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Wray AC, Downey AR, Nodal AA, Park KK, Gorman-Lewis D. Bioenergetic characterization of hyperthermophilic archaean Methanocaldococcus sp. FS406-22. Extremophiles 2024; 28:32. [PMID: 39023751 DOI: 10.1007/s00792-024-01349-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Accepted: 06/28/2024] [Indexed: 07/20/2024]
Abstract
Hyperthermophilic archaean Methanocaldococcus sp. FS406-22 (hereafter FS406) is a hydrogenotrophic methanogen isolated from a deep-sea hydrothermal vent. To better understand the energetic requirements of hydrogen oxidation under extreme conditions, the thermodynamic characterization of FS406 incubations is necessary and notably underexplored. In this work, we quantified the bioenergetics of FS406 incubations at a range of temperatures (65, 76, and 85 ℃) and hydrogen concentrations (1.1, 1.4, and 2.1 mm). The biomass yields (C-mol of biomass per mol of H2 consumed) ranged from 0.02 to 0.19. Growth rates ranged from 0.4 to 1.5 h-1. Gibbs energies of incubation based on macrochemical equations of cell growth ranged from - 198 kJ/C-mol to - 1840 kJ/C-mol. Enthalpies of incubation determined from calorimetric measurements ranged from - 4150 kJ/C-mol to - 36333 kJ/C-mol. FS406 growth rates were most comparable to hyperthermophilic methanogen Methanocaldococcus jannaschii. Maintenance energy calculations from the thermodynamic parameters of FS406 and previously determined heterotrophic methanogen data revealed that temperature is a primary determinant rather than an electron donor. This work provides new insights into the thermodynamic underpinnings of a hyperthermophilic hydrothermal vent methanogen and helps to better constrain the energetic requirements of life in extreme environments.
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Affiliation(s)
- Addien C Wray
- Earth and Space Sciences, University of Washington, Seattle, WA, USA.
| | - Autum R Downey
- Earth and Space Sciences, University of Washington, Seattle, WA, USA
| | - Andrea A Nodal
- Earth and Space Sciences, University of Washington, Seattle, WA, USA
| | - Katherine K Park
- Earth and Space Sciences, University of Washington, Seattle, WA, USA
| | - Drew Gorman-Lewis
- Earth and Space Sciences, University of Washington, Seattle, WA, USA
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2
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Meyer NR, Morono Y, Dekas AE. Single-cell analysis reveals an active and heterotrophic microbiome in the Guaymas Basin deep subsurface with significant inorganic carbon fixation by heterotrophs. Appl Environ Microbiol 2024; 90:e0044624. [PMID: 38709099 PMCID: PMC11334695 DOI: 10.1128/aem.00446-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Accepted: 04/04/2024] [Indexed: 05/07/2024] Open
Abstract
The marine subsurface is a long-term sink of atmospheric carbon dioxide with significant implications for climate on geologic timescales. Subsurface microbial cells can either enhance or reduce carbon sequestration in the subsurface, depending on their metabolic lifestyle. However, the activity of subsurface microbes is rarely measured. Here, we used nanoscale secondary ion mass spectrometry (nanoSIMS) to quantify anabolic activity in 3,203 individual cells from the thermally altered deep subsurface in the Guaymas Basin, Mexico (3-75 m below the seafloor, 0-14°C). We observed that a large majority of cells were active (83%-100%), although the rates of biomass generation were low, suggesting cellular maintenance rather than doubling. Mean single-cell activity decreased with increasing sediment depth and temperature and was most strongly correlated with porewater sulfate concentrations. Intracommunity heterogeneity in microbial activity decreased with increasing sediment depth and age. Using a dual-isotope labeling approach, we determined that all active cells analyzed were heterotrophic, deriving the majority of their cellular carbon from organic sources. However, we also detected inorganic carbon assimilation in these heterotrophic cells, likely via processes such as anaplerosis, and determined that inorganic carbon contributes at least 5% of the total biomass carbon in heterotrophs in this community. Our results demonstrate that the deep marine biosphere at Guaymas Basin is largely active and contributes to subsurface carbon cycling primarily by not only assimilating organic carbon but also fixing inorganic carbon. Heterotrophic assimilation of inorganic carbon may be a small yet significant and widespread underappreciated source of labile carbon in the global subsurface. IMPORTANCE The global subsurface is the largest reservoir of microbial life on the planet yet remains poorly characterized. The activity of life in this realm has implications for long-term elemental cycling, particularly of carbon, as well as how life survives in extreme environments. Here, we recovered cells from the deep subsurface of the Guaymas Basin and investigated the level and distribution of microbial activity, the physicochemical drivers of activity, and the relative significance of organic versus inorganic carbon to subsurface biomass. Using a sensitive single-cell assay, we found that the majority of cells are active, that activity is likely driven by the availability of energy, and that although heterotrophy is the dominant metabolism, both organic and inorganic carbon are used to generate biomass. Using a new approach, we quantified inorganic carbon assimilation by heterotrophs and highlighted the importance of this often-overlooked mode of carbon assimilation in the subsurface and beyond.
