurred at the sediment-water interface, penecontemporaneously with mat growth. In some cases, silica is the primary precipitated mineral phase and is not associated with replacement of precursor mineral phases. In other cases, silica deposition includes the mimetic replacement of carbonate, gypsum, and halite mineral phases. These petrographic constraints suggest that silicification potentially occurred under a range of fluid chemistries associated with environmental variability in nearshore peritidal environments. Here we provide the first direct thermodynamic modeling of hypothetical Proterozoic seawater solutions, seawater-derived brines, and mixed seawater-freshwater solutions, and demonstrate that peritidal environments are capable of providing a wide range of fluid chemistries under which early diagenetic silica can both precipitate and replace primary mineralogical phases. Despite the thermodynamic potential for silica deposition under a wide range of fluid compositions, chert is not ubiquitous in Proterozoic nearshore environments, suggesting that the kinetics of silica polymerization exert a primary control over deposition.
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Affiliation(s)
- A R Manning-Berg
- Department of Earth and Planetary Science, University of Tennessee, Knoxville, TN, USA
| | - L C Kah
- Department of Earth and Planetary Science, University of Tennessee, Knoxville, TN, USA
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15
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Picard A, Obst M, Schmid G, Zeitvogel F, Kappler A. Limited influence of Si on the preservation of Fe mineral-encrusted microbial cells during experimental diagenesis. GEOBIOLOGY 2016; 14:276-292. [PMID: 26695194 DOI: 10.1111/gbi.12171] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 11/10/2015] [Indexed: 06/05/2023]
Abstract
The reconstruction of the history of microbial life since its emergence on early Earth is impaired by the difficulty to prove the biogenicity of putative microfossils in the rock record. While most of the oldest rocks on Earth have been exposed to different grades of diagenetic alterations, little is known about how the remains of micro-organisms evolve when exposed to pressure (P) and temperature (T) conditions typical of diagenesis. Using spectroscopy and microscopy, we compared morphological, mineralogical, and chemical biosignatures exhibited by Fe mineral-encrusted cells of the bacterium Acidovorax sp. BoFeN1 after long-term incubation under ambient conditions and after experimental diagenesis. We also evaluated the effects of Si on the preservation of microbial cells during the whole process. At ambient conditions, Si affected the morphology but not the identity (goethite) of Fe minerals that formed around cells. Fe-encrusted cells were morphologically well preserved after 1 week at 250 °C-140 MPa and after 16 weeks at 170 °C-120 MPa in the presence or in the absence of Si. Some goethite transformed to hematite and magnetite at 250 °C-140 MPa, but in the presence of Si more goethite was preserved. Proteins-the most abundant cellular components-were preserved over several months at ambient conditions but disappeared after incubations at high temperature and pressure conditions, both in the presence and in the absence of Si. Other organic compounds, such as lipids and extracellular polysaccharides seemed well preserved after exposure to diagenetic conditions. This study provides insights about the composition and potential preservation of microfossils that could have formed in Fe- and Si-rich Precambrian oceans.
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Affiliation(s)
- A Picard
- Center for Applied Geoscience, Eberhard Karls University Tübingen, Tübingen, Germany
| | - M Obst
- Center for Applied Geoscience, Eberhard Karls University Tübingen, Tübingen, Germany
| | - G Schmid
- Center for Applied Geoscience, Eberhard Karls University Tübingen, Tübingen, Germany
| | - F Zeitvogel
- Center for Applied Geoscience, Eberhard Karls University Tübingen, Tübingen, Germany
| | - A Kappler
- Center for Applied Geoscience, Eberhard Karls University Tübingen, Tübingen, Germany
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16
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Zhou X, Chen D, Tang D, Dong S, Guo C, Guo Z, Zhang Y. Biogenic Iron-Rich Filaments in the Quartz Veins in the Uppermost Ediacaran Qigebulake Formation, Aksu Area, Northwestern Tarim Basin, China: Implications for Iron Oxidizers in Subseafloor Hydrothermal Systems. ASTROBIOLOGY 2015; 15:523-537. [PMID: 26168395 DOI: 10.1089/ast.2014.1234] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Fe-(oxyhydr)oxide-encrusted filamentous microstructures produced by microorganisms have been widely reported in various modern and ancient extreme environments; however, the iron-dependent microorganisms preserved in hydrothermal quartz veins have not been explored in detail because of limited materials available. In this study, abundant well-preserved filamentous microstructures were observed in the hydrothermal quartz veins of the uppermost dolostones of the terminal-Ediacaran Qigebulake Formation in the Aksu area, northwestern Tarim Basin, China. These filamentous microstructures were permineralized by goethite and hematite as revealed by Raman spectroscopy and completely entombed in chalcedony and quartz cements. Microscopically, they are characterized by biogenic filamentous morphologies (commonly 20-200 μm in length and 1-5 μm in diameter) and structures (curved, tubular sheath-like, segmented, and mat-like filaments), similar to the Fe-oxidizing bacteria (FeOB) living in modern and ancient hydrothermal vent fields. A previous study revealed that quartz-barite vein swarms were subseafloor channels of low-temperature, silica-rich, diffusive hydrothermal vents in the earliest Cambrian, which contributed silica to the deposition of the overlying bedded chert of the Yurtus Formation. In this context, this study suggests that the putative filamentous FeOB preserved in the quartz veins might have thrived in the low-temperature, silica- and Fe(II)-rich hydrothermal vent channels in subseafloor mixing zones and were rapidly fossilized by subsequent higher-temperature, silica-rich hydrothermal fluids in response to waning and waxing fluctuations of diffuse hydrothermal venting. In view of the occurrence in a relatively stable passive continental margin shelf environment in Tarim Block, the silica-rich submarine hydrothermal vent system may represent a new and important geological niche favorable for FeOB colonization, which is different from their traditional habitats reported in hydrothermal vent systems at oceanic spreading centers or volcanic seamounts. Thus, these newly recognized microfossils offer a new clue to explore the biological signatures and habitat diversity of microorganisms on Earth and beyond.
