1
|
Beaver RC, Vachon MA, Tully CS, Engel K, Spasov E, Binns WJ, Noël JJ, Neufeld JD. Impact of dry density and incomplete saturation on microbial growth in bentonite clay for nuclear waste storage. J Appl Microbiol 2024; 135:lxae053. [PMID: 38458234 DOI: 10.1093/jambio/lxae053] [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: 04/28/2023] [Revised: 10/12/2023] [Accepted: 03/07/2024] [Indexed: 03/10/2024]
Abstract
AIMS Many countries are in the process of designing a deep geological repository (DGR) for long-term storage of used nuclear fuel. For several designs, used fuel containers will be placed belowground, with emplacement tunnels being backfilled using a combination of highly compacted powdered bentonite clay buffer boxes surrounded by a granulated "gapfill" bentonite. To limit the potential for microbiologically influenced corrosion of used fuel containers, identifying conditions that suppress microbial growth is critical for sustainable DGR design. This study investigated microbial communities in powdered and gapfill bentonite clay incubated in oxic pressure vessels at dry densities between 1.1 g cm-3 (i.e. below repository target) and 1.6 g cm-3 (i.e. at or above repository target) as a 1-year time series. RESULTS Our results showed an initial (i.e. 1 month) increase in the abundance of culturable heterotrophs associated with all dry densities <1.6 g cm-3, which reveals growth during transient low-pressure conditions associated with the bentonite saturation process. Following saturation, culturable heterotroph abundances decreased to those of starting material by the 6-month time point for all 1.4 and 1.6 g cm-3 pressure vessels, and the most probable numbers of culturable sulfate-reducing bacteria (SRB) remained constant for all vessels and time points. The 16S rRNA gene sequencing results showed a change in microbial community composition from the starting material to the 1-month time point, after which time most samples were dominated by sequences associated with Pseudomonas, Bacillus, Cupriavidus, and Streptomyces. Similar taxa were identified as dominant members of the culture-based community composition, demonstrating that the dominant members of the clay microbial communities are viable. Members of the spore-forming Desulfosporosinus genus were the dominant SRB for both clay and culture profiles. CONCLUSIONS After initial microbial growth while bentonite was below target pressure in the early phases of saturation, microbial growth in pressure vessels with dry densities of at least 1.4 g cm-3 was eventually suppressed as bentonite neared saturation.
Collapse
Affiliation(s)
- Rachel C Beaver
- Department of Biology, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada
| | - Melody A Vachon
- Department of Biology, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada
| | - Claire S Tully
- Department of Chemistry, Western University, London, Ontario, N6A 3K7, Canada
| | - Katja Engel
- Department of Biology, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada
| | - Emilie Spasov
- Department of Biology, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada
| | - W Jeffrey Binns
- Nuclear Waste Management Organization, Toronto, Ontario, M4T 2S3, Canada
| | - James J Noël
- Department of Chemistry, Western University, London, Ontario, N6A 3K7, Canada
| | - Josh D Neufeld
- Department of Biology, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada
| |
Collapse
|
2
|
Song M, Warr O, Telling J, Sherwood Lollar B. Hydrogeological controls on microbial activity and habitability in the Precambrian continental crust. GEOBIOLOGY 2024; 22:e12592. [PMID: 38445449 DOI: 10.1111/gbi.12592] [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: 07/26/2023] [Revised: 12/21/2023] [Accepted: 02/19/2024] [Indexed: 03/07/2024]
Abstract
Earth's deep continental subsurface is a prime setting to study the limits of life's relationship with environmental conditions and habitability. In Precambrian crystalline rocks worldwide, deep ancient groundwaters in fracture networks are typically oligotrophic, highly saline, and locally inhabited by low-biomass communities in which chemolithotrophic microorganisms may dominate. Periodic opening of new fractures can lead to penetration of surface water and/or migration of fracture fluids, both of which may trigger changes in subsurface microbial composition and activity. These hydrogeological processes and their impacts on subsurface communities may play a significant role in global cycles of key elements in the crust. However, to date, considerable uncertainty remains on how subsurface microbial communities may respond to these changes in hydrogeochemical conditions. To address this uncertainty, the biogeochemistry of Thompson mine (Manitoba, Canada) was investigated. Compositional and isotopic analyses of fracture waters collected here at ~1 km below land surface revealed different extents of mixing between subsurface brine and (paleo)meteoric waters. To investigate the effects this mixing may have had on microbial communities, the Most Probable Number technique was applied to test community response for a total of 13 different metabolisms. The results showed that all fracture waters were dominated by viable heterotrophic microorganisms which can utilize organic materials associated with aerobic/facultative anaerobic processes, sulfate reduction, or fermentation. Where mixing between subsurface brines and (paleo)meteoric waters occurs, the communities demonstrate higher cell densities and increased viable functional potentials, compared to the most saline sample. This study therefore highlights the connection between hydrogeologic heterogeneity and the heterogeneity of subsurface ecosystems in the crystalline rocks, and suggests that hydrogeology can have a considerable impact on the scope and scale of subsurface microbial communities on Earth and potentially beyond.
Collapse
Affiliation(s)
- Min Song
- Department of Earth Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Oliver Warr
- Department of Earth Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Jon Telling
- Department of Earth Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Barbara Sherwood Lollar
- Department of Earth Sciences, University of Toronto, Toronto, Ontario, Canada
- Institut de Physique du Globe de Paris (IPGP), Université Paris Cité, Paris, France
| |
Collapse
|
3
|
Herzig M, Hyötyläinen T, Vettese GF, Law GTW, Vierinen T, Bomberg M. Altering environmental conditions induce shifts in simulated deep terrestrial subsurface bacterial communities-Secretion of primary and secondary metabolites. Environ Microbiol 2024; 26:e16552. [PMID: 38098179 DOI: 10.1111/1462-2920.16552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 11/24/2023] [Indexed: 01/30/2024]
Abstract
The deep terrestrial subsurface (DTS) harbours a striking diversity of microorganisms. However, systematic research on microbial metabolism, and how varying groundwater composition affects the bacterial communities and metabolites in these environments is lacking. In this study, DTS groundwater bacterial consortia from two Fennoscandian Shield sites were enriched and studied. We found that the enriched communities from the two sites consisted of distinct bacterial taxa, and alterations in the growth medium composition induced changes in cell counts. The lack of an exogenous organic carbon source (ECS) caused a notable increase in lipid metabolism in one community, while in the other, carbon starvation resulted in low overall metabolism, suggesting a dormant state. ECS supplementation increased CO2 production and SO4 2- utilisation, suggesting activation of a dissimilatory sulphate reduction pathway and sulphate-reducer-dominated total metabolism. However, both communities shared common universal metabolic features, most probably involving pathways needed for the maintenance of cell homeostasis (e.g., mevalonic acid pathway). Collectively, our findings indicate that the most important metabolites related to microbial reactions under varying growth conditions in enriched DTS communities include, but are not limited to, those linked to cell homeostasis, osmoregulation, lipid biosynthesis and degradation, dissimilatory sulphate reduction and isoprenoid production.
Collapse
Affiliation(s)
- Merja Herzig
- Faculty of Nuclear Sciences and Physical Engineering, Department of Nuclear Chemistry, Czech Technical University in Prague, Prague, Czech Republic
- Radiochemistry Unit, Faculty of Science, Department of Chemistry, University of Helsinki, Helsinki, Finland
| | - Tuulia Hyötyläinen
- School of Science and Technology, EnForce, Environment and Health and Systems Medicine, Örebro University, Örebro, Sweden
| | - Gianni F Vettese
- Radiochemistry Unit, Faculty of Science, Department of Chemistry, University of Helsinki, Helsinki, Finland
| | - Gareth T W Law
- Radiochemistry Unit, Faculty of Science, Department of Chemistry, University of Helsinki, Helsinki, Finland
| | - Taavi Vierinen
- Radiochemistry Unit, Faculty of Science, Department of Chemistry, University of Helsinki, Helsinki, Finland
| | - Malin Bomberg
- VTT Technical Research Centre of Finland, Espoo, Finland
| |
Collapse
|
4
|
Verrone V, Gupta A, Laloo AE, Dubey RK, Hamid NAA, Swarup S. Organic matter stability and lability in terrestrial and aquatic ecosystems: A chemical and microbial perspective. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 906:167757. [PMID: 37852479 DOI: 10.1016/j.scitotenv.2023.167757] [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: 07/18/2023] [Revised: 10/06/2023] [Accepted: 10/10/2023] [Indexed: 10/20/2023]
Abstract
Terrestrial and aquatic ecosystems have specific carbon fingerprints and sequestration potential, due to the intrinsic properties of the organic matter (OM), mineral content, environmental conditions, and microbial community composition and functions. A small variation in the OM pool can imbalance the carbon dynamics that ultimately affect the climate and functionality of each ecosystem, at regional and global scales. Here, we review the factors that continuously contribute to carbon stability and lability, with particular attention to the OM formation and nature, as well as the microbial activities that drive OM aggregation, degradation and eventually greenhouse gas emissions. We identified that in both aquatic and terrestrial ecosystems, microbial attributes (i.e., carbon metabolism, carbon use efficiency, necromass, enzymatic activities) play a pivotal role in transforming the carbon stock and yet they are far from being completely characterised and not often included in carbon estimations. Therefore, future research must focus on the integration of microbial components into carbon mapping and models, as well as on translating molecular-scaled studies into practical approaches. These strategies will improve carbon management and restoration across ecosystems and contribute to overcome current climate challenges.
