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Symeonidou E, Jørgensen UG, Madsen MB, Priemé A. Effects of temperature, chloride and perchlorate salt concentration on the metabolic activity of Deinococcus radiodurans. Extremophiles 2024; 28:34. [PMID: 39044042 PMCID: PMC11266278 DOI: 10.1007/s00792-024-01351-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 07/16/2024] [Indexed: 07/25/2024]
Abstract
The extremophile bacterium Deinococcus radiodurans is characterized by its ability to survive and sustain its activity at high levels of radiation and is considered an organism that might survive in extraterrestrial environments. In the present work, we studied the combined effects of temperature and chlorine-containing salts, with focus on perchlorate salts which have been detected at high concentrations in Martian regolith, on D. radiodurans activity (CO2 production rates) and viability after incubation in liquid cultures for up to 30 days. Reduced CO2 production capacity and viability was observed at high perchlorate concentrations (up to 10% w/v) during incubation at 0 or 25 °C. Both the metabolic activity and viability were reduced as the perchlorate and chloride salt concentration increased and temperature decreased, and an interactive effect of temperature and salt concentration on the metabolic activity was found. These results indicate the ability of D. radiodurans to remain metabolically active and survive in low temperature environments rich in perchlorate.
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Affiliation(s)
- Eftychia Symeonidou
- Astrophysics and Planetary Science, Niels Bohr Institute, University of Copenhagen, Øster Voldgade 5-7, 1350, Copenhagen, Denmark
- Center for ExoLife Sciences, (CELS), Niels Bohr Institute, University of Copenhagen, Øster Voldgade 5-7, 1350, Copenhagen, Denmark
| | - Uffe Gråe Jørgensen
- Astrophysics and Planetary Science, Niels Bohr Institute, University of Copenhagen, Øster Voldgade 5-7, 1350, Copenhagen, Denmark
- Center for ExoLife Sciences, (CELS), Niels Bohr Institute, University of Copenhagen, Øster Voldgade 5-7, 1350, Copenhagen, Denmark
| | - Morten Bo Madsen
- Astrophysics and Planetary Science, Niels Bohr Institute, University of Copenhagen, Øster Voldgade 5-7, 1350, Copenhagen, Denmark
- Center for ExoLife Sciences, (CELS), Niels Bohr Institute, University of Copenhagen, Øster Voldgade 5-7, 1350, Copenhagen, Denmark
| | - Anders Priemé
- Center for ExoLife Sciences, (CELS), Niels Bohr Institute, University of Copenhagen, Øster Voldgade 5-7, 1350, Copenhagen, Denmark.
- Department of Biology, University of Copenhagen, Universitetsparken 15, 2100, Copenhagen, Denmark.
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2
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Caro-Astorga J, Meyerowitz JT, Stork DA, Nattermann U, Piszkiewicz S, Vimercati L, Schwendner P, Hocher A, Cockell C, DeBenedictis E. Polyextremophile engineering: a review of organisms that push the limits of life. Front Microbiol 2024; 15:1341701. [PMID: 38903795 PMCID: PMC11188471 DOI: 10.3389/fmicb.2024.1341701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 05/16/2024] [Indexed: 06/22/2024] Open
Abstract
Nature exhibits an enormous diversity of organisms that thrive in extreme environments. From snow algae that reproduce at sub-zero temperatures to radiotrophic fungi that thrive in nuclear radiation at Chernobyl, extreme organisms raise many questions about the limits of life. Is there any environment where life could not "find a way"? Although many individual extremophilic organisms have been identified and studied, there remain outstanding questions about the limits of life and the extent to which extreme properties can be enhanced, combined or transferred to new organisms. In this review, we compile the current knowledge on the bioengineering of extremophile microbes. We summarize what is known about the basic mechanisms of extreme adaptations, compile synthetic biology's efforts to engineer extremophile organisms beyond what is found in nature, and highlight which adaptations can be combined. The basic science of extremophiles can be applied to engineered organisms tailored to specific biomanufacturing needs, such as growth in high temperatures or in the presence of unusual solvents.
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Affiliation(s)
| | | | - Devon A. Stork
- Pioneer Research Laboratories, San Francisco, CA, United States
| | - Una Nattermann
- Pioneer Research Laboratories, San Francisco, CA, United States
| | | | - Lara Vimercati
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, United States
| | | | - Antoine Hocher
- London Institute of Medical Sciences, London, United Kingdom
| | - Charles Cockell
- UK Centre for Astrobiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Erika DeBenedictis
- The Francis Crick Institute, London, United Kingdom
- Pioneer Research Laboratories, San Francisco, CA, United States
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3
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Moanis R, Geeraert H, Van den Brande N, Hennecke U, Peeters E. Paracoccus kondratievae produces poly(3-hydroxybutyrate) under elevated temperature conditions. ENVIRONMENTAL MICROBIOLOGY REPORTS 2024; 16:e13260. [PMID: 38838099 DOI: 10.1111/1758-2229.13260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Accepted: 03/13/2024] [Indexed: 06/07/2024]
Abstract
As part of ongoing efforts to discover novel polyhydroxyalkanoate-producing bacterial species, we embarked on characterizing the thermotolerant species, Paracoccus kondratievae, for biopolymer synthesis. Using traditional chemical and thermal characterization techniques, we found that P. kondratievae accumulates poly(3-hydroxybutyrate) (PHB), reaching up to 46.8% of the cell's dry weight after a 24-h incubation at 42°C. Although P. kondratievae is phylogenetically related to the prototypical polyhydroxyalkanoate producer, Paracoccus denitrificans, we observed significant differences in the PHB production dynamics between these two Paracoccus species. Notably, P. kondratievae can grow and produce PHB at elevated temperatures ranging from 42 to 47°C. Furthermore, P. kondratievae reaches its peak PHB content during the early stationary growth phase, specifically after 24 h of growth in a flask culture. This is then followed by a decline in the later stages of the stationary growth phase. The depolymerization observed in this growth phase is facilitated by the abundant presence of the PhaZ depolymerase enzyme associated with PHB granules. We observed the highest PHB levels when the cells were cultivated in a medium with glycerol as the sole carbon source and a carbon-to-nitrogen ratio of 10. Finally, we found that PHB production is induced as an osmotic stress response, similar to other polyhydroxyalkanoate-producing species.
