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Rojano-Nisimura AM, Grismore KB, Ruzek JS, Avila JL, Contreras LM. The Post-Transcriptional Regulatory Protein CsrA Amplifies Its Targetome through Direct Interactions with Stress-Response Regulatory Hubs: The EvgA and AcnA Cases. Microorganisms 2024; 12:636. [PMID: 38674581 PMCID: PMC11052181 DOI: 10.3390/microorganisms12040636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2024] [Revised: 03/08/2024] [Accepted: 03/19/2024] [Indexed: 04/28/2024] Open
Abstract
Global rewiring of bacterial gene expressions in response to environmental cues is mediated by regulatory proteins such as the CsrA global regulator from E. coli. Several direct mRNA and sRNA targets of this protein have been identified; however, high-throughput studies suggest an expanded RNA targetome for this protein. In this work, we demonstrate that CsrA can extend its network by directly binding and regulating the evgA and acnA transcripts, encoding for regulatory proteins. CsrA represses EvgA and AcnA expression and disrupting the CsrA binding sites of evgA and acnA, results in broader gene expression changes to stress response networks. Specifically, altering CsrA-evgA binding impacts the genes related to acidic stress adaptation, and disrupting the CsrA-acnA interaction affects the genes involved in metal-induced oxidative stress responses. We show that these interactions are biologically relevant, as evidenced by the improved tolerance of evgA and acnA genomic mutants depleted of CsrA binding sites when challenged with acid and metal ions, respectively. We conclude that EvgA and AcnA are intermediate regulatory hubs through which CsrA can expand its regulatory role. The indirect CsrA regulation of gene networks coordinated by EvgA and AcnA likely contributes to optimizing cellular resources to promote exponential growth in the absence of stress.
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Affiliation(s)
| | - Kobe B. Grismore
- McKetta Department of Chemical Engineering, The University of Texas at Austin, 200 E. Dean Keeton St. Stop C0400, Austin, TX 78712, USA; (K.B.G.); (J.S.R.); (J.L.A.)
| | - Josie S. Ruzek
- McKetta Department of Chemical Engineering, The University of Texas at Austin, 200 E. Dean Keeton St. Stop C0400, Austin, TX 78712, USA; (K.B.G.); (J.S.R.); (J.L.A.)
| | - Jacqueline L. Avila
- McKetta Department of Chemical Engineering, The University of Texas at Austin, 200 E. Dean Keeton St. Stop C0400, Austin, TX 78712, USA; (K.B.G.); (J.S.R.); (J.L.A.)
| | - Lydia M. Contreras
- Department of Molecular Biosciences, The University of Texas at Austin, 100 East 24th St. Stop A5000, Austin, TX 78712, USA;
- McKetta Department of Chemical Engineering, The University of Texas at Austin, 200 E. Dean Keeton St. Stop C0400, Austin, TX 78712, USA; (K.B.G.); (J.S.R.); (J.L.A.)
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Naz N, Harandi BF, Newmark J, Kounaves SP. Microbial growth in actual martian regolith in the form of Mars meteorite EETA79001. COMMUNICATIONS EARTH & ENVIRONMENT 2023; 4:381. [PMID: 38665180 PMCID: PMC11041791 DOI: 10.1038/s43247-023-01042-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 10/04/2023] [Indexed: 04/28/2024]
Abstract
Studies to understand the growth of organisms on Mars are hampered by the use of simulants to duplicate martian mineralogy and chemistry. Even though such materials are improving, no terrestrial simulant can replace a real martian sample. Here we report the use of actual martian regolith, in the form of Mars meteorite EETA79001 sawdust, to demonstrate its ability to support the growth of four microorganisms, E. coli. Eucapsis sp., Chr20-20201027-1, and P. halocryophilus, for up to 23 days under terrestrial conditions using regolith:water ratios from 4:1 to 1:10. If the EETA79001 sawdust is widely representative of regolith on the martian surface, our results imply that microbial life under appropriate conditions could have been present on Mars in the past and/or today in the subsurface, and that the regolith does not contain any bactericidal agents. The results of our study have implications not only for putative martian microbial life but also for building bio-sustainable human habitats on Mars.
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Affiliation(s)
- Neveda Naz
- Department of Chemistry, Tufts University, Medford, MA 02155 USA
| | - Bijan F. Harandi
- Department of Chemistry, Tufts University, Medford, MA 02155 USA
| | - Jacob Newmark
- Department of Chemistry, Tufts University, Medford, MA 02155 USA
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3
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Vrankar D, Verseux C, Heinicke C. An airlock concept to reduce contamination risks during the human exploration of Mars. NPJ Microgravity 2023; 9:81. [PMID: 37805607 PMCID: PMC10560228 DOI: 10.1038/s41526-023-00329-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 09/22/2023] [Indexed: 10/09/2023] Open
Abstract
Protecting the Martian environment from contamination with terrestrial microbes is generally seen as essential to the scientific exploration of Mars, especially when it comes to the search for indigenous life. However, while companies and space agencies aim at getting to Mars within ambitious timelines, the state-of-the-art planetary protection measures are only applicable to uncrewed spacecraft. With this paper, we attempt to reconcile these two conflicting goals: the human exploration of Mars and its protection from biological contamination. In our view, the one nominal mission activity that is most prone to introducing terrestrial microbes into the Martian environment is when humans leave their habitat to explore the Martian surface, if one were to use state-of-the-art airlocks. We therefore propose to adapt airlocks specifically to the goals of planetary protection. We suggest a concrete concept for such an adapted airlock, believing that only practical and implementable solutions will be followed by human explorers in the long run.
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Affiliation(s)
- Daniel Vrankar
- Faculty of Business and Economics, Technische Universität Dresden, Helmholtzstraße 10, 01069, Dresden, Germany
- Center of Applied Space Technology and Microgravity - ZARM, University of Bremen, Am Fallturm 2, 28359, Bremen, Germany
| | - Cyprien Verseux
- Center of Applied Space Technology and Microgravity - ZARM, University of Bremen, Am Fallturm 2, 28359, Bremen, Germany
| | - Christiane Heinicke
- Center of Applied Space Technology and Microgravity - ZARM, University of Bremen, Am Fallturm 2, 28359, Bremen, Germany.
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4
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McDonagh F, Cormican M, Morris D, Burke L, Singh NK, Venkateswaran K, Miliotis G. Medical Astro-Microbiology: Current Role and Future Challenges. J Indian Inst Sci 2023; 103:1-26. [PMID: 37362850 PMCID: PMC10082442 DOI: 10.1007/s41745-023-00360-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 02/03/2023] [Indexed: 06/28/2023]
Abstract
The second and third decades of the twenty-first century are marked by a flourishing of space technology which may soon realise human aspirations of a permanent multiplanetary presence. The prevention, control and management of infection with microbial pathogens is likely to play a key role in how successful human space aspirations will become. This review considers the emerging field of medical astro-microbiology. It examines the current evidence regarding the risk of infection during spaceflight via host susceptibility, alterations to the host's microbiome as well as exposure to other crew members and spacecraft's microbiomes. It also considers the relevance of the hygiene hypothesis in this regard. It then reviews the current evidence related to infection risk associated with microbial adaptability in spaceflight conditions. There is a particular focus on the International Space Station (ISS), as one of the only two crewed objects in low Earth orbit. It discusses the effects of spaceflight related stressors on viruses and the infection risks associated with latent viral reactivation and increased viral shedding during spaceflight. It then examines the effects of the same stressors on bacteria, particularly in relation to changes in virulence and drug resistance. It also considers our current understanding of fungal adaptability in spaceflight. The global public health and environmental risks associated with a possible re-introduction to Earth of invasive species are also briefly discussed. Finally, this review examines the largely unknown microbiology and infection implications of celestial body habitation with an emphasis placed on Mars. Overall, this review summarises much of our current understanding of medical astro-microbiology and identifies significant knowledge gaps. Graphical Abstract
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Affiliation(s)
- Francesca McDonagh
- Antimicrobial Resistance and Microbial Ecology Group, School of Medicine, University of Galway, Galway, Ireland
| | - Martin Cormican
- Antimicrobial Resistance and Microbial Ecology Group, School of Medicine, University of Galway, Galway, Ireland
- Department of Medical Microbiology, Galway University Hospitals, Galway, Ireland
| | - Dearbháile Morris
- Antimicrobial Resistance and Microbial Ecology Group, School of Medicine, University of Galway, Galway, Ireland
| | - Liam Burke
- Antimicrobial Resistance and Microbial Ecology Group, School of Medicine, University of Galway, Galway, Ireland
| | - Nitin Kumar Singh
- Biotechnology and Planetary Protection Group, NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA USA
| | - Kasthuri Venkateswaran
- Biotechnology and Planetary Protection Group, NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA USA
| | - Georgios Miliotis
- Antimicrobial Resistance and Microbial Ecology Group, School of Medicine, University of Galway, Galway, Ireland
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5
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Matthews A, Lima-Zaloumis J, Debes Ii RV, Boyer G, Trembath-Reichert E. Heterotrophic Growth Dominates in the Most Extremotolerant Extremophile Cultures. ASTROBIOLOGY 2023; 23:446-459. [PMID: 36723486 DOI: 10.1089/ast.2022.0100] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Due to their ability to withstand "extreme" conditions, Earth's extremophilic organisms can constrain habitability windows for other planetary systems. However, there are many other considerations to microbial growth requirements beyond environmental extremes, such as nutrient availability. Here, we conduct a literature review of the most extremotolerant extremophiles in culture, since working with cultured organisms allows environmental and nutrient variables to be constrained with a high level of specificity. We generated a database that includes the isolation environment, carbon source(s) used, and growth preferences across temperature, pressure, salinity, and pH extremes. We found that the "most extreme" conditions were primarily sustained by heterotrophs, except for hyperthermophiles. These results highlight the importance of considering organic carbon availability when using extremophiles for habitability constraints. We also interrogated polyextreme potential across temperature, pressure, salinity, and pH conditions. Our findings suggest that the investigation of growth tolerance rather than growth optimum may reveal wider habitability parameters. Overall, these results highlight the potential polyextremes, environments, nutrient requirements, and additional analyses that could improve the application of cultured investigations to astrobiology questions.