Collapse
Affiliation(s)
- Valeria Verrone
- National University of Singapore Environmental Research Institute, National University of Singapore,117411, Singapore
| | - Abhishek Gupta
- Singapore Centre of Environmental Engineering and Life Sciences, National University of Singapore, Singapore.
| | - Andrew Elohim Laloo
- National University of Singapore Environmental Research Institute, National University of Singapore,117411, Singapore; Singapore Centre of Environmental Engineering and Life Sciences, National University of Singapore, Singapore
| | - Rama Kant Dubey
- National University of Singapore Environmental Research Institute, National University of Singapore,117411, Singapore; Department of Biological Sciences, National University of Singapore, Singapore 117558, Singapore; Department of Biotechnology, GLA University, Mathura, Uttar Pradesh 281406, India
| | - Nur Ashikin Abdul Hamid
- National University of Singapore Environmental Research Institute, National University of Singapore,117411, Singapore
| | - Sanjay Swarup
- National University of Singapore Environmental Research Institute, National University of Singapore,117411, Singapore; Singapore Centre of Environmental Engineering and Life Sciences, National University of Singapore, Singapore; Department of Biological Sciences, National University of Singapore, Singapore 117558, Singapore
| |
Collapse
|
5
|
Hart R, Cardace D. Mineral Indicators of Geologically Recent Past Habitability on Mars. Life (Basel) 2023; 13:2349. [PMID: 38137950 PMCID: PMC10744562 DOI: 10.3390/life13122349] [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: 10/07/2023] [Revised: 11/25/2023] [Accepted: 12/05/2023] [Indexed: 12/24/2023] Open
Abstract
We provide new support for habitable microenvironments in the near-subsurface of Mars, hosted in Fe- and Mg-rich rock units, and present a list of minerals that can serve as indicators of specific water-rock reactions in recent geologic paleohabitats for follow-on study. We modeled, using a thermodynamic basis without selective phase suppression, the reactions of published Martian meteorites and Jezero Crater igneous rock compositions and reasonable planetary waters (saline, alkaline waters) using Geochemist's Workbench Ver. 12.0. Solid-phase inputs were meteorite compositions for ALH 77005, Nakhla, and Chassigny, and two rock units from the Mars 2020 Perseverance rover sites, Máaz and Séítah. Six plausible Martian groundwater types [NaClO4, Mg(ClO4)2, Ca(ClO4)2, Mg-Na2(ClO4)2, Ca-Na2(ClO4)2, Mg-Ca(ClO4)2] and a unique Mars soil-water analog solution (dilute saline solution) named "Rosy Red", related to the Phoenix Lander mission, were the aqueous-phase inputs. Geophysical conditions were tuned to near-subsurface Mars (100 °C or 373.15 K, associated with residual heat from a magmatic system, impact event, or a concentration of radionuclides, and 101.3 kPa, similar to <10 m depth). Mineral products were dominated by phyllosilicates such as serpentine-group minerals in most reaction paths, but differed in some important indicator minerals. Modeled products varied in physicochemical properties (pH, Eh, conductivity), major ion activities, and related gas fugacities, with different ecological implications. The microbial habitability of pore spaces in subsurface groundwater percolation systems was interrogated at equilibrium in a thermodynamic framework, based on Gibbs Free Energy Minimization. Models run with the Chassigny meteorite produced the overall highest H2 fugacity. Models reliant on the Rosy Red soil-water analog produced the highest sustained CH4 fugacity (maximum values observed for reactant ALH 77005). In general, Chassigny meteorite protoliths produced the best yield regarding Gibbs Free Energy, from an astrobiological perspective. Occurrences of serpentine and saponite across models are key: these minerals have been observed using CRISM spectral data, and their formation via serpentinization would be consistent with geologically recent-past H2 and CH4 production and sustained energy sources for microbial life. We list index minerals to be used as diagnostic for paleo water-rock models that could have supported geologically recent-past microbial activity, and suggest their application as criteria for future astrobiology study-site selections.
Collapse
Affiliation(s)
- Roger Hart
- Department of Physics and Engineering, Community College of Rhode Island, Lincoln, RI 02865, USA
- Department of Geosciences, University of Rhode Island, Kingston, RI 02881, USA;
| | - Dawn Cardace
- Department of Geosciences, University of Rhode Island, Kingston, RI 02881, USA;
| |
Collapse
|
6
|
Nisson DM, Walters CC, Chacón-Patiño ML, Weisbrod CR, Kieft TL, Sherwood Lollar B, Warr O, Castillo J, Perl SM, Cason ED, Freifeld BM, Onstott TC. Radiolytically reworked Archean organic matter in a habitable deep ancient high-temperature brine. Nat Commun 2023; 14:6163. [PMID: 37789019 PMCID: PMC10547683 DOI: 10.1038/s41467-023-41900-8] [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: 02/07/2023] [Accepted: 09/20/2023] [Indexed: 10/05/2023] Open
Abstract
Investigations of abiotic and biotic contributions to dissolved organic carbon (DOC) are required to constrain microbial habitability in continental subsurface fluids. Here we investigate a large (101-283 mg C/L) DOC pool in an ancient (>1Ga), high temperature (45-55 °C), low biomass (102-104 cells/mL), and deep (3.2 km) brine from an uranium-enriched South African gold mine. Excitation-emission matrices (EEMs), negative electrospray ionization (-ESI) 21 tesla Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS), and amino acid analyses suggest the brine DOC is primarily radiolytically oxidized kerogen-rich shales or reefs, methane and ethane, with trace amounts of C3-C6 hydrocarbons and organic sulfides. δ2H and δ13C of C1-C3 hydrocarbons are consistent with abiotic origins. These findings suggest water-rock processes control redox and C cycling, helping support a meagre, slow biosphere over geologic time. A radiolytic-driven, habitable brine may signal similar settings are good targets in the search for life beyond Earth.
Collapse
Affiliation(s)
- Devan M Nisson
- Department of Geosciences, Princeton University, Princeton, NJ, 08540, USA.
| | | | | | - Chad R Weisbrod
- National High Magnetic Field Laboratory, Tallahassee, FL, 32310, USA
| | - Thomas L Kieft
- Department of Biology, New Mexico Institute of Mining and Technology, Socorro, NM, 87801, USA
| | - Barbara Sherwood Lollar
- Department of Earth Sciences, University of Toronto, Toronto, ON, M5S 3B1, Canada
- Institut de Physique du Globe de Paris (IPGP), Université Paris Cité, 1 rue Jussieu, 75005, Paris, France
| | - Oliver Warr
- Department of Earth Sciences, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
| | - Julio Castillo
- Department of Microbiology and Biochemistry, University of the Free State, Bloemfontein, 9300, South Africa
| | - Scott M Perl
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, 91109, USA
| | - Errol D Cason
- Department of Animal Sciences, University of the Free State, Bloemfontein, 9300, South Africa
| | | | - Tullis C Onstott
- Department of Geosciences, Princeton University, Princeton, NJ, 08540, USA
| |
Collapse
|
7
|
Nuppunen-Puputti M, Kietäväinen R, Kukkonen I, Bomberg M. Implications of a short carbon pulse on biofilm formation on mica schist in microcosms with deep crystalline bedrock groundwater. Front Microbiol 2023; 14:1054084. [PMID: 36819068 PMCID: PMC9932282 DOI: 10.3389/fmicb.2023.1054084] [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: 09/26/2022] [Accepted: 01/06/2023] [Indexed: 02/05/2023] Open
Abstract
Microbial life in the deep subsurface occupies rock surfaces as attached communities and biofilms. Previously, epilithic Fennoscandian deep subsurface bacterial communities were shown to host genetic potential, especially for heterotrophy and sulfur cycling. Acetate, methane, and methanol link multiple biogeochemical pathways and thus represent an important carbon and energy source for microorganisms in the deep subsurface. In this study, we examined further how a short pulse of low-molecular-weight carbon compounds impacts the formation and structure of sessile microbial communities on mica schist surfaces over an incubation period of ∼3.5 years in microcosms containing deep subsurface groundwater from the depth of 500 m, from Outokumpu, Finland. The marker gene copy counts in the water and rock phases were estimated with qPCR, which showed that bacteria dominated the mica schist communities with a relatively high proportion of epilithic sulfate-reducing bacteria in all microcosms. The dominant bacterial phyla in the microcosms were Proteobacteria, Firmicutes, and Actinobacteria, whereas most fungal genera belonged to Ascomycota and Basidiomycota. Dissimilarities between planktic and sessile rock surface microbial communities were observed, and the supplied carbon substrates led to variations in the bacterial community composition.
Collapse
Affiliation(s)
- Maija Nuppunen-Puputti
- VTT Technical Research Centre of Finland Ltd., Espoo, Finland,*Correspondence: Maija Nuppunen-Puputti,
| | | | - Ilmo Kukkonen
- Department of Physics, University of Helsinki, Helsinki, Finland
| | - Malin Bomberg
- VTT Technical Research Centre of Finland Ltd., Espoo, Finland
| |
Collapse
|
8
|
Mandal S, Bose H, Ramesh K, Sahu RP, Saha A, Sar P, Kazy SK. Depth wide distribution and metabolic potential of chemolithoautotrophic microorganisms reactivated from deep continental granitic crust underneath the Deccan Traps at Koyna, India. Front Microbiol 2022; 13:1018940. [PMID: 36504802 PMCID: PMC9731672 DOI: 10.3389/fmicb.2022.1018940] [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: 08/14/2022] [Accepted: 11/01/2022] [Indexed: 11/25/2022] Open
Abstract
Characterization of inorganic carbon (C) utilizing microorganisms from deep crystalline rocks is of major scientific interest owing to their crucial role in global carbon and other elemental cycles. In this study we investigate the microbial populations from the deep [up to 2,908 meters below surface (mbs)] granitic rocks within the Koyna seismogenic zone, reactivated (enriched) under anaerobic, high temperature (50°C), chemolithoautotrophic conditions. Subsurface rock samples from six different depths (1,679-2,908 mbs) are incubated (180 days) with CO2 (+H2) or HCO3 - as the sole C source. Estimation of total protein, ATP, utilization of NO3 - and SO4 2- and 16S rRNA gene qPCR suggests considerable microbial growth within the chemolithotrophic conditions. We note a better response of rock hosted community towards CO2 (+H2) over HCO3 -. 16S rRNA gene amplicon sequencing shows a depth-wide distribution of diverse chemolithotrophic (and a few fermentative) Bacteria and Archaea. Comamonas, Burkholderia-Caballeronia-Paraburkholderia, Ralstonia, Klebsiella, unclassified Burkholderiaceae and Enterobacteriaceae are reactivated as dominant organisms from the enrichments of the deeper rocks (2335-2,908 mbs) with both CO2 and HCO3 -. For the rock samples from shallower depths, organisms of varied taxa are enriched under CO2 (+H2) and HCO3 -. Pseudomonas, Rhodanobacter, Methyloversatilis, and Thaumarchaeota are major CO2 (+H2) utilizers, while Nocardioides, Sphingomonas, Aeromonas, respond towards HCO3 -. H2 oxidizing Cupriavidus, Hydrogenophilus, Hydrogenophaga, CO2 fixing Cyanobacteria Rhodobacter, Clostridium, Desulfovibrio and methanogenic archaea are also enriched. Enriched chemolithoautotrophic members show good correlation with CO2, CH4 and H2 concentrations of the native rock environments, while the organisms from upper horizons correlate more to NO3 -, SO4 2- , Fe and TIC levels of the rocks. Co-occurrence networks suggest close interaction between chemolithoautotrophic and chemoorganotrophic/fermentative organisms. Carbon fixing 3-HP and DC/HB cycles, hydrogen, sulfur oxidation, CH4 and acetate metabolisms are predicted in the enriched communities. Our study elucidates the presence of live, C and H2 utilizing Bacteria and Archaea in deep subsurface granitic rocks, which are enriched successfully. Significant impact of depth and geochemical controls on relative distribution of various chemolithotrophic species enriched and their C and H2 metabolism are highlighted. These endolithic microorganisms show great potential for answering the fundamental questions of deep life and their exploitation in CO2 capture and conversion to useful products.