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Affiliation(s)
- Radwa Moanis
- Research Group of Microbiology, Department of Bioengineering Sciences, Vrije Universiteit Brussel, Brussels, Belgium
- Faculty of Sciences, Botany and Microbiology Department, Damanhour University, Damanhour, Egypt
| | - Hannelore Geeraert
- Research Group of Physical Chemistry and Polymer Science, Vrije Universiteit Brussel, Brussels, Belgium
| | - Niko Van den Brande
- Research Group of Physical Chemistry and Polymer Science, Vrije Universiteit Brussel, Brussels, Belgium
| | - Ulrich Hennecke
- Research Group of Organic Chemistry, Department of Chemistry and Department of Bioengineering Sciences, Vrije Universiteit Brussel, Brussels, Belgium
| | - Eveline Peeters
- Research Group of Microbiology, Department of Bioengineering Sciences, Vrije Universiteit Brussel, Brussels, Belgium
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4
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Fischer FC, Schulze-Makuch D, Heinz J. Microbial preference for chlorate over perchlorate under simulated shallow subsurface Mars-like conditions. Sci Rep 2024; 14:11537. [PMID: 38773211 PMCID: PMC11109124 DOI: 10.1038/s41598-024-62346-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Accepted: 05/15/2024] [Indexed: 05/23/2024] Open
Abstract
The Martian surface and shallow subsurface lacks stable liquid water, yet hygroscopic salts in the regolith may enable the transient formation of liquid brines. This study investigated the combined impact of water scarcity, UV exposure, and regolith depth on microbial survival under Mars-like environmental conditions. Both vegetative cells of Debaryomyces hansenii and Planococcus halocryophilus, alongside with spores of Aspergillus niger, were exposed to an experimental chamber simulating Martian environmental conditions (constant temperatures of about - 11 °C, low pressure of approximately 6 mbar, a CO2 atmosphere, and 2 h of daily UV irradiation). We evaluated colony-forming units (CFU) and water content at three different regolith depths before and after exposure periods of 3 and 7 days, respectively. Each organism was tested under three conditions: one without the addition of salts to the regolith, one containing sodium chlorate, and one with sodium perchlorate. Our results reveal that the residual water content after the exposure experiments increased with regolith depth, along with the organism survival rates in chlorate-containing and salt-free samples. The survival rates of the three organisms in perchlorate-containing regolith were consistently lower for all organisms and depths compared to chlorate, with the most significant difference being observed at a depth of 10-12 cm, which corresponds to the depth with the highest residual water content. The postulated reason for this is an increase in the salt concentration at this depth due to the freezing of water, showing that for these organisms, perchlorate brines are more toxic than chlorate brines under the experimental conditions. This underscores the significance of chlorate salts when considering the habitability of Martian environments.
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Affiliation(s)
- Florian Carlo Fischer
- Center for Astronomy and Astrophysics, RG Astrobiology, Technische Universität Berlin, Berlin, Germany
| | - Dirk Schulze-Makuch
- Center for Astronomy and Astrophysics, RG Astrobiology, Technische Universität Berlin, Berlin, Germany
- GFZ German Research Center for Geosciences, Section Geomicrobiology, Potsdam, Germany
- Department of Plankton and Microbial Ecology, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Stechlin, Germany
| | - Jacob Heinz
- Center for Astronomy and Astrophysics, RG Astrobiology, Technische Universität Berlin, Berlin, Germany.
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5
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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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6
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Chumjan W, Sangchalee A, Somwang C, Mookda N, Yaikeaw S, Somsakeesit LO. Outer membrane protein N expressed in Gram-negative bacterial strain of Escherichia coli BL21 (DE3) Omp8 Rosetta strains under osmoregulation by salts, sugars, and pHs. PLoS One 2023; 18:e0288096. [PMID: 37535641 PMCID: PMC10399875 DOI: 10.1371/journal.pone.0288096] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 06/19/2023] [Indexed: 08/05/2023] Open
Abstract
This study presented the expression of the outer membrane protein N in E. coli BL21 (DE3) Omp8 Rosetta under its growth condition and by osmoregulation. The effects of osmotic stress caused by salts, sugars, or pH values on the survival of the target Gram-negative bacterial strain of E. coli BL21 (DE3) Omp8 Rosetta and OmpN expression remain unknown. Here, tryptone yeast extract with varied salts and concentrations was initially used to generate an LB broth medium. To show how salts and concentration affect bacterial growth, the optical density at 600 nm was measured. The findings supported the hypothesis that salts and concentrations control bacterial growth. Moreover, a Western blotting study revealed that OmpN overexpression was present in all tested salts after stimulation with both glucose and fructose after being treated individually with anti-OmpN and anti-histidine tag polyclonal antibodies on transferred nitrocellulose membrane containing crude OmpN. Following the presence of the plasmid pET21b(+)/ompN-BOR into E. coli BL21 (DE3) Omp8 Rosetta, which was expressed in the recombinant OmpN protein (BOR), OmpN expression was demonstrated for all monovalent cations as well as MgCl2. All of the tested salts, except for BaCl2, NaH2PO4, and KH2PO4, showed overexpression of recombinant BOR after Isopropyl β-D-1-thiogalactopyranoside (IPTG) induction. Using CH3COONa, both with and without IPTG induction, there was very little bacterial growth and no OmpN expression. With NaCl, a pH value of 7 was suitable for bacterial development, whereas KCl required a pH value of 8. According to this research, bacterial growth in addition to salts, sugars, and pH values influences how the OmpN protein is produced.