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Affiliation(s)
- Adrianna Matthews
- School of Earth and Space Exploration, Arizona State University, Tempe, Arizona, USA
| | | | - R Vincent Debes Ii
- School of Earth and Space Exploration, Arizona State University, Tempe, Arizona, USA
| | - Grayson Boyer
- School of Earth and Space Exploration, Arizona State University, Tempe, Arizona, USA
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6
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Olsson-Francis K, Doran PT, Ilyin V, Raulin F, Rettberg P, Kminek G, Mier MPZ, Coustenis A, Hedman N, Shehhi OA, Ammannito E, Bernardini J, Fujimoto M, Grasset O, Groen F, Hayes A, Gallagher S, Kumar K P, Mustin C, Nakamura A, Seasly E, Suzuki Y, Peng J, Prieto-Ballesteros O, Sinibaldi S, Xu K, Zaitsev M. The COSPAR Planetary Protection Policy for robotic missions to Mars: A review of current scientific knowledge and future perspectives. LIFE SCIENCES IN SPACE RESEARCH 2023; 36:27-35. [PMID: 36682826 DOI: 10.1016/j.lssr.2022.12.001] [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: 10/03/2022] [Revised: 12/07/2022] [Accepted: 12/09/2022] [Indexed: 06/17/2023]
Abstract
Planetary protection guidance for martian exploration has become a notable point of discussion over the last decade. This is due to increased scientific interest in the habitability of the red planet with updated techniques, missions becoming more attainable by smaller space agencies, and both the private sector and governments engaging in activities to facilitate commercial opportunities and human-crewed missions. The international standards for planetary protection have been developed through consultation with the scientific community and the space agencies by the Committee on Space Research's (COSPAR) Panel on Planetary Protection, which provides guidance for compliance with the Outer Space Treaty of 1967. In 2021, the Panel evaluated recent scientific data and literature regarding the planetary protection requirements for Mars and the implications of this on the guidelines. In this paper, we discuss the COSPAR Planetary Protection Policy for Mars, review the new scientific findings and discuss the next steps required to enable the next generation of robotic missions to Mars.
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Affiliation(s)
- Karen Olsson-Francis
- AstrobiologyOU, Faculty of Science, Technology, Engineering and Mathematics, The Open University, Milton Keynes, UK.
| | - Peter T Doran
- Department of Geology and Geophysics, Louisiana State, Baton Rouge, Louisiana, USA
| | - Vyacheslav Ilyin
- Institute for Biomedical Problems, Russian Academy of Sciences, Moscow, Russia
| | - Francois Raulin
- Univ Paris Est Cr Univ Paris Est Créteil and Université Paris Cité, CNRS, LISA, F-94010 Créteil, France
| | - Petra Rettberg
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Radiation Biology Department, Research Group Astrobiology, 51147 Cologne, Germany
| | | | - María-Paz Zorzano Mier
- Centro deAstrobiología (CAB), CSIC-INTA, Carretera de Ajalvir km 4, 28850 Torrejón de Ardoz, Madrid, Spain
| | - Athena Coustenis
- LESIA, Paris Observatory, PSL University, CNRS, Paris University, 92195 Meudon Cedex, France
| | - Niklas Hedman
- Committee, Policy and Legal Affairs Section, Office for Outer Space Affairs, United Nations Office at Vienna, Austria
| | | | | | - James Bernardini
- Office of Safety and Mission Assurance, NASA Headquarters, Washington, DC 20546, USA
| | - Masaki Fujimoto
- Japan Aerospace Exploration Agency (JAXA), Institute of Space and Astronautical Science (ISAS), Kanagawa, Japan
| | | | - Frank Groen
- Office of Safety and Mission Assurance, NASA Headquarters, Washington, DC 20546, USA
| | - Alex Hayes
- Cornell University, Ithaca, NY 14853-6801, USA
| | - Sarah Gallagher
- Institute of Earth and Space Exploration, Western University, London, Ontario, Canada
| | | | | | - Akiko Nakamura
- Department of Earth and Planetary Science, The University of Tokyo,7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Elaine Seasly
- Office of Safety and Mission Assurance, NASA Headquarters, Washington, DC 20546, USA
| | - Yohey Suzuki
- Department of Earth and Planetary Science, The University of Tokyo,7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Jing Peng
- China National Space Administration, Beijing, China
| | - Olga Prieto-Ballesteros
- Centro deAstrobiología (CAB), CSIC-INTA, Carretera de Ajalvir km 4, 28850 Torrejón de Ardoz, Madrid, Spain
| | | | - Kanyan Xu
- Laboratory of Space Microbiology, Shenzhou Space Biotechnology Group, Chinese Academy of Space Technology, Beijing, China
| | - Maxim Zaitsev
- Planetary Physics Dept., Space Research Inst. of Russian Acad. of Sciences, Moscow, Russia
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7
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Weingarten EA, Zee PC, Jackson CR. Microbial Communities in Saltpan Sediments Show Tolerance to Mars Analog Conditions, but Susceptibility to Chloride and Perchlorate Toxicity. ASTROBIOLOGY 2022; 22:838-850. [PMID: 35731161 PMCID: PMC9464085 DOI: 10.1089/ast.2021.0132] [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: 08/12/2021] [Accepted: 02/28/2022] [Indexed: 06/15/2023]
Abstract
Brines at or near the surface of present-day Mars are a potential explanation for seasonally recurring dark streaks on the walls of craters, termed recurring slope lineae (RSL). Deliquescence and freezing point depression are possible drivers of brine stability, attributable to the high salinity observed in martian regolith including chlorides and perchlorates. Investigation of life, which may inhabit RSL, and the cellular mechanisms necessary for survival, must consider the tolerance of highly variable hydration, freeze-thaw cycles, and high osmolarity in addition to the anaerobic, oligotrophic, and irradiated environment. We propose the saltpan, an ephemeral, hypersaline wetland as an analogue for putative RSL hydrology. Saltpan sediment archaeal and bacterial communities showed tolerance of the Mars-analogous atmosphere, hydration, minerology, salinity, and temperature. Although active growth and a shift to well-adapted taxa were observed, susceptibility to low-concentration chloride and perchlorate addition suggested that such a composition was insufficient for beneficial water retention relative to added salt stress.
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Affiliation(s)
- Eric A. Weingarten
- Department of Biology, University of Mississippi, University, Mississippi, USA
- U.S. Army Engineer Research and Development Center, Vicksburg, Mississippi, USA
| | - Peter C. Zee
- Department of Biology, University of Mississippi, University, Mississippi, USA
| | - Colin R. Jackson
- Department of Biology, University of Mississippi, University, Mississippi, USA
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8
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Rzymski P, Poniedziałek B, Hippmann N, Kaczmarek Ł. Screening the Survival of Cyanobacteria Under Perchlorate Stress. Potential Implications for Mars In Situ Resource Utilization. ASTROBIOLOGY 2022; 22:672-684. [PMID: 35196144 PMCID: PMC9233533 DOI: 10.1089/ast.2021.0100] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 01/21/2022] [Indexed: 06/14/2023]
Abstract
Cyanobacteria are good candidates for various martian applications as a potential source of food, fertilizer, oxygen, and biofuels. However, the increased levels of highly toxic perchlorates may be a significant obstacle to their growth on Mars. Therefore, in the present study, 17 cyanobacteria strains that belong to Chroococcales, Chroococcidiopsidales, Nostocales, Oscillatoriales, Pleurocapsales, and Synechococcales were exposed to 0.25-1.0% magnesium perchlorate concentrations (1.5-6.0 mM ClO4- ions) for 14 days. The exposure to perchlorate induced at least partial inhibition of growth in all tested strains, although five of them were able to grow at the highest perchlorate concentration: Chroococcidiopsis thermalis, Leptolyngbya foveolarum, Arthronema africanum, Geitlerinema cf. acuminatum, and Cephalothrix komarekiana. Chroococcidiopsis sp. Chroococcidiopsis cubana demonstrated growth up to 0.5%. Strains that maintained growth displayed significantly increased malondialdehyde content, indicating perchlorate-induced oxidative stress, whereas the chlorophyll a/carotenoids ratio tended to be decreased. The results show that selected cyanobacteria from different orders can tolerate perchlorate concentrations typical for the martian regolith, indicating that they may be useful in Mars exploration. Further studies are required to elucidate the biochemical and molecular basis for the perchlorate tolerance in selected cyanobacteria.