Collapse
Affiliation(s)
- Sunanda Mandal
- Environmental Microbiology and Biotechnology Laboratory, Department of Biotechnology, National Institute of Technology Durgapur, Durgapur, WB, India
| | - Himadri Bose
- Environmental Microbiology and Genomics Laboratory, Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, WB, India
| | - Kheerthana Ramesh
- Environmental Microbiology and Biotechnology Laboratory, Department of Biotechnology, National Institute of Technology Durgapur, Durgapur, WB, India
| | - Rajendra Prasad Sahu
- Environmental Microbiology and Genomics Laboratory, Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, WB, India
| | - Anumeha Saha
- Environmental Microbiology and Genomics Laboratory, Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, WB, India
| | - Pinaki Sar
- Environmental Microbiology and Genomics Laboratory, Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, WB, India
| | - Sufia Khannam Kazy
- Environmental Microbiology and Biotechnology Laboratory, Department of Biotechnology, National Institute of Technology Durgapur, Durgapur, WB, India,*Correspondence: Sufia Khannam Kazy,
| |
Collapse
|
9
|
Meyer-Dombard DR, Malas J. Advances in Defining Ecosystem Functions of the Terrestrial Subsurface Biosphere. Front Microbiol 2022; 13:891528. [PMID: 35722320 PMCID: PMC9201636 DOI: 10.3389/fmicb.2022.891528] [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: 03/07/2022] [Accepted: 05/03/2022] [Indexed: 11/13/2022] Open
Abstract
The subsurface is one of the last remaining 'uncharted territories' of Earth and is now accepted as a biosphere in its own right, at least as critical to Earth systems as the surface biosphere. The terrestrial deep biosphere is connected through a thin veneer of Earth's crust to the surface biosphere, and many subsurface biosphere ecosystems are impacted by surface topography, climate, and near surface groundwater movement and represent a transition zone (at least ephemerally). Delving below this transition zone, we can examine how microbial metabolic functions define a deep terrestrial subsurface. This review provides a survey of the most recent advances in discovering the functional and genomic diversity of the terrestrial subsurface biosphere, how microbes interact with minerals and obtain energy and carbon in the subsurface, and considers adaptations to the presented environmental extremes. We highlight the deepest subsurface studies in deep mines, deep laboratories, and boreholes in crystalline and altered host rock lithologies, with a focus on advances in understanding ecosystem functions in a holistic manner.
Collapse
|
10
|
Yun Y, Gui Z, Su T, Tian X, Wang S, Chen Y, Su Z, Fan H, Xie J, Li G, Xia W, Ma T. Deep mining decreases the microbial taxonomic and functional diversity of subsurface oil reservoirs. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 821:153564. [PMID: 35101516 DOI: 10.1016/j.scitotenv.2022.153564] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Revised: 01/25/2022] [Accepted: 01/26/2022] [Indexed: 06/14/2023]
Abstract
Microbes in subsurface oil reservoirs play important roles in elemental cycles and biogeochemical processes. However, the community assembly pattern of indigenous microbiome and their succession under long-term human activity remain poorly understood. Here we studied the microbial community assembly in underground sandstone cores from 190 to 2050 m in northeast China and their response to long-term oil recovery (10-50 years). Indigenous microbiome in subsurface petroleum reservoirs were dominated by Gammaproteobacteria, Firmicutes, Alphaproteobacteria, Bacteroidetes, and Actinobacteria, which exhibited a higher contribution of homogenizing dispersal assembly and different taxonomy distinct ecological modules when compared with perturbed samples. Specifically, the long-term oil recovery reduced the bacterial taxonomic- and functional-diversity, and increased the community co-occurrence associations in subsurface oil reservoirs. Moreover, distinguished from the perturbed samples, both variation partition analysis and structural equation model revealed that the contents of quartz, NO3- and Cl- significantly structured the α- and β-diversity in indigenous subsurface bacterial communities. These findings first provide the holistic picture of microbiome in the deep oil reservoirs, which demonstrate the significant impact of human activity on microbiome in deep continental subsurface.
Collapse
Affiliation(s)
- Yuan Yun
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Ziyu Gui
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Tianqi Su
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Xuefeng Tian
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Shaojing Wang
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Yu Chen
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Zhaoying Su
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Huiqiang Fan
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Jinxia Xie
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Guoqiang Li
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Wenjie Xia
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Ting Ma
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China.
| |
Collapse
|
11
|
Nuppunen-Puputti M, Kietäväinen R, Raulio M, Soro A, Purkamo L, Kukkonen I, Bomberg M. Epilithic Microbial Community Functionality in Deep Oligotrophic Continental Bedrock. Front Microbiol 2022; 13:826048. [PMID: 35300483 PMCID: PMC8921683 DOI: 10.3389/fmicb.2022.826048] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 01/12/2022] [Indexed: 01/03/2023] Open
Abstract
The deep terrestrial biosphere hosts vast sessile rock surface communities and biofilms, but thus far, mostly planktic communities have been studied. We enriched deep subsurface microbial communities on mica schist in microcosms containing bedrock groundwater from the depth of 500 m from Outokumpu, Finland. The biofilms were visualized using scanning electron microscopy, revealing numerous different microbial cell morphologies and attachment strategies on the mica schist surface, e.g., bacteria with outer membrane vesicle-like structures, hair-like extracellular extensions, and long tubular cell structures expanding over hundreds of micrometers over mica schist surfaces. Bacterial communities were analyzed with amplicon sequencing showing that Pseudomonas, Desulfosporosinus, Hydrogenophaga, and Brevundimonas genera dominated communities after 8–40 months of incubation. A total of 21 metagenome assembled genomes from sessile rock surface metagenomes identified genes involved in biofilm formation, as well as a wide variety of metabolic traits indicating a high degree of environmental adaptivity to oligotrophic environment and potential for shifting between multiple energy or carbon sources. In addition, we detected ubiquitous organic carbon oxidation and capacity for arsenate and selenate reduction within our rocky MAGs. Our results agree with the previously suggested interaction between the deep subsurface microbial communities and the rock surfaces, and that this interaction could be crucial for sustaining life in the harsh anoxic and oligotrophic deep subsurface of crystalline bedrock environment.
Collapse
Affiliation(s)
| | | | - Mari Raulio
- European Chemicals Agency (ECHA), Helsinki, Finland
| | - Aino Soro
- VTT Technical Research Centre of Finland Ltd., Espoo, Finland
| | | | - Ilmo Kukkonen
- Department of Physics, University of Helsinki, Helsinki, Finland
| | - Malin Bomberg
- VTT Technical Research Centre of Finland Ltd., Espoo, Finland
| |
Collapse
|
12
|
Sahu RP, Kazy SK, Bose H, Mandal S, Dutta A, Saha A, Roy S, Dutta Gupta S, Mukherjee A, Sar P. Microbial diversity and function in crystalline basement beneath the Deccan Traps explored in a 3 km borehole at Koyna, western India. Environ Microbiol 2021; 24:2837-2853. [PMID: 34897962 DOI: 10.1111/1462-2920.15867] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 11/29/2021] [Accepted: 12/05/2021] [Indexed: 12/20/2022]
Abstract
Deep terrestrial subsurface represents a huge repository of global prokaryotic biomass. Given its vastness and importance, microbial life within the deep subsurface continental crust remains under-represented in global studies. We characterize the microbial communities of deep, extreme and oligotrophic realm hosted by crystalline Archaean granitic rocks underneath the Deccan Traps, through sampling via 3000 m deep scientific borehole at Koyna, India through metagenomics, amplicon sequencing and cultivation-based analyses. Gene sequences 16S rRNA (7.37 × 106 ) show considerable bacterial diversity and the existence of a core microbiome (5724 operational taxonomic units conserved out of a total 118,064 OTUs) across the depths. Relative abundance of different taxa of core microbiome varies with depth in response to prevailing lithology and geochemistry. Co-occurrence network analysis and cultivation attempt to elucidate close interactions among autotrophic and organotrophic bacteria. Shotgun metagenomics reveals a major role of autotrophic carbon fixation via the Wood-Ljungdahl pathway and genes responsible for energy and carbon metabolism. Deeper analysis suggests the existence of an 'acetate switch', coordinating biosynthesis and cellular homeostasis. We conclude that the microbial life in the nutrient- and energy-limited deep granitic crust is constrained by the depth and managed by a few core members via a close interplay between autotrophy and organotrophy.
Collapse
Affiliation(s)
- Rajendra Prasad Sahu
- Environmental Microbiology and Genomics Laboratory, Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, WB, 721302, India
| | - Sufia K Kazy
- Department of Biotechnology, National Institute of Technology Durgapur, Durgapur, WB, 713209, India
| | - Himadri Bose
- Environmental Microbiology and Genomics Laboratory, Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, WB, 721302, India
| | - Sunanda Mandal
- Department of Biotechnology, National Institute of Technology Durgapur, Durgapur, WB, 713209, India
| | - Avishek Dutta
- Environmental Microbiology and Genomics Laboratory, Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, WB, 721302, India
| | - Anumeha Saha
- Environmental Microbiology and Genomics Laboratory, Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, WB, 721302, India
| | - Sukanta Roy
- Ministry of Earth Sciences, Borehole Geophysics Research Laboratory, Karad, MH, 415114, India
| | - Srimanti Dutta Gupta
- School of Environmental Science and Engineering, Indian Institute of Technology Kharagpur, Kharagpur, WB, 721302, India
| | - Abhijit Mukherjee
- School of Environmental Science and Engineering, Indian Institute of Technology Kharagpur, Kharagpur, WB, 721302, India.,Department of Geology and Geophysics, Indian Institute of Technology Kharagpur, Kharagpur, WB, 721302, India
| | - Pinaki Sar
- Environmental Microbiology and Genomics Laboratory, Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, WB, 721302, India
| |
Collapse
|
13
|
Beaver RC, Engel K, Binns WJ, Neufeld JD. Microbiology of barrier component analogues of a deep geological repository. Can J Microbiol 2021; 68:73-90. [PMID: 34648720 DOI: 10.1139/cjm-2021-0225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Canada is currently implementing a site selection process to identify a location for a deep geological repository (DGR) for the long-term storage of Canada's used nuclear fuel, wherein used nuclear fuel bundles will be sealed inside copper-coated carbon steel containers, encased in highly compacted bentonite clay buffer boxes, and sealed deep underground in a stable geosphere. Because a DGR must remain functional for a million years, it is important to examine ancient natural systems that serve as analogues for planned DGR components. Specifically, studying the microbiology of natural analogue components of a DGR is important for developing an understanding of the types of microorganisms that may be able to grow and influence the long-term stability of a DGR. This study explored the abundance, viability, and composition of microorganisms in several ancient natural analogues using a combination of cultivation and cultivation-independent approaches. Samples were obtained from the Tsukinuno bentonite deposit (Japan) that formed ∼10 mya, the Opalinus Clay formation (Switzerland) that formed ∼174 mya, and Canadian shield crystalline rock from Northern Ontario that formed ∼2.7 bya. Analysis of 16S rRNA gene amplicons revealed that three of the ten Tsukinuno bentonite samples analyzed were dominated by putative aerobic heterotrophs and fermenting bacteria from the phylum Actinobacteria, whereas five of the Tsukinuno bentonite samples were dominated by sequences associated with putative acidophilic chemolithoautotrophs capable of sulfur reduction. The remaining Tsukinuno bentonite samples, the Northern Ontario rock samples, and the Opalinus Clay samples generated inconsistent replicate 16S rRNA gene profiles and were associated primarily with contaminant sequences, suggesting that the microbial profiles detected were not sample-specific but spurious. Culturable aerobic heterotroph abundances were relatively low for all Tsukinuno bentonite samples, culturable anaerobic heterotrophs were only detected in half of the Tsukinuno samples, and sulfate-reducing bacteria (SRB) were only detected in one Tsukinuno sample by cultivation. Culture-specific 16S rRNA gene profiles from Tsukinuno clay samples demonstrated the presence of phyla Bacteroidetes, Proteobacteria, Actinobacteria, and Firmicutes among aerobic heterotroph cultures and additional bacteria from the phyla Actinobacteria and Firmicutes from anaerobic heterotroph plate incubations. Only one nucleic acid sequence detected from a culture was also associated with its corresponding clay sample profile, suggesting that nucleic acids from culturable bacteria were relatively rare within the clay samples. Sequencing of DNA extracted from the SRB culture revealed that the taxon present in the culture was affiliated with the genus Desulfosporosinus, which has been found in related bentonite clay analyses. Although the crystalline rock and Opalinus Clay samples were associated with inconsistent, likely spurious 16S rRNA gene profiles, we show evidence for viable and detectable microorganisms within several Tsukinuno natural analogue bentonite samples.