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Affiliation(s)
- Watcharin Chumjan
- Department of Chemistry, Rajamangala University of Technology Isan Khon Kaen Campus, Khon Kaen, Thailand
| | - Akira Sangchalee
- Department of Chemistry, Rajamangala University of Technology Isan Khon Kaen Campus, Khon Kaen, Thailand
| | - Cholthicha Somwang
- Department of Chemistry, Rajamangala University of Technology Isan Khon Kaen Campus, Khon Kaen, Thailand
| | - Nattida Mookda
- Department of Chemistry, Rajamangala University of Technology Isan Khon Kaen Campus, Khon Kaen, Thailand
| | - Sriwannee Yaikeaw
- Department of Chemistry, Rajamangala University of Technology Isan Khon Kaen Campus, Khon Kaen, Thailand
| | - La-Or Somsakeesit
- Department of Chemistry, Rajamangala University of Technology Isan Khon Kaen Campus, Khon Kaen, Thailand
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7
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Yang Z, Zhang W, Liu X, Zhao S, Yang Z, Jia X. Chloride Salt of Oligourea Ligand: Synthesis, Crystal Structure, Thermal Analyses, and Chloride Anion Binding Properties. INORG CHEM COMMUN 2023. [DOI: 10.1016/j.inoche.2023.110568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
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8
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Cassaro A, Pacelli C, Onofri S. Survival, metabolic activity, and ultrastructural damages of Antarctic black fungus in perchlorates media. Front Microbiol 2022; 13:992077. [PMID: 36523839 PMCID: PMC9744811 DOI: 10.3389/fmicb.2022.992077] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 10/06/2022] [Indexed: 09/12/2023] Open
Abstract
Evidence from recent Mars landers identified the presence of perchlorates salts at 1 wt % in regolith and their widespread distribution on the Martian surface that has been hypothesized as a critical chemical hazard for putative life forms. However, the hypersaline environment may also potentially preserve life and its biomolecules over geological timescales. The high concentration of natural perchlorates is scarcely reported on Earth. The presence of perchlorates in soil and ice has been recorded in some extreme environments including the McMurdo Dry Valleys in Antarctica, one of the best terrestrial analogues for Mars. In the frame of "Life in space" Italian astrobiology project, the polyextremophilic black fungus Cryomyces antarcticus, a eukaryotic test organism isolated from the Antarctic cryptoendolithic communities, has been tested for its resistance, when grown on different hypersaline substrata. In addition, C. antarcticus was grown on Martian relevant perchlorate medium (0.4 wt% of Mg(ClO4)2 and 0.6 wt% of Ca(ClO4)2) to investigate the possibility for the fungus to survive in Martian environment. Here, the results indicate a good survivability and metabolic activity recovery of the black fungus when grown on four Martian relevant perchlorates. A low percentage of damaged cellular membranes have been found, confirming the ultrastructural investigation.
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Affiliation(s)
- Alessia Cassaro
- Department of Ecological and Biological Sciences, University of Tuscia, Largo dell’Università snc, Viterbo, Italy
| | - Claudia Pacelli
- Department of Ecological and Biological Sciences, University of Tuscia, Largo dell’Università snc, Viterbo, Italy
- Human Spaceflight and Scientific Research Unit, Italian Space Agency, via del Politecnico, Rome, Italy
| | - Silvano Onofri
- Department of Ecological and Biological Sciences, University of Tuscia, Largo dell’Università snc, Viterbo, Italy
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9
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Naranjo D. A scenario for the origin of life: Volume regulation by bacteriorhodopsin required extremely voltage sensitive Na‐channels and very selective K‐channels. Bioessays 2022; 44:e2100210. [DOI: 10.1002/bies.202100210] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 07/20/2022] [Accepted: 07/21/2022] [Indexed: 12/25/2022]
Affiliation(s)
- David Naranjo
- Instituto de Neurociencia, Facultad de Ciencias Universidad de Valparaíso Playa Ancha Valparaíso Chile
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10
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Heinz J, Doellinger J, Maus D, Schneider A, Lasch P, Grossart HP, Schulze-Makuch D. Perchlorate-Specific Proteomic Stress Responses of Debaryomyces hansenii Could Enable Microbial Survival in Martian Brines. Environ Microbiol 2022; 24:5051-5065. [PMID: 35920032 DOI: 10.1111/1462-2920.16152] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 07/27/2022] [Indexed: 11/29/2022]
Abstract
If life exists on Mars, it would face several challenges including the presence of perchlorates, which destabilize biomacromolecules by inducing chaotropic stress. However, little is known about perchlorate toxicity for microorganism on the cellular level. Here we present the first proteomic investigation on the perchlorate-specific stress responses of the halotolerant yeast Debaryomyces hansenii and compare these to generally known salt stress adaptations. We found that the responses to NaCl and NaClO4 -induced stresses share many common metabolic features, e.g., signaling pathways, elevated energy metabolism, or osmolyte biosynthesis. Nevertheless, several new perchlorate-specific stress responses could be identified, such as protein glycosylation and cell wall remodulations, presumably in order to stabilize protein structures and the cell envelope. These stress responses would also be relevant for life on Mars, which - given the environmental conditions - likely developed chaotropic defense strategies such as stabilized confirmations of biomacromolecules and the formation of cell clusters. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Jacob Heinz
