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Sparks WB, Parenteau MN, Blankenship RE, Germer TA, Patty CHL, Bott KM, Telesco CM, Meadows VS. Spectropolarimetry of Primitive Phototrophs as Global Surface Biosignatures. ASTROBIOLOGY 2021; 21:219-234. [PMID: 33216615 PMCID: PMC7876348 DOI: 10.1089/ast.2020.2272] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 10/12/2020] [Indexed: 06/11/2023]
Abstract
Photosynthesis is an ancient metabolic process that began on early Earth and offers plentiful energy to organisms that can utilize it such that that they achieve global significance. The potential exists for similar processes to operate on habitable exoplanets and result in observable biosignatures. Before the advent of oxygenic photosynthesis, the most primitive phototrophs, anoxygenic phototrophs, dominated surface environments on the planet. Here, we characterize surface polarization biosignatures associated with a diverse sample of anoxygenic phototrophs and cyanobacteria, examining both pure cultures and microbial communities from the natural environment. Polarimetry is a tool that can be used to measure the chiral signature of biomolecules. Chirality is considered a universal, agnostic biosignature that is independent of a planet's biochemistry, receiving considerable interest as a target biosignature for life-detection missions. In contrast to preliminary indications from earlier work, we show that there is a diversity of distinctive circular polarization signatures, including the magnitude of the polarization, associated with the variety of chiral photosynthetic pigments and pigment complexes of anoxygenic and oxygenic phototrophs. We also show that the apparent death and release of pigments from one of the phototrophs is accompanied by an elevation of the reflectance polarization signal by an order of magnitude, which may be significant for remotely detectable environmental signatures. This work and others suggest that circular polarization signals up to ∼1% may occur, significantly stronger than previously anticipated circular polarization levels. We conclude that global surface polarization biosignatures may arise from anoxygenic and oxygenic phototrophs, which have dominated nearly 80% of the history of our rocky, inhabited planet.
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Affiliation(s)
- William B. Sparks
- SETI Institute, Mountain View, California, USA
- Space Telescope Science Institute, Baltimore, Maryland, USA
| | - Mary Niki Parenteau
- Virtual Planetary Laboratory, University of Washington, Seattle, Washington, USA
- NASA Ames Research Center, Moffett Field, California, USA
| | - Robert E. Blankenship
- Virtual Planetary Laboratory, University of Washington, Seattle, Washington, USA
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Thomas A. Germer
- National Institute of Standards and Technology, Gaithersburg, Maryland, USA
| | - Christian Herman Lucas Patty
- Institute of Plant Biology, Hungarian Academy of Sciences, Szeged, Hungary
- Space Research and Planetary Sciences, University of Bern, Bern, Switzerland
| | - Kimberly M. Bott
- Virtual Planetary Laboratory, University of Washington, Seattle, Washington, USA
- Department of Earth and Planetary Sciences, University of California, Riverside, Riverside, California, USA
| | - Charles M. Telesco
- Department of Astronomy, University of Florida, Gainesville, Florida, USA
| | - Victoria S. Meadows
- Virtual Planetary Laboratory, University of Washington, Seattle, Washington, USA
- Department of Astronomy, University of Washington, Seattle, Washington, USA
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Taubner RS, Olsson-Francis K, Vance SD, Ramkissoon NK, Postberg F, de Vera JP, Antunes A, Camprubi Casas E, Sekine Y, Noack L, Barge L, Goodman J, Jebbar M, Journaux B, Karatekin Ö, Klenner F, Rabbow E, Rettberg P, Rückriemen-Bez T, Saur J, Shibuya T, Soderlund KM. Experimental and Simulation Efforts in the Astrobiological Exploration of Exooceans. SPACE SCIENCE REVIEWS 2020; 216:9. [PMID: 32025060 PMCID: PMC6977147 DOI: 10.1007/s11214-020-0635-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 01/06/2020] [Indexed: 05/05/2023]
Abstract
The icy satellites of Jupiter and Saturn are perhaps the most promising places in the Solar System regarding habitability. However, the potential habitable environments are hidden underneath km-thick ice shells. The discovery of Enceladus' plume by the Cassini mission has provided vital clues in our understanding of the processes occurring within the interior of exooceans. To interpret these data and to help configure instruments for future missions, controlled laboratory experiments and simulations are needed. This review aims to bring together studies and experimental designs from various scientific fields currently investigating the icy moons, including planetary sciences, chemistry, (micro-)biology, geology, glaciology, etc. This chapter provides an overview of successful in situ, in silico, and in vitro experiments, which explore different regions of interest on icy moons, i.e. a potential plume, surface, icy shell, water and brines, hydrothermal vents, and the rocky core.