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Affiliation(s)
- Xiqiang Zhou
- 1 Key Lab of Petroleum Resources Research, Institute of Geology and Geophysics , Chinese Academy of Sciences, Beijing, China
- 2 University of Chinese Academy of Sciences , Beijing, China
| | - Daizhao Chen
- 1 Key Lab of Petroleum Resources Research, Institute of Geology and Geophysics , Chinese Academy of Sciences, Beijing, China
| | - Dongjie Tang
- 3 School of Geosciences and Resources, China University of Geosciences , Beijing, China
| | - Shaofeng Dong
- 1 Key Lab of Petroleum Resources Research, Institute of Geology and Geophysics , Chinese Academy of Sciences, Beijing, China
| | - Chuan Guo
- 1 Key Lab of Petroleum Resources Research, Institute of Geology and Geophysics , Chinese Academy of Sciences, Beijing, China
- 2 University of Chinese Academy of Sciences , Beijing, China
| | - Zenghui Guo
- 1 Key Lab of Petroleum Resources Research, Institute of Geology and Geophysics , Chinese Academy of Sciences, Beijing, China
- 2 University of Chinese Academy of Sciences , Beijing, China
| | - Yanqiu Zhang
- 1 Key Lab of Petroleum Resources Research, Institute of Geology and Geophysics , Chinese Academy of Sciences, Beijing, China
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17
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Experimental diagenesis of organo-mineral structures formed by microaerophilic Fe(II)-oxidizing bacteria. Nat Commun 2015; 6:6277. [DOI: 10.1038/ncomms7277] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 01/13/2015] [Indexed: 11/08/2022] Open
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18
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The Deep Biosphere of the Subseafloor Igneous Crust. THE HANDBOOK OF ENVIRONMENTAL CHEMISTRY 2015. [DOI: 10.1007/698_2015_5014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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19
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Cosmidis J, Benzerara K, Gheerbrant E, Estève I, Bouya B, Amaghzaz M. Nanometer-scale characterization of exceptionally preserved bacterial fossils in Paleocene phosphorites from Ouled Abdoun (Morocco). GEOBIOLOGY 2013; 11:139-153. [PMID: 23301909 DOI: 10.1111/gbi.12022] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Accepted: 11/21/2012] [Indexed: 06/01/2023]
Abstract
Micrometer-sized spherical and rod-shaped forms have been reported in many phosphorites and often interpreted as microbes fossilized by apatite, based on their morphologic resemblance with modern bacteria inferred by scanning electron microscopy (SEM) observations. This interpretation supports models involving bacteria in the formation of phosphorites. Here, we studied a phosphatic coprolite of Paleocene age originating from the Ouled Abdoun phosphate basin (Morocco) down to the nanometer-scale using focused ion beam milling, transmission electron microscopy (TEM), and scanning transmission x-ray microscopy (STXM) coupled with x-ray absorption near-edge structure spectroscopy (XANES). The coprolite, exclusively composed of francolite (a carbonate-fluroapatite), is formed by the accumulation of spherical objects, delimited by a thin envelope, and whose apparent diameters are between 0.5 and 3 μm. The envelope of the spheres is composed of a continuous crown dense to electrons, which measures 20-40 nm in thickness. It is surrounded by two thinner layers that are more porous and transparent to electrons and enriched in organic carbon. The observed spherical objects are very similar with bacteria encrusting in hydroxyapatite as observed in laboratory experiments. We suggest that they are Gram-negative bacteria fossilized by francolite, the precipitation of which started within the periplasm of the cells. We discuss the role of bacteria in the fossilization mechanism and propose that they could have played an active role in the formation of francolite. This study shows that ancient phosphorites can contain fossil biological subcellular structures as fine as a bacterial periplasm. Moreover, we demonstrate that while morphological information provided by SEM analyses is valuable, the use of additional nanoscale analyses is a powerful approach to help inferring the biogenicity of biomorphs found in phosphorites. A more systematic use of this approach could considerably improve our knowledge and understanding of the microfossils present in the geological record.
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Affiliation(s)
- J Cosmidis
- Institut de Minéralogie et de Physique des Milieux Condensés, Université Pierre et Marie Curie, CNRS, UMR 7590, Campus Jussieu, F-75005, Paris, France.