- Center for Astronomy and Astrophysics, RG Astrobiology, Technische Universität Berlin, Berlin, Germany
| | - Joerg Doellinger
- Robert Koch-Institute, Centre for Biological Threats and Special Pathogens, Proteomics and Spectroscopy (ZBS6), Berlin, Germany
| | - Deborah Maus
- Robert Koch-Institute, Metabolism of Microbial Pathogens (NG2), Berlin, Germany
| | - Andy Schneider
- Robert Koch-Institute, Centre for Biological Threats and Special Pathogens, Proteomics and Spectroscopy (ZBS6), Berlin, Germany
| | - Peter Lasch
- Robert Koch-Institute, Centre for Biological Threats and Special Pathogens, Proteomics and Spectroscopy (ZBS6), Berlin, Germany
| | - Hans-Peter Grossart
- Department of Plankton and Microbial Ecology, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), 16775 Stechlin, Germany.,Institute for Biochemistry and Biology, Potsdam University, Potsdam, Germany
| | - Dirk Schulze-Makuch
- Center for Astronomy and Astrophysics, RG Astrobiology, Technische Universität Berlin, Berlin, Germany.,Department of Plankton and Microbial Ecology, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), 16775 Stechlin, Germany.,GFZ German Research Center for Geosciences, Section Geomicrobiology, Potsdam, Germany.,School of the Environment, Washington State University, Pullman, Washington, USA
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11
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Piszkin L, Bowman J. Extremophile enzyme optimization for low temperature and high salinity are fundamentally incompatible. Extremophiles 2021; 26:5. [PMID: 34940913 DOI: 10.1007/s00792-021-01254-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 12/09/2021] [Indexed: 11/25/2022]
Abstract
The evolutionary mechanisms behind cold and high-saline co-adaptation of proteins are not thoroughly understood. To explore how enzymes evolve in response to multiple environmental pressures we developed a novel in silico method to model the directed evolution of proteins, the Protein Evolution Parameter Calculator (PEPC). PEPC carries out single amino acid substitutions that lead to improvements in the selected user-defined parameters. To investigate the evolutionary relationship between increased flexibility and decreased isoelectric point, which are presumed indicators of cold and saline adaptation in proteins, we applied PEPC to a subset of core haloarchaea orthologous group (cHOG) proteins from the mesophilic Halobacterium salinarum NRC-1 and cold-tolerant Halorubrum lacusprofundi strain ATCC 49239. The results suggest that mutations that increase flexibility will also generally increase isoelectric point. These findings suggest that enzyme adaptation to low temperature and high salinity might be evolutionarily counterposed based on the structural characteristics of probable amino acid mutations. This may help to explain the apparent lack of truly psychrophilic halophiles in nature, and why microbes adapted to polar hypersaline environments typically have mesophilic temperature optima. A better understanding of protein evolution to extremely cold and salty conditions will aid in our understanding of where and how life is distributed on Earth and in our solar system.
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Affiliation(s)
- Luke Piszkin
- Department of Physics, UC San Diego, La Jolla, CA, USA.
| | - Jeff Bowman
- Scripps Institution of Oceanography, UC San Diego, La Jolla, CA, USA
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12
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Physicochemical Parameters Limiting Growth of Debaryomyces hansenii in Solutions of Hygroscopic Compounds and Their Effects on the Habitability of Martian Brines. Life (Basel) 2021; 11:life11111194. [PMID: 34833070 PMCID: PMC8619379 DOI: 10.3390/life11111194] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 11/01/2021] [Accepted: 11/04/2021] [Indexed: 11/27/2022] Open
Abstract
The availability of liquid water is a prerequisite for all lifeforms on Earth. In hyperarid subzero environments like the Dry Valleys in Antarctica or the near-subsurface of Mars liquid water might be provided temporarily by hygroscopic substances that absorb water from the atmosphere and lower the freezing point of water. To evaluate the potential of hygroscopic compounds to serve as a habitat, it is necessary to explore the microbial tolerances towards these substances and their life-limiting properties. Here we present a study investigating the tolerances of the halotolerant yeast Debaryomyces hansenii to various solutes. Growth experiments were conducted via counting colony forming units (CFUs) after inoculation of a liquid growth medium containing a specific solute concentration. The lowest water activities (aw) enabling growth were determined to be ~0.83 in glycerol and fructose-rich media. For all other solutes the growth-enabling aw was higher, due to additional stress factors such as chaotropicity and ionic strength. Additionally, we found that the solute tolerances of D. hansenii correlate with both the eutectic freezing point depressions and the deliquescence relative humidities of the respective solutes. Our findings strongly impact our understanding of the habitability of solute-rich low aw environments on Earth and beyond.