Collapse
Affiliation(s)
- Rachel C Beaver
- Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
| | - Katja Engel
- Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
| | - W Jeffrey Binns
- Nuclear Waste Management Organization, Toronto, Ontario, Canada
| | - Josh D Neufeld
- Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
| |
Collapse
|
14
|
Sanz JL, Rodriguez N, Escudero C, Carrizo D, Amils R. Biological production of H 2 , CH 4 and CO 2 in the deep subsurface of the Iberian Pyrite Belt. Environ Microbiol 2021; 23:3913-3922. [PMID: 33973338 DOI: 10.1111/1462-2920.15561] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 04/29/2021] [Accepted: 05/01/2021] [Indexed: 11/26/2022]
Abstract
Most of the terrestrial deep subsurfaces are oligotrophic environments in which some gases, mainly H2 , CH4 and CO2 , play an important role as energy and/or carbon sources. In this work, we assessed their biotic and abiotic origin in samples from subsurface hard-rock cores of the Iberian Pyrite Belt (IPB) at three different depths (414, 497 and 520 m). One set of samples was sterilized (abiotic control) and all samples were incubated under anaerobic conditions. Our results showed that H2 , CH4 and CO2 remained low and constant in the sterilized controls while their levels were 4, 4.1 and 2.5 times higher respectively, in the unsterilized samples compared to the abiotic controls. The δ13 CCH4 -values measured in the samples (range -31.2 to -43.0 ‰) reveals carbon isotopic signatures that are within the range for biological methane production. Possible microorganisms responsible for the biotic production of the gases were assessed by CARD-FISH. The analysis of sequenced genomes of detected microorganisms within the subsurface of the IPB allowed to identify possible metabolic activities involved in H2 (Rhodoplanes, Shewanella and Desulfosporosinus), CH4 (Methanobacteriales) and CO2 production. The obtained results suggest that part of the H2 , CH4 and CO2 detected in the deep subsurface has a biological origin.
Collapse
Affiliation(s)
- Jose L Sanz
- Molecular Biology Department, Universidad Autónoma de Madrid, Madrid, Spain
| | - Nuria Rodriguez
- Centro de Astrobiología (INTA-CSIC), Torrejón de Ardoz, 28850, Spain
| | - Cristina Escudero
- Centro de Astrobiología (INTA-CSIC), Torrejón de Ardoz, 28850, Spain.,Centro de Biología Molecular Severo Ochoa (UAM-CSIC), Universidad Autónoma de Madrid, Madrid, 28049, Spain
| | - Daniel Carrizo
- Centro de Astrobiología (INTA-CSIC), Torrejón de Ardoz, 28850, Spain
| | - Ricardo Amils
- Centro de Astrobiología (INTA-CSIC), Torrejón de Ardoz, 28850, Spain.,Centro de Biología Molecular Severo Ochoa (UAM-CSIC), Universidad Autónoma de Madrid, Madrid, 28049, Spain
| |
Collapse
|
15
|
Active sulfur cycling in the terrestrial deep subsurface. ISME JOURNAL 2020; 14:1260-1272. [PMID: 32047278 DOI: 10.1038/s41396-020-0602-x] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 01/27/2020] [Accepted: 01/28/2020] [Indexed: 11/09/2022]
Abstract
The deep terrestrial subsurface remains an environment where there is limited understanding of the extant microbial metabolisms. At Olkiluoto, Finland, a deep geological repository is under construction for the final storage of spent nuclear fuel. It is therefore critical to evaluate the potential impact microbial metabolism, including sulfide generation, could have upon the safety of the repository. We investigated a deep groundwater where sulfate is present, but groundwater geochemistry suggests limited microbial sulfate-reducing activity. Examination of the microbial community at the genome-level revealed microorganisms with the metabolic capacity for both oxidative and reductive sulfur transformations. Deltaproteobacteria are shown to have the genetic capacity for sulfate reduction and possibly sulfur disproportionation, while Rhizobiaceae, Rhodocyclaceae, Sideroxydans, and Sulfurimonas oxidize reduced sulfur compounds. Further examination of the proteome confirmed an active sulfur cycle, serving for microbial energy generation and growth. Our results reveal that this sulfide-poor groundwater harbors an active microbial community of sulfate-reducing and sulfide-oxidizing bacteria, together mediating a sulfur cycle that remained undetected by geochemical monitoring alone. The ability of sulfide-oxidizing bacteria to limit the accumulation of sulfide was further demonstrated in groundwater incubations and highlights a potential sink for sulfide that could be beneficial for geological repository safety.
Collapse
|
16
|
Purkamo L, Kietäväinen R, Nuppunen-Puputti M, Bomberg M, Cousins C. Ultradeep Microbial Communities at 4.4 km within Crystalline Bedrock: Implications for Habitability in a Planetary Context. Life (Basel) 2020; 10:E2. [PMID: 31947979 PMCID: PMC7175195 DOI: 10.3390/life10010002] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 12/31/2019] [Accepted: 01/01/2020] [Indexed: 01/06/2023] Open
Abstract
The deep bedrock surroundings are an analog for extraterrestrial habitats for life. In this study, we investigated microbial life within anoxic ultradeep boreholes in Precambrian bedrock, including the adaptation to environmental conditions and lifestyle of these organisms. Samples were collected from Pyhäsalmi mine environment in central Finland and from geothermal drilling wells in Otaniemi, Espoo, in southern Finland. Microbial communities inhabiting the up to 4.4 km deep bedrock were characterized with phylogenetic marker gene (16S rRNA genes and fungal ITS region) amplicon and DNA and cDNA metagenomic sequencing. Functional marker genes (dsrB, mcrA, narG) were quantified with qPCR. Results showed that although crystalline bedrock provides very limited substrates for life, the microbial communities are diverse. Gammaproteobacterial phylotypes were most dominant in both studied sites. Alkanindiges -affiliating OTU was dominating in Pyhäsalmi fluids, while different depths of Otaniemi samples were dominated by Pseudomonas. One of the most common OTUs detected from Otaniemi could only be classified to phylum level, highlighting the uncharacterized nature of the deep biosphere in bedrock. Chemoheterotrophy, fermentation and nitrogen cycling are potentially significant metabolisms in these ultradeep environments. To conclude, this study provides information on microbial ecology of low biomass, carbon-depleted and energy-deprived deep subsurface environment. This information is useful in the prospect of finding life in other planetary bodies.
Collapse
Affiliation(s)
- Lotta Purkamo
- School of Earth and Environmental Sciences, University of St Andrews, St Andrews KY16 9AL, UK
- Geological Survey of Finland, 02151 Espoo, Finland
| | - Riikka Kietäväinen
- Geological Survey of Finland, 02151 Espoo, Finland
- Department of Geosciences and Geography, University of Helsinki, 00014 Helsinki, Finland
| | | | - Malin Bomberg
- VTT Technical Research Centre of Finland, 02044 VTT, Finland
| | - Claire Cousins
- School of Earth and Environmental Sciences, University of St Andrews, St Andrews KY16 9AL, UK
| |
Collapse
|
17
|
Onstott T, Ehlmann B, Sapers H, Coleman M, Ivarsson M, Marlow J, Neubeck A, Niles P. Paleo-Rock-Hosted Life on Earth and the Search on Mars: A Review and Strategy for Exploration. ASTROBIOLOGY 2019; 19:1230-1262. [PMID: 31237436 PMCID: PMC6786346 DOI: 10.1089/ast.2018.1960] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Accepted: 04/25/2019] [Indexed: 05/19/2023]
Abstract
Here we review published studies on the abundance and diversity of terrestrial rock-hosted life, the environments it inhabits, the evolution of its metabolisms, and its fossil biomarkers to provide guidance in the search for life on Mars. Key findings are (1) much terrestrial deep subsurface metabolic activity relies on abiotic energy-yielding fluxes and in situ abiotic and biotic recycling of metabolic waste products rather than on buried organic products of photosynthesis; (2) subsurface microbial cell concentrations are highest at interfaces with pronounced chemical redox gradients or permeability variations and do not correlate with bulk host rock organic carbon; (3) metabolic pathways for chemolithoautotrophic microorganisms evolved earlier in Earth's history than those of surface-dwelling phototrophic microorganisms; (4) the emergence of the former occurred at a time when Mars was habitable, whereas the emergence of the latter occurred at a time when the martian surface was not continually habitable; (5) the terrestrial rock record has biomarkers of subsurface life at least back hundreds of millions of years and likely to 3.45 Ga with several examples of excellent preservation in rock types that are quite different from those preserving the photosphere-supported biosphere. These findings suggest that rock-hosted life would have been more likely to emerge and be preserved in a martian context. Consequently, we outline a Mars exploration strategy that targets subsurface life and scales spatially, focusing initially on identifying rocks with evidence for groundwater flow and low-temperature mineralization, then identifying redox and permeability interfaces preserved within rock outcrops, and finally focusing on finding minerals associated with redox reactions and associated traces of carbon and diagnostic chemical and isotopic biosignatures. Using this strategy on Earth yields ancient rock-hosted life, preserved in the fossil record and confirmable via a suite of morphologic, organic, mineralogical, and isotopic fingerprints at micrometer scale. We expect an emphasis on rock-hosted life and this scale-dependent strategy to be crucial in the search for life on Mars.