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20
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Orange F, Lalonde SV, Konhauser KO. Experimental simulation of evaporation-driven silica sinter formation and microbial silicification in hot spring systems. ASTROBIOLOGY 2013; 13:163-76. [PMID: 23384170 PMCID: PMC3582282 DOI: 10.1089/ast.2012.0887] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Accepted: 11/07/2012] [Indexed: 05/22/2023]
Abstract
Evaporation of silica-rich geothermal waters is one of the main abiotic drivers of the formation of silica sinters around hot springs. An important role in sinter structural development is also played by the indigenous microbial communities, which are fossilized and eventually encased in the silica matrix. The combination of these two factors results in a wide variety of sinter structures and fabrics. Despite this, no previous experimental fossilization studies have focused on evaporative-driven silica precipitation. We present here the results of several experiments aimed at simulating the formation of sinters through evaporation. Silica solutions at different concentrations were repeatedly allowed to evaporate in both the presence and absence of the cyanobacterium Synechococcus elongatus. Without microorganisms, consecutive silica additions led to the formation of well-laminated deposits. By contrast, when microorganisms were present, they acted as reactive surfaces for heterogeneous silica particle nucleation; depending on the initial silica concentration, the deposits were then either porous with a mixture of silicified and unmineralized cells, or they formed a denser structure with a complete entombment of the cells by a thick silica crust. The deposits obtained experimentally showed numerous similarities in terms of their fabric to those previously reported for natural hot springs, demonstrating the complex interplay between abiotic and biotic processes during silica sinter growth.
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Affiliation(s)
- François Orange
- Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada.
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21
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Kremer B, Kazmierczak J, Lukomska-Kowalczyk M, Kempe S. Calcification and silicification: fossilization potential of cyanobacteria from stromatolites of Niuafo'ou's Caldera Lakes (Tonga) and implications for the early fossil record. ASTROBIOLOGY 2012; 12:535-48. [PMID: 22794297 PMCID: PMC3397119 DOI: 10.1089/ast.2011.0742] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Calcification and silicification processes of cyanobacterial mats that form stromatolites in two caldera lakes of Niuafo'ou Island (Vai Lahi and Vai Si'i) were evaluated, and their importance as analogues for interpreting the early fossil record are discussed. It has been shown that the potential for morphological preservation of Niuafo'ou cyanobacteria is highly dependent on the timing and type of mineral phase involved in the fossilization process. Four main modes of mineralization of cyanobacteria organic parts have been recognized: (i) primary early postmortem calcification by aragonite nanograins that transform quickly into larger needle-like crystals and almost totally destroy the cellular structures, (ii) primary early postmortem silicification of almost intact cyanobacterial cells that leave a record of spectacularly well-preserved cellular structures, (iii) replacement by silica of primary aragonite that has already recrystallized and obliterated the cellular structures, (iv) occasional replacement of primary aragonite precipitated in the mucopolysaccharide sheaths and extracellular polymeric substances by Al-Mg-Fe silicates. These observations suggest that the extremely scarce earliest fossil record may, in part, be the result of (a) secondary replacement by silica of primary carbonate minerals (aragonite, calcite, siderite), which, due to recrystallization, had already annihilated the cellular morphology of the mineralized microbiota or (b) relatively late primary silicification of already highly degraded and no longer morphologically identifiable microbial remains.
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Affiliation(s)
- Barbara Kremer
- Institute of Paleobiology, Polish Academy of Sciences, Warsaw, Poland.
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22
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Tobler DJ, Benning LG. Bacterial diversity in five Icelandic geothermal waters: temperature and sinter growth rate effects. Extremophiles 2011; 15:473-85. [PMID: 21607550 DOI: 10.1007/s00792-011-0378-z] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Accepted: 04/26/2011] [Indexed: 11/25/2022]
Abstract
The microbial ecology associated with siliceous sinters was studied in five geochemically diverse Icelandic geothermal systems. Bacterial 16S rRNA clone libraries were constructed from water-saturated precipitates from each site resulting in a total of 342 bacterial clone sequences and 43 species level phylotypes. In near-neutral, saline (2.6-4.7% salinity) geothermal waters where sinter growth varied between 10 and ~300 kg year(-1) m(-2), 16S rRNA gene analyses revealed very low (no OTUs could be detected) to medium (9 OTUs) microbial activity. The most dominant phylotypes found in these waters belong to marine genera of the Proteobacteria. In contrast, in alkaline (pH = 9-10), meteoric geothermal waters with temperature = 66-96°C and <1-20 kg year(-1)m(-2) sinter growth, extensive biofilms (a total of 34 OTUs) were observed within the waters and these were dominated by members of the class Aquificae (mostly related to Thermocrinis), Deinococci (Thermus species) as well as Proteobacteria. The observed phylogenetic diversity (i.e., number and composition of detected OTUs) is argued to be related to the physico-chemical regime prevalent in the studied geothermal waters; alkaliphilic thermophilic microbial communities with phylotypes related to heterotrophic and autotrophic microorganisms developed in alkaline high temperature waters, whereas halophilic mesophilic communities dominated coastal geothermal waters.
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Affiliation(s)
- Dominique J Tobler
- Earth and Biosphere Institute, School of Earth and Environment, University of Leeds, UK.
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Character, Analysis, and Preservation of Biogenicity in Terrestrial Siliceous Stromatolites from Geothermal Settings. CELLULAR ORIGIN, LIFE IN EXTREME HABITATS AND ASTROBIOLOGY 2011. [DOI: 10.1007/978-94-007-0397-1_16] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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24
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Laidler JR, Stedman KM. Virus silicification under simulated hot spring conditions. ASTROBIOLOGY 2010; 10:569-576. [PMID: 20735248 DOI: 10.1089/ast.2010.0463] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Silicification of organisms in silica-depositing environments can impact both their ecology and their presence in the fossil record. Although microbes have been silicified under laboratory and environmental conditions, viruses have not. Bacteriophage T4 was successfully silicified under laboratory conditions that closely simulated those found in silica-depositing hot springs. Virus morphology was maintained, and a clear elemental signature of phosphorus was detected by energy-dispersive X-ray spectrophotometry (EDS).