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Affiliation(s)
- Piotr Rzymski
- Department of Environmental Medicine, Poznan University of Medical Sciences, Poznań, Poland
- Integrated Science Association (ISA), Universal Scientific Education and Research Network (USERN), Poznań, Poland
| | - Barbara Poniedziałek
- Department of Environmental Medicine, Poznan University of Medical Sciences, Poznań, Poland
| | - Natalia Hippmann
- Department of Environmental Medicine, Poznan University of Medical Sciences, Poznań, Poland
| | - Łukasz Kaczmarek
- Department of Animal Taxonomy and Ecology, Faculty of Biology, Adam Mickiewicz University in Poznań, Poznań, Poland
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9
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Kelbrick M, Oliver JAW, Ramkissoon NK, Dugdale A, Stephens BP, Kucukkilic-Stephens E, Schwenzer SP, Antunes A, Macey MC. Microbes from Brine Systems with Fluctuating Salinity Can Thrive under Simulated Martian Chemical Conditions. Life (Basel) 2021; 12:life12010012. [PMID: 35054406 PMCID: PMC8781782 DOI: 10.3390/life12010012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/15/2021] [Accepted: 12/18/2021] [Indexed: 12/01/2022] Open
Abstract
The waters that were present on early Mars may have been habitable. Characterising environments analogous to these waters and investigating the viability of their microbes under simulated martian chemical conditions is key to developing hypotheses on this habitability and potential biosignature formation. In this study, we examined the viability of microbes from the Anderton Brine Springs (United Kingdom) under simulated martian chemistries designed to simulate the chemical conditions of water that may have existed during the Hesperian. Associated changes in the fluid chemistries were also tested using inductively coupled plasma-optical emission spectroscopy (ICP-OES). The tested Hesperian fluid chemistries were shown to be habitable, supporting the growth of all of the Anderton Brine Spring isolates. However, inter and intra-generic variation was observed both in the ability of the isolates to tolerate more concentrated fluids and in their impact on the fluid chemistry. Therefore, whilst this study shows microbes from fluctuating brines can survive and grow in simulated martian water chemistry, further investigations are required to further define the potential habitability under past martian conditions.
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Affiliation(s)
- Matthew Kelbrick
- Biology Department, Edge Hill University, Ormskirk L39 4QP, UK;
- Department of Evolution, Ecology and Behaviour, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool L69 3GJ, UK
- Correspondence: (M.K.); (M.C.M.)
| | | | - Nisha K. Ramkissoon
- AstrobiologyOU, School of Environment, Earth and Ecosystem Sciences, Faculty of Science, Technology, Engineering and Mathematics, The Open University, Milton Keynes MK7 6AA, UK; (N.K.R.); (B.P.S.); (E.K.-S.); (S.P.S.)
| | - Amy Dugdale
- AstrobiologyOU, School of Physical Sciences, Faculty of Science, Technology, Engineering and Mathematics, The Open University, Milton Keynes W23 F2H6, UK;
- Biology Department, Maynooth University, Maynooth, W23 F2H6 Kildare, Ireland
| | - Ben P. Stephens
- AstrobiologyOU, School of Environment, Earth and Ecosystem Sciences, Faculty of Science, Technology, Engineering and Mathematics, The Open University, Milton Keynes MK7 6AA, UK; (N.K.R.); (B.P.S.); (E.K.-S.); (S.P.S.)
| | - Ezgi Kucukkilic-Stephens
- AstrobiologyOU, School of Environment, Earth and Ecosystem Sciences, Faculty of Science, Technology, Engineering and Mathematics, The Open University, Milton Keynes MK7 6AA, UK; (N.K.R.); (B.P.S.); (E.K.-S.); (S.P.S.)
| | - Susanne P. Schwenzer
- AstrobiologyOU, School of Environment, Earth and Ecosystem Sciences, Faculty of Science, Technology, Engineering and Mathematics, The Open University, Milton Keynes MK7 6AA, UK; (N.K.R.); (B.P.S.); (E.K.-S.); (S.P.S.)
| | - André Antunes
- State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology (MUST), Macau, China;
- China National Space Administration (CNSA), Macau Center for Space Exploration and Science, Macau, China
| | - Michael C. Macey
- AstrobiologyOU, School of Environment, Earth and Ecosystem Sciences, Faculty of Science, Technology, Engineering and Mathematics, The Open University, Milton Keynes MK7 6AA, UK; (N.K.R.); (B.P.S.); (E.K.-S.); (S.P.S.)
- Correspondence: (M.K.); (M.C.M.)
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10
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Hallsworth JE. Mars' surface is not universally biocidal. Environ Microbiol 2021; 23:3345-3350. [DOI: 10.1111/1462-2920.15494] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 03/24/2021] [Accepted: 03/26/2021] [Indexed: 12/19/2022]
Affiliation(s)
- John E. Hallsworth
- Institute for Global Food Security, School of Biological Sciences Queen's University Belfast 19 Chlorine Gardens Belfast BT9 7BL UK
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11
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Simões MF, Antunes A. Microbial Pathogenicity in Space. Pathogens 2021; 10:450. [PMID: 33918768 PMCID: PMC8069885 DOI: 10.3390/pathogens10040450] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 04/04/2021] [Accepted: 04/08/2021] [Indexed: 12/25/2022] Open
Abstract
After a less dynamic period, space exploration is now booming. There has been a sharp increase in the number of current missions and also of those being planned for the near future. Microorganisms will be an inevitable component of these missions, mostly because they hitchhike, either attached to space technology, like spaceships or spacesuits, to organic matter and even to us (human microbiome), or to other life forms we carry on our missions. Basically, we never travel alone. Therefore, we need to have a clear understanding of how dangerous our "travel buddies" can be; given that, during space missions, our access to medical assistance and medical drugs will be very limited. Do we explore space together with pathogenic microorganisms? Do our hitchhikers adapt to the space conditions, as well as we do? Do they become pathogenic during that adaptation process? The current review intends to better clarify these questions in order to facilitate future activities in space. More technological advances are needed to guarantee the success of all missions and assure the reduction of any possible health and environmental risks for the astronauts and for the locations being explored.
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Affiliation(s)
- Marta Filipa Simões
- State Key Laboratory of Lunar and Planetary Sciences (SKLPlanets), Macau University of Science and Technology (MUST), Avenida Wai Long, Taipa, Macau, China;
- China National Space Administration (CNSA), Macau Center for Space Exploration and Science, Macau, China
| | - André Antunes
- State Key Laboratory of Lunar and Planetary Sciences (SKLPlanets), Macau University of Science and Technology (MUST), Avenida Wai Long, Taipa, Macau, China;
- China National Space Administration (CNSA), Macau Center for Space Exploration and Science, Macau, China
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12
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Godin PJ, Schuerger AC, Moores JE. Salt Tolerance and UV Protection of Bacillus subtilis and Enterococcus faecalis under Simulated Martian Conditions. ASTROBIOLOGY 2021; 21:394-404. [PMID: 33237800 DOI: 10.1089/ast.2020.2285] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Ultraviolet (UV) irradiation on the surface of Mars is an important factor that affects the survivability of microorganisms on Mars. The possibility of martian brines made from Fe2(SO4)3, MnSO4, and MgSO4 salts providing a habitable niche on Mars via attenuation of UV radiation was investigated on the bacteria Bacillus subtilis and Enterococcus faecalis. Results demonstrate that it is possible for brines containing Fe2(SO4)3 on Mars to provide protection from harmful UV irradiation, even at concentrations as low as 0.5%. Brines made from MnSO4 and MgSO4 did not provide significant UV protection, and most spores/cells died over the course of short-term experiments. However, Fe2(SO4)3 brines are strongly acidic and thus were lethal to E. faecalis, when cells were exposed for 7 days. In contrast, B. subtilis, a spore-forming bacterium resistant to pH extremes, was unaffected by the acidic conditions of the brines and did not experience any significant lethal effects in Fe2(SO4)3. Any extant microbial life in martian Fe2(SO4)3 brines (if present) would need to be capable of surviving acidic environments, if these brines are to be considered a possible habitable niche. The results from this work are important to the search for life on planets with atmospheres that do not significantly attenuate UV radiation (i.e., like Mars) and to planetary protection, since it is possible that terrestrial bacteria in the genus Bacillus are likely to survive in Fe-sulfate brines on Mars.
