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Rasmussen KL, Thieringer PH, Nevadomski S, Martinez AM, Dawson KS, Corsetti FA, Zheng XY, Lv Y, Chen X, Celestian AJ, Berelson WM, Rollins NE, Spear JR. Living to Lithified: Construction and Preservation of Silicified Biomarkers. GEOBIOLOGY 2024; 22:1-30. [PMID: 39319483 DOI: 10.1111/gbi.12620] [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: 01/03/2024] [Revised: 07/21/2024] [Accepted: 09/03/2024] [Indexed: 09/26/2024]
Abstract
Whole microorganisms are rarely preserved in the fossil record but actively silicifying environments like hot springs provide an opportunity for microbial preservation, making silicifying environments critical for the study of microbial life through time on Earth and possibly other planetary bodies. Yet, the changes that biosignatures may undergo through lithification and burial remain unconstrained. At Steep Cone Geyser in Yellowstone National Park, we collected microbial material from (1) the living system across the active outflows, (2) the silicified areas adjacent to flows, and (3) lithified and buried material to assess the preservation of biosignatures and their changes across the lithification transect. Five biofabrics, built predominantly by Cyanobacteria Geitlerinema, Pseudanabaenaceae, and Leptolyngbya with some filamentous anoxygenic phototrophs contributions, were identified and tracked from the living system through the process of silicification/lithification. In the living systems, δ30Si values decrease from +0.13‰ in surficial waters to -2‰ in biomat samples, indicating a kinetic isotope effect potentially induced by increased association with actively growing biofabrics. The fatty acids C16:1 and iso-C14:0 and the hydrocarbon C17:0 were disentangled from confounding signals and determined to be reliable lipid biosignatures for living biofabric builders and tenant microorganisms. Builder and tenant microbial biosignatures were linked to specific Cyanobacteria, anoxygenic phototrophs, and heterotrophs, which are prominent members of the living communities. Upon lithification and burial, silicon isotopes of silicified biomass began to re-equilibrate, increasing from δ30Si -2‰ in living biomats to -0.55‰ in lithified samples. Active endolithic microbial communities were identified in lithified samples and were dominated by Cyanobacteria, heterotrophic bacteria, and fungi. Results indicate that distinct microbial communities build and inhabit silicified biofabrics through time and that microbial biosignatures shift over the course of lithification. These findings improve our understanding of how microbial communities silicify, the biomarkers they retain, and transitionary impacts that may occur through lithification and burial.
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Affiliation(s)
- Kalen L Rasmussen
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado, USA
| | - Patrick H Thieringer
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado, USA
| | - Sophia Nevadomski
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado, USA
| | - Aaron M Martinez
- Department of Environmental Sciences, Rutgers University, New Brunswick, New Jersey, USA
| | - Katherine S Dawson
- Department of Environmental Sciences, Rutgers University, New Brunswick, New Jersey, USA
| | - Frank A Corsetti
- Department of Earth Sciences, University of Southern California, Los Angeles, California, USA
| | - Xin-Yuan Zheng
- Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, Minnesota, USA
| | - Yiwen Lv
- Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, Minnesota, USA
| | - Xinyang Chen
- Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, Minnesota, USA
| | - Aaron J Celestian
- Natural History Museum of Los Angeles County, Los Angeles, California, USA
| | - William M Berelson
- Department of Earth Sciences, University of Southern California, Los Angeles, California, USA
| | - Nick E Rollins
- Department of Earth Sciences, University of Southern California, Los Angeles, California, USA
| | - John R Spear
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado, USA
- Quantitative Biosciences and Engineering Programs, Colorado School of Mines, Golden, Colorado, USA
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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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Buckner DK, Anderson MJ, Wisnosky S, Alvarado W, Nuevo M, Williams AJ, Ricco AJ, Anamika, Debic S, Friend L, Hoac T, Jahnke L, Radosevich L, Williams R, Wilhelm MB. Quantifying Global Origin-Diagnostic Features and Patterns in Biotic and Abiotic Acyclic Lipids for Life Detection. ASTROBIOLOGY 2024; 24:1-35. [PMID: 38150549 DOI: 10.1089/ast.2023.0012] [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: 12/29/2023]
Abstract
Lipids are a geologically robust class of organics ubiquitous to life as we know it. Lipid-like soluble organics are synthesized abiotically and have been identified in carbonaceous meteorites and on Mars. Ascertaining the origin of lipids on Mars would be a profound astrobiological achievement. We enumerate origin-diagnostic features and patterns in two acyclic lipid classes, fatty acids (i.e., carboxylic acids) and acyclic hydrocarbons, by collecting and analyzing molecular data reported in over 1500 samples from previously published studies of terrestrial and meteoritic organics. We identify 27 combined (15 for fatty acids, 12 for acyclic hydrocarbons) molecular patterns and structural features that can aid in distinguishing biotic from abiotic synthesis. Principal component analysis (PCA) demonstrates that multivariate analyses of molecular features (16 for fatty acids, 14 for acyclic hydrocarbons) can potentially indicate sample origin. Terrestrial lipids are dominated by longer straight-chain molecules (C4-C34 fatty acids, C14-C46 acyclic hydrocarbons), with predominance for specific branched and unsaturated isomers. Lipid-like meteoritic soluble organics are shorter, with random configurations. Organic solvent-extraction techniques are most commonly reported, motivating the design of our novel instrument, the Extractor for Chemical Analysis of Lipid Biomarkers in Regolith (ExCALiBR), which extracts lipids while preserving origin-diagnostic features that can indicate biogenicity.