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Affiliation(s)
- Nicolette R. Meyer
- Department of Earth System Science, Stanford University, Stanford, California, USA
| | - Yuki Morono
- Kochi Institute for Core Sample Research, Institute for Extra-cutting-edge Science and Technology Avantgarde Research (X-STAR), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Nankoku, Kochi, Japan
| | - Anne E. Dekas
- Department of Earth System Science, Stanford University, Stanford, California, USA
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3
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Schmider T, Hestnes AG, Brzykcy J, Schmidt H, Schintlmeister A, Roller BRK, Teran EJ, Söllinger A, Schmidt O, Polz MF, Richter A, Svenning MM, Tveit AT. Physiological basis for atmospheric methane oxidation and methanotrophic growth on air. Nat Commun 2024; 15:4151. [PMID: 38755154 DOI: 10.1038/s41467-024-48197-1] [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: 02/13/2024] [Accepted: 04/22/2024] [Indexed: 05/18/2024] Open
Abstract
Atmospheric methane oxidizing bacteria (atmMOB) constitute the sole biological sink for atmospheric methane. Still, the physiological basis allowing atmMOB to grow on air is not well understood. Here we assess the ability and strategies of seven methanotrophic species to grow with air as sole energy, carbon, and nitrogen source. Four species, including three outside the canonical atmMOB group USCα, enduringly oxidized atmospheric methane, carbon monoxide, and hydrogen during 12 months of growth on air. These four species exhibited distinct substrate preferences implying the existence of multiple metabolic strategies to grow on air. The estimated energy yields of the atmMOB were substantially lower than previously assumed necessary for cellular maintenance in atmMOB and other aerobic microorganisms. Moreover, the atmMOB also covered their nitrogen requirements from air. During growth on air, the atmMOB decreased investments in biosynthesis while increasing investments in trace gas oxidation. Furthermore, we confirm that a high apparent specific affinity for methane is a key characteristic of atmMOB. Our work shows that atmMOB grow on the trace concentrations of methane, carbon monoxide, and hydrogen present in air and outlines the metabolic strategies that enable atmMOB to mitigate greenhouse gases.
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Affiliation(s)
- Tilman Schmider
- Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, UiT-The Arctic University of Norway, 9037, Tromsø, Norway.
| | - Anne Grethe Hestnes
- Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, UiT-The Arctic University of Norway, 9037, Tromsø, Norway
| | - Julia Brzykcy
- Department of Geomicrobiology, Institute of Microbiology, Faculty of Biology, University of Warsaw, 02-096, Warsaw, Poland
| | - Hannes Schmidt
- Department of Microbiology and Environmental Systems Science, Division of Terrestrial Ecosystem Research, University of Vienna, 1030, Vienna, Austria
| | - Arno Schintlmeister
- Department of Microbiology and Environmental Systems Science, Division of Microbial Ecology, University of Vienna, 1030, Vienna, Austria
| | - Benjamin R K Roller
- Department of Microbiology and Environmental Systems Science, Division of Microbial Ecology, University of Vienna, 1030, Vienna, Austria
| | - Ezequiel Jesús Teran
- Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires (CIFICEN-UNCPBA-CONICET-CICPBA), Pinto, 399, Tandil (7000), Argentina
- Universidad Nacional del Centro de la Provincia de Buenos Aires, Facultad de Ciencias Exactas, Instituto de Física Arroyo Seco (IFAS), Pinto, 399, Tandil (7000), Argentina
| | - Andrea Söllinger
- Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, UiT-The Arctic University of Norway, 9037, Tromsø, Norway
| | - Oliver Schmidt
- Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, UiT-The Arctic University of Norway, 9037, Tromsø, Norway
| | - Martin F Polz
- Department of Microbiology and Environmental Systems Science, Division of Microbial Ecology, University of Vienna, 1030, Vienna, Austria
| | - Andreas Richter
- Department of Microbiology and Environmental Systems Science, Division of Terrestrial Ecosystem Research, University of Vienna, 1030, Vienna, Austria
| | - Mette M Svenning
- Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, UiT-The Arctic University of Norway, 9037, Tromsø, Norway
| | - Alexander T Tveit
- Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, UiT-The Arctic University of Norway, 9037, Tromsø, Norway.
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4
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Bains W, Petkowski JJ, Seager S. Venus' Atmospheric Chemistry and Cloud Characteristics Are Compatible with Venusian Life. ASTROBIOLOGY 2024; 24:371-385. [PMID: 37306952 DOI: 10.1089/ast.2022.0113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Venus is Earth's sister planet, with similar mass and density but an uninhabitably hot surface, an atmosphere with a water activity 50-100 times lower than anywhere on Earths' surface, and clouds believed to be made of concentrated sulfuric acid. These features have been taken to imply that the chances of finding life on Venus are vanishingly small, with several authors describing Venus' clouds as "uninhabitable," and that apparent signs of life there must therefore be abiotic, or artefactual. In this article, we argue that although many features of Venus can rule out the possibility that Earth life could live there, none rule out the possibility of all life based on what we know of the physical principle of life on Earth. Specifically, there is abundant energy, the energy requirements for retaining water and capturing hydrogen atoms to build biomass are not excessive, defenses against sulfuric acid are conceivable and have terrestrial precedent, and the speculative possibility that life uses concentrated sulfuric acid as a solvent instead of water remains. Metals are likely to be available in limited supply, and the radiation environment is benign. The clouds can support a biomass that could readily be detectable by future astrobiology-focused space missions from its impact on the atmosphere. Although we consider the prospects for finding life on Venus to be speculative, they are not absent. The scientific reward from finding life in such an un-Earthlike environment justifies considering how observations and missions should be designed to be capable of detecting life if it is there.