Collapse
Affiliation(s)
- T.C. Onstott
- Department of Geosciences, Princeton University, Princeton, New Jersey, USA
- Address correspondence to: T.C. Onstott, Department of Geosciences, Princeton University,, Princeton, NJ 008544
| | - B.L. Ehlmann
- Division of Geological & Planetary Sciences, California Institute of Technology, Pasadena, California, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
- B.L. Ehlmann, Division of Geological & Planetary Sciences, California Institute of Technology, Pasadena, CA 91125
| | - H. Sapers
- Division of Geological & Planetary Sciences, California Institute of Technology, Pasadena, California, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
- Department of Earth Sciences, University of Southern California, Los Angeles, California, USA
| | - M. Coleman
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
- NASA Astrobiology Institute, Pasadena, California, USA
| | - M. Ivarsson
- Department of Biology, University of Southern Denmark, Odense, Denmark
| | - J.J. Marlow
- Department of Organismic & Evolutionary Biology, Harvard University, Cambridge, Massachusetts, USA
| | - A. Neubeck
- Department of Earth Sciences, Uppsala University, Uppsala, Sweden
| | - P. Niles
- Astromaterials Research and Exploration Science Division, NASA Johnson Space Center, Houston, Texas, USA
| |
Collapse
|
18
|
Dutta A, Sar P, Sarkar J, Dutta Gupta S, Gupta A, Bose H, Mukherjee A, Roy S. Archaeal Communities in Deep Terrestrial Subsurface Underneath the Deccan Traps, India. Front Microbiol 2019; 10:1362. [PMID: 31379755 PMCID: PMC6646420 DOI: 10.3389/fmicb.2019.01362] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 05/31/2019] [Indexed: 11/13/2022] Open
Abstract
Archaeal community structure and potential functions within the deep, aphotic, oligotrophic, hot, igneous provinces of ∼65 Myr old basalt and its Archean granitic basement was explored through archaeal 16S rRNA gene amplicon sequencing from extracted environmental DNA of rocks. Rock core samples from three distinct horizons, basaltic (BS), transition (weathered granites) (TZ) and granitic (GR) showed limited organic carbon (4–48 mg/kg) and varied concentrations (<1.0–5000 mg/kg) of sulfate, nitrate, nitrite, iron and metal oxides. Quantitative PCR estimated the presence of nearly 103–104 archaeal cells per gram of rock. Archaeal communities within BS and GR horizons were distinct. The absence of any common OTU across the samples indicated restricted dispersal of archaeal cells. Younger, relatively organic carbon- and Fe2O3-rich BS rocks harbor Euryarchaeota, along with varied proportions of Thaumarchaeota and Crenarchaeota. Extreme acid loving, thermotolerant sulfur respiring Thermoplasmataceae, heterotrophic, ferrous-/H-sulfide oxidizing Ferroplasmaceae and Halobacteriaceae were more abundant and closely interrelated within BS rocks. Samples from the GR horizon represent a unique composition with higher proportions of Thaumarchaeota and uneven distribution of Euryarchaeota and Bathyarchaeota affiliated to Methanomicrobia, SAGMCG-1, FHMa11 terrestrial group, AK59 and unclassified taxa. Acetoclastic methanogenic Methanomicrobia, autotrophic SAGMCG-1 and MCG of Thaumarcheaota could be identified as the signature groups within the organic carbon lean GR horizon. Sulfur-oxidizing Sulfolobaceae was relatively more abundant in sulfate-rich amygdaloidal basalt and migmatitic gneiss samples. Methane-oxidizing ANME-3 populations were found to be ubiquitous, but their abundance varied greatly between the analyzed samples. Changes in diversity pattern among the BS and GR horizons highlighted the significance of local rock geochemistry, particularly the availability of organic carbon, Fe2O3 and other nutrients as well as physical constraints (temperature and pressure) in a niche-specific colonization of extremophilic archaeal communities. The study provided the first deep sequencing-based illustration of an intricate association between diverse extremophilic groups (acidophile-halophile-methanogenic), capable of sulfur/iron/methane metabolism and thus shed new light on their potential role in biogeochemical cycles and energy flow in deep biosphere hosted by hot, oligotrophic igneous crust.
Collapse
Affiliation(s)
- Avishek Dutta
- Environmental Microbiology and Genomics Laboratory, Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, India.,School of Bioscience, Indian Institute of Technology Kharagpur, Kharagpur, India
| | - Pinaki Sar
- Environmental Microbiology and Genomics Laboratory, Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, India
| | - Jayeeta Sarkar
- Environmental Microbiology and Genomics Laboratory, Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, India
| | - Srimanti Dutta Gupta
- School of Environmental Science and Engineering, Indian Institute of Technology Kharagpur, Kharagpur, India
| | - Abhishek Gupta
- Environmental Microbiology and Genomics Laboratory, Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, India
| | - Himadri Bose
- Environmental Microbiology and Genomics Laboratory, Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, India
| | - Abhijit Mukherjee
- School of Environmental Science and Engineering, Indian Institute of Technology Kharagpur, Kharagpur, India.,Department of Geology and Geophysics, Indian Institute of Technology Kharagpur, Kharagpur, India
| | - Sukanta Roy
- Ministry of Earth Sciences, Borehole Geophysics Research Laboratory, Karad, India.,CSIR-National Geophysical Research Institute, Hyderabad, India
| |
Collapse
|
19
|
Feng G, Zhang F, Banakar S, Karlep L, Li Z. Analysis of functional gene transcripts suggests active CO2 assimilation and CO oxidation by diverse bacteria in marine sponges. FEMS Microbiol Ecol 2019; 95:5513993. [DOI: 10.1093/femsec/fiz087] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 06/08/2019] [Indexed: 11/13/2022] Open
Affiliation(s)
- Guofang Feng
- State Key Laboratory of Microbial Metabolism, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Dongchuan Road 800, Shanghai 200240, China
| | - Fengli Zhang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Dongchuan Road 800, Shanghai 200240, China
| | - Shivakumar Banakar
- State Key Laboratory of Microbial Metabolism, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Dongchuan Road 800, Shanghai 200240, China
| | - Liisi Karlep
- Department of Chemistry and Biotechnology, Division of Gene Technology, Tallinn University of Technology, Ehitajate 5, Tallinn 19086, Estonia
| | - Zhiyong Li
- State Key Laboratory of Microbial Metabolism, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Dongchuan Road 800, Shanghai 200240, China
| |
Collapse
|
20
|
Purkamo L, Kietäväinen R, Miettinen H, Sohlberg E, Kukkonen I, Itävaara M, Bomberg M. Diversity and functionality of archaeal, bacterial and fungal communities in deep Archaean bedrock groundwater. FEMS Microbiol Ecol 2019; 94:5035813. [PMID: 29893836 DOI: 10.1093/femsec/fiy116] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 06/08/2018] [Indexed: 01/19/2023] Open
Abstract
The diversity and metabolic functions of deep subsurface ecosystems remain relatively unexplored. Microbial communities in previously studied deep subsurface sites of the Fennoscandian Shield are distinctive to each site. Thus, we hypothesized that the microbial communities of the deep Archaean bedrock fracture aquifer in Romuvaara, northern Finland, differ both in community composition and metabolic functionality from the other sites in the Fennoscandian Shield. We characterized the composition, functionality and substrate preferences of the microbial communities at different depths in a 600 m deep borehole. In contrast to other Fennoscandian deep biosphere communities studied to date, iron-oxidizing Gallionella dominated the bacterial communities, while methanogenic and ammonia-oxidizing archaea were the most prominent archaea, and a diverse fungal community was also detected. Potential for methane cycling and sulfate and nitrate reduction was confirmed by detection of the functional genes of these metabolic pathways. Organotrophs were less abundant, although carbohydrates were the most preferred of the tested substrates. The microbial communities shared features with those detected from other deep groundwaters with similar geochemistry, but the majority of taxa distinctive to Romuvaara are different from the taxa previously detected in saline deep groundwater in the Fennoscandian Shield, most likely because of the differences in water chemistry.
Collapse
Affiliation(s)
- Lotta Purkamo
- VTT Technical Research Centre of Finland, 02044 VTT, Finland
| | - Riikka Kietäväinen
- Geological Survey of Finland (GTK), Betonimiehenkuja 4, 02151 Espoo, Finland
| | - Hanna Miettinen
- VTT Technical Research Centre of Finland, 02044 VTT, Finland
| | - Elina Sohlberg
- VTT Technical Research Centre of Finland, 02044 VTT, Finland
| | - Ilmo Kukkonen
- Geological Survey of Finland (GTK), Betonimiehenkuja 4, 02151 Espoo, Finland
| | - Merja Itävaara
- VTT Technical Research Centre of Finland, 02044 VTT, Finland
| | - Malin Bomberg
- VTT Technical Research Centre of Finland, 02044 VTT, Finland
| |
Collapse
|
21
|
Exploration of deep terrestrial subsurface microbiome in Late Cretaceous Deccan traps and underlying Archean basement, India. Sci Rep 2018; 8:17459. [PMID: 30498254 PMCID: PMC6265293 DOI: 10.1038/s41598-018-35940-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 11/05/2018] [Indexed: 11/08/2022] Open
Abstract
Scientific deep drilling at Koyna, western India provides a unique opportunity to explore microbial life within deep biosphere hosted by ~65 Myr old Deccan basalt and Archaean granitic basement. Characteristic low organic carbon content, mafic/felsic nature but distinct trend in sulfate and nitrate concentrations demarcates the basaltic and granitic zones as distinct ecological habitats. Quantitative PCR indicates a depth independent distribution of microorganisms predominated by bacteria. Abundance of dsrB and mcrA genes are relatively higher (at least one order of magnitude) in basalt compared to granite. Bacterial communities are dominated by Alpha-, Beta-, Gammaproteobacteria, Actinobacteria and Firmicutes, whereas Euryarchaeota is the major archaeal group. Strong correlation among the abundance of autotrophic and heterotrophic taxa is noted. Bacteria known for nitrite, sulfur and hydrogen oxidation represent the autotrophs. Fermentative, nitrate/sulfate reducing and methane metabolising microorganisms represent the heterotrophs. Lack of shared operational taxonomic units and distinct clustering of major taxa indicate possible community isolation. Shotgun metagenomics corroborate that chemolithoautotrophic assimilation of carbon coupled with fermentation and anaerobic respiration drive this deep biosphere. This first report on the geomicrobiology of the subsurface of Deccan traps provides an unprecedented opportunity to understand microbial composition and function in the terrestrial, igneous rock-hosted, deep biosphere.