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Affiliation(s)
- Denise K Buckner
- Department of Geological Sciences, University of Florida, Gainesville, Florida, USA
- Blue Marble Space Institute of Science, Seattle, Washington, USA
- Space Science & Astrobiology Division, NASA Ames Research Center, Moffett Field, California, USA
| | - Morgan J Anderson
- Space Science & Astrobiology Division, NASA Ames Research Center, Moffett Field, California, USA
- Axient Corporation, Huntsville, Alabama, USA
| | - Sydney Wisnosky
- Axient Corporation, Huntsville, Alabama, USA
- Department of Biology, University of Miami, Coral Gables, Florida, USA
| | - Walter Alvarado
- Space Science & Astrobiology Division, NASA Ames Research Center, Moffett Field, California, USA
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois, USA
| | - Michel Nuevo
- Space Science & Astrobiology Division, NASA Ames Research Center, Moffett Field, California, USA
| | - Amy J Williams
- Department of Geological Sciences, University of Florida, Gainesville, Florida, USA
| | - Antonio J Ricco
- Space Science & Astrobiology Division, NASA Ames Research Center, Moffett Field, California, USA
- Electrical Engineering-Integrated Circuits Laboratory, Stanford University, Stanford, California, USA
| | - Anamika
- Department of Space Studies, University of North Dakota, Grand Forks, North Dakota, USA
| | - Sara Debic
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, USA
| | | | - Trinh Hoac
- Axient Corporation, Huntsville, Alabama, USA
| | - Linda Jahnke
- Space Science & Astrobiology Division, NASA Ames Research Center, Moffett Field, California, USA
| | | | - Ross Williams
- Civil & Environmental Engineering & Earth Sciences, Notre Dame University, Notre Dame, Indiana, USA
| | - Mary Beth Wilhelm
- Space Science & Astrobiology Division, NASA Ames Research Center, Moffett Field, California, USA
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Finkel PL, Carrizo D, Parro V, Sánchez-García L. An Overview of Lipid Biomarkers in Terrestrial Extreme Environments with Relevance for Mars Exploration. ASTROBIOLOGY 2023; 23:563-604. [PMID: 36880883 PMCID: PMC10150655 DOI: 10.1089/ast.2022.0083] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 01/25/2023] [Indexed: 05/03/2023]
Abstract
Lipid molecules are organic compounds, insoluble in water, and based on carbon-carbon chains that form an integral part of biological cell membranes. As such, lipids are ubiquitous in life on Earth, which is why they are considered useful biomarkers for life detection in terrestrial environments. These molecules display effective membrane-forming properties even under geochemically hostile conditions that challenge most of microbial life, which grants lipids a universal biomarker character suitable for life detection beyond Earth, where a putative biological membrane would also be required. What discriminates lipids from nucleic acids or proteins is their capacity to retain diagnostic information about their biological source in their recalcitrant hydrocarbon skeletons for thousands of millions of years, which is indispensable in the field of astrobiology given the time span that the geological ages of planetary bodies encompass. This work gathers studies that have employed lipid biomarker approaches for paleoenvironmental surveys and life detection purposes in terrestrial environments with extreme conditions: hydrothermal, hyperarid, hypersaline, and highly acidic, among others; all of which are analogous to current or past conditions on Mars. Although some of the compounds discussed in this review may be abiotically synthesized, we focus on those with a biological origin, namely lipid biomarkers. Therefore, along with appropriate complementary techniques such as bulk and compound-specific stable carbon isotope analysis, this work recapitulates and reevaluates the potential of lipid biomarkers as an additional, powerful tool to interrogate whether there is life on Mars, or if there ever was.