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13
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Lu Q, Wang Z, Sa D, Hou M, Ge G, Wang Z, Jia Y. The Potential Effects on Microbiota and Silage Fermentation of Alfalfa Under Salt Stress. Front Microbiol 2021; 12:688695. [PMID: 34707575 PMCID: PMC8544858 DOI: 10.3389/fmicb.2021.688695] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 09/06/2021] [Indexed: 11/24/2022] Open
Abstract
This study investigated the fermentation quality of alfalfa grown in different salt stress regions in China. Following the production of silage from the natural fermentation of alfalfa, the interplay between the chemical composition, fermentation characteristics, and microbiome was examined to understand the influence of these factors on the fermentation quality of silage. The alfalfa was cultivated under salt stress with the following: (a) soil content of <1%0 (CK); (b) 1–2%0 (LS); (c) 2–3%0 (MS); (d) 3–4%0 (HS). The pH of the silage was high (4.9–5.3), and lactic acid content was high (26.3–51.0 g/kg DM). As the salt stress increases, the NA+ of the silages was higher (2.2–5.4 g/kg DM). The bacterial alpha diversities of the alfalfa silages were distinct. There was a predominance of desirable genera including Lactococcus and Lactobacillus in silage produced from alfalfa under salt stress, and this led to better fermentation quality. The chemical composition and fermentation characteristics of the silage were closely correlated with the composition of the bacterial community. Furthermore, NA+ was found to significantly influence the microbiome of the silage. The results confirmed that salt stress has a great impact on the quality and bacterial community of fresh alfalfa and silage. The salt stress and plant ions were thus most responsible for their different fermentation modes in alfalfa silage. The results of the study indicate that exogenous epiphytic microbiota of alfalfa under salt stress could be used as a potential bioresource to improve the fermentation quality.
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Affiliation(s)
- Qiang Lu
- College of Grassland and Resources and Environment, Inner Mongolia Agricultural University, Hohhot, China
| | - Zhen Wang
- Grassland Research Institute, Chinese Academy of Agricultural Sciences, Hohhot, China
| | - Duowen Sa
- College of Grassland and Resources and Environment, Inner Mongolia Agricultural University, Hohhot, China
| | - Meiling Hou
- College of Agriculture, Inner Mongolia University for Nationalities, Tongliao, China
| | - Gentu Ge
- College of Grassland and Resources and Environment, Inner Mongolia Agricultural University, Hohhot, China
| | - ZhiJun Wang
- College of Grassland and Resources and Environment, Inner Mongolia Agricultural University, Hohhot, China
| | - Yushan Jia
- College of Grassland and Resources and Environment, Inner Mongolia Agricultural University, Hohhot, China
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14
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Complex Brines and Their Implications for Habitability. Life (Basel) 2021; 11:life11080847. [PMID: 34440591 PMCID: PMC8398403 DOI: 10.3390/life11080847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 08/09/2021] [Accepted: 08/11/2021] [Indexed: 11/16/2022] Open
Abstract
There is evidence that life on Earth originated in cold saline waters around scorching hydrothermal vents, and that similar conditions might exist or have existed on Mars, Europa, Ganymede, Enceladus, and other worlds. Could potentially habitable complex brines with extremely low freezing temperatures exist in the shallow subsurface of these frigid worlds? Earth, Mars, and carbonaceous chondrites have similar bulk elemental abundances, but while the Earth is depleted in the most volatile elements, the Icy Worlds of the outer solar system are expected to be rich in them. The cooling of ionic solutions containing substances that likely exist in the Icy Worlds could form complex brines with the lowest eutectic temperature possible for the compounds available in them. Indeed, here, we show observational and theoretical evidence that even elements present in trace amounts in nature are concentrated by freeze–thaw cycles, and therefore contribute significantly to the formation of brine reservoirs that remain liquid throughout the year in some of the coldest places on Earth. This is interesting because the eutectic temperature of water–ammonia solutions can be as low as ~160 K, and significant fractions of the mass of the Icy Worlds are estimated to be water substance and ammonia. Thus, briny solutions with eutectic temperature of at least ~160 K could have formed where, historically, temperature have oscillated above and below ~160 K. We conclude that complex brines must exist in the shallow subsurface of Mars and the Icy Worlds, and that liquid saline water should be present where ice has existed, the temperature is above ~160 K, and evaporation and sublimation have been inhibited.
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15
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Pineda LH, Tecuapa-Flores ED, Hernández JG, Thangarasu P, Vázquez Ramos JM. Ruthenium complex of bis(benzimidazole-yl-ethyl)sulfide as chemo-sensor for selective recognition of chloride ion, and its application in real bacterial samples. Inorganica Chim Acta 2021. [DOI: 10.1016/j.ica.2021.120354] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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16
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Orevi T, Kashtan N. Life in a Droplet: Microbial Ecology in Microscopic Surface Wetness. Front Microbiol 2021; 12:655459. [PMID: 33927707 PMCID: PMC8076497 DOI: 10.3389/fmicb.2021.655459] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 03/19/2021] [Indexed: 12/16/2022] Open
Abstract
While many natural and artificial surfaces may appear dry, they are in fact covered by thin liquid films and microdroplets invisible to the naked eye known as microscopic surface wetness (MSW). Central to the formation and the retention of MSW are the deliquescent properties of hygroscopic salts that prevent complete drying of wet surfaces or that drive the absorption of water until dissolution when the relative humidity is above a salt-specific level. As salts are ubiquitous, MSW occurs in many microbial habitats, such as soil, rocks, plant leaf, and root surfaces, the built environment, and human and animal skin. While key properties of MSW, including very high salinity and segregation into droplets, greatly affect microbial life therein, it has been scarcely studied, and systematic studies are only in their beginnings. Based on recent findings, we propose that the harsh micro-environment that MSW imposes, which is very different from bulk liquid, affects key aspects of bacterial ecology including survival traits, antibiotic response, competition, motility, communication, and exchange of genetic material. Further research is required to uncover the fundamental principles that govern microbial life and ecology in MSW. Such research will require multidisciplinary science cutting across biology, physics, and chemistry, while incorporating approaches from microbiology, genomics, microscopy, and computational modeling. The results of such research will be critical to understand microbial ecology in vast terrestrial habitats, affecting global biogeochemical cycles, as well as plant, animal, and human health.