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Affiliation(s)
- William Bains
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- School of Physics and Astronomy, Cardiff University, Cardiff, United Kingdom
| | - Janusz J Petkowski
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- JJ Scientific, Warsaw, Poland
| | - Sara Seager
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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5
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Ortega-Arzola E, Higgins PM, Cockell CS. The minimum energy required to build a cell. Sci Rep 2024; 14:5267. [PMID: 38438463 PMCID: PMC11306549 DOI: 10.1038/s41598-024-54303-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 02/11/2024] [Indexed: 03/06/2024] Open
Abstract
Understanding the energy requirements for cell synthesis accurately and comprehensively has been a longstanding challenge. We introduce a computational model that estimates the minimum energy necessary to build any cell from its constituent parts. This method combines omics and internal cell compositions from various sources to calculate the Gibbs Free Energy of biosynthesis independently of specific metabolic pathways. Our public tool, Synercell, can be used with other models for minumum species-specific energy estimations in any well-sequenced species. The energy for synthesising the genome, transcriptome, proteome, and lipid bilayer of four cell types: Escherichia coli, Saccharomyces cerevisiae, an average mammalian cell and JCVI-syn3A were estimated. Their modelled minimum synthesis energies at 298 K were 9.54 × 10 - 11 J/cell, 4.99 × 10 - 9 J/cell, 3.71 × 10 - 7 J/cell and 3.69 × 10 - 12 respectively. Gram-for-gram synthesis of lipid bilayers requires the most energy, followed by the proteome, genome, and transcriptome. The average per gram cost of biomass synthesis is in the 300s of J/g for all four cells. Implications for the generalisability of cell construction and applications to biogeosciences, cellular biology, biotechnology, and astrobiology are discussed.
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Affiliation(s)
- Edwin Ortega-Arzola
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK.
| | - Peter M Higgins
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
- Department of Earth Sciences, University of Toronto, Toronto, ON, Canada
| | - Charles S Cockell
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
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6
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Gorter de Vries PJ, Mol V, Sonnenschein N, Jensen TØ, Nielsen AT. Probing efficient microbial CO 2 utilisation through metabolic and process modelling. Microb Biotechnol 2024; 17:e14414. [PMID: 38380934 PMCID: PMC10880515 DOI: 10.1111/1751-7915.14414] [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: 07/24/2023] [Revised: 11/29/2023] [Accepted: 01/10/2024] [Indexed: 02/22/2024] Open
Abstract
Acetogenic gas fermentation is increasingly studied as a promising technology to upcycle carbon-rich waste gasses. Currently the product range is limited, and production yields, rates and titres for a number of interesting products do not allow for economically viable processes. By pairing process modelling and host-agnostic metabolic modelling, we compare fermentation conditions and various products to optimise the processes. The models were then used in a simulation of an industrial-scale bubble column reactor. We find that increased temperatures favour gas transfer rates, particularly for the valuable and limiting H2 , while furthermore predicting an optimal feed composition of 9:1 mol H2 to mol CO2 . Metabolically, the increased non-growth associated maintenance requirements of thermophiles favours the formation of catabolic products. To assess the expansion of the product portfolio beyond acetate, both a product volatility analysis and a metabolic pathway model were implemented. In-situ recovery of volatile products is shown to be within range for acetone but challenging due to the extensive evaporation of water, while the direct production of more valuable compounds by acetogens is metabolically unfavourable compared to acetate and ethanol. We discuss alternative approaches to overcome these challenges to utilise acetogenic CO2 fixation to produce a wider range of carbon negative chemicals.