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Affiliation(s)
- James R Laidler
- Biology Department and Center for Life in Extreme Environments, Portland State University, Portland, Oregon, USA
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25
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Oehler DZ, Robert F, Walter MR, Sugitani K, Meibom A, Mostefaoui S, Gibson EK. Diversity in the Archean biosphere: new insights from NanoSIMS. ASTROBIOLOGY 2010; 10:413-424. [PMID: 20528196 DOI: 10.1089/ast.2009.0426] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The origin of organic microstructures in the approximately 3 Ga Farrel Quartzite is controversial due to their relatively poor state of preservation, the Archean age of the cherts in which they occur, and the unusual spindle-like morphology of some of the forms. To provide more insight into the significance of these microstructures, nano-scale secondary ion mass spectrometry (NanoSIMS) maps of carbon, nitrogen, sulfur, silicon, and oxygen were obtained for spheroidal and spindle-shaped constituents of the Farrel Quartzite assemblage. Results suggest that the structures are all bona fide approximately 3 Ga microfossils. The spindles demonstrate an architecture that is remarkable for 3 Ga organisms. They are relatively large, robust, and morphologically complex. The NanoSIMS element maps corroborate their complexity by demonstrating an intricate, internal network of organic material that fills many of the spindles and extends continuously from the body of these structures into their spearlike appendages. Results from this study combine with previous morphological and chemical analyses to argue that the microstructures in the Farrel Quartzite comprise a diverse assemblage of Archean microfossils. This conclusion adds to a growing body of geochemical, stromatolitic, and morphological evidence that indicates the Archean biosphere was varied and well established by at least approximately 3 Ga. Together, the data paint a picture of Archean evolution that is one of early development of morphological and chemical complexity. The evidence for Archean evolutionary innovation may augur well for the possibility that primitive life on other planets could adapt to adverse conditions by ready development of diversity in form and biochemistry.
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Affiliation(s)
- Dorothy Z Oehler
- Astromaterials Research and Exploration Science, NASA, Johnson Space Center, Houston, Texas 77058, USA.
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26
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Iwai S, Doi K, Fujino Y, Nakazono T, Fukuda K, Motomura Y, Ogata S. Silica deposition and phenotypic changes to Thermus thermophilus cultivated in the presence of supersaturated silicia. ISME JOURNAL 2010; 4:809-16. [DOI: 10.1038/ismej.2010.12] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Evolutionary Trends in Remarkable Fossil Preservation Across the Ediacaran–Cambrian Transition and the Impact of Metazoan Mixing. TOPICS IN GEOBIOLOGY 2010. [DOI: 10.1007/978-90-481-8643-3_15] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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28
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Orange F, Westall F, Disnar JR, Prieur D, Bienvenu N, Le Romancer M, Défarge C. Experimental silicification of the extremophilic Archaea Pyrococcus abyssi and Methanocaldococcus jannaschii: applications in the search for evidence of life in early Earth and extraterrestrial rocks. GEOBIOLOGY 2009; 7:403-18. [PMID: 19656214 DOI: 10.1111/j.1472-4669.2009.00212.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Hydrothermal activity was common on the early Earth and associated micro-organisms would most likely have included thermophilic to hyperthermophilic species. 3.5-3.3 billion-year-old, hydrothermally influenced rocks contain silicified microbial mats and colonies that must have been bathed in warm to hot hydrothermal emanations. Could they represent thermophilic or hyperthermophilic micro-organisms and if so, how were they preserved? We present the results of an experiment to silicify anaerobic, hyperthermophilic micro-organisms from the Archaea Domain Pyrococcus abyssi and Methanocaldococcus jannaschii, that could have lived on the early Earth. The micro-organisms were placed in a silica-saturated medium for periods up to 1 year. Pyrococcus abyssi cells were fossilized but the M. jannaschii cells lysed naturally after the exponential growth phase, apart from a few cells and cell remains, and were not silicified although their extracellular polymeric substances were. In this first simulated fossilization of archaeal strains, our results suggest that differences between species have a strong influence on the potential for different micro-organisms to be preserved by fossilization and that those found in the fossil record represent probably only a part of the original diversity. Our results have important consequences for biosignatures in hydrothermal or hydrothermally influenced deposits on Earth, as well as on early Mars, as environmental conditions were similar on the young terrestrial planets and traces of early Martian life may have been similarly preserved as silicified microfossils.