Collapse
|
22
|
Lopez-Fernandez M, Åström M, Bertilsson S, Dopson M. Depth and Dissolved Organic Carbon Shape Microbial Communities in Surface Influenced but Not Ancient Saline Terrestrial Aquifers. Front Microbiol 2018; 9:2880. [PMID: 30538690 PMCID: PMC6277548 DOI: 10.3389/fmicb.2018.02880] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 11/09/2018] [Indexed: 12/31/2022] Open
Abstract
The continental deep biosphere is suggested to contain a substantial fraction of the earth's total biomass and microorganisms inhabiting this environment likely have a substantial impact on biogeochemical cycles. However, the deep microbial community is still largely unknown and can be influenced by parameters such as temperature, pressure, water residence times, and chemistry of the waters. In this study, 21 boreholes representing a range of deep continental groundwaters from the Äspö Hard Rock Laboratory were subjected to high-throughput 16S rRNA gene sequencing to characterize how the different water types influence the microbial communities. Geochemical parameters showed the stability of the waters and allowed their classification into three groups. These were (i) waters influenced by infiltration from the Baltic Sea with a "modern marine (MM)" signature, (ii) a "thoroughly mixed (TM)" water containing groundwaters of several origins, and (iii) deep "old saline (OS)" waters. Decreasing microbial cell numbers positively correlated with depth. In addition, there was a stronger positive correlation between increased cell numbers and dissolved organic carbon for the MM compared to the OS waters. This supported that the MM waters depend on organic carbon infiltration from the Baltic Sea while the ancient saline waters were fed by "geogases" such as carbon dioxide and hydrogen. The 16S rRNA gene relative abundance of the studied groundwaters revealed different microbial community compositions. Interestingly, the TM water showed the highest dissimilarity compared to the other two water types, potentially due to the several contrasting water types contributing to this groundwater. The main identified microbial phyla in the groundwaters were Gammaproteobacteria, unclassified sequences, Campylobacterota (formerly Epsilonproteobacteria), Patescibacteria, Deltaproteobacteria, and Alphaproteobacteria. Many of these taxa are suggested to mediate ferric iron and nitrate reduction, especially in the MM waters. This indicated that nitrate reduction may be a neglected but important process in the deep continental biosphere. In addition to the high number of unclassified sequences, almost 50% of the identified phyla were archaeal or bacterial candidate phyla. The percentage of unknown and candidate phyla increased with depth, pointing to the importance and necessity of further studies to characterize deep biosphere microbial populations.
Collapse
Affiliation(s)
| | - Mats Åström
- Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden
| | - Stefan Bertilsson
- Limnology and Science for Life Laboratory, Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
| | - Mark Dopson
- Centre for Ecology and Evolution in Microbial Model Systems, Linnaeus University, Kalmar, Sweden
| |
Collapse
|
23
|
Rare Biosphere Archaea Assimilate Acetate in Precambrian Terrestrial Subsurface at 2.2 km Depth. GEOSCIENCES 2018. [DOI: 10.3390/geosciences8110418] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The deep biosphere contains a large portion of the total microbial communities on Earth, but little is known about the carbon sources that support deep life. In this study, we used Stable Isotope Probing (SIP) and high throughput amplicon sequencing to identify the acetate assimilating microbial communities at 2260 m depth in the bedrock of Outokumpu, Finland. The long-term and short-term effects of acetate on the microbial communities were assessed by DNA-targeted SIP and RNA targeted cell activation. The microbial communities reacted within hours to the amended acetate. Archaeal taxa representing the rare biosphere at 2260 m depth were identified and linked to the cycling of acetate, and were shown to have an impact on the functions and activity of the microbial communities in general through small key carbon compounds. The major archaeal lineages identified to assimilate acetate and metabolites derived from the labelled acetate were Methanosarcina spp., Methanococcus spp., Methanolobus spp., and unclassified Methanosarcinaceae. These archaea have previously been detected in the Outokumpu deep subsurface as minor groups. Nevertheless, their involvement in the assimilation of acetate and secretion of metabolites derived from acetate indicated an important role in the supporting of the whole community in the deep subsurface, where carbon sources are limited.
Collapse
|
24
|
Bell E, Lamminmäki T, Alneberg J, Andersson AF, Qian C, Xiong W, Hettich RL, Balmer L, Frutschi M, Sommer G, Bernier-Latmani R. Biogeochemical Cycling by a Low-Diversity Microbial Community in Deep Groundwater. Front Microbiol 2018; 9:2129. [PMID: 30245678 PMCID: PMC6137086 DOI: 10.3389/fmicb.2018.02129] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 08/20/2018] [Indexed: 11/13/2022] Open
Abstract
Olkiluoto, an island on the south-west coast of Finland, will host a deep geological repository for the storage of spent nuclear fuel. Microbially induced corrosion from the generation of sulphide is therefore a concern as it could potentially compromise the longevity of the copper waste canisters. Groundwater at Olkiluoto is geochemically stratified with depth and elevated concentrations of sulphide are observed when sulphate-rich and methane-rich groundwaters mix. Particularly high sulphide is observed in methane-rich groundwater from a fracture at 530.6 mbsl, where mixing with sulphate-rich groundwater occurred as the result of an open drill hole connecting two different fractures at different depths. To determine the electron donors fuelling sulphidogenesis, we combined geochemical, isotopic, metagenomic and metaproteomic analyses. This revealed a low diversity microbial community fuelled by hydrogen and organic carbon. Sulphur and carbon isotopes of sulphate and dissolved inorganic carbon, respectively, confirmed that sulphate reduction was ongoing and that CO2 came from the degradation of organic matter. The results demonstrate the impact of introducing sulphate to a methane-rich groundwater with limited electron acceptors and provide insight into extant metabolisms in the terrestrial subsurface.
Collapse
Affiliation(s)
- Emma Bell
- Environmental Microbiology Laboratory, Environmental Engineering Institute, School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | | | - Johannes Alneberg
- Science for Life Laboratory, School of Engineering Sciences in Chemistry, Biotechnology and Health, Department of Gene Technology, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Anders F Andersson
- Science for Life Laboratory, School of Engineering Sciences in Chemistry, Biotechnology and Health, Department of Gene Technology, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Chen Qian
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Weili Xiong
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Robert L Hettich
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Louise Balmer
- Environmental Microbiology Laboratory, Environmental Engineering Institute, School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Manon Frutschi
- Environmental Microbiology Laboratory, Environmental Engineering Institute, School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Guillaume Sommer
- Environmental Microbiology Laboratory, Environmental Engineering Institute, School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Rizlan Bernier-Latmani
- Environmental Microbiology Laboratory, Environmental Engineering Institute, School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| |
Collapse
|
25
|
Lopez-Fernandez M, Broman E, Turner S, Wu X, Bertilsson S, Dopson M. Investigation of viable taxa in the deep terrestrial biosphere suggests high rates of nutrient recycling. FEMS Microbiol Ecol 2018; 94:5040220. [PMID: 29931252 PMCID: PMC6030916 DOI: 10.1093/femsec/fiy121] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 06/15/2018] [Indexed: 11/14/2022] Open
Abstract
The deep biosphere is the largest 'bioreactor' on earth, and microbes inhabiting this biome profoundly influence global nutrient and energy cycles. An important question for deep biosphere microbiology is whether or not specific populations are viable. To address this, we used quantitative PCR and high throughput 16S rRNA gene sequencing of total and viable cells (i.e. with an intact cellular membrane) from three groundwaters with different ages and chemical constituents. There were no statistically significant differences in 16S rRNA gene abundances and microbial diversity between total and viable communities. This suggests that populations were adapted to prevailing oligotrophic conditions and that non-viable cells are rapidly degraded and recycled into new biomass. With higher concentrations of organic carbon, the modern marine and undefined mixed waters hosted a community with a larger range of predicted growth strategies than the ultra-oligotrophic old saline water. These strategies included fermentative and potentially symbiotic lifestyles by candidate phyla that typically have streamlined genomes. In contrast, the old saline waters had more 16S rRNA gene sequences in previously cultured lineages able to oxidize hydrogen and fix carbon dioxide. This matches the paradigm of a hydrogen and carbon dioxide-fed chemolithoautotrophic deep biosphere.
Collapse
Affiliation(s)
- Margarita Lopez-Fernandez
- Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Barlastgatan 11, Kalmar, Sweden
| | - Elias Broman
- Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Barlastgatan 11, Kalmar, Sweden
| | - Stephanie Turner
- Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Barlastgatan 11, Kalmar, Sweden
| | - Xiaofen Wu
- Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Barlastgatan 11, Kalmar, Sweden
| | - Stefan Bertilsson
- Department of Ecology and Genetics, Limnology and Science for Life Laboratory, Uppsala University, Norbyvägen 18D, Uppsala, Sweden
| | - Mark Dopson
- Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Barlastgatan 11, Kalmar, Sweden
| |
Collapse
|
26
|
Escudero C, Oggerin M, Amils R. The deep continental subsurface: the dark biosphere. Int Microbiol 2018; 21:3-14. [DOI: 10.1007/s10123-018-0009-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 05/08/2018] [Accepted: 05/09/2018] [Indexed: 11/28/2022]
|
27
|
Bomberg M, Raulio M, Jylhä S, Mueller CW, Höschen C, Rajala P, Purkamo L, Kietäväinen R, Ahonen L, Itävaara M. CO 2 and carbonate as substrate for the activation of the microbial community in 180 m deep bedrock fracture fluid of Outokumpu Deep Drill Hole, Finland. AIMS Microbiol 2017; 3:846-871. [PMID: 31294193 PMCID: PMC6604968 DOI: 10.3934/microbiol.2017.4.846] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 10/17/2017] [Indexed: 01/22/2023] Open
Abstract
Microbial communities in deep subsurface environments comprise a large portion of Earth's biomass, but the metabolic activities in these habitats are largely unknown. Here the effect of CO2 and carbonate on the microbial community of an isolated groundwater fracture zone at 180 m depth of the Outokumpu Deep Scientific Drill Hole (Finland) was tested. Outokumpu groundwater at 180 m depth contains approximately 0.45 L L−1 dissolved gas of which methane contributes 76%. CO2, on the other hand, is scarce. The number of microbial cells with intracellular activity in the groundwater was low when examined with redox staining. Fluorescence Assisted Cell Sorting (FACS) analyses indicated that only 1% of the microbial community stained active with the redox sensing dye in the untreated groundwater after 4 weeks of starvation. However, carbon substrate and sulfate addition increased the abundance of fluorescent cells up to 7%. CO2 and CO2 + sulfate activated the greatest number of microbes, especially increasing the abundance of Pseudomonas sp., which otherwise was present at only low abundance in Outokumpu. Over longer exposure time (2 months) up to 50% of the bacterial cells in the groundwater were shown to incorporate inorganic carbon from carbonate into biomass. Carbon recapture is an important feature in this ecosystem since it may decrease the rate of carbon loss in form of CO2 released from cellular processes.
