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Enya K, Yamagishi A, Kobayashi K, Yoshimura Y, Tasker EJ. A Comparative Study of Methods for Detecting Extraterrestrial Life in Exploration Missions to Mars and the Solar System II: Targeted Characteristics, Detection Techniques, and Their Combination for Survey, Detection, and Analysis. ASTROBIOLOGY 2023; 23:1099-1117. [PMID: 37768711 PMCID: PMC10616949 DOI: 10.1089/ast.2022.0148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2022] [Accepted: 08/15/2023] [Indexed: 09/29/2023]
Abstract
We present a comparative study of the methods used in the search for extraterrestrial microorganism life, including a summary table where different life-detection techniques can be easily compared as an aid to mission and instrument design aimed at life detection. This is an extension of previous study, where detection techniques for a series of target characteristics and molecules that could constitute a positive life detection were evaluated. This comparison has been extended with a particular consideration to sources of false positives, the causes of negative detection, the results of detection techniques when presented regarding terrestrial life, and additional science objectives that could be achieved outside the primary aim of detecting life. These additions address both the scientific and programmatic side of exploration mission design, where a successful proposal must demonstrate probable outcomes and be able to return valuable results even if no life is found. The applicability of the life detection techniques is considered for Earth life, Earth-independent life (life emerging independently from that on Earth,) and Earth-kin life (sharing a common ancestor with life on Earth), and techniques effective in detecting Earth life should also be useful in the detection of Earth-kin life. However, their applicability is not guaranteed for Earth-independent life. As found in our previous study, there exists no realistic single detection method that can conclusively determine the discovery of extraterrestrial life, and no method is superior to all others. In this study, we further consider combinations of detection techniques and identify imaging as a valuable addition to molecule detection methods, even in cases where there is insufficient resolution to observe the detailed morphology of a microbial cell. The search for extraterrestrial life is further divided into a survey-and-detection and analysis-and-conclusion step. These steps benefit from different detection techniques, but imaging is necessary for both parts.
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Affiliation(s)
- Keigo Enya
- Department of Solar System Sciences, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan
- Space and Astronautical Science, Graduate Institute for Advanced Studies, SOKENDAI, Hayama, Japan
| | - Akihiko Yamagishi
- Department of Applied Life Science, School of Life Science, Tokyo University of Pharmacy and Life Sciences, Tokyo, Japan
| | - Kensei Kobayashi
- Department of Chemistry, Yokohama National University, Yokohama, Japan
- Department of Earth and Planetary Science, Tokyo Institute of Technology, Tokyo, Japan
| | | | - Elizabeth J. Tasker
- Department of Solar System Sciences, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan
- Space and Astronautical Science, Graduate Institute for Advanced Studies, SOKENDAI, Hayama, Japan
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Ernst L, Barayeu U, Hädeler J, Dick TP, Klatt JM, Keppler F, Rebelein JG. Methane formation driven by light and heat prior to the origin of life and beyond. Nat Commun 2023; 14:4364. [PMID: 37528079 PMCID: PMC10394037 DOI: 10.1038/s41467-023-39917-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 07/03/2023] [Indexed: 08/03/2023] Open
Abstract
Methane is a potent greenhouse gas, which likely enabled the evolution of life by keeping the early Earth warm. Here, we demonstrate routes towards abiotic methane and ethane formation under early-earth conditions from methylated sulfur and nitrogen compounds with prebiotic origin. These compounds are demethylated in Fenton reactions governed by ferrous iron and reactive oxygen species (ROS) produced by light and heat in aqueous environments. After the emergence of life, this phenomenon would have greatly intensified in the anoxic Archean by providing methylated sulfur and nitrogen substrates. This ROS-driven Fenton chemistry can occur delocalized from serpentinization across Earth's humid realm and thereby substantially differs from previously suggested methane formation routes that are spatially restricted. Here, we report that Fenton reactions driven by light and heat release methane and ethane and might have shaped the chemical evolution of the atmosphere prior to the origin of life and beyond.
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Affiliation(s)
- Leonard Ernst
- Max Planck Institute for Terrestrial Microbiology, 35043, Marburg, Germany.
- Center for Synthetic Microbiology (SYNMIKRO), 35032, Marburg, Germany.
| | - Uladzimir Barayeu
- Division of Redox Regulation, German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, 69120, Heidelberg, Germany
- Faculty of Biosciences, Heidelberg University, 69120, Heidelberg, Germany
| | - Jonas Hädeler
- Institute of Earth Sciences, Heidelberg University, 69120, Heidelberg, Germany
| | - Tobias P Dick
- Division of Redox Regulation, German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, 69120, Heidelberg, Germany
- Faculty of Biosciences, Heidelberg University, 69120, Heidelberg, Germany
| | - Judith M Klatt
- Center for Synthetic Microbiology (SYNMIKRO), 35032, Marburg, Germany
- Microcosm Earth Center, Max Planck Institute for Terrestrial Microbiology & Philipps University Marburg, 35032, Marburg, Germany
- Biogeochemistry Group, Department for Chemistry, Philipps University Marburg, 35032, Marburg, Germany
| | - Frank Keppler
- Institute of Earth Sciences, Heidelberg University, 69120, Heidelberg, Germany
- Heidelberg Center for the Environment HCE, Heidelberg University, 69120, Heidelberg, Germany
| | - Johannes G Rebelein
- Max Planck Institute for Terrestrial Microbiology, 35043, Marburg, Germany.
- Center for Synthetic Microbiology (SYNMIKRO), 35032, Marburg, Germany.