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Affiliation(s)
- F Orange
- Centre de Biophysique Moléculaire, CNRS, Orléans cedex, France
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29
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Hitchcock AP, Dynes JJ, Lawrence JR, Obst M, Swerhone GDW, Korber DR, Leppard GG. Soft X-ray spectromicroscopy of nickel sorption in a natural river biofilm. GEOBIOLOGY 2009; 7:432-453. [PMID: 19656215 DOI: 10.1111/j.1472-4669.2009.00211.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Scanning transmission X-ray microscopy (STXM) at the C 1s, O 1s, Ni 2p, Ca 2p, Mn 2p, Fe 2p, Mg 1s, Al 1s and Si 1s edges was used to study Ni sorption in a complex natural river biofilm. The 10-week grown river biofilm was exposed to 10 mg L(-1) Ni(2+) (as NiCl(2)) for 24 h. The region of the biofilm examined was dominated by filamentous structures, which were interpreted as the discarded sheaths of filamentous bacteria, as well as a sparse distribution of rod-shaped bacteria. The region also contained discrete particles with spectra similar to those of muscovite, SiO(2) and CaCO(3). The Ni(II) ions were selectively adsorbed by the sheaths of the filamentous bacteria. The sheaths were observed to be metal rich with significant amounts of Ca, Fe and Mn, along with the Ni. In addition, the sheaths had a large silicate content but little organic material. The metal content of the rod-shaped bacterial cells was much lower. The Fe on the sheath was mainly in the Fe(III) oxidation state. Mn was found in II, III and IV oxidation states. The Ni was likely sorbed to Mn-Fe minerals on the sheath. These STXM results have probed nano-scale biogeochemistry associated with bacterial species in a complex, natural biofilm community. They have implications for selective Ni contamination of the food chain and for developing bioremediation strategies.
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Affiliation(s)
- A P Hitchcock
- Brockhouse Institute for Materials Research, McMaster University, ON, Canada.
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Stimulation of expression of a silica-induced protein (Sip) in Thermus thermophilus by supersaturated silicic acid. Appl Environ Microbiol 2009; 75:2406-13. [PMID: 19233950 DOI: 10.1128/aem.02387-08] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The effects of silicic acid on the growth of Thermus thermophilus TMY, an extreme thermophile isolated from a siliceous deposit formed from geothermal water at a geothermal power plant in Japan, were examined at 75 degrees C. At concentrations higher than the solubility of amorphous silica (400 to 700 ppm SiO(2)), a silica-induced protein (Sip) was isolated from the cell envelope fraction of log-phase TMY cells grown in the presence of supersaturated silicic acid. Two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed the molecular mass and pI of Sip to be about 35 kDa and 9.5, respectively. Induction of Sip expression occurred within 1 h after the addition of a supersaturating concentration of silicic acid to TM broth. Expression of Sip-like proteins was also observed in other thermophiles, including T. thermophilus HB8 and Thermus aquaticus YT-1. The amino acid sequence of Sip was similar to that of the predicted solute-binding protein of the Fe(3+) ABC transporter in T. thermophilus HB8 (locus tag, TTHA1628; GenBank accession no. NC_006461; GeneID, 3169376). The sip gene (987-bp) product showed 87% identity with the TTHA1628 product and the presumed Fe(3+)-binding protein of T. thermophilus HB27 (locus tag TTC1264; GenBank accession no. NC_005835; GeneID, 2774619). Within the genome, sip is situated as a component of the Fbp-type ABC transporter operon, which contains a palindromic structure immediately downstream of sip. This structure is conserved in other T. thermophilus genomes and may function as a terminator that causes definitive Sip expression in response to silica stress.
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Schelble RT, Hall JA, Nealson KH, Steele A. DNA perseverance of microorganisms exposed to silica: an experimental study. GEOBIOLOGY 2008; 6:503-511. [PMID: 19076640 DOI: 10.1111/j.1472-4669.2008.00177.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The persistence of DNA from microorganisms exposed to various concentrations of SiO2 (ranging from 0 to 3000 p.p.m.) was monitored over time. The impact of silica mineralization or silicification on the longevity of 16S rRNA and 16 s rDNA genes from whole cells of Bacillus subtilis and Escherichia coli K12 was quantified using real-time polymerase chain reaction (RT-PCR), and cells were visualized using optical microscopy. For B. subtilis, DNA longevity decreased in experiments with higher levels of SiO2 (1000 and 3000 p.p.m.), in comparison to zero or low (100 p.p.m.) levels. For B. subtilis, cell viability was greatest in the absence of silica, and markedly decreased in the presence of any concentration of silica. Survival of Escherichia coli cells, on the other hand, was not sensitive to silica in the solution. All cells died at similar rates over the 180 days they were monitored, decreasing to about 1% survival. DNA longevity for E. coli did appear to be enhanced to some degree by the presence of 1000 p.p.m. silica, but higher or lower concentrations showed no increased longevity in comparison to the no-silica control. Overall, findings of this study do not support the hypothesis that siliceous environments provide enhanced protection and preservation of DNA over time. However, results of this study do provide guidelines on the persistence of DNA that might be expected in modern silica-rich environments, which may be an important factor for proper characterization of present-day microbial communities.
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Affiliation(s)
- R T Schelble
- Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road NW, Washington, DC 20015, USA.