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Affiliation(s)
- Philip J. Gorter de Vries
- The Novo Nordisk Foundation Center for BiosustainabilityTechnical University of DenmarkKongens LyngbyDenmark
| | - Viviënne Mol
- The Novo Nordisk Foundation Center for BiosustainabilityTechnical University of DenmarkKongens LyngbyDenmark
| | - Nikolaus Sonnenschein
- Department of Biotechnology and BiomedicineTechnical University of DenmarkKongens LyngbyDenmark
| | - Torbjørn Ølshøj Jensen
- The Novo Nordisk Foundation Center for BiosustainabilityTechnical University of DenmarkKongens LyngbyDenmark
- AgainSøborgDenmark
| | - Alex Toftgaard Nielsen
- The Novo Nordisk Foundation Center for BiosustainabilityTechnical University of DenmarkKongens LyngbyDenmark
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7
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Wang C, Kuzyakov Y. Mechanisms and implications of bacterial-fungal competition for soil resources. THE ISME JOURNAL 2024; 18:wrae073. [PMID: 38691428 PMCID: PMC11104273 DOI: 10.1093/ismejo/wrae073] [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: 02/10/2024] [Revised: 03/24/2024] [Accepted: 04/24/2024] [Indexed: 05/03/2024]
Abstract
Elucidating complex interactions between bacteria and fungi that determine microbial community structure, composition, and functions in soil, as well as regulate carbon (C) and nutrient fluxes, is crucial to understand biogeochemical cycles. Among the various interactions, competition for resources is the main factor determining the adaptation and niche differentiation between these two big microbial groups in soil. This is because C and energy limitations for microbial growth are a rule rather than an exception. Here, we review the C and energy demands of bacteria and fungi-the two major kingdoms in soil-the mechanisms of their competition for these and other resources, leading to niche differentiation, and the global change impacts on this competition. The normalized microbial utilization preference showed that bacteria are 1.4-5 times more efficient in the uptake of simple organic compounds as substrates, whereas fungi are 1.1-4.1 times more effective in utilizing complex compounds. Accordingly, bacteria strongly outcompete fungi for simple substrates, while fungi take advantage of complex compounds. Bacteria also compete with fungi for the products released during the degradation of complex substrates. Based on these specifics, we differentiated spatial, temporal, and chemical niches for these two groups in soil. The competition will increase under the main five global changes including elevated CO2, N deposition, soil acidification, global warming, and drought. Elevated CO2, N deposition, and warming increase bacterial dominance, whereas soil acidification and drought increase fungal competitiveness.
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Affiliation(s)
- Chaoqun Wang
- National Key Laboratory of Wheat Improvement, College of Agronomy, Shandong Agricultural University, Tai'an 271018, Shandong, China
- Biogeochemistry of Agroecosystems, University of Göttingen, Göttingen 37077, Germany
- Faculty of Land and Food Systems, The University of British Columbia, Vancouver V6T1Z4, Canada
| | - Yakov Kuzyakov
- National Key Laboratory of Wheat Improvement, College of Agronomy, Shandong Agricultural University, Tai'an 271018, Shandong, China
- Department of Soil Science of Temperate Ecosystems, University of Göttingen, Göttingen 37077, Germany
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8
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Wray AC, Gorman-Lewis D. Bioenergetics of aerobic and anaerobic growth of Shewanella putrefaciens CN32. Front Microbiol 2023; 14:1234598. [PMID: 37601367 PMCID: PMC10433392 DOI: 10.3389/fmicb.2023.1234598] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Accepted: 07/17/2023] [Indexed: 08/22/2023] Open
Abstract
Shewanella putrefaciens is a model dissimilatory iron-reducing bacterium that can use Fe(III) and O2 as terminal electron acceptors. Consequently, it has the ability to influence both aerobic and anaerobic groundwater systems, making it an ideal microorganism for improving our understanding of facultative anaerobes with iron-based metabolism. In this work, we examine the bioenergetics of O2 and Fe(III) reduction coupled to lactate oxidation in Shewanella putrefaciens CN32. Bioenergetics were measured directly via isothermal calorimetry and by changes to the chemically defined growth medium. We performed these measurements from 25 to 36°C. Modeling metabolism with macrochemical equations allowed us to define a theoretical growth stoichiometry for the catabolic reaction of 1.00 O2:lactate and 1.33 Fe(III):lactate that was consistent with the observed ratios of O2:lactate (1.20 ± 0.23) and Fe(III):lactate (1.46 ± 0.15) consumption. Aerobic growth showed minimal variation with temperature and minimal variation in thermodynamic potentials of incubation. Fe(III)-based growth showed a strong temperature dependence. The Gibbs energy and enthalpy of incubation was minimized at ≥30°C. Energy partitioning modeling of Fe(III)-based calorimetric incubation data predicted that energy consumption for non-growth associate maintenance increases substantially above 30°C. This prediction agrees with the data at 33 and 35°C. These results suggest that the effects of temperature on Shewanella putrefaciens CN32 are metabolism dependent. Gibbs energy of incubation above 30°C was 3-5 times more exergonic with Fe(III)-based growth than with aerobic growth. We compared data gathered in this study with predictions of microbial growth based on standard-state conditions and based on the thermodynamic efficiency of microbial growth. Quantifying the growth requirements of Shewanella putrefaciens CN32 has advanced our understanding of the thermodynamic constraints of this dissimilatory iron-reducing bacterium.