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Affiliation(s)
- Paul J Godin
- Department of Earth and Space Science and Engineering, York University, Toronto, Canada
| | - Andrew C Schuerger
- Department of Plant Pathology, University of Florida, Space Life Sciences Lab, Merritt Island, Florida, USA
| | - John E Moores
- Department of Earth and Space Science and Engineering, York University, Toronto, Canada
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13
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Cortesão M, Siems K, Koch S, Beblo-Vranesevic K, Rabbow E, Berger T, Lane M, James L, Johnson P, Waters SM, Verma SD, Smith DJ, Moeller R. MARSBOx: Fungal and Bacterial Endurance From a Balloon-Flown Analog Mission in the Stratosphere. Front Microbiol 2021; 12:601713. [PMID: 33692763 PMCID: PMC7937622 DOI: 10.3389/fmicb.2021.601713] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 01/20/2021] [Indexed: 11/29/2022] Open
Abstract
Whether terrestrial life can withstand the martian environment is of paramount interest for planetary protection measures and space exploration. To understand microbial survival potential in Mars-like conditions, several fungal and bacterial samples were launched in September 2019 on a large NASA scientific balloon flight to the middle stratosphere (∼38 km altitude) where radiation levels resembled values at the equatorial Mars surface. Fungal spores of Aspergillus niger and bacterial cells of Salinisphaera shabanensis, Staphylococcus capitis subsp. capitis, and Buttiauxella sp. MASE-IM-9 were launched inside the MARSBOx (Microbes in Atmosphere for Radiation, Survival, and Biological Outcomes Experiment) payload filled with an artificial martian atmosphere and pressure throughout the mission profile. The dried microorganisms were either exposed to full UV-VIS radiation (UV dose = 1148 kJ m−2) or were shielded from radiation. After the 5-h stratospheric exposure, samples were assayed for survival and metabolic changes. Spores from the fungus A. niger and cells from the Gram-(–) bacterium S. shabanensis were the most resistant with a 2- and 4-log reduction, respectively. Exposed Buttiauxella sp. MASE-IM-9 was completely inactivated (both with and without UV exposure) and S. capitis subsp. capitis only survived the UV shielded experimental condition (3-log reduction). Our results underscore a wide variation in survival phenotypes of spacecraft associated microorganisms and support the hypothesis that pigmented fungi may be resistant to the martian surface if inadvertently delivered by spacecraft missions.
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Affiliation(s)
- Marta Cortesão
- Aerospace Microbiology Research Group, Department of Radiation Biology, Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
| | - Katharina Siems
- Aerospace Microbiology Research Group, Department of Radiation Biology, Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
| | - Stella Koch
- Aerospace Microbiology Research Group, Department of Radiation Biology, Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
| | - Kristina Beblo-Vranesevic
- Astrobiology Research Group, Department of Radiation Biology, Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
| | - Elke Rabbow
- Astrobiology Research Group, Department of Radiation Biology, Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
| | - Thomas Berger
- Biophysics Research Group, Department of Radiation Biology, Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
| | - Michael Lane
- NASA Kennedy Space Center, Engineering Directorate, Kennedy Space Center, Merritt Island, FL, United States
| | - Leandro James
- NASA Kennedy Space Center, Engineering Directorate, Kennedy Space Center, Merritt Island, FL, United States
| | - Prital Johnson
- NASA Kennedy Space Center, Engineering Directorate, Kennedy Space Center, Merritt Island, FL, United States
| | - Samantha M Waters
- Universities Space Research Association, Moffett Field, CA, United States.,NASA Ames Research Center, Space Biosciences Research Branch, Moffett Field, CA, United States
| | - Sonali D Verma
- NASA Ames Research Center, Space Biosciences Research Branch, Moffett Field, CA, United States.,Blue Marble Space Institute of Science, Moffett Field, CA, United States
| | - David J Smith
- NASA Ames Research Center, Space Biosciences Research Branch, Moffett Field, CA, United States
| | - Ralf Moeller
- Aerospace Microbiology Research Group, Department of Radiation Biology, Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
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The Hypopiezotolerant Bacterium, Serratia liquefaciens, Failed to Grow in Mars Analog Soils under Simulated Martian Conditions at 7 hPa. Life (Basel) 2020; 10:life10060077. [PMID: 32466370 PMCID: PMC7344922 DOI: 10.3390/life10060077] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 05/13/2020] [Accepted: 05/20/2020] [Indexed: 12/16/2022] Open
Abstract
The search for life on Mars is predicated on the idea that Earth and Mars life (if present) should be both carbon- and water-based with similar forms of evolution. However, the astrobiology community can currently only investigate plausible Martian microbial ecosystems by using Terran life-forms as proxies. In order to examine how life might persist on Mars, we used a hypopiezotolerant bacterium (def., able to grow at 7-10 hPa)-Serratia liquefaciens-in growth assays with four Mars analog soils conducted under a subset of simulated Martian conditions including 7 hPa, 0 °C, and a CO2-enriched anoxic atmosphere (called low-PTA conditions). The four Mars analog soils included an Aeolian dust analog, the Mars JSC-1 analog, a Phoenix lander-site simulant, and a high-Salts analog. Serratia liquefaciens cells were able to grow at 30 °C in a liquid minimal basal medium (MBM) supplemented with 10- or 20-mM sucrose, Spizizen salts, and micronutrients. When the four analog soils were doped with both MBM and cells of S. liquefaciens, and subsequently incubated at 30 °C for 72 h, cell densities increased between 2-logs (Phoenix analog) and 4-logs (Aeolian and JSC-1 analogs); the Salts analog led to complete inactivation of S. liquefaciens within 24 h. In contrast, when the experiment was repeated, but incubated under low-PTA conditions, S. liquefaciens cells were either killed immediately by the Salts analog, or decreased by > 5 logs over 28 d by the Aeolian, JSC-1, and Phoenix analogs. The failure of S. liquefaciens to grow in the analog soils under low-PTA conditions was attributed to the synergistic interactions among six factors (i.e., low pressure, low temperature, anoxic atmosphere (i.e., the low-PTA conditions), low-pH in the Salts soil, dissolved salts in all analogs, and oligotrophic conditions) that increased the biocidal or inhibitory conditions within the analog soils. Results suggest that even if a hypopiezotolerant Terran microbe is displaced from a spacecraft surface on Mars, and lands in a hydrated and nutrient-rich niche, growth in the Martian regolith is not automatically assured.
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Seto M, Noguchi K, Cappellen PV. Potential for Aerobic Methanotrophic Metabolism on Mars. ASTROBIOLOGY 2019; 19:1187-1195. [PMID: 31173512 PMCID: PMC6785171 DOI: 10.1089/ast.2018.1943] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 05/07/2019] [Indexed: 06/09/2023]
Abstract
Observational evidence supports the presence of methane (CH4) in the martian atmosphere on the order of parts per billion by volume (ppbv). Here, we assess whether aerobic methanotrophy is a potentially viable metabolism in the martian upper regolith, by calculating metabolic energy gain rates under assumed conditions of martian surface temperature, pressure, and atmospheric composition. Using kinetic parameters for 19 terrestrial aerobic methanotrophic strains, we show that even under the imposed low temperature and pressure extremes (180-280 K and 6-11 hPa), methane oxidation by oxygen (O2) should in principle be able to generate the minimum energy production rate required to support endogenous metabolism (i.e., cellular maintenance). Our results further indicate that the corresponding metabolic activity would be extremely low, with cell doubling times in excess of 4000 Earth years at the present-day ppbv-level CH4 mixing ratios in the atmosphere of Mars. Thus, while aerobic methanotrophic microorganisms similar to those found on Earth could theoretically maintain their vital functions, they are unlikely to constitute prolific members of hypothetical martian soil communities.
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Affiliation(s)
- Mayumi Seto
- Department of Chemistry, Biology, and Environmental Sciences, Faculty of Science, Nara Women's University, Nara, Japan
| | - Katsuyuki Noguchi
- Department of Chemistry, Biology, and Environmental Sciences, Faculty of Science, Nara Women's University, Nara, Japan
| | - Philippe Van Cappellen
- Ecohydrology Research Group, Department of Earth and Environmental Sciences, Water Institute, University of Waterloo, Waterloo, Canada
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16
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Habitability of Mars: How Welcoming Are the Surface and Subsurface to Life on the Red Planet? GEOSCIENCES 2019. [DOI: 10.3390/geosciences9090361] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Mars is a planet of great interest in the search for signatures of past or present life beyond Earth. The years of research, and more advanced instrumentation, have yielded a lot of evidence which may be considered by the scientific community as proof of past or present habitability of Mars. Recent discoveries including seasonal methane releases and a subglacial lake are exciting, yet challenging findings. Concurrently, laboratory and environmental studies on the limits of microbial life in extreme environments on Earth broaden our knowledge of the possibility of Mars habitability. In this review, we aim to: (1) Discuss the characteristics of the Martian surface and subsurface that may be conducive to habitability either in the past or at present; (2) discuss laboratory-based studies on Earth that provide us with discoveries on the limits of life; and (3) summarize the current state of knowledge in terms of direction for future research.