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Ivarsson M, Lausmaa J, Lindblom S, Broman C, Holm NG. Fossilized microorganisms from the Emperor Seamounts: implications for the search for a subsurface fossil record on Earth and Mars. ASTROBIOLOGY 2008; 8:1139-1157. [PMID: 19191540 DOI: 10.1089/ast.2007.0226] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We have observed filamentous carbon-rich structures in samples drilled at 3 different seamounts that belong to the Emperor Seamounts in the Pacific Ocean: Detroit (81 Ma), Nintoku (56 Ma), and Koko Seamounts (48 Ma). The samples consist of low-temperature altered basalts recovered from all 3 seamounts. The maximum depth from which the samples were retrieved was 954 meters below seafloor (mbsf). The filamentous structures occur in veins and fractures in the basalts, where they are attached to the vein walls and embedded in vein-filling minerals like calcite, aragonite, and gypsum. The filaments were studied with a combination of optical microscopy, environmental scanning electron microscopy (ESEM), Raman spectroscopy, and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Minerals were identified by a combination of optical microscopy, X-ray diffraction, Raman spectrometry, and energy dispersive spectrometry on an environmental scanning electron microscope. Carbon content of the filaments ranges between approximately 10 wt % and approximately 50 wt % and is not associated with carbonates. These results indicate an organic origin of the carbon. The presence of C(2)H(4), phosphate, and lipid-like molecules in the filaments further supports a biogenic origin. We also found microchannels in volcanic glass enriched in carbon (approximately 10-40 wt %) compatible with putative microbial activity. Our findings suggest new niches for life in subseafloor environments and have implications for further exploration of the subseafloor biosphere on Earth and beyond.
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Affiliation(s)
- M Ivarsson
- Department of Geology and Geochemistry, Stockholm University, Stockholm, Sweden.
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Handley KM, Turner SJ, Campbell KA, Mountain BW. Silicifying biofilm exopolymers on a hot-spring microstromatolite: templating nanometer-thick laminae. ASTROBIOLOGY 2008; 8:747-770. [PMID: 18781887 DOI: 10.1089/ast.2007.0172] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Exopolymeric substances (EPS) are an integral component of microbial biofilms; however, few studies have addressed their silicification and preservation in hot-spring deposits. Through comparative analyses with the use of a range of microscopy techniques, we identified abundant EPS significant to the textural development of spicular, microstromatolitic, siliceous sinter at Champagne Pool, Waiotapu, New Zealand. Examination of biofilms coating sinter surfaces by confocal laser scanning microscopy (CLSM), environmental scanning electron microscopy (ESEM), cryo-scanning electron microscopy (cryo-SEM), and transmission electron microscopy (TEM) revealed contraction of the gelatinous EPS matrix into films (approximately 10 nm thick) or fibrillar structures, which is common in conventional SEM analyses and analogous to products of naturally occurring desiccation. Silicification of fibrillar EPS contributed to the formation of filamentous sinter. Matrix surfaces or dehydrated films templated sinter laminae (nanometers to microns thick) that, in places, preserved fenestral voids beneath. Laminae of similar thickness are, in general, common to spicular geyserites. This is the first report to demonstrate EPS templation of siliceous stromatolite laminae. Considering the ubiquity of biofilms on surfaces in hot-spring environments, EPS silicification studies are likely to be important to a better understanding of the origins of laminae in other modern and ancient stromatolitic sinters, and EPS potentially may serve as biosignatures in extraterrestrial rocks.
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Affiliation(s)
- Kim M Handley
- School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Manchester, United Kingdom
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34
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Jones B, de Ronde CEJ, Renaut RW. Mineralized microbes from Giggenbach submarine volcano. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2007jb005482] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Brian Jones
- Department of Earth and Atmospheric Sciences; University of Alberta; Edmonton, Alberta Canada
| | | | - Robin W. Renaut
- Department of Geological Sciences; University of Saskatchewan; Saskatoon, Saskatchewan Canada
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McLoughlin N, Brasier MD, Wacey D, Green OR, Perry RS. On biogenicity criteria for endolithic microborings on early Earth and beyond. ASTROBIOLOGY 2007; 7:10-26. [PMID: 17407401 DOI: 10.1089/ast.2006.0122] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Micron-sized cavities created by the actions of rock-etching microorganisms known as euendoliths are explored as a biosignature for life on early Earth and perhaps Mars. Rock-dwelling organisms can tolerate extreme environmental stresses and are excellent candidates for the colonization of early Earth and planetary surfaces. Here, we give a brief overview of the fossil record of euendoliths in both sedimentary and volcanic rocks. We then review the current understanding of the controls upon the distribution of euendolithic microborings and use these to propose three lines of approach for testing their biogenicity: first, a geological setting that demonstrates a syngenetic origin for the euendolithic microborings; second, microboring morphologies and distributions that are suggestive of biogenic behavior and distinct from ambient inclusion trails; and third, elemental and isotopic evidence suggestive of biological processing. We use these criteria and the fossil record of terrestrial euendoliths to outline potential environments and techniques to search for endolithic microborings on Mars.
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Oehler DZ, Robert F, Mostefaoui S, Meibom A, Selo M, McKay DS. Chemical mapping of proterozoic organic matter at submicron spatial resolution. ASTROBIOLOGY 2006; 6:838-50. [PMID: 17155884 DOI: 10.1089/ast.2006.6.838] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
A NanoSIMS ion microprobe was used to map the submicron-scale distributions of carbon, nitrogen, sulfur, silicon, and oxygen in organic microfossils and laminae in a thin section of the approximately 0.85 billion year old Bitter Springs Formation of Australia. The data provide clues about the original chemistry of the microfossils, the silicification process, and the biosignatures of specific microorganisms and microbial communities. Chemical maps of fossil unicells and filaments revealed distinct wall- and sheath-like structures enriched in C, N, and S, consistent with their accepted biological origin. Surprisingly, organic laminae, previously considered to be amorphous, also exhibited filamentous and apparently compressed spheroidal structures defined by strong enrichments in C, N, and S. By analogy to NanoSIMS data from the well-preserved microfossils, these structures were interpreted as being of biological origin, most likely representing densely packed remnants of microbial mats. Given that the preponderance of organic matter in Precambrian sediments is similarly "amorphous," our findings indicate that a re-evaluation of ancient specimens via in situ structural, chemical, and isotopic study is warranted. Our analyses have led us to propose new criteria for assessing the biogenicity of problematic kerogenous materials, and, thus, these criteria can be applied to assessments of poorly preserved or fragmentary organic residues in early Archean sediments and any that might occur in meteorites or other extraterrestrial samples.