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Affiliation(s)
- Ruth-Sophie Taubner
- Archaea Biology and Ecogenomics Division, University of Vienna, Vienna, Austria
| | | | | | | | | | | | - André Antunes
- State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology, Macau SAR, China
| | | | | | - Lena Noack
- Freie Universität Berlin, Berlin, Germany
| | | | | | | | | | | | | | - Elke Rabbow
- German Aerospace Center (DLR), Cologne, Germany
| | | | | | | | - Takazo Shibuya
- Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, Japan
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Taubner RS, Baumann LMF, Bauersachs T, Clifford EL, Mähnert B, Reischl B, Seifert R, Peckmann J, Rittmann SKMR, Birgel D. Membrane Lipid Composition and Amino Acid Excretion Patterns of Methanothermococcus okinawensis Grown in the Presence of Inhibitors Detected in the Enceladian Plume. Life (Basel) 2019; 9:E85. [PMID: 31739502 PMCID: PMC6958431 DOI: 10.3390/life9040085] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 11/08/2019] [Accepted: 11/11/2019] [Indexed: 01/05/2023] Open
Abstract
Lipids and amino acids are regarded as important biomarkers for the search for extraterrestrial life in the Solar System. Such biomarkers may be used to trace methanogenic life on other planets or moons in the Solar System, such as Saturn's icy moon Enceladus. However, little is known about the environmental conditions shaping the synthesis of lipids and amino acids. Here, we present the lipid production and amino acid excretion patterns of the methanogenic archaeon Methanothermococcus okinawensis after exposing it to different multivariate concentrations of the inhibitors ammonium, formaldehyde, and methanol present in the Enceladian plume. M. okinawensis shows different patterns of lipid and amino acids excretion, depending on the amount of these inhibitors in the growth medium. While methanol did not show a significant impact on growth, lipid or amino acid production rates, ammonium and formaldehyde strongly affected these parameters. These findings are important for understanding the eco-physiology of methanogens on Earth and have implications for the use of biomarkers as possible signs of extraterrestrial life for future space missions in the Solar System.
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Affiliation(s)
- Ruth-Sophie Taubner
- Archaea Physiology & Biotechnology Group, Archaea Biology and Ecogenomics Division, Department of Ecogenomics and Systems Biology, Universität Wien, 1010 Vienna, Austria; (R.-S.T.); (B.R.); (S.K.-M.R.R.)
| | - Lydia M. F. Baumann
- Institute for Geology, Center for Earth System Research and Sustainability, Universität Hamburg, 20146 Hamburg, Germany; (L.M.F.B.); (R.S.); (J.P.)
| | - Thorsten Bauersachs
- Institute of Geosciences, Department of Organic Geochemistry, Christian-Albrechts-Universität, 24118 Kiel, Germany;
| | - Elisabeth L. Clifford
- Department of Limnology and Bio-Oceanography, Universität Wien, 1010 Vienna, Austria; (E.L.C.); (B.M.)
| | - Barbara Mähnert
- Department of Limnology and Bio-Oceanography, Universität Wien, 1010 Vienna, Austria; (E.L.C.); (B.M.)
| | - Barbara Reischl
- Archaea Physiology & Biotechnology Group, Archaea Biology and Ecogenomics Division, Department of Ecogenomics and Systems Biology, Universität Wien, 1010 Vienna, Austria; (R.-S.T.); (B.R.); (S.K.-M.R.R.)
| | - Richard Seifert
- Institute for Geology, Center for Earth System Research and Sustainability, Universität Hamburg, 20146 Hamburg, Germany; (L.M.F.B.); (R.S.); (J.P.)
| | - Jörn Peckmann
- Institute for Geology, Center for Earth System Research and Sustainability, Universität Hamburg, 20146 Hamburg, Germany; (L.M.F.B.); (R.S.); (J.P.)
| | - Simon K.-M. R. Rittmann
- Archaea Physiology & Biotechnology Group, Archaea Biology and Ecogenomics Division, Department of Ecogenomics and Systems Biology, Universität Wien, 1010 Vienna, Austria; (R.-S.T.); (B.R.); (S.K.-M.R.R.)
| | - Daniel Birgel
- Institute for Geology, Center for Earth System Research and Sustainability, Universität Hamburg, 20146 Hamburg, Germany; (L.M.F.B.); (R.S.); (J.P.)
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Survival of Radioresistant Bacteria on Europa’s Surface after Pulse Ejection of Subsurface Ocean Water. GEOSCIENCES 2018. [DOI: 10.3390/geosciences9010009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We briefly present preliminary results of our study of the radioresistant bacteria in a low temperature and pressure and high-radiation environment and hypothesize the ability of microorganisms to survive extraterrestrial high-radiation environments, such as the icy surface of Jupiter’s moon, Europa. In this study, samples containing a strain of Deinococcus radiodurans VKM B-1422T embedded into a simulated version of Europa’s ice were put under extreme environmental (−130 °C, 0.01 mbar) and radiation conditions using a specially designed experimental vacuum chamber. The samples were irradiated with 5, 10, 50, and 100 kGy doses and subsequently studied for residual viable cells. We estimate the limit of the accumulated dose that viable cells in those conditions could withstand at 50 kGy. Combining our numerical modelling of the accumulated dose in ice with observations of water eruption events on Europa, we hypothesize that in the case of such events, it is possible that putative extraterrestrial organisms might retain viability in a dormant state for up to 10,000 years, and could be sampled and studied by future probe missions.
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Porco CC. A Community Grows around the Geysering World of Enceladus. ASTROBIOLOGY 2017; 17:815-819. [PMID: 28742370 PMCID: PMC5610423 DOI: 10.1089/ast.2017.1711] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The discovery by NASA's Cassini mission at Saturn in 2005 of a large plume of material erupting from the south polar terrain of Enceladus, sourced within a subsurface ocean of salty liquid water laced with organic compounds, has brought together scientists from a diverse range of disciplines over the last decade to evaluate this small moon's potential for extraterrestrial life. The collection of papers published today in Astrobiology, as the mission draws to a close, is the outcome of our most recent meeting at UC Berkeley in June 2016. Key Words: Enceladus-Enceladus Focus Group-Ocean world-Search for biosignatures. Astrobiology 17, 815-819.
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Affiliation(s)
- Carolyn C Porco
- University of California , Berkeley, California
- Space Science Institute , Boulder, Colorado
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