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Mahjoub A, Altwegg K, Poston MJ, Rubin M, Hodyss R, Choukroun M, Ehlmann BL, Hänni N, Brown ME, Blacksberg J, Eiler JM, Hand KP. Complex organosulfur molecules on comet 67P: Evidence from the ROSINA measurements and insights from laboratory simulations. SCIENCE ADVANCES 2023; 9:eadh0394. [PMID: 37285429 DOI: 10.1126/sciadv.adh0394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 05/01/2023] [Indexed: 06/09/2023]
Abstract
The ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) instrument aboard the Rosetta mission revolutionized our understanding of cometary material composition. One of Rosetta's key findings is the complexity of the composition of comet 67P/Churyumov-Gerasimenko. Here, we used ROSINA data to analyze dust particles that were volatilized during a dust event in September 2016 and report the detection of large organosulfur species and an increase in the abundances of sulfurous species previously detected in the coma. Our data support the presence of complex sulfur-bearing organics on the surface of the comet. In addition, we conducted laboratory simulations that show that this material may have formed from chemical reactions that were initiated by the irradiation of mixed ices containing H2S. Our findings highlight the importance of sulfur chemistry in cometary and precometary materials and the possibility of characterizing organosulfur materials in other comets and small icy bodies using the James Webb Space Telescope.
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Affiliation(s)
- Ahmed Mahjoub
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
- Space Science Institute, 4765 Walnut St, Suite B, Boulder, CO 80301, USA
| | - Kathrin Altwegg
- Physikalisches Institut, University of Bern, Bern, Switzerland
| | | | - Martin Rubin
- Physikalisches Institut, University of Bern, Bern, Switzerland
| | - Robert Hodyss
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
| | - Mathieu Choukroun
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
| | - Bethany L Ehlmann
- Division of Planetary and Space Sciences, Caltech, Pasadena, CA 91125, USA
| | - Nora Hänni
- Physikalisches Institut, University of Bern, Bern, Switzerland
| | - Michael E Brown
- Division of Planetary and Space Sciences, Caltech, Pasadena, CA 91125, USA
| | - Jordana Blacksberg
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
| | - John M Eiler
- Division of Planetary and Space Sciences, Caltech, Pasadena, CA 91125, USA
| | - Kevin P Hand
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
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Bacterial Biological Factories Intended for the Desulfurization of Petroleum Products in Refineries. FERMENTATION-BASEL 2023. [DOI: 10.3390/fermentation9030211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Abstract
The removal of sulfur by deep hydrodesulfurization is expensive and environmentally unfriendly. Additionally, sulfur is not separated completely from heterocyclic poly-aromatic compounds. In nature, several microorganisms (Rhodococcus erythropolis IGTS8, Gordonia sp., Bacillus sp., Mycobacterium sp., Paenibacillus sp. A11-2 etc.) have been reported to remove sulfur from petroleum fractions. All these microbes remove sulfur from recalcitrant organosulfur compounds via the 4S pathway, showing potential for some organosulfur compounds only. Activity up to 100 µM/g dry cell weights is needed to meet the current demand for desulfurization. The present review describes the desulfurization capability of various microorganisms acting on several kinds of sulfur sources. Genetic engineering approaches on Gordonia sp. and other species have revealed a variety of good substrate ranges of desulfurization, both for aliphatic and aromatic organosulfur compounds. Whole genome sequence analysis and 4S pathway inhibition by a pTeR group inhibitor have also been discussed. Now, emphasis is being placed on how to commercialize the microbes for industrial-level applications by incorporating biodesulfurization into hydrodesulfurization systems. Thus, this review summarizes the potentialities of microbes for desulfurization of petroleum. The information included in this review could be useful for researchers as well as the economical commercialization of bacteria in petroleum industries.
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A Closer Look at Non-random Patterns Within Chemistry Space for a Smaller, Earlier Amino Acid Alphabet. J Mol Evol 2022; 90:307-323. [PMID: 35666290 DOI: 10.1007/s00239-022-10061-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 05/11/2022] [Indexed: 10/18/2022]
Abstract
Recent findings, in vitro and in silico, are strengthening the idea of a simpler, earlier stage of genetically encoded proteins which used amino acids produced by prebiotic chemistry. These findings motivate a re-examination of prior work which has identified unusual properties of the set of twenty amino acids found within the full genetic code, while leaving it unclear whether similar patterns also characterize the subset of prebiotically plausible amino acids. We have suggested previously that this ambiguity may result from the low number of amino acids recognized by the definition of prebiotic plausibility used for the analysis. Here, we test this hypothesis using significantly updated data for organic material detected within meteorites, which contain several coded and non-coded amino acids absent from prior studies. In addition to confirming the well-established idea that "late" arriving amino acids expanded the chemistry space encoded by genetic material, we find that a prebiotically plausible subset of coded amino acids generally emulates the patterns found in the full set of 20, namely an exceptionally broad and even distribution of volumes and an exceptionally even distribution of hydrophobicities (quantified as logP) over a narrow range. However, the strength of this pattern varies depending on both the size and composition the library used to create a background (null model) for a random alphabet, and the precise definition of exactly which amino acids were present in a simpler, earlier code. Findings support the idea that a small sample size of amino acids caused previous ambiguous results, and further improvements in meteorite analysis, and/or prebiotic simulations will further clarify the nature and extent of unusual properties. We discuss the case of sulfur-containing amino acids as a specific and clear example and conclude by reviewing the potential impact of better understanding the chemical "logic" of a smaller forerunner to the standard amino acid alphabet.
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