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Affiliation(s)
- Addien C. Wray
- Earth and Space Sciences, University of Washington, Seattle, WA, United States
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9
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Kanaan G, Hoehler TM, Iwahana G, Deming JW. Modeled energetics of bacterial communities in ancient subzero brines. Front Microbiol 2023; 14:1206641. [PMID: 37564288 PMCID: PMC10411740 DOI: 10.3389/fmicb.2023.1206641] [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: 04/16/2023] [Accepted: 07/06/2023] [Indexed: 08/12/2023] Open
Abstract
Cryopeg brines are isolated volumes of hypersaline water in subzero permafrost. The cryopeg system at Utqiaġvik, Alaska, is estimated to date back to 40 ka BP or earlier, a remnant of a late Pleistocene Ocean. Surprisingly, the cryopeg brines contain high concentrations of organic carbon, including extracellular polysaccharides, and high densities of bacteria. How can these physiologically extreme, old, and geologically isolated systems support such an ecosystem? This study addresses this question by examining the energetics of the Utqiaġvik cryopeg brine ecosystem. Using literature-derived assumptions and new measurements on archived borehole materials, we first estimated the quantity of organic carbon when the system formed. We then considered two bacterial growth trajectories to calculate the lower and upper bounds of the cell-specific metabolic rate of these communities. These bounds represent the first community estimates of metabolic rate in a subzero hypersaline environment. To assess the plausibility of the different growth trajectories, we developed a model of the organic carbon cycle and applied it to three borehole scenarios. We also used dissolved inorganic carbon and nitrogen measurements to independently estimate the metabolic rate. The model reconstructs the growth trajectory of the microbial community and predicts the present-day cell density and organic carbon content. Model input included measured rates of the in-situ enzymatic conversion of particulate to dissolved organic carbon under subzero brine conditions. A sensitivity analysis of model parameters was performed, revealing an interplay between growth rate, cell-specific metabolic rate, and extracellular enzyme activity. This approach allowed us to identify plausible growth trajectories consistent with the observed bacterial densities in the cryopeg brines. We found that the cell-specific metabolic rate in this system is relatively high compared to marine sediments. We attribute this finding to the need to invest energy in the production of extracellular enzymes, for generating bioavailable carbon from particulate organic carbon, and the production of extracellular polysaccharides for cryoprotection and osmoprotection. These results may be relevant to other isolated systems in the polar regions of Earth and to possible ice-bound brines on worlds such as Europa, Enceladus, and Mars.
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Affiliation(s)
- Georges Kanaan
- School of Oceanography and Astrobiology Program, University of Washington, Seattle, WA, United States
| | | | - Go Iwahana
- International Arctic Research Center, University of Alaska Fairbanks, Fairbanks, AK, United States
| | - Jody W. Deming
- School of Oceanography and Astrobiology Program, University of Washington, Seattle, WA, United States
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10
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Seeburger R, Higgins PM, Whiteford NP, Cockell CS. Linking Methanogenesis in Low-Temperature Hydrothermal Vent Systems to Planetary Spectra: Methane Biosignatures on an Archean-Earth-like Exoplanet. ASTROBIOLOGY 2023; 23:415-430. [PMID: 37017441 DOI: 10.1089/ast.2022.0127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In this work, the viability of the detection of methane produced by microbial activity in low-temperature hydrothermal vents on an Archean-Earth-like exoplanet in the habitable zone is explored via a simplified bottom-up approach using a toy model. By simulating methanogens at hydrothermal vent sites in the deep ocean, biological methane production for a range of substrate inflow rates was determined and compared to literature values. These production rates were then used, along with a range of ocean floor vent coverage fractions, to determine likely methane concentrations in the simplified atmosphere. At maximum production rates, a vent coverage of 4-15 × 10-4 % (roughly 2000-6500 times that of modern Earth) is required to achieve 0.25% atmospheric methane. At minimum production rates, 100% vent coverage is not enough to produce 0.25% atmospheric methane. NASA's Planetary Spectrum Generator was then used to assess the detectability of methane features at various atmospheric concentrations. Even with future space-based observatory concepts (such as LUVOIR and HabEx), our results show the importance of both mirror size and distance to the observed planet. Planets with a substantial biomass of methanogens in hydrothermal vents can still lack a detectable, convincingly biological methane signature if they are beyond the scope of the chosen instrument. This work shows the value of coupling microbial ecological modeling with exoplanet science to better understand the constraints on biosignature gas production and its detectability.
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Affiliation(s)
- Rhys Seeburger
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
- Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh, UK
- Max Planck Institute for Astronomy, Heidelberg, Germany
| | - Peter M Higgins
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
- Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh, UK
- Department of Earth Sciences, University of Toronto, Toronto, Canada
| | - Niall P Whiteford
- Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh, UK
- Centre for Exoplanet Science, University of Edinburgh, Edinburgh, UK
- American Museum of Natural History, New York, New York, USA
| | - Charles S Cockell
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
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11
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Straathof AJ. Modelling of end-product inhibition in fermentation. Biochem Eng J 2022. [DOI: 10.1016/j.bej.2022.108796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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12
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Bradley JA, Arndt S, Amend JP, Burwicz-Galerne E, LaRowe DE. Sources and Fluxes of Organic Carbon and Energy to Microorganisms in Global Marine Sediments. Front Microbiol 2022; 13:910694. [PMID: 35875517 PMCID: PMC9301249 DOI: 10.3389/fmicb.2022.910694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 06/20/2022] [Indexed: 11/13/2022] Open
Abstract
Marine sediments comprise one of the largest microbial habitats and organic carbon sinks on the planet. However, it is unclear how variations in sediment physicochemical properties impact microorganisms on a global scale. Here we investigate patterns in the distribution of microbial cells, organic carbon, and the amounts of power used by microorganisms in global sediments. Our results show that sediment on continental shelves and margins is predominantly anoxic and contains cells whose power utilization decreases with sediment depth and age. Sediment in abyssal zones contains microbes that use low amounts of power on a per cell basis, across large gradients in sediment depth and age. We find that trends in cell abundance, POC storage and degradation, and microbial power utilization are mainly structured by depositional setting and redox conditions, rather than sediment depth and age. We also reveal distinct trends in per-cell power regime across different depositional settings, from maxima of ∼10–16 W cell–1 in recently deposited shelf sediments to minima of <10–20 W cell–1 in deeper and ancient sediments. Overall, we demonstrate broad global-scale connections between the depositional setting and redox conditions of global sediment, and the amounts of organic carbon and activity of deep biosphere microorganisms.