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Affiliation(s)
- Pablo L. Finkel
- Centro de Astrobiología (CAB), CSIC-INTA, Madrid, Spain
- Department of Physics and Mathematics and Department of Automatics, University of Alcalá, Madrid, Spain
| | | | - Victor Parro
- Centro de Astrobiología (CAB), CSIC-INTA, Madrid, Spain
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Havig JR, Kuether JE, Gangidine AJ, Schroeder S, Hamilton TL. Hot Spring Microbial Community Elemental Composition: Hot Spring and Soil Inputs, and the Transition from Biocumulus to Siliceous Sinter. ASTROBIOLOGY 2021; 21:1526-1546. [PMID: 34889663 DOI: 10.1089/ast.2019.2086] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Hydrothermal systems host microbial communities that include some of the most deeply branching members of the tree of life, and recent work has suggested that terrestrial hot springs may have provided ideal conditions for the origin of life. Hydrothermal microbial communities are a potential source for biosignatures, and the presence of terrestrial hot spring deposits in 3.48 Ga rocks as well as on the surface of Mars lends weight to a need to better understand the preservation of biosignatures in these systems. Although there are general patterns of elemental enrichment in hydrothermal water dependent on physical and geochemical conditions, the elemental composition of bulk hydrothermal microbial communities (here termed biocumulus, including cellular biomass and accumulated non-cellular material) is largely unexplored. However, recent work has suggested both bulk and spatial trace element enrichment as a potential biosignature in hot spring deposits. To elucidate the elemental composition of hot spring biocumulus samples and explore the sources of those elements, we analyzed a suite of 16 elements in hot spring water samples and corresponding biocumulus from 60 hot springs sinter samples, and rock samples from 8 hydrothermal areas across Yellowstone National Park. We combined these data with values reported in literature to assess the patterns of elemental uptake into biocumulus and retention in associated siliceous sinter. Hot spring biocumuli are of biological origin, but organic carbon comprises a minor percentage of the total mass of both thermophilic chemotrophic and phototrophic biocumulus. Instead, the majority of hot spring biocumulus is inorganic material-largely silica-and the distribution of major and trace elements mimics that of surrounding rock and soil rather than the hot spring fluids. Analyses indicate a systematic loss of biologically associated elements during diagenetic transformation of biocumulus to siliceous sinter, suggesting a potential for silica sinter to preserve a trace element biosignature.
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Affiliation(s)
- Jeff R Havig
- Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, Minnesota, USA
- Department of Plant and Microbial Biology, University of Minnesota, Saint Paul, Minnesota, USA
| | - Joshua E Kuether
- Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, Minnesota, USA
| | | | - Sarah Schroeder
- Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, Minnesota, USA
| | - Trinity L Hamilton
- Department of Plant and Microbial Biology, University of Minnesota, Saint Paul, Minnesota, USA
- BioTechnology Institute, University of Minnesota, Saint Paul, Minnesota, USA
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The Ground-Based BIOMEX Experiment Verification Tests for Life Detection on Mars. Life (Basel) 2021; 11:life11111212. [PMID: 34833088 PMCID: PMC8619271 DOI: 10.3390/life11111212] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 10/27/2021] [Accepted: 10/27/2021] [Indexed: 01/10/2023] Open
Abstract
The success of an astrobiological search for life campaign on Mars, or other planetary bodies in the Solar System, relies on the detectability of past or present microbial life traces, namely, biosignatures. Spectroscopic methods require little or no sample preparation, can be repeated almost endlessly, and can be performed in contact or even remotely. Such methods are therefore ideally suited to use for the detection of biosignatures, which can be confirmed with supporting instrumentation. Here, we discuss the use of Raman and Fourier Transform Infrared (FT-IR) spectroscopies for the detection and characterization of biosignatures from colonies of the fungus Cryomyces antarcticus, grown on Martian analogues and exposed to increasing doses of UV irradiation under dried conditions. The results report significant UV-induced DNA damage, but the non-exceeding of thresholds for allowing DNA amplification and detection, while the spectral properties of the fungal melanin remained unaltered, and pigment detection and identification was achieved via complementary analytical techniques. Finally, this work found that fungal cell wall compounds, likely chitin, were not degraded, and were still detectable even after high UV irradiation doses. The implications for the preservation and detection of biosignatures in extraterrestrial environments are discussed.