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Affiliation(s)
- Tomer Orevi
- Department of Plant Pathology and Microbiology, Robert H. Smith Faculty of Agriculture, Food, and Environment, Institute of Environmental Sciences, Hebrew University, Rehovot, Israel
| | - Nadav Kashtan
- Department of Plant Pathology and Microbiology, Robert H. Smith Faculty of Agriculture, Food, and Environment, Institute of Environmental Sciences, Hebrew University, Rehovot, Israel
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Garcia-Descalzo L, Gil-Lozano C, Muñoz-Iglesias V, Prieto-Ballesteros O, Azua-Bustos A, Fairén AG. Can Halophilic and Psychrophilic Microorganisms Modify the Freezing/Melting Curve of Cold Salty Solutions? Implications for Mars Habitability. ASTROBIOLOGY 2020; 20:1067-1075. [PMID: 32833498 PMCID: PMC7116095 DOI: 10.1089/ast.2019.2094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 06/24/2020] [Indexed: 06/11/2023]
Abstract
We present the hypothesis that microorganisms can change the freezing/melting curve of cold salty solutions by protein expression, as it is known that proteins can affect the liquid-to-ice transition, an ability that could be of ecological advantage for organisms on Earth and on Mars. We tested our hypothesis by identifying a suitable candidate, the well-known psycrophile and halotolerant bacteria Rhodococcus sp. JG3, and analyzing its response in culture conditions that included specific hygroscopic salts relevant to Mars-that is, highly concentrated magnesium perchlorate solutions of 20 wt % and 50 wt % Mg(ClO4)2 at both end members of the eutectic concentration (44 wt %)-and subfreezing temperatures (263 K and 253 K). Using a combination of techniques of molecular microbiology and aqueous geochemistry, we evaluated the potential roles of proteins over- or underexpressed as important players in different mechanisms for the adaptability of life to cold environments. We recorded the changes observed by micro-differential scanning calorimetry. Unfortunately, Rhodococcus sp. JG3 did not show our hypothesized effect on the melting characteristics of cold Mg-perchlorate solutions. However, the question remains as to whether our novel hypothesis that halophilic/psychrophilic bacteria or archaea can alter the freezing/melting curve of salt solutions could be validated. The null result obtained after analyzing just one case lays the foundation to continue the search for proteins produced by microorganisms that thrive in very cold, high-saline solutions, which would involve testing different microorganisms with different salt components. The immediate implications for the habitability of Mars are discussed.
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Affiliation(s)
| | - Carolina Gil-Lozano
- Centro de Astrobiología (CSIC-INTA), Madrid, Spain
- Departamento de Geociencias Marinas, Universidad de Vigo, Vigo, Spain
| | | | | | - Armando Azua-Bustos
- Centro de Astrobiología (CSIC-INTA), Madrid, Spain
- Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Santiago, Chile
| | - Alberto G. Fairén
- Centro de Astrobiología (CSIC-INTA), Madrid, Spain
- Department of Astronomy, Cornell University, Ithaca, New York, USA
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18
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Waajen AC, Heinz J, Airo A, Schulze-Makuch D. Physicochemical Salt Solution Parameters Limit the Survival of Planococcus halocryophilus in Martian Cryobrines. Front Microbiol 2020; 11:1284. [PMID: 32733393 PMCID: PMC7358355 DOI: 10.3389/fmicb.2020.01284] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 05/20/2020] [Indexed: 11/13/2022] Open
Abstract
Microorganisms living in sub-zero environments can benefit from the presence of dissolved salts, as they significantly increase the temperature range of liquid water by lowering the freezing point. However, high concentrations of salts can reduce microbial growth and survival, and can evoke a physiological stress response. It remains poorly understood how the physicochemical parameters of brines (e.g. water activity, ionic strength, solubility and hydration shell strength between the ions and the surrounding water molecules) influence the survival of microorganisms. We used the cryo- and halotolerant bacterial strain Planococcus halocryophilus as a model organism to evaluate the degree of stress different salts assert. Cells were incubated in liquid media at -15°C containing single salts at eutectic concentrations (CaCl2, LiCl, LiI, MgBr2, MgCl2, NaBr, NaCl, NaClO4 and NaI). Four of these salts (LiCl, LiI, MgBr2 and NaClO4) were also investigated at concentrations with a low water activity (0.635) and, separately, with a high ionic strength (8 mol/L). Water activity of all solutions was measured at -15°C. This is the first time that water activity has been measured for such a large number of liquid salt solutions at constant sub-zero temperatures (-15°C). Colony-Forming Unit (CFU) counts show that the survival of P. halocryophilus has a negative correlation with the salt concentration, molecular weight of the anion and anion radius; and a positive correlation with the water activity and anions' hydration shell strength. The survival of P. halocryophilus did not show a significant correlation with the ionic strength, the molecular weight of the cation, the hydrated and unhydrated cation and hydrated anion radius, and the cations' hydration bond length. Thus, the water activity, salt concentration and anion parameters play the largest role in the survival of P. halocryophilus in concentrated brines. These findings improve our understanding of the limitations of microbial life in saline environments, which provides a basis for better evaluation of the habitability of extraterrestrial environments such as Martian cryobrines.