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Affiliation(s)
- James A. Bradley
- School of Geography, Queen Mary University of London, London, United Kingdom
- GFZ German Research Center for Geosciences, Potsdam, Germany
- *Correspondence: James A. Bradley,
| | - Sandra Arndt
- BGeosys, Department of Earth and Environmental Sciences, Université Libre de Bruxelles, Brussels, Belgium
| | - Jan P. Amend
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, United States
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, United States
| | - Ewa Burwicz-Galerne
- MARUM Center for Marine Environmental Sciences, Faculty of Geosciences, University of Bremen, Bremen, Germany
| | - Douglas E. LaRowe
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, United States
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13
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Hunt KA, von Netzer F, Gorman-Lewis D, Stahl DA. Microbial maintenance energy quantified and modeled with microcalorimetry. Biotechnol Bioeng 2022; 119:2413-2422. [PMID: 35680566 DOI: 10.1002/bit.28155] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 06/06/2022] [Accepted: 06/08/2022] [Indexed: 11/08/2022]
Abstract
Refining the energetic costs of cellular maintenance is essential for predicting microbial growth and survival in the environment. Here, we evaluate a simple batch culture method to quantify energy partitioning between growth and maintenance using microcalorimetry and thermodynamic modeling. The constants derived from the batch culture system were comparable to those that have been reported from meta-analyses of data derived from chemostat studies. The model accurately predicted temperature-dependent biomass yield and the upper temperature limit of growth for Desulfovibrio alaskensis G20, suggesting the method may have broad application. An Arrhenius temperature dependence for the specific energy consumption rate, inferred from substrate consumption and heat evolution, was observed over the entire viable temperature range. By combining this relationship for specific energy consumption rates and observed specific growth rates, the model describes an increase in nongrowth associated maintenance at higher temperatures and the corresponding decrease in energy available for growth. This analytical and thermodynamic formulation suggests that simply monitoring heat evolution in batch culture could be a useful complement to the recognized limitations of estimating maintenance using extrapolation to zero growth in chemostats.
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Affiliation(s)
- Kristopher A Hunt
- Department of Civil and Environmental Engineering, University of Washington, Seattle, Washington, USA
| | - Frederick von Netzer
- Department of Civil and Environmental Engineering, University of Washington, Seattle, Washington, USA
| | - Drew Gorman-Lewis
- Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA
| | - David A Stahl
- Department of Civil and Environmental Engineering, University of Washington, Seattle, Washington, USA
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14
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Miri S, Rasooli A, Brar SK, Rouissi T, Martel R. Biodegradation of p-xylene-a comparison of three psychrophilic Pseudomonas strains through the lens of gene expression. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:21465-21479. [PMID: 34762239 DOI: 10.1007/s11356-021-17387-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 11/02/2021] [Indexed: 05/21/2023]
Abstract
p-Xylene is considered a recalcitrant compound despite showing a similar aromatic structure to other BTEXs (benzene, toluene, ethylbenzene, xylene isomers). This study evaluated the p-xylene biodegradation potential of three psychrophilic Pseudomonas strains (Pseudomonas putida S2TR-01, Pseudomonas synxantha S2TR-20, and Pseudomonas azotoformans S2TR-09). The p-xylene metabolism-related catabolic genes (xylM, xylA, and xylE) and the corresponding regulatory genes (xylR and xylS) of the selected strains were investigated. The biodegradation results showed that the P. azotoformans S2TR-09 strain was the only strain that was able to degrade 200 mg/L p-xylene after 60 h at 15 °C. The gene expression study indicated that the xylE (encoding catechol 2,3-dioxygenase) gene represents the bottleneck in p-xylene biodegradation. A lack of xylE expression leads to the accumulation of intermediates and the inhibition of biomass production and complete carbon recovery. The activity of xylene monooxygenase and catechol 2,3-dioxygenase was significantly increased in P. azotoformans S2TR-09 (0.5 and 0.08 U/mg, respectively) in the presence of p-xylene. The expression of the ring cleavage enzyme and its encoding gene (xylE) and activator (xylS) explained the differences in the p-xylene metabolism of the isolated bacteria and can be used as a novel biomarker of efficient p-xylene biodegradation at contaminated sites.