Collapse
Affiliation(s)
- Malin Bomberg
- VTT Technical Research Centre of Finland, P.O. Box 1000, FIN-02044 VTT, Finland
| | - Mari Raulio
- VTT Technical Research Centre of Finland, P.O. Box 1000, FIN-02044 VTT, Finland.,Tikkurila Oyj, P.O. Box 53, Kuninkaalantie 1, FI-01301 Vantaa, Finland
| | - Sirpa Jylhä
- VTT Technical Research Centre of Finland, P.O. Box 1000, FIN-02044 VTT, Finland
| | - Carsten W Mueller
- Lehrstuhl für Bodenkunde, Department Ecology and Ecosystem Management, Center of Life and Food Sciences Weihenstephan, Technische Universität München, D-85350, Freising-Weihenstephan, Germany
| | - Carmen Höschen
- Lehrstuhl für Bodenkunde, Department Ecology and Ecosystem Management, Center of Life and Food Sciences Weihenstephan, Technische Universität München, D-85350, Freising-Weihenstephan, Germany
| | - Pauliina Rajala
- VTT Technical Research Centre of Finland, P.O. Box 1000, FIN-02044 VTT, Finland
| | - Lotta Purkamo
- VTT Technical Research Centre of Finland, P.O. Box 1000, FIN-02044 VTT, Finland
| | | | - Lasse Ahonen
- Geological Survey of Finland (GTK), P.O. Box 96, 02151 Espoo, Finland
| | - Merja Itävaara
- VTT Technical Research Centre of Finland, P.O. Box 1000, FIN-02044 VTT, Finland
| |
Collapse
|
28
|
Wu X, Pedersen K, Edlund J, Eriksson L, Åström M, Andersson AF, Bertilsson S, Dopson M. Potential for hydrogen-oxidizing chemolithoautotrophic and diazotrophic populations to initiate biofilm formation in oligotrophic, deep terrestrial subsurface waters. MICROBIOME 2017; 5:37. [PMID: 28335808 PMCID: PMC5364579 DOI: 10.1186/s40168-017-0253-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 03/12/2017] [Indexed: 06/06/2023]
Abstract
BACKGROUND Deep terrestrial biosphere waters are separated from the light-driven surface by the time required to percolate to the subsurface. Despite biofilms being the dominant form of microbial life in many natural environments, they have received little attention in the oligotrophic and anaerobic waters found in deep bedrock fractures. This study is the first to use community DNA sequencing to describe biofilm formation under in situ conditions in the deep terrestrial biosphere. RESULTS In this study, flow cells were attached to boreholes containing either "modern marine" or "old saline" waters of different origin and degree of isolation from the light-driven surface of the earth. Using 16S rRNA gene sequencing, we showed that planktonic and attached populations were dissimilar while gene frequencies in the metagenomes suggested that hydrogen-fed, carbon dioxide- and nitrogen-fixing populations were responsible for biofilm formation across the two aquifers. Metagenome analyses further suggested that only a subset of the populations were able to attach and produce an extracellular polysaccharide matrix. Initial biofilm formation is thus likely to be mediated by a few bacterial populations which were similar to Epsilonproteobacteria, Deltaproteobacteria, Betaproteobacteria, Verrucomicrobia, and unclassified bacteria. CONCLUSIONS Populations potentially capable of attaching to a surface and to produce extracellular polysaccharide matrix for attachment were identified in the terrestrial deep biosphere. Our results suggest that the biofilm populations were taxonomically distinct from the planktonic community and were enriched in populations with a chemolithoautotrophic and diazotrophic metabolism coupling hydrogen oxidation to energy conservation under oligotrophic conditions.
Collapse
Affiliation(s)
- Xiaofen Wu
- Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, 391 82 Kalmar, Sweden
| | | | | | | | - Mats Åström
- Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden
| | - Anders F. Andersson
- KTH Royal Institute of Technology, Science for Life Laboratory, School of Biotechnology, Stockholm, Sweden
| | - Stefan Bertilsson
- Department of Ecology and Genetics, Limnology and Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Mark Dopson
- Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, 391 82 Kalmar, Sweden
| |
Collapse
|
29
|
Rajala P, Bomberg M. Reactivation of Deep Subsurface Microbial Community in Response to Methane or Methanol Amendment. Front Microbiol 2017; 8:431. [PMID: 28367144 PMCID: PMC5355647 DOI: 10.3389/fmicb.2017.00431] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2016] [Accepted: 02/28/2017] [Indexed: 02/01/2023] Open
Abstract
Microbial communities in deep subsurface environments comprise a large portion of Earth’s biomass, but the microbial activity in these habitats is largely unknown. Here, we studied how microorganisms from two isolated groundwater fractures at 180 and 500 m depths of the Outokumpu Deep Drillhole (Finland) responded to methane or methanol amendment, in the presence or absence of sulfate as an additional electron acceptor. Methane is a plausible intermediate in the deep subsurface carbon cycle, and electron acceptors such as sulfate are critical components for oxidation processes. In fact, the majority of the available carbon in the Outokumpu deep biosphere is present as methane. Methanol is an intermediate of methane oxidation, but may also be produced through degradation of organic matter. The fracture fluid samples were incubated in vitro with methane or methanol in the presence or absence of sulfate as electron acceptor. The metabolic response of microbial communities was measured by staining the microbial cells with fluorescent redox sensitive dye combined with flow cytometry, and DNA or cDNA-derived amplicon sequencing. The microbial community of the fracture zone at the 180 m depth was originally considerably more respiratory active and 10-fold more numerous (105 cells ml-1 at 180 m depth and 104 cells ml-1 at 500 m depth) than the community of the fracture zone at the 500 m. However, the dormant microbial community at the 500 m depth rapidly reactivated their transcription and respiration systems in the presence of methane or methanol, whereas in the shallower fracture zone only a small sub-population was able to utilize the newly available carbon source. In addition, the composition of substrate activated microbial communities differed at both depths from original microbial communities. The results demonstrate that OTUs representing minor groups of the total microbial communities play an important role when microbial communities face changes in environmental conditions.
Collapse
Affiliation(s)
- Pauliina Rajala
- Materials Performance, VTT Technical Research Centre of Finland Espoo, Finland
| | - Malin Bomberg
- Materials Performance, VTT Technical Research Centre of FinlandEspoo, Finland; Material Processing and Geotechnology, VTT Technical Research Centre of FinlandEspoo, Finland
| |
Collapse
|
30
|
Purkamo L, Bomberg M, Nyyssönen M, Ahonen L, Kukkonen I, Itävaara M. Response of Deep Subsurface Microbial Community to Different Carbon Sources and Electron Acceptors during ∼2 months Incubation in Microcosms. Front Microbiol 2017; 8:232. [PMID: 28265265 PMCID: PMC5316538 DOI: 10.3389/fmicb.2017.00232] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 02/02/2017] [Indexed: 11/13/2022] Open
Abstract
Acetate plays a key role as electron donor and acceptor and serves as carbon source in oligotrophic deep subsurface environments. It can be produced from inorganic carbon by acetogenic microbes or through breakdown of more complex organic matter. Acetate is an important molecule for sulfate reducers that are substantially present in several deep bedrock environments. Aceticlastic methanogens use acetate as an electron donor and/or a carbon source. The goal of this study was to shed light on carbon cycling and competition in microbial communities in fracture fluids of Finnish crystalline bedrock groundwater system. Fracture fluid was anaerobically collected from a fracture zone at 967 m depth of the Outokumpu Deep Drill Hole and amended with acetate, acetate + sulfate, sulfate only or left unamended as a control and incubated up to 68 days. The headspace atmosphere of microcosms consisted of 80% hydrogen and 20% CO2. We studied the changes in the microbial communities with community fingerprinting technique as well as high-throughput 16S rRNA gene amplicon sequencing. The amended microcosms hosted more diverse bacterial communities compared to the intrinsic fracture zone community and the control treatment without amendments. The majority of the bacterial populations enriched with acetate belonged to clostridial hydrogenotrophic thiosulfate reducers and Alphaproteobacteria affiliating with groups earlier found from subsurface and groundwater environments. We detected a slight increase in the number of sulfate reducers after the 68 days of incubation. The microbial community changed significantly during the experiment, but increase in specifically acetate-cycling microbial groups was not observed.
Collapse
Affiliation(s)
- Lotta Purkamo
- VTT Technical Research Centre of Finland Espoo, Finland
| | - Malin Bomberg
- VTT Technical Research Centre of Finland Espoo, Finland
| | | | | | - Ilmo Kukkonen
- Department of Physics, University of Helsinki Helsinki, Finland
| | | |
Collapse
|
31
|
Wu X, Holmfeldt K, Hubalek V, Lundin D, Åström M, Bertilsson S, Dopson M. Microbial metagenomes from three aquifers in the Fennoscandian shield terrestrial deep biosphere reveal metabolic partitioning among populations. THE ISME JOURNAL 2016; 10:1192-203. [PMID: 26484735 PMCID: PMC5029217 DOI: 10.1038/ismej.2015.185] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 09/01/2015] [Accepted: 09/06/2015] [Indexed: 11/16/2022]
Abstract
Microorganisms in the terrestrial deep biosphere host up to 20% of the earth's biomass and are suggested to be sustained by the gases hydrogen and carbon dioxide. A metagenome analysis of three deep subsurface water types of contrasting age (from <20 to several thousand years) and depth (171 to 448 m) revealed phylogenetically distinct microbial community subsets that either passed or were retained by a 0.22 μm filter. Such cells of <0.22 μm would have been overlooked in previous studies relying on membrane capture. Metagenomes from the three water types were used for reconstruction of 69 distinct microbial genomes, each with >86% coverage. The populations were dominated by Proteobacteria, Candidate divisions, unclassified archaea and unclassified bacteria. The estimated genome sizes of the <0.22 μm populations were generally smaller than their phylogenetically closest relatives, suggesting that small dimensions along with a reduced genome size may be adaptations to oligotrophy. Shallow 'modern marine' water showed community members with a predominantly heterotrophic lifestyle. In contrast, the deeper, 'old saline' water adhered more closely to the current paradigm of a hydrogen-driven deep biosphere. The data were finally used to create a combined metabolic model of the deep terrestrial biosphere microbial community.