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Metabolic fingerprints of Serratia liquefaciens under simulated Martian conditions using Biolog GN2 microarrays. Sci Rep 2018; 8:15721. [PMID: 30356072 PMCID: PMC6200771 DOI: 10.1038/s41598-018-33856-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 10/07/2018] [Indexed: 01/28/2023] Open
Abstract
Microorganisms growing at atmospheric pressures of 0.7 kPa may have a significant impact on the search for life on Mars. Data on their nutrient requirements in a simulated Martian environment are required to ascertain both the potential risk of forward contamination and the potential of past or present habitability of Mars. Serratia liquefaciens can grow at concomitant conditions of low pressure, low temperature, and anoxic atmosphere. Changes in the metabolic fingerprint of S. liquefaciens grown under varying physical conditions including diverse atmospheric pressures (0.7 kPa to 101.3 kPa), temperatures (30 °C or 0 °C), and atmospheric gas compositions (Earth or CO2) were investigated using Biolog GN2 assays. Distinct patterns for each condition were observed. Above 10 kPa S. liquefaciens performed similar to Earth-normal pressure conditions (101.3 kPa) whereas below 10 kPa shifts in metabolic patterns were observed. The differences indicated a physiological alteration in which S. liquefaciens lost its ability to metabolize the majority of the provided carbon sources at 0.7 kPa with a significant decrease in the oxidation of amino acids. By measuring the physiological responses to different carbon sources we were able to identify nutritional constraints that support cellular replication under simulated shallow Mars subsurface conditions.
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Fajardo-Cavazos P, Morrison MD, Miller KM, Schuerger AC, Nicholson WL. Transcriptomic responses of Serratia liquefaciens cells grown under simulated Martian conditions of low temperature, low pressure, and CO 2-enriched anoxic atmosphere. Sci Rep 2018; 8:14938. [PMID: 30297913 PMCID: PMC6175911 DOI: 10.1038/s41598-018-33140-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 09/21/2018] [Indexed: 11/21/2022] Open
Abstract
Results from previous experiments indicated that the Gram-negative α-proteobacterium Serratia liquefaciens strain ATCC 27592 was capable of growth under low temperature (0 °C), low pressure (0.7 kPa), and anoxic, CO2-dominated atmosphere–conditions intended to simulate the near-subsurface environment of Mars. To probe the response of its transcriptome to this extreme environment, S. liquefaciens ATCC 27592 was cultivated under 4 different environmental simulations: 0 °C, 0.7 kPa, CO2 atmosphere (Condition A); 0 °C, ~101.3 kPa, CO2 atmosphere (Condition B); 0 °C, ~101.3 kPa, ambient N2/O2 atmosphere (Condition C); and 30 °C, ~101.3 kPa, N2/O2 atmosphere (Condition D; ambient laboratory conditions). RNA-seq was performed on ribosomal RNA-depleted total RNA isolated from triplicate cultures grown under Conditions A-D and the datasets generated were subjected to transcriptome analyses. The data from Conditions A, B, or C were compared to laboratory Condition D. Significantly differentially expressed transcripts were identified belonging to a number of KEGG pathway categories. Up-regulated genes under all Conditions A, B, and C included those encoding transporters (ABC and PTS transporters); genes involved in translation (ribosomes and their biogenesis, biosynthesis of both tRNAs and aminoacyl-tRNAs); DNA repair and recombination; and non-coding RNAs. Genes down-regulated under all Conditions A, B, and C included: transporters (mostly ABC transporters); flagellar and motility proteins; genes involved in phenylalanine metabolism; transcription factors; and two-component systems. The results are discussed in the context of Mars astrobiology and planetary protection.
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Affiliation(s)
- Patricia Fajardo-Cavazos
- Department of Microbiology and Cell Science, University of Florida, Merritt Island, FL 32953, USA
| | - Michael D Morrison
- Department of Microbiology and Cell Science, University of Florida, Merritt Island, FL 32953, USA
| | - Kathleen M Miller
- Department of Microbiology and Cell Science, University of Florida, Merritt Island, FL 32953, USA
| | - Andrew C Schuerger
- Department of Plant Pathology, University of Florida, Merritt Island, FL 32953, USA
| | - Wayne L Nicholson
- Department of Microbiology and Cell Science, University of Florida, Merritt Island, FL 32953, USA.
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19
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Mickol RL, Page JL, Schuerger AC. Magnesium Sulfate Salt Solutions and Ices Fail to Protect Serratia liquefaciens from the Biocidal Effects of UV Irradiation under Martian Conditions. ASTROBIOLOGY 2017; 17:401-412. [PMID: 28459604 DOI: 10.1089/ast.2015.1448] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The growth of Serratia liquefaciens has been demonstrated under martian conditions of 0.7 kPa (7 mbar), 0°C, and CO2-enriched anoxic atmospheres (Schuerger et al., 2013, Astrobiology 13:115-131), but studies into the survivability of cells under hypersaline conditions that are likely to be encountered on Mars are lacking. Serratia liquefaciens cells were suspended in aqueous MgSO4 solutions, or frozen brines, and exposed to terrestrial (i.e., 101.3 kPa, 24°C, O2/N2-normal atmosphere) or martian (i.e., 0.7 kPa, -25°C, CO2-anoxic atmosphere) conditions to assess the roles of MgSO4 and UV irradiation on the survival of S. liquefaciens. Four solutions were tested for their capability to attenuate martian UV irradiation in both liquid and frozen forms: sterile deionized water (SDIW), 10 mM PO4 buffer, 5% MgSO4, and 10% MgSO4. None of the solutions in either liquid or frozen forms provided enhanced protection against martian UV irradiation. Sixty minutes of UV irradiation reduced cell densities from 2.0 × 106 cells/mL to less than 10 cells/mL for both liquid and frozen solutions. In contrast, 3-4 mm of a Mars analog soil were sufficient to attenuate 100% of UV irradiation. Results suggest that terrestrial microorganisms may not survive on Sun-exposed surfaces on Mars, even if the cells are embedded in frozen martian brines composed of MgSO4. However, if dispersed microorganisms can be covered by only a few millimeters of dust or regolith, long-term survival is probable. Key Words: Hypobaria-Mars-Planetary protection-Brines. Astrobiology 17, 401-412.
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Affiliation(s)
- Rebecca L Mickol
- 1 Center for Space and Planetary Sciences, University of Arkansas , Fayetteville, Arkansas
| | - Jessica L Page
- 2 Department of Physics and Space Science, Florida Institute of Technology , Melbourne, Florida
| | - Andrew C Schuerger
- 3 Department of Plant Pathology, University of Florida , Gainesville, Florida
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20
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Smith SA, Benardini JN, Anderl D, Ford M, Wear E, Schrader M, Schubert W, DeVeaux L, Paszczynski A, Childers SE. Identification and Characterization of Early Mission Phase Microorganisms Residing on the Mars Science Laboratory and Assessment of Their Potential to Survive Mars-like Conditions. ASTROBIOLOGY 2017; 17:253-265. [PMID: 28282220 PMCID: PMC5373329 DOI: 10.1089/ast.2015.1417] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 10/04/2016] [Indexed: 05/23/2023]
Abstract
Planetary protection is governed by the Outer Space Treaty and includes the practice of protecting planetary bodies from contamination by Earth life. Although studies are constantly expanding our knowledge about life in extreme environments, it is still unclear what the probability is for terrestrial organisms to survive and grow on Mars. Having this knowledge is paramount to addressing whether microorganisms transported from Earth could negatively impact future space exploration. The objectives of this study were to identify cultivable microorganisms collected from the surface of the Mars Science Laboratory, to distinguish which of the cultivable microorganisms can utilize energy sources potentially available on Mars, and to determine the survival of the cultivable microorganisms upon exposure to physiological stresses present on the martian surface. Approximately 66% (237) of the 358 microorganisms identified are related to members of the Bacillus genus, although surprisingly, 22% of all isolates belong to non-spore-forming genera. A small number could grow by reduction of potential growth substrates found on Mars, such as perchlorate and sulfate, and many were resistant to desiccation and ultraviolet radiation (UVC). While most isolates either grew in media containing ≥10% NaCl or at 4°C, many grew when multiple physiological stresses were applied. The study yields details about the microorganisms that inhabit the surfaces of spacecraft after microbial reduction measures, information that will help gauge whether microorganisms from Earth pose a forward contamination risk that could impact future planetary protection policy. Key Words: Planetary protection-Spore-Bioburden-MSL-Curiosity-Contamination-Mars. Astrobiology 17, 253-265.