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Affiliation(s)
- Annemiek C Waajen
- UK Centre for Astrobiology, School of Physics and Astronomy, The University of Edinburgh, Edinburgh, United Kingdom.,Astrobiology Research Group, Center of Astronomy and Astrophysics, Technische Universität Berlin, Berlin, Germany
| | - Jacob Heinz
- Astrobiology Research Group, Center of Astronomy and Astrophysics, Technische Universität Berlin, Berlin, Germany
| | - Alessandro Airo
- Astrobiology Research Group, Center of Astronomy and Astrophysics, Technische Universität Berlin, Berlin, Germany
| | - Dirk Schulze-Makuch
- Astrobiology Research Group, Center of Astronomy and Astrophysics, Technische Universität Berlin, Berlin, Germany.,School of the Environment, Washington State University, Pullman, WA, United States.,Section Geomicrobiology, GFZ German Research Centre for Geosciences, Potsdam, Germany.,Department of Experimental Limnology, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Stechlin, Germany
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19
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Stevens AH, Cockell CS. A Systematic Study of the Limits of Life in Mixed Ion Solutions: Physicochemical Parameters Do Not Predict Habitability. Front Microbiol 2020; 11:1478. [PMID: 32670258 PMCID: PMC7332579 DOI: 10.3389/fmicb.2020.01478] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 06/08/2020] [Indexed: 11/13/2022] Open
Abstract
This study investigated what defines the limits of life in mixed ion solutions. Better understanding these limits should allow us to better predict the habitability of extreme environments on the Earth and extraterrestrial environments. We systematically examined the response of Bacillus subtilis, a well characterized non-halophile model organism, to a range of solutions made from single and mixed salts up to their solubility limits and measured at what concentration growth was arrested, specifically exploring Na, Mg, and Ca cations and Cl, SO4, and ClO4 anions. We measured the physicochemical properties of the solutions to identify which properties correlated with the limits of growth. Individual salts imposed a growth limit specific to the combination of cation and anion, although we generally observe that chloride salts allow growth at lower water activity than sulfate salts, with perchlorate restricting growth even at the highest measured water activity. Growth was limited at a wide range of ionic strength, with no apparently correlation. Despite the theoretically counteracting disordering effects (chaotropic) of perchlorates and ordering effects (kosmotropic) effects of sulfates, when these salts were combined they instead additively narrowed the window for growth in both the Na and Mg cation systems, in the same manner as the combined effects of two chaotropic Ca salts. Our results imply that away from hard limits that might be imposed by physicochemical properties such as water activity, ionic strength or chaotropicity in highly concentrated brines, these properties do not set the limits of life. Instead these limits are highly specific to the salts and organisms in question. This specificity means that the habitability of extreme environments cannot be predicted, even with accurate measurements of the physicochemical conditions present.
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Affiliation(s)
- Adam H. Stevens
- UK Centre for Astrobiology, School of Physics and Astronomy, The University of Edinburgh, Edinburgh, United Kingdom
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20
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A New Record for Microbial Perchlorate Tolerance: Fungal Growth in NaClO 4 Brines and its Implications for Putative Life on Mars. Life (Basel) 2020; 10:life10050053. [PMID: 32353964 PMCID: PMC7281446 DOI: 10.3390/life10050053] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 04/21/2020] [Accepted: 04/24/2020] [Indexed: 11/21/2022] Open
Abstract
The habitability of Mars is strongly dependent on the availability of liquid water, which is essential for life as we know it. One of the few places where liquid water might be found on Mars is in liquid perchlorate brines that could form via deliquescence. As these concentrated perchlorate salt solutions do not occur on Earth as natural environments, it is necessary to investigate in lab experiments the potential of these brines to serve as a microbial habitat. Here, we report on the sodium perchlorate (NaClO4) tolerances for the halotolerant yeast Debaryomyces hansenii and the filamentous fungus Purpureocillium lilacinum. Microbial growth was determined visually, microscopically and via counting colony forming units (CFU). With the observed growth of D. hansenii in liquid growth medium containing 2.4 M NaClO4, we found by far the highest microbial perchlorate tolerance reported to date, more than twice as high as the record reported prior (for the bacterium Planococcus halocryophilus). It is plausible to assume that putative Martian microbes could adapt to even higher perchlorate concentrations due to their long exposure to these environments occurring naturally on Mars, which also increases the likelihood of microbial life thriving in the Martian brines.
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21
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Maus D, Heinz J, Schirmack J, Airo A, Kounaves SP, Wagner D, Schulze-Makuch D. Methanogenic Archaea Can Produce Methane in Deliquescence-Driven Mars Analog Environments. Sci Rep 2020; 10:6. [PMID: 31913316 PMCID: PMC6949245 DOI: 10.1038/s41598-019-56267-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 12/05/2019] [Indexed: 11/09/2022] Open
Abstract
The current understanding of the Martian surface indicates that briny environments at the near-surface are temporarily possible, e.g. in the case of the presumably deliquescence-driven Recurring Slope Lineae (RSL). However, whether such dynamic environments are habitable for terrestrial organisms remains poorly understood. This hypothesis was tested by developing a Closed Deliquescence System (CDS) consisting of a mixture of desiccated Martian Regolith Analog (MRA) substrate, salts, and microbial cells, which over the course of days became wetted through deliquescence. The methane produced via metabolic activity for three methanogenic archaea: Methanosarcina mazei, M. barkeri and M. soligelidi, was measured after exposing them to three different MRA substrates using either NaCl or NaClO4 as a hygroscopic salt. Our experiments showed that (1) M. soligelidi rapidly produced methane at 4 °C, (2) M. barkeri produced methane at 28 °C though not at 4 °C, (3) M. mazei was not metabolically reactivated through deliquescence, (4) none of the species produced methane in the presence of perchlorate, and (5) all species were metabolically most active in the phyllosilicate-containing MRA. These results emphasize the importance of the substrate, microbial species, salt, and temperature used in the experiments. Furthermore, we show here for the first time that water provided by deliquescence alone is sufficient to rehydrate methanogenic archaea and to reactivate their metabolism under conditions roughly analogous to the near-subsurface Martian environment.