Collapse
Affiliation(s)
- Xiaofen Wu
- Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Kalmar, Sweden
| | - Karin Holmfeldt
- Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Kalmar, Sweden
| | - Valerie Hubalek
- Department of Ecology and Genetics, Limnology and Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Daniel Lundin
- Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Kalmar, Sweden
| | - Mats Åström
- Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden
| | - Stefan Bertilsson
- Department of Ecology and Genetics, Limnology and Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Mark Dopson
- Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Kalmar, Sweden
| |
Collapse
|
32
|
Connectivity to the surface determines diversity patterns in subsurface aquifers of the Fennoscandian shield. ISME JOURNAL 2016; 10:2447-58. [PMID: 27022994 PMCID: PMC5030689 DOI: 10.1038/ismej.2016.36] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 01/29/2016] [Accepted: 02/07/2016] [Indexed: 11/14/2022]
Abstract
Little research has been conducted on microbial diversity deep under the Earth's surface. In this study, the microbial communities of three deep terrestrial subsurface aquifers were investigated. Temporal community data over 6 years revealed that the phylogenetic structure and community dynamics were highly dependent on the degree of isolation from the earth surface biomes. The microbial community at the shallow site was the most dynamic and was dominated by the sulfur-oxidizing genera Sulfurovum or Sulfurimonas at all-time points. The microbial community in the meteoric water filled intermediate aquifer (water turnover approximately every 5 years) was less variable and was dominated by candidate phylum OD1. Metagenomic analysis of this water demonstrated the occurrence of key genes for nitrogen and carbon fixation, sulfate reduction, sulfide oxidation and fermentation. The deepest water mass (5000 year old waters) had the lowest taxon richness and surprisingly contained Cyanobacteria. The high relative abundance of phylogenetic groups associated with nitrogen and sulfur cycling, as well as fermentation implied that these processes were important in these systems. We conclude that the microbial community patterns appear to be shaped by the availability of energy and nutrient sources via connectivity to the surface or from deep geological processes.
Collapse
|
33
|
Itävaara M, Salavirta H, Marjamaa K, Ruskeeniemi T. Geomicrobiology and Metagenomics of Terrestrial Deep Subsurface Microbiomes. ADVANCES IN APPLIED MICROBIOLOGY 2016; 94:1-77. [PMID: 26917241 DOI: 10.1016/bs.aambs.2015.12.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Fractures in the deep subsurface of Earth's crust are inhabited by diverse microbial communities that participate in biogeochemical cycles of the Earth. Life on Earth, which arose c. 3.5-4.0 billion years ago, reaches down at least 5 km in the crust. Deep mines, caves, and boreholes have provided scientists with opportunities to sample deep subsurface microbiomes and to obtain information on the species diversity and functions. A wide variety of bacteria, archaea, eukaryotes, and viruses are now known to reside in the crust, but their functions are still largely unknown. The crust at different depths has varying geological composition and hosts endemic microbiomes accordingly. The diversity is driven by geological formations and gases evolving from deeper depths. Cooperation among different species is still mostly unexplored, but viruses are known to restrict density of bacterial and archaeal populations. Due to the complex growth requirements of the deep subsurface microbiomes, the new knowledge about their diversity and functions is mostly obtained by molecular methods, eg, meta'omics'. Geomicrobiology is a multidisciplinary research area combining disciplines from geology, mineralogy, geochemistry, and microbiology. Geomicrobiology is concerned with the interaction of microorganisms and geological processes. At the surface of mineralogical or rock surfaces, geomicrobial processes occur mainly under aerobic conditions. In the deep subsurface, however, the environmental conditions are reducing and anaerobic. The present chapter describes the world of microbiomes in deep terrestrial geological environments as well as metagenomic and metatranscriptomic methods suitable for studies of these enigmatic communities.
Collapse
Affiliation(s)
- M Itävaara
- VTT Technical Research Centre of Finland Ltd, Espoo, Finland
| | - H Salavirta
- VTT Technical Research Centre of Finland Ltd, Espoo, Finland
| | - K Marjamaa
- VTT Technical Research Centre of Finland Ltd, Espoo, Finland
| | | |
Collapse
|
34
|
Kutvonen H, Rajala P, Carpén L, Bomberg M. Nitrate and ammonia as nitrogen sources for deep subsurface microorganisms. Front Microbiol 2015; 6:1079. [PMID: 26528251 PMCID: PMC4606121 DOI: 10.3389/fmicb.2015.01079] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 09/21/2015] [Indexed: 11/13/2022] Open
Abstract
We investigated the N-utilizing bacterial community in anoxic brackish groundwater of the low and intermediate level nuclear waste repository cave in Olkiluoto, Finland, at 100 m depth using 15N-based stable isotope probing (SIP) and enrichment with 14∕15N-ammonium or 14∕15N-nitrate complemented with methane. Twenty-eight days of incubation at 12°C increased the concentration of bacterial 16S rRNA and nitrate reductase (narG) gene copies in the substrate amended microcosms simultaneously with a radical drop in the overall bacterial diversity and OTU richness. Hydrogenophaga/Malikia were enriched in all substrate amended microcosms and Methylobacter in the ammonium and ammonium+methane supplemented microcosms. Sulfuricurvum was especially abundant in the nitrate+methane treatment and the unamended incubation control. Membrane-bound nitrate reductase genes (narG) from Polarimonas sp. were detected in the original groundwater, while Burkholderia, Methylibium, and Pseudomonas narG genes were enriched due to substrate supplements. Identified amoA genes belonged to Nitrosomonas sp. 15N-SIP revealed that Burkholderiales and Rhizobiales clades belonging to the minority groups in the original groundwater used 15N from ammonium and nitrate as N source indicating an important ecological function of these bacteria, despite their low number, in the groundwater N cycle in Olkiluoto bedrock system.
Collapse
Affiliation(s)
- Heini Kutvonen
- Material Recycling and Geotechnology, VTT Technical Research Centre of Finland Espoo, Finland
| | - Pauliina Rajala
- Materials Performance, VTT Technical Research Centre of Finland Espoo, Finland
| | - Leena Carpén
- Materials Performance, VTT Technical Research Centre of Finland Espoo, Finland
| | - Malin Bomberg
- Material Recycling and Geotechnology, VTT Technical Research Centre of Finland Espoo, Finland
| |
Collapse
|
35
|
Kietäväinen R, Purkamo L. The origin, source, and cycling of methane in deep crystalline rock biosphere. Front Microbiol 2015; 6:725. [PMID: 26236303 PMCID: PMC4505394 DOI: 10.3389/fmicb.2015.00725] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 07/02/2015] [Indexed: 11/13/2022] Open
Abstract
The emerging interest in using stable bedrock formations for industrial purposes, e.g., nuclear waste disposal, has increased the need for understanding microbiological and geochemical processes in deep crystalline rock environments, including the carbon cycle. Considering the origin and evolution of life on Earth, these environments may also serve as windows to the past. Various geological, chemical, and biological processes can influence the deep carbon cycle. Conditions of CH4 formation, available substrates and time scales can be drastically different from surface environments. This paper reviews the origin, source, and cycling of methane in deep terrestrial crystalline bedrock with an emphasis on microbiology. In addition to potential formation pathways of CH4, microbial consumption of CH4 is also discussed. Recent studies on the origin of CH4 in continental bedrock environments have shown that the traditional separation of biotic and abiotic CH4 by the isotopic composition can be misleading in substrate-limited environments, such as the deep crystalline bedrock. Despite of similarities between Precambrian continental sites in Fennoscandia, South Africa and North America, where deep methane cycling has been studied, common physicochemical properties which could explain the variation in the amount of CH4 and presence or absence of CH4 cycling microbes were not found. However, based on their preferred carbon metabolism, methanogenic microbes appeared to have similar spatial distribution among the different sites.
Collapse
Affiliation(s)
| | - Lotta Purkamo
- VTT Technical Research Centre of Finland Espoo, Finland
| |
Collapse
|
36
|
Rajala P, Bomberg M, Kietäväinen R, Kukkonen I, Ahonen L, Nyyssönen M, Itävaara M. Rapid Reactivation of Deep Subsurface Microbes in the Presence of C-1 Compounds. Microorganisms 2015; 3:17-33. [PMID: 27682076 PMCID: PMC5023232 DOI: 10.3390/microorganisms3010017] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Revised: 01/26/2015] [Accepted: 01/29/2015] [Indexed: 11/30/2022] Open
Abstract
Microorganisms in the deep biosphere are believed to conduct little metabolic activity due to low nutrient availability in these environments. However, destructive penetration to long-isolated bedrock environments during construction of underground waste repositories can lead to increased nutrient availability and potentially affect the long-term stability of the repository systems, Here, we studied how microorganisms present in fracture fluid from a depth of 500 m in Outokumpu, Finland, respond to simple carbon compounds (C-1 compounds) in the presence or absence of sulphate as an electron acceptor. C-1 compounds such as methane and methanol are important intermediates in the deep subsurface carbon cycle, and electron acceptors such as sulphate are critical components of oxidation processes. Fracture fluid samples were incubated in vitro with either methane or methanol in the presence or absence of sulphate as an electron acceptor. Metabolic response was measured by staining the microbial cells with fluorescent dyes that indicate metabolic activity and transcriptional response with RT-qPCR. Our results show that deep subsurface microbes exist in dormant states but rapidly reactivate their transcription and respiration systems in the presence of C-1 substrates, particularly methane. Microbial activity was further enhanced by the addition of sulphate as an electron acceptor. Sulphate- and nitrate-reducing microbes were particularly responsive to the addition of C-1 compounds and sulphate. These taxa are common in deep biosphere environments and may be affected by conditions disturbed by bedrock intrusion, as from drilling and excavation for long-term storage of hazardous waste.
Collapse
Affiliation(s)
- Pauliina Rajala
- Technical Research Centre of Finland (VTT), Kemistintie 3/Tietotie 2, FI-02044, Espoo, Finland.
| | - Malin Bomberg
- Technical Research Centre of Finland (VTT), Kemistintie 3/Tietotie 2, FI-02044, Espoo, Finland.
| | - Riikka Kietäväinen
- Geological Survey of Finland (GTK), P.O. Box 96, FI-02151, Espoo, Finland.
| | - Ilmo Kukkonen
- University of Helsinki, P.O. Box 33, University of Helsinki, FI-00014, Helsinki, Finland.
| | - Lasse Ahonen
- Geological Survey of Finland (GTK), P.O. Box 96, FI-02151, Espoo, Finland.
| | - Mari Nyyssönen
- Technical Research Centre of Finland (VTT), Kemistintie 3/Tietotie 2, FI-02044, Espoo, Finland.
| | - Merja Itävaara
- Technical Research Centre of Finland (VTT), Kemistintie 3/Tietotie 2, FI-02044, Espoo, Finland.
| |
Collapse
|