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Affiliation(s)
- Saba Miri
- Department of Civil Engineering, Lassonde School of Engineering, York University, North York, Toronto, ON, M3J 1P3, Canada
- INRS-ETE, Université du Québec, 490, Rue de la Couronne, Québec, G1K 9A9, Canada
| | - Azadeh Rasooli
- Department of Civil Engineering, Lassonde School of Engineering, York University, North York, Toronto, ON, M3J 1P3, Canada
| | - Satinder Kaur Brar
- Department of Civil Engineering, Lassonde School of Engineering, York University, North York, Toronto, ON, M3J 1P3, Canada.
- INRS-ETE, Université du Québec, 490, Rue de la Couronne, Québec, G1K 9A9, Canada.
| | - Tarek Rouissi
- INRS-ETE, Université du Québec, 490, Rue de la Couronne, Québec, G1K 9A9, Canada
| | - Richard Martel
- INRS-ETE, Université du Québec, 490, Rue de la Couronne, Québec, G1K 9A9, Canada
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15
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Kundu K, Melsbach A, Heckel B, Schneidemann S, Kanapathi D, Marozava S, Merl-Pham J, Elsner M. Linking Increased Isotope Fractionation at Low Concentrations to Enzyme Activity Regulation: 4-Cl Phenol Degradation by Arthrobacter chlorophenolicus A6. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:3021-3032. [PMID: 35148097 PMCID: PMC8892832 DOI: 10.1021/acs.est.1c04939] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 01/23/2022] [Accepted: 01/26/2022] [Indexed: 06/14/2023]
Abstract
Slow microbial degradation of organic trace chemicals ("micropollutants") has been attributed to either downregulation of enzymatic turnover or rate-limiting substrate supply at low concentrations. In previous biodegradation studies, a drastic decrease in isotope fractionation of atrazine revealed a transition from rate-limiting enzyme turnover to membrane permeation as a bottleneck when concentrations fell below the Monod constant of microbial growth. With degradation of the pollutant 4-chlorophenol (4-CP) by Arthrobacter chlorophenolicus A6, this study targeted a bacterium which adapts its enzyme activity to concentrations. Unlike with atrazine degradation, isotope fractionation of 4-CP increased at lower concentrations, from ε(C) = -1.0 ± 0.5‰ in chemostats (D = 0.090 h-1, 88 mg L-1) and ε(C) = -2.1 ± 0.5‰ in batch (c0 = 220 mg L-1) to ε(C) = -4.1 ± 0.2‰ in chemostats at 90 μg L-1. Surprisingly, fatty acid composition indicated increased cell wall permeability at high concentrations, while proteomics revealed that catabolic enzymes (CphCI and CphCII) were differentially expressed at D = 0.090 h-1. These observations support regulation on the enzyme activity level─through either a metabolic shift between catabolic pathways or decreased enzymatic turnover at low concentrations─and, hence, reveal an alternative end-member scenario for bacterial adaptation at low concentrations. Including more degrader strains into this multidisciplinary analytical approach offers the perspective to build a knowledge base on bottlenecks of bioremediation at low concentrations that considers bacterial adaptation.
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Affiliation(s)
- Kankana Kundu
- Institute
of Groundwater Ecology, Helmholtz Zentrum
Munchen, Ingolstadter
Landstraße 1, 85764 Neuherberg, Bavaria, Germany
- Center
for Microbial Ecology and Technology (CMET), Faculty of Bioscience
Engineering, University of Ghent, Coupure Links 653, 9000 Ghent, Belgium
| | - Aileen Melsbach
- Institute
of Groundwater Ecology, Helmholtz Zentrum
Munchen, Ingolstadter
Landstraße 1, 85764 Neuherberg, Bavaria, Germany
- Chair
of Analytical Chemistry and Water Chemistry, Technical University of Munich, Lichtenbergstr. 4, D-85748 Garching, Germany
| | - Benjamin Heckel
- Institute
of Groundwater Ecology, Helmholtz Zentrum
Munchen, Ingolstadter
Landstraße 1, 85764 Neuherberg, Bavaria, Germany
| | - Sarah Schneidemann
- Institute
of Groundwater Ecology, Helmholtz Zentrum
Munchen, Ingolstadter
Landstraße 1, 85764 Neuherberg, Bavaria, Germany
| | - Dheeraj Kanapathi
- Institute
of Groundwater Ecology, Helmholtz Zentrum
Munchen, Ingolstadter
Landstraße 1, 85764 Neuherberg, Bavaria, Germany
| | - Sviatlana Marozava
- Institute
of Groundwater Ecology, Helmholtz Zentrum
Munchen, Ingolstadter
Landstraße 1, 85764 Neuherberg, Bavaria, Germany
| | - Juliane Merl-Pham
- Core
Facility Proteomics, Helmholtz Zentrum München, Heidemannstr. 1, 80939 Munich, Germany
| | - Martin Elsner
- Institute
of Groundwater Ecology, Helmholtz Zentrum
Munchen, Ingolstadter
Landstraße 1, 85764 Neuherberg, Bavaria, Germany
- Chair
of Analytical Chemistry and Water Chemistry, Technical University of Munich, Lichtenbergstr. 4, D-85748 Garching, Germany
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16