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Affiliation(s)
- Dorothy Z Oehler
- Astrobiology Group, Astromaterials Research and Exploration Science (ARES) Directorate, NASA-Johnson Space Center, Houston, Texas 77058, USA.
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37
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Westall F, de Ronde CEJ, Southam G, Grassineau N, Colas M, Cockell C, Lammer H. Implications of a 3.472-3.333 Gyr-old subaerial microbial mat from the Barberton greenstone belt, South Africa for the UV environmental conditions on the early Earth. Philos Trans R Soc Lond B Biol Sci 2006; 361:1857-75. [PMID: 17008224 PMCID: PMC1664690 DOI: 10.1098/rstb.2006.1896] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Modelling suggests that the UV radiation environment of the early Earth, with DNA weighted irradiances of about three orders of magnitude greater than those at present, was hostile to life forms at the surface, unless they lived in specific protected habitats. However, we present empirical evidence that challenges this commonly held view. We describe a well-developed microbial mat that formed on the surface of volcanic littoral sediments in an evaporitic environment in a 3.5-3.3Ga-old formation from the Barberton greenstone belt. Using a multiscale, multidisciplinary approach designed to strongly test the biogenicity of potential microbial structures, we show that the mat was constructed under flowing water by 0.25 microm filaments that produced copious quantities of extracellular polymeric substances, representing probably anoxygenic photosynthesizers. Associated with the mat is a small colony of rods-vibroids that probably represent sulphur-reducing bacteria. An embedded suite of evaporite minerals and desiccation cracks in the surface of the mat demonstrates that it was periodically exposed to the air in an evaporitic environment. We conclude that DNA-damaging UV radiation fluxes at the surface of the Earth at this period must either have been low (absorbed by CO2, H2O, a thin organic haze from photo-dissociated CH4, or SO2 from volcanic outgassing; scattered by volcanic, and periodically, meteorite dust, as well as by the upper layers of the microbial mat) and/or that the micro-organisms exhibited efficient gene repair/survival strategies.
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Affiliation(s)
- Frances Westall
- Centre de Biophysique Moléculaire, CNRS, Rue Charles Sadron, 45071 Orléans Cedex 2, France.
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The early record of life. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/164gm18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Wierzchos J, Sancho LG, Ascaso C. Biomineralization of endolithic microbes in rocks from the McMurdo Dry Valleys of Antarctica: implications for microbial fossil formation and their detection. Environ Microbiol 2005; 7:566-75. [PMID: 15816933 DOI: 10.1111/j.1462-2920.2005.00725.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In some zones of Antarctica's cold and dry desert, the extinction of cryptoendolithic microorganisms leaves behind inorganic traces of microbial life. In this paper, we examine the transition from live microorganisms, through their decay, to microbial fossils using in situ microscopy (transmission electron microscopy, scanning electron microscopy in back-scattered electron mode) and microanalytical (energy dispersive X-ray spectroscopy) techniques. Our results demonstrate that, after their death, endolithic microorganisms inhabiting Commonwealth Glacier sandstone from the Antarctica McMurdo Dry Valleys become mineralized. In some cases, epicellular deposition of minerals and/or simply filling up of empty moulds by minerals leads to the formation of cell-shaped structures that may be considered biomarkers. The continuous deposition of allochthonous clay minerals and sulfate-rich salts fills the sandstone pores. This process can give rise to microbial fossils with distinguishable cell wall structures. Often, fossilized cell interiors were of a different chemical composition to the mineralized cell walls. We propose that the microbial fossil formation observed was induced by mineral precipitation resulting from inorganic processes occurring after the death of cryptoendolithic microorganisms. Nevertheless, it must have been the organic template that provoked the diffusion of mineral elements and gave rise to their characteristic distribution pattern inside the fossilized cells.
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Affiliation(s)
- Jacek Wierzchos
- Servei de Microscòpia Electrònica, Universitat de Lleida, c/Rovira Roure, 44, 25198 Lleida, Spain.
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Schweitzer MH, Wittmeyer J, Avci R, Pincus S. Experimental support for an immunological approach to the search for life on other planets. ASTROBIOLOGY 2005; 5:30-47. [PMID: 15711168 DOI: 10.1089/ast.2005.5.30] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We propose a three-phase approach to test for evidence of life in extraterrestrial samples. The approach capitalizes on the flexibility, sensitivity, and specificity of antibody-antigen interactions. Data are presented to support the first phase, in which various extraction protocols are compared for efficiency, and in which a preliminary suite of antibodies are tested against various antigens. The antigens and antibodies were chosen on the basis of criteria designed to optimize the detection of extraterrestrial biomarkers unique to living or once-living organisms.
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Affiliation(s)
- Mary Higby Schweitzer
- Department of Marine, Earth and Atmospheric Sciences, North Carolina State University, Raleigh, North Carolina 27695, USA.