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Affiliation(s)
| | - James N Benardini
- 2 Biotechnology and Planetary Protection Group, Jet Propulsion Laboratory, California Institute of Technology , Pasadena, California
| | - David Anderl
- 1 School of Food Science, University of Idaho , Moscow, Idaho
| | - Matt Ford
- 3 Department of Biological Sciences, Idaho State University , Pocatello, Idaho
| | - Emmaleen Wear
- 1 School of Food Science, University of Idaho , Moscow, Idaho
| | | | - Wayne Schubert
- 2 Biotechnology and Planetary Protection Group, Jet Propulsion Laboratory, California Institute of Technology , Pasadena, California
| | - Linda DeVeaux
- 4 Department of Chemistry and Applied Biological Sciences, South Dakota School of Mines and Technology , Rapid City, South Dakota
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Schuerger AC, Nicholson WL. Twenty Species of Hypobarophilic Bacteria Recovered from Diverse Soils Exhibit Growth under Simulated Martian Conditions at 0.7 kPa. ASTROBIOLOGY 2016; 16:964-976. [PMID: 27870556 DOI: 10.1089/ast.2016.1587] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Bacterial growth at low pressure is a new research area with implications for predicting microbial activity in clouds and the bulk atmosphere on Earth and for modeling the forward contamination of planetary surfaces like Mars. Here, we describe experiments on the recovery and identification of 20 species of bacterial hypobarophiles (def., growth under hypobaric conditions of approximately 1-2 kPa) in 10 genera capable of growth at 0.7 kPa. Hypobarophilic bacteria, but not archaea or fungi, were recovered from diverse soils, and high numbers of hypobarophiles were recovered from Arctic and Siberian permafrost soils. Isolates were identified through 16S rRNA sequencing to belong to the genera Bacillus, Carnobacterium, Clostridium, Cryobacterium, Exiguobacterium, Paenibacillus, Rhodococcus, Streptomyces, and Trichococcus. The highest population of culturable hypobarophilic bacteria (5.1 × 104 cfu/g) was recovered from Colour Lake soils from Axel Heiberg Island in the Canadian Arctic. In addition, we extend the number of hypobarophilic species in the genus Serratia to six type-strains that include S. ficaria, S. fonticola, S. grimesii, S. liquefaciens, S. plymuthica, and S. quinivorans. Microbial growth at 0.7 kPa suggests that pressure alone will not be growth-limiting on the martian surface, or in Earth's atmosphere up to an altitude of 34 km. Key Words: Barophile-Extremophilic microorganisms-Habitability-Mars-Special Region. Astrobiology 16, 964-976.
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Affiliation(s)
- Andrew C Schuerger
- 1 Department of Plant Pathology, University of Florida , Gainesville, Florida
| | - Wayne L Nicholson
- 2 Department of Microbiology and Cell Science, University of Florida , Gainesville, Florida
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22
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Schuerger AC, Nicholson WL. Twenty-Three Species of Hypobarophilic Bacteria Recovered from Diverse Ecosystems Exhibit Growth under Simulated Martian Conditions at 0.7 kPa. ASTROBIOLOGY 2016; 16:335-47. [PMID: 27135839 PMCID: PMC4876496 DOI: 10.1089/ast.2015.1394] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
UNLABELLED Bacterial growth at low pressure is a new research area with implications for predicting microbial activity in clouds and the bulk atmosphere on Earth, and for modeling the forward contamination of planetary surfaces like Mars. Here, we describe experiments on the recovery and identification of 23 species of bacterial hypobarophiles (def., growth under hypobaric conditions of approximately 1-2 kPa) in 11 genera capable of growth at 0.7 kPa. Hypobarophilic bacteria, but not archaea or fungi, were recovered from soil and non-soil ecosystems. The highest numbers of hypobarophiles were recovered from Arctic soil, Siberian permafrost, and human saliva. Isolates were identified through 16S rRNA sequencing to belong to the genera Carnobacterium, Exiguobacterium, Leuconostoc, Paenibacillus, and Trichococcus. The highest population of culturable hypobarophilic bacteria (5.1 × 10(4) cfu/g) was recovered from Colour Lake soils from Axel Heiberg Island in the Canadian Arctic. In addition, we extend the number of hypobarophilic species in the genus Serratia to six type-strains that include S. ficaria, S. fonticola, S. grimesii, S. liquefaciens, S. plymuthica, and S. quinivorans. Microbial growth at 0.7 kPa suggests that pressure alone will not be growth-limiting on the martian surface or in Earth's atmosphere up to an altitude of 34 km. KEY WORDS Planetary protection-Simulated martian atmosphere-Piezophile-Habitability-Extremophilic microorganisms. Astrobiology 16, 335-347.
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Affiliation(s)
| | - Wayne L. Nicholson
- Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida
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Carbon monoxide as a metabolic energy source for extremely halophilic microbes: implications for microbial activity in Mars regolith. Proc Natl Acad Sci U S A 2015; 112:4465-70. [PMID: 25831529 DOI: 10.1073/pnas.1424989112] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Carbon monoxide occurs at relatively high concentrations (≥800 parts per million) in Mars' atmosphere, where it represents a potentially significant energy source that could fuel metabolism by a localized putative surface or near-surface microbiota. However, the plausibility of CO oxidation under conditions relevant for Mars in its past or at present has not been evaluated. Results from diverse terrestrial brines and saline soils provide the first documentation, to our knowledge, of active CO uptake at water potentials (-41 MPa to -117 MPa) that might occur in putative brines at recurrent slope lineae (RSL) on Mars. Results from two extremely halophilic isolates complement the field observations. Halorubrum str. BV1, isolated from the Bonneville Salt Flats, Utah (to our knowledge, the first documented extremely halophilic CO-oxidizing member of the Euryarchaeota), consumed CO in a salt-saturated medium with a water potential of -39.6 MPa; activity was reduced by only 28% relative to activity at its optimum water potential of -11 MPa. A proteobacterial isolate from hypersaline Mono Lake, California, Alkalilimnicola ehrlichii MLHE-1, also oxidized CO at low water potentials (-19 MPa), at temperatures within ranges reported for RSL, and under oxic, suboxic (0.2% oxygen), and anoxic conditions (oxygen-free with nitrate). MLHE-1 was unaffected by magnesium perchlorate or low atmospheric pressure (10 mbar). These results collectively establish the potential for microbial CO oxidation under conditions that might obtain at local scales (e.g., RSL) on contemporary Mars and at larger spatial scales earlier in Mars' history.
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Martin D, Cockell CS. PELS (Planetary Environmental Liquid Simulator): a new type of simulation facility to study extraterrestrial aqueous environments. ASTROBIOLOGY 2015; 15:111-118. [PMID: 25651097 DOI: 10.1089/ast.2014.1240] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Investigations of other planetary bodies, including Mars and icy moons such as Enceladus and Europa, show that they may have hosted aqueous environments in the past and may do so even today. Therefore, a major challenge in astrobiology is to build facilities that will allow us to study the geochemistry and habitability of these extraterrestrial environments. Here, we describe a simulation facility (PELS: Planetary Environmental Liquid Simulator) with the capability for liquid input and output that allows for the study of such environments. The facility, containing six separate sample vessels, allows for statistical replication of samples. Control of pressure, gas composition, UV irradiation conditions, and temperature allows for the precise replication of aqueous conditions, including subzero brines under martian atmospheric conditions. A sample acquisition system allows for the collection of both liquid and solid samples from within the chamber without breaking the atmospheric conditions, enabling detailed studies of the geochemical evolution and habitability of past and present extraterrestrial environments. The facility we describe represents a new frontier in planetary simulation-continuous flow-through simulation of extraterrestrial aqueous environments.