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7
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He Y, Buch A, Szopa C, Millan M, Freissinet C, Navarro-Gonzalez R, Guzman M, Johnson S, Glavin D, Williams A, Eigenbrode J, Teinturier S, Malespin C, Coscia D, Bonnet JY, Lu P, Cabane M, Mahaffy P. Influence of Calcium Perchlorate on the Search for Martian Organic Compounds with MTBSTFA/DMF Derivatization. ASTROBIOLOGY 2021; 21:1137-1156. [PMID: 34534003 DOI: 10.1089/ast.2020.2393] [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: 06/13/2023]
Abstract
N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide (MTBSTFA), mixed with the solvent N,N-dimethylformamide (DMF), is used as a derivatizing reagent by the Sample Analysis at Mars (SAM) experiment onboard NASA's Curiosity rover and will soon be utilized by the Mars Organic Molecule Analyzer experiment onboard the ESA/Roscosmos Rosalind Franklin rover. The pyrolysis products of MTBSTFA, DMF, and the MTBSTFA/DMF mixtures, obtained at different temperatures, were analyzed. Two different pyrolysis modes were studied, flash pyrolysis and ramp pyrolysis (35°C/min), to evaluate the potential influence of the sample heating speed on the production of products in space chromatographs. The effect of the presence of calcium perchlorate on the pyrolysis products of MTBSTFA/DMF was also studied to ascertain the potential effect of perchlorate species known to be present at the martian surface. The results show that MTBSTFA/DMF derivatization should be applied below 300°C when using flash pyrolysis, as numerous products of MTBSTFA/DMF were formed at high pyrolysis temperatures. However, when an SAM-like ramp pyrolysis was applied, the final pyrolysis temperature did not appear to influence the degradation products of MTBSTFA/DMF. All products of MTBSTFA/DMF pyrolysis are listed in this article, providing a major database of products for the analysis of martian analog samples, meteorites, and the in situ analysis of martian rocks and soils. In addition, the presence of calcium perchlorate does not show any obvious effects on the pyrolysis of MTBSTFA/DMF: Only chloromethane and TBDMS-Cl (chloro-tertbutyldimethylsilane) were detected, whereas chlorobenzene and other chlorine-bearing compounds were not detected. However, other chlorine-bearing compounds were detected after pyrolysis of the Murchison meteorite in the presence of calcium perchlorate. This result reinforces previous suggestions that chloride-bearing compounds could be reaction products of martian samples and perchlorate.
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Affiliation(s)
- Yuanyuan He
- Laboratoire Génie des Procédés et Matériaux, CentraleSupélec, University Paris-Saclay, Gif-sur-Yvette, France
| | - Arnaud Buch
- Laboratoire Génie des Procédés et Matériaux, CentraleSupélec, University Paris-Saclay, Gif-sur-Yvette, France
| | - Cyril Szopa
- LATMOS/IPSL, UVSQ Université Paris-Saclay, Sorbonne Université, CNRS, Guyancourt, France
| | - Maëva Millan
- Department of Biology, Georgetown University, Washington, District of Columbia, USA
- Space Science Exploration Division (Code 690), NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - Caroline Freissinet
- LATMOS/IPSL, UVSQ Université Paris-Saclay, Sorbonne Université, CNRS, Guyancourt, France
| | - Rafael Navarro-Gonzalez
- Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Ciudad de México, Mexico
| | - Melissa Guzman
- LATMOS/IPSL, UVSQ Université Paris-Saclay, Sorbonne Université, CNRS, Guyancourt, France
| | - Sarah Johnson
- Department of Biology, Georgetown University, Washington, District of Columbia, USA
| | - Danny Glavin
- Space Science Exploration Division (Code 690), NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - Amy Williams
- Space Science Exploration Division (Code 690), NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
- Department of Geological Sciences, University of Florida, Gainesville, Florida, USA
| | - Jennifer Eigenbrode
- Space Science Exploration Division (Code 690), NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - Samuel Teinturier
- Space Science Exploration Division (Code 690), NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - Charles Malespin
- Space Science Exploration Division (Code 690), NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - David Coscia
- LATMOS/IPSL, UVSQ Université Paris-Saclay, Sorbonne Université, CNRS, Guyancourt, France
| | - Jean-Yves Bonnet
- Department of Geological Sciences, University of Florida, Gainesville, Florida, USA
- Telespazio France, Toulouse, France
| | - Pin Lu
- LGPM, CentraleSupélec, SFR Condorcet FR CNRS 3417, Université Paris-Saclay, Centre Européen de Biotechnologie et de Bioéconomie (CEBB), Pomacle, France
| | - Michel Cabane
- LATMOS/IPSL, UVSQ Université Paris-Saclay, Sorbonne Université, CNRS, Guyancourt, France
| | - Paul Mahaffy
- Space Science Exploration Division (Code 690), NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
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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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