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Affiliation(s)
- Deborah Maus
- Zentrum für Astronomie und Astrophysik (ZAA), AG Astrobiologie, Technische Universität Berlin, Hardenbergstr. 36, 10623, Berlin, Germany.,Metabolism of Microbial Pathogens, Robert Koch-Institute, Berlin, Germany
| | - Jacob Heinz
- Zentrum für Astronomie und Astrophysik (ZAA), AG Astrobiologie, Technische Universität Berlin, Hardenbergstr. 36, 10623, Berlin, Germany
| | - Janosch Schirmack
- Zentrum für Astronomie und Astrophysik (ZAA), AG Astrobiologie, Technische Universität Berlin, Hardenbergstr. 36, 10623, Berlin, Germany
| | - Alessandro Airo
- Zentrum für Astronomie und Astrophysik (ZAA), AG Astrobiologie, Technische Universität Berlin, Hardenbergstr. 36, 10623, Berlin, Germany
| | - Samuel P Kounaves
- Department of Chemistry, Tufts University, Medford, Massachusetts, USA.,Department of Earth Science and Engineering, Imperial College, London, UK
| | - Dirk Wagner
- GFZ German Research Center for Geosciences, Section Geomicrobiology, Potsdam, Germany.,Institute of Geosciences, University of Potsdam, Potsdam, Germany
| | - Dirk Schulze-Makuch
- Zentrum für Astronomie und Astrophysik (ZAA), AG Astrobiologie, Technische Universität Berlin, Hardenbergstr. 36, 10623, Berlin, Germany. .,GFZ German Research Center for Geosciences, Section Geomicrobiology, Potsdam, Germany. .,Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Department of Experimental Limnology, Stechlin, Germany.
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22
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Cosciotti B, Balbi A, Ceccarelli A, Fagliarone C, Mattei E, Lauro SE, Di Paolo F, Pettinelli E, Billi D. Survivability of Anhydrobiotic Cyanobacteria in Salty Ice: Implications for the Habitability of Icy Worlds. Life (Basel) 2019; 9:life9040086. [PMID: 31766612 PMCID: PMC6958388 DOI: 10.3390/life9040086] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2019] [Revised: 11/14/2019] [Accepted: 11/19/2019] [Indexed: 11/16/2022] Open
Abstract
Two anhydrobiotic strains of the cyanobacterium Chroococcidiopsis, namely CCMEE 029 and CCMEE 171, isolated from the Negev Desert in Israel and from the Dry Valleys in Antarctica, were exposed to salty-ice simulations. The aim of the experiment was to investigate the cyanobacterial capability to survive under sub-freezing temperatures in samples simulating the environment of icy worlds. The two strains were mixed with liquid solutions having sub-eutectic concentration of Na2SO4, MgSO4 and NaCl, then frozen down to different final temperatures (258 K, 233 K and 203 K) in various experimental runs. Both strains survived the exposure to 258 K in NaCl solution, probably as they migrated in the liquid veins between ice grain boundaries. However, they also survived at 258 K in Na2SO4 and MgSO4-salty-ice samples-that is, a temperature well below the eutectic temperature of the solutions, where liquid veins should not exist anymore. Moreover, both strains survived the exposure at 233 K in each salty-ice sample, with CCMEE 171 showing an enhanced survivability, whereas there were no survivors at 203 K. The survival limit at low temperature was further extended when both strains were exposed to 193 K as air-dried cells. The results suggest that vitrification might be a strategy for microbial life forms to survive in potentially habitable icy moons, for example in Europa's icy crust. By entering a dried, frozen state, they could be transported from niches, which became non-habitable to new habitable ones, and possibly return to metabolic activity.
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Affiliation(s)
- Barbara Cosciotti
- Department of Mathematics and Physics, University of Rome Tre, 00154 Rome, Italy; (B.C.); (A.C.); (E.M.); (S.E.L.); (F.D.P.); (E.P.)
| | - Amedeo Balbi
- Department of Physics, University of Rome Tor Vergata, 00133 Rome, Italy;
| | - Alessandra Ceccarelli
- Department of Mathematics and Physics, University of Rome Tre, 00154 Rome, Italy; (B.C.); (A.C.); (E.M.); (S.E.L.); (F.D.P.); (E.P.)
| | - Claudia Fagliarone
- Department of Biology, University of Rome Tor Vergata, 00133 Rome, Italy;
| | - Elisabetta Mattei
- Department of Mathematics and Physics, University of Rome Tre, 00154 Rome, Italy; (B.C.); (A.C.); (E.M.); (S.E.L.); (F.D.P.); (E.P.)
| | - Sebastian Emanuel Lauro
- Department of Mathematics and Physics, University of Rome Tre, 00154 Rome, Italy; (B.C.); (A.C.); (E.M.); (S.E.L.); (F.D.P.); (E.P.)
| | - Federico Di Paolo
- Department of Mathematics and Physics, University of Rome Tre, 00154 Rome, Italy; (B.C.); (A.C.); (E.M.); (S.E.L.); (F.D.P.); (E.P.)
| | - Elena Pettinelli
- Department of Mathematics and Physics, University of Rome Tre, 00154 Rome, Italy; (B.C.); (A.C.); (E.M.); (S.E.L.); (F.D.P.); (E.P.)
| | - Daniela Billi
- Department of Biology, University of Rome Tor Vergata, 00133 Rome, Italy;
- Correspondence:
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