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Affiliation(s)
- Derek Martin
- School of Physics and Astronomy, University of Edinburgh , Edinburgh, UK
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25
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Rummel JD, Beaty DW, Jones MA, Bakermans C, Barlow NG, Boston PJ, Chevrier VF, Clark BC, de Vera JPP, Gough RV, Hallsworth JE, Head JW, Hipkin VJ, Kieft TL, McEwen AS, Mellon MT, Mikucki JA, Nicholson WL, Omelon CR, Peterson R, Roden EE, Sherwood Lollar B, Tanaka KL, Viola D, Wray JJ. A new analysis of Mars "Special Regions": findings of the second MEPAG Special Regions Science Analysis Group (SR-SAG2). ASTROBIOLOGY 2014; 14:887-968. [PMID: 25401393 DOI: 10.1089/ast.2014.1227] [Citation(s) in RCA: 148] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
A committee of the Mars Exploration Program Analysis Group (MEPAG) has reviewed and updated the description of Special Regions on Mars as places where terrestrial organisms might replicate (per the COSPAR Planetary Protection Policy). This review and update was conducted by an international team (SR-SAG2) drawn from both the biological science and Mars exploration communities, focused on understanding when and where Special Regions could occur. The study applied recently available data about martian environments and about terrestrial organisms, building on a previous analysis of Mars Special Regions (2006) undertaken by a similar team. Since then, a new body of highly relevant information has been generated from the Mars Reconnaissance Orbiter (launched in 2005) and Phoenix (2007) and data from Mars Express and the twin Mars Exploration Rovers (all 2003). Results have also been gleaned from the Mars Science Laboratory (launched in 2011). In addition to Mars data, there is a considerable body of new data regarding the known environmental limits to life on Earth-including the potential for terrestrial microbial life to survive and replicate under martian environmental conditions. The SR-SAG2 analysis has included an examination of new Mars models relevant to natural environmental variation in water activity and temperature; a review and reconsideration of the current parameters used to define Special Regions; and updated maps and descriptions of the martian environments recommended for treatment as "Uncertain" or "Special" as natural features or those potentially formed by the influence of future landed spacecraft. Significant changes in our knowledge of the capabilities of terrestrial organisms and the existence of possibly habitable martian environments have led to a new appreciation of where Mars Special Regions may be identified and protected. The SR-SAG also considered the impact of Special Regions on potential future human missions to Mars, both as locations of potential resources and as places that should not be inadvertently contaminated by human activity.
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Affiliation(s)
- John D Rummel
- 1 Department of Biology, East Carolina University , Greenville, North Carolina, USA
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Daneshvar Alavi HE, Truelstrup Hansen L. Kinetics of biofilm formation and desiccation survival of Listeria monocytogenes in single and dual species biofilms with Pseudomonas fluorescens, Serratia proteamaculans or Shewanella baltica on food-grade stainless steel surfaces. BIOFOULING 2013; 29:1253-1268. [PMID: 24102145 DOI: 10.1080/08927014.2013.835805] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
This study investigated the dynamics of static biofilm formation (100% RH, 15 °C, 48-72 h) and desiccation survival (43% RH, 15 °C, 21 days) of Listeria monocytogenes, in dual species biofilms with the common spoilage bacteria, Pseudomonas fluorescens, Serratia proteamaculans and Shewanella baltica, on the surface of food grade stainless steel. The Gram-negative bacteria reduced the maximum biofilm population of L. monocytogenes in dual species biofilms and increased its inactivation during desiccation. However, due to the higher desiccation resistance of Listeria relative to P. fluorescens and S. baltica, the pathogen survived in greater final numbers. In contrast, S. proteamaculans outcompeted the pathogen during the biofilm formation and exhibited similar desiccation survival, causing the N21 days of Serratia to be ca 3 Log10(CFU cm(-2)) greater than that of Listeria in the dual species biofilm. Microscopy revealed biofilm morphologies with variable amounts of exopolymeric substance and the presence of separate microcolonies. Under these simulated food plant conditions, the fate of L. monocytogenes during formation of mixed biofilms and desiccation depended on the implicit characteristics of the co-cultured bacterium.
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Affiliation(s)
- Hessam Edin Daneshvar Alavi
- a Food Science Program, Faculty of Engineering, Department of Process Engineering and Applied Science , Dalhousie University , Halifax , Canada
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27
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The limits for life under multiple extremes. Trends Microbiol 2013; 21:204-12. [DOI: 10.1016/j.tim.2013.01.006] [Citation(s) in RCA: 168] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 01/28/2013] [Accepted: 01/31/2013] [Indexed: 12/19/2022]
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Arunasri K, Adil M, Venu Charan K, Suvro C, Himabindu Reddy S, Shivaji S. Effect of simulated microgravity on E. coli K12 MG1655 growth and gene expression. PLoS One 2013; 8:e57860. [PMID: 23472115 PMCID: PMC3589462 DOI: 10.1371/journal.pone.0057860] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Accepted: 01/26/2013] [Indexed: 12/23/2022] Open
Abstract
This study demonstrates the effects of simulated microgravity on E. coli K 12 MG1655 grown on LB medium supplemented with glycerol. Global gene expression analysis indicated that the expressions of hundred genes were significantly altered in simulated microgravity conditions compared to that of normal gravity conditions. Under these conditions genes coding for adaptation to stress are up regulated (sufE and ssrA) and simultaneously genes coding for membrane transporters (ompC, exbB, actP, mgtA, cysW and nikB) and carbohydrate catabolic processes (ldcC, ptsA, rhaD and rhaS) are down regulated. The enhanced growth in simulated gravity conditions may be because of the adequate supply of energy/reducing equivalents and up regulation of genes involved in DNA replication (srmB) and repression of the genes encoding for nucleoside metabolism (dfp, pyrD and spoT). In addition, E. coli cultured in LB medium supplemented with glycerol (so as to protect the cells from freezing temperatures) do not exhibit multiple stress responses that are normally observed when cells are exposed to microgravity in LB medium without glycerol.
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Affiliation(s)
| | - Mohammed Adil
- Centre for Cellular and Molecular Biology, Hyderabad, India
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Schuerger AC, Ulrich R, Berry BJ, Nicholson WL. Growth of Serratia liquefaciens under 7 mbar, 0°C, and CO2-enriched anoxic atmospheres. ASTROBIOLOGY 2013; 13:115-31. [PMID: 23289858 PMCID: PMC3582281 DOI: 10.1089/ast.2011.0811] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Accepted: 11/28/2012] [Indexed: 05/21/2023]
Abstract
Twenty-six strains of 22 bacterial species were tested for growth on trypticase soy agar (TSA) or sea-salt agar (SSA) under hypobaric, psychrophilic, and anoxic conditions applied singly or in combination. As each factor was added to multi-parameter assays, the interactive stresses decreased the numbers of strains capable of growth and, in general, reduced the vigor of the strains observed to grow. Only Serratia liquefaciens strain ATCC 27592 exhibited growth at 7 mbar, 0°C, and CO2-enriched anoxic atmospheres. To discriminate between the effects of desiccation and hypobaria, vegetative cells of Bacillus subtilis strain 168 and Escherichia coli strain K12 were grown on TSA surfaces and simultaneously in liquid Luria-Bertani (LB) broth media. Inhibition of growth under hypobaria for 168 and K12 decreased in similar ways for both TSA and LB assays as pressures were reduced from 100 to 25 mbar. Results for 168 and K12 on TSA and LB are interpreted to indicate a direct low-pressure effect on microbial growth with both species and do not support the hypothesis that desiccation alone on TSA was the cause of reduced growth at low pressures. The growth of S. liquefaciens at 7 mbar, 0°C, and CO2-enriched anoxic atmospheres was surprising since S. liquefaciens is ecologically a generalist that occurs in terrestrial plant, fish, animal, and food niches. In contrast, two extremophiles tested in the assays, Deinococcus radiodurans strain R1 and Psychrobacter cryohalolentis strain K5, failed to grow under hypobaric (25 mbar; R1 only), psychrophilic (0°C; R1 only), or anoxic (< 0.1% ppO2; both species) conditions.
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Affiliation(s)
- Andrew C Schuerger
- Department of Plant Pathology, University of Florida , Space Life Sciences Lab, Kennedy Space Center, Florida 32899, USA.
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Growth of Carnobacterium spp. from permafrost under low pressure, temperature, and anoxic atmosphere has implications for Earth microbes on Mars. Proc Natl Acad Sci U S A 2012; 110:666-71. [PMID: 23267097 DOI: 10.1073/pnas.1209793110] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The ability of terrestrial microorganisms to grow in the near-surface environment of Mars is of importance to the search for life and protection of that planet from forward contamination by human and robotic exploration. Because most water on present-day Mars is frozen in the regolith, permafrosts are considered to be terrestrial analogs of the martian subsurface environment. Six bacterial isolates were obtained from a permafrost borehole in northeastern Siberia capable of growth under conditions of low temperature (0 °C), low pressure (7 mbar), and a CO(2)-enriched anoxic atmosphere. By 16S ribosomal DNA analysis, all six permafrost isolates were identified as species of the genus Carnobacterium, most closely related to C. inhibens (five isolates) and C. viridans (one isolate). Quantitative growth assays demonstrated that the six permafrost isolates, as well as nine type species of Carnobacterium (C. alterfunditum, C. divergens, C. funditum, C. gallinarum, C. inhibens, C. maltaromaticum, C. mobile, C. pleistocenium, and C. viridans) were all capable of growth under cold, low-pressure, anoxic conditions, thus extending the low-pressure extreme at which life can function.
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Protective role of spore structural components in determining Bacillus subtilis spore resistance to simulated mars surface conditions. Appl Environ Microbiol 2012; 78:8849-53. [PMID: 23064347 DOI: 10.1128/aem.02527-12] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Spores of wild-type and mutant Bacillus subtilis strains lacking various structural components were exposed to simulated Martian atmospheric and UV irradiation conditions. Spore survival and mutagenesis were strongly dependent on the functionality of all of the structural components, with small acid-soluble spore proteins, coat layers, and dipicolinic acid as key protectants.