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41
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Krumbein WE, Gorbushina AA, Holtkamp-Tacken E. Hypersaline microbial systems of sabkhas: examples of life's survival in "extreme" conditions. ASTROBIOLOGY 2004; 4:450-459. [PMID: 15684726 DOI: 10.1089/ast.2004.4.450] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Life and living systems need several important factors to establish themselves and to have a continued tradition. In this article the nature of the borderline situation for microbial life under heavy salt stress is analyzed and discussed using the example of biofilms and microbial mats of sabkha systems of the Red Sea. Important factors ruling such environments are described, and include the following: (1) Microbial life is better suited for survival in extremely changing and only sporadically water-supplied environments than are larger organisms (including humans). (2) Microbial life shows extremely poikilophilic adaptation patterns to conditions that deviate significantly from conditions normal for life processes on Earth today. (3) Microbial life adapts itself to such extremely changing and only ephemerally supportive conditions by the capacity of extreme changes (a) in morphology (pleomorphy), (b) in metabolic patterns (poikilotrophy), (c) in survival strategies (poikilophily), and (d) by trapping and enclosing all necessary sources of energy matter in an inwardly oriented diffusive cycle. All this is achieved without any serious attempt at escaping from the extreme and extremely changing conditions. Furthermore, these salt swamp systems are geophysiological generators of energy and material reservoirs recycled over a geological time scale. Neither energy nor material is wasted for propagation by spore formation. This capacity is summarized as poikilophilic and poikilotroph behavior of biofilm or microbial mat communities in salt and irradiationstressed environmental conditions of the sabkha or salt desert type. We use mainly cyanobacteria as an example, although other bacteria and even eukaryotic fungi may exhibit the same potential of living and surviving under conditions usually not suitable for life on Earth. It may, however, be postulated that such poikilophilic organisms are the true candidates for life support and survival under conditions never recorded on Planet Earth. Mars and some planets of other suns may be good candidates to search for life under conditions normally not thought to be favorable for the maintenance of life.
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Affiliation(s)
- Wolfgang Elisabeth Krumbein
- Geomicrobiology, Institute for Chemistry and Biology of the Marine Environment, Carl von Ossietzky Universitaet, Oldenburg, Germany.
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Benzerara K, Menguy N, Guyot F, Dominici C, Gillet P. Nanobacteria-like calcite single crystals at the surface of the Tataouine meteorite. Proc Natl Acad Sci U S A 2003; 100:7438-42. [PMID: 12792020 PMCID: PMC164604 DOI: 10.1073/pnas.0832464100] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nanobacteria-like objects evidenced at the surface of the orthopyroxenes of the Tataouine meteorite in South Tunisia have been studied by scanning and transmission electron microscopies. A method of micromanipulation has been developed to ensure that exactly the same objects were studied by both methods. We have shown that the nanobacteria-like objects are spatially correlated with filaments of microorganisms that colonized the surface of the meteoritic pyroxene during its 70 years of residence in the aridic Tataouine soil. Depressions of a few micrometers in depth are observed in the pyroxene below the carbonates, indicating preferential dissolution of the pyroxene and calcite precipitation at these locations. The nanobacteria-like small rods that constitute calcium carbonate rosettes are well crystallized calcite single crystals surrounded by a thin amorphous layer of carbonate composition that smoothes the crystal edges and induces rounded shapes. Those morphologies are unusual for calcite single crystals observed in natural samples. A survey of recent literature suggests that the intervention of organic compounds derived from biological activity is likely in their formation.
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Affiliation(s)
- Karim Benzerara
- Laboratoire de Minéralogie-Cristallographie, Unité Mixte de Recherche 7590 Centre National de la Recherche Scientifique and Institut de Physique du Globe de Paris, 4 Place Jussieu, 75252 Paris Cedex, France.
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Hode T, von Dalwigk I, Broman C. A hydrothermal system associated with the Siljan impact structure, Sweden--implications for the search for fossil life on Mars. ASTROBIOLOGY 2003; 3:271-289. [PMID: 14582511 DOI: 10.1089/153110703769016370] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The Siljan ring structure (368 +/- 1.1 Ma) is the largest known impact structure in Europe. It isa 65-km-wide, eroded, complex impact structure, displaying several structural units, including a central uplifted region surrounded by a ring-shaped depression. Associated with the impact crater are traces of a post-impact hydrothermal system indicated by precipitated and altered hydrothermal mineral assemblages. Precipitated hydrothermal minerals include quartz veins and breccia fillings associated with granitic rocks at the outer margin of the central uplift, and calcite, fluorite, galena, and sphalerite veins associated with Paleozoic carbonate rocks located outside the central uplift. Two-phase water/gas and oil/gas inclusions in calcite and fluorite display homogenization temperatures between 75 degrees C and 137 degrees C. With an estimated erosional unloading of approximately 1 km, the formation temperatures were probably not more than 10-15 degrees C higher. Fluid inclusion ice-melting temperatures indicate a very low salt content, reducing the probability that the mineralization was precipitated during the Caledonian Orogeny. Our findings suggest that large impacts induce low-temperature hydrothermal systems that may be habitats for thermophilic organisms. Large impact structures on Mars may therefore be suitable targets in the search for fossil thermophilic organisms.
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Affiliation(s)
- Tomas Hode
- Department of Paleozoology, Swedish Museum of Natural History, Stockholm, Sweden.
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