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Gong XC, Liu ZS, Guo P, Chi CQ, Chen J, Wang XB, Tang YQ, Wu XL, Liu CZ. Bacteria in crude oil survived autoclaving and stimulated differentially by exogenous bacteria. PLoS One 2012; 7:e40842. [PMID: 23028421 PMCID: PMC3444520 DOI: 10.1371/journal.pone.0040842] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Accepted: 06/13/2012] [Indexed: 11/19/2022] Open
Abstract
Autoclaving of crude oil is often used to evaluate the hydrocarbon-degrading abilities of bacteria. This may be potentially useful for bioaugmentation and microbial enhanced oil recovery (MEOR). However, it is not entirely clear if “endogenous” bacteria (e.g., spores) in/on crude oil survive the autoclaving process, or influence subsequent evaluation of the hydrocarbon-degradation abilities of the “exogenous” bacterial strains. To test this, we inoculated autoclaved crude oil medium with six exogenous bacterial strains (three Dietzia strains, two Acinetobacter strains, and one Pseudomonas strain). The survival of the spore-forming Bacillus and Paenibacillus and the non-spore-forming mesophilic Pseudomonas, Dietzia, Alcaligenes, and Microbacterium was detected using a 16S rRNA gene clone library and terminal restriction fragment length polymorphism (T-RFLP) analysis. However, neither bacteria nor bacterial activity was detected in three controls consisting of non-inoculated autoclaved crude oil medium. These results suggest that detection of endogenous bacteria was stimulated by the six inoculated strains. In addition, inoculation with Acinetobacter spp. stimulated detection of Bacillus, while inoculation with Dietzia spp. and Pseudomonas sp. stimulated the detection of more Pseudomonas. In contrast, similar exogenous bacteria stimulated similar endogenous bacteria at the genus level. Based on these results, special emphasis should be applied to evaluate the influence of bacteria capable of surviving autoclaving on the hydrocarbon-degrading abilities of exogenous bacteria, in particular, with regard to bioaugmentation and MEOR. Bioaugmentation and MEOR technologies could then be developed to more accurately direct the growth of specific endogenous bacteria that may then improve the efficiency of treatment or recovery of crude oil.
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Affiliation(s)
| | | | | | | | | | | | | | - Xiao-Lei Wu
- Department of Energy and Resources Engineering, College of Engineering, Peking University, Beijing, P.R. China
- * E-mail:
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Fajardo-Cavazos P, Waters SM, Schuerger AC, George S, Marois JJ, Nicholson WL. Evolution of Bacillus subtilis to enhanced growth at low pressure: up-regulated transcription of des-desKR, encoding the fatty acid desaturase system. ASTROBIOLOGY 2012; 12:258-270. [PMID: 22416764 DOI: 10.1089/ast.2011.0728] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The atmospheric pressure on Mars ranges from 1-10 mbar, about 1% of Earth pressure (∼1013 mbar). Low pressure is a growth-inhibitory factor for terrestrial microorganisms on Mars, and a putative low-pressure barrier for growth of Earth bacteria of ∼25 mbar has been postulated. In a previous communication, we described the isolation of a strain of Bacillus subtilis that had evolved enhanced growth ability at the near-inhibitory low pressure of 50 mbar. To explore mechanisms that enabled growth of the low-pressure-adapted strain, numerous genes differentially transcribed between the ancestor strain WN624 and low-pressure-evolved strain WN1106 at 50 mbar were identified by microarray analysis. Among these was a cluster of three candidate genes (des, desK, and desR), whose mRNA levels in WN1106 were higher than the ancestor on the microarrays. Up-regulation of these genes was confirmed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis. The des, desK, and desR genes encode the Des membrane fatty acid (FA) desaturase, the DesK sensor kinase, and the DesR response regulator, respectively, which function to maintain membrane fluidity in acute response to temperature downshift. Pressure downshift caused an up-regulation of des mRNA levels only in WN1106, but expression of a des-lacZ transcriptional fusion was unaffected, which suggests that des regulation was different in response to temperature versus pressure downshift. Competition experiments showed that inactivation of the des gene caused a slight, but statistically significant, loss of fitness of strain WN1106 at 50 mbar. Further, analysis of membrane FA composition of cells grown at 1013 versus 50 mbar revealed a decrease in the ratio of unsaturated to saturated FAs but an increase in the ratio of anteiso- to iso-FAs. The present study represents a first step toward identification of molecular mechanisms by which B. subtilis could sense and respond to the novel environmental stress of low pressure.
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Affiliation(s)
- Patricia Fajardo-Cavazos
- Department of Microbiology and Cell Science, University of Florida, Kennedy Space Center, 32899, USA
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Goldman RP, Travisano M. Experimental evolution of ultraviolet radiation resistance in Escherichia coli. Evolution 2011; 65:3486-98. [PMID: 22133220 DOI: 10.1111/j.1558-5646.2011.01438.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ultraviolet (UV) light is a major cause of stress, mutation, and mortality in microorganisms, causing numerous forms of cellular damage. Nevertheless, there is tremendous variation within and among bacterial species in their sensitivity to UV light. We investigated direct and correlated responses to selection during exposure to UV. Replicate lines of Escherichia coli K12 were propagated for 600 generations, half with UV and half as a control without UV. All lines responded to selection, and we found strong positive and negative correlated responses to selection associated with increased UV resistance. Compared to Control populations, UV-selected populations increased in desiccation and starvation resistance approximately twofold but were 10 times more sensitive to hypersalinity. There was little evidence for a persistent large competitive fitness cost to UV resistance. These results suggest that natural variation in UV resistance may be maintained by trade-offs for resistance to other abiotic sources of mortality. We observed an average twofold increase in cell size by the UV-selected populations, consistent with a structural mode of adaptation to UV exposure having preadaptive and maladaptive consequences to other abiotic stresses.
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Affiliation(s)
- Robert P Goldman
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, California 91766, USA.
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Kerney KR, Schuerger AC. Survival of Bacillus subtilis endospores on ultraviolet-irradiated rover wheels and Mars regolith under simulated Martian conditions. ASTROBIOLOGY 2011; 11:477-485. [PMID: 21707388 DOI: 10.1089/ast.2011.0615] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Endospores of Bacillus subtilis HA101 were applied to a simulated Mars Exploration Rover (MER) wheel and exposed to Mars-normal UV irradiation for 1, 3, or 6 h. The experiment was designed to simulate a contaminated rover wheel sitting on its landing platform before rolling off onto the martian terrain, as was encountered during the Spirit and Opportunity missions. When exposed to 1 h of Mars UV, a reduction of 81% of viable endospores was observed compared to the non-UV irradiated controls. When exposed for 3 or 6 h, reductions of 94.6% and 96.6%, respectively, were observed compared to controls. In a second experiment, the contaminated rover wheel was rolled over a bed of heat-sterilized Mars analog soil; then the analog soil was exposed to full martian conditions of UV irradiation, low pressure (6.9 mbar), low temperature (-10°C), and an anaerobic CO(2) martian atmosphere for 24 h to determine whether endospores of B. subtilis on the contaminated rover wheel could be transferred to the surface of the analog soil and survive martian conditions. The experiment simulated conditions in which a rover wheel might come into contact with martian regolith immediately after landing, such as is designed for the upcoming Mars Science Laboratory (MSL) rover. The contaminated rover wheel transferred viable endospores of B. subtilis to the Mars analog soil, as demonstrated by 31.7% of samples showing positive growth. However, when contaminated soil samples were exposed to full martian conditions for 24 h, only 16.7% of samples exhibited positive growth-a 50% reduction in the number of soil samples positive for the transferred viable endospores.
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Affiliation(s)
- Krystal R Kerney
- Department of Plant Pathology, University of Florida , Space Life Sciences Lab, Kennedy Space Center, USA
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Exploring the low-pressure growth limit: evolution of Bacillus subtilis in the laboratory to enhanced growth at 5 kilopascals. Appl Environ Microbiol 2010; 76:7559-65. [PMID: 20889789 DOI: 10.1128/aem.01126-10] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Growth of Bacillus subtilis cells, normally adapted at Earth-normal atmospheric pressure (∼101.3 kPa), was progressively inhibited by lowering of pressure in liquid LB medium until growth essentially ceased at 2.5 kPa. Growth inhibition was immediately reversible upon return to 101.3 kPa, albeit at a slower rate. A population of B. subtilis cells was cultivated at the near-inhibitory pressure of 5 kPa for 1,000 generations, where a stepwise increase in growth was observed, as measured by the turbidity of 24-h cultures. An isolate from the 1,000-generation population was obtained that showed an increase in fitness at 5 kPa when compared to the ancestral strain or a strain obtained from a parallel population that evolved for 1,000 generations at 101.3 kPa. The results from this preliminary study have implications for understanding the ability of terrestrial microbes to grow in low-pressure environments such as Mars.
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