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Schurer R, Hijnen WAM, van der Wal A. The significance of the biomass subfraction of high-MW organic carbon for the microbial growth and maintenance potential of disinfectant-free drinking water produced from surface water. WATER RESEARCH 2022; 209:117898. [PMID: 34896810 DOI: 10.1016/j.watres.2021.117898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 11/15/2021] [Accepted: 11/23/2021] [Indexed: 06/14/2023]
Abstract
Drinking water must be sufficiently biostable to avoid excessive microbial and invertebrate growth in disinfectant-free distribution systems. The production of biologically stable drinking water is challenging for conventional surface water treatment plants using reservoirs as feed water due to the presence of slowly biodegradable particulate and high-molecular weight biopolymeric organic carbon (high-MW OC) which increases the Microbial Growth Potential (MGP) in the feed water and produced drinking water. The study presented here provides new insights in the relationship between high-MW OC and MGP for a full-scale surface water treatment plant. Controlled-conditions addition series experiments showed that MGP increases linearly with the high-MW OC concentration with a seasonally variable ratio. Laboratory filtration indicated that MGP is mainly attributable to the high-MW OC subfraction of > 0.12 µm particle size coinciding with microbial biomass. Intensive field monitoring revealed clear seasonal patterns in the plant's feed water and treated water levels of high-MW OC, biomass and MGP. These parameters reach maximum levels in the periods of high water temperature with the notable exception of the treated water's high-MW OC concentration which exhibits an opposite seasonal pattern (reflecting seasonally variable removal in the treatment). Moreover, the field monitoring showed that MGP correlates well with the concentrations of biodegradable biopolymeric OC and with microbial biomass measured as ATP (adenosine triphosphate) and cell counts, but not with the total high-MW OC concentration in the treated water. Theoretical estimations showed that the OC quantities present in and consumed by the microbial biomass are in the same order of magnitude as slowly biodegradable biopolymers. From these results it is concluded that specifically the microbial biomass-associated and biodegradable biopolymeric OC subfraction of the totally present high-MW OC is important for MGP. Finally, the MGP-assay results and theoretical calculations showed for the high-MW OC matrix that the microbial biomass' OC consumption for maintenance is significant vis-á-vis that for growth, and that stable and high levels of biomass are sustained in the treated water which may adversely affect biological stability in the distribution network.
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Affiliation(s)
- R Schurer
- Evides Water Company, PO Box 4472, 3006 AL Rotterdam, the Netherlands; Department of Environmental Technology, Wageningen University, Bornse Weilanden 9, 6708 WG Wageningen, the Netherlands; IHE Delft Institute for Water Education, Environmental Engineering and Water Technology Department, Westvest 7, 2611 AX Delft, the Netherlands.
| | - W A M Hijnen
- Evides Water Company, PO Box 4472, 3006 AL Rotterdam, the Netherlands; KWR Watercycle Research Institute, P.O. Box 1072, 3430 BB, Nieuwegein, the Netherlands
| | - A van der Wal
- Evides Water Company, PO Box 4472, 3006 AL Rotterdam, the Netherlands; Department of Environmental Technology, Wageningen University, Bornse Weilanden 9, 6708 WG Wageningen, the Netherlands
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17
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Okabe S, Kamigaito A, Kobayashi K. Maintenance power requirements of anammox bacteria "Candidatus Brocadia sinica" and "Candidatus Scalindua sp.". THE ISME JOURNAL 2021; 15:3566-3575. [PMID: 34145389 PMCID: PMC8629980 DOI: 10.1038/s41396-021-01031-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 05/27/2021] [Accepted: 06/02/2021] [Indexed: 02/05/2023]
Abstract
Little is known about the cell physiology of anammox bacteria growing at extremely low growth rates. Here, "Candidatus Brocadia sinica" and "Candidatus Scalindua sp." were grown in continuous anaerobic membrane bioreactors (MBRs) with complete biomass retention to determine maintenance energy (i.e., power) requirements at near-zero growth rates. After prolonged retentostat cultivations, the specific growth rates (μ) of "Ca. B. sinica" and "Ca. Scalindua sp." decreased to 0.000023 h-1 (doubling time of 1255 days) and 0.000157 h-1 (184 days), respectively. Under these near-zero growth conditions, substrate was continuously utilized to meet maintenance energy demands (me) of 6.7 ± 0.7 and 4.3 ± 0.7 kJ mole of biomass-C-1 h-1 for "Ca. B. sinica" and "Ca. Scalindua sp.", which accorded with the theoretically predicted values of all anaerobic microorganisms (9.7 and 4.4 kJ mole of biomass-C-1 h-1at 37 °C and 28 °C, respectively). These me values correspond to 13.4 × 10-15 and 8.6 × 10-15 watts cell-1 for "Ca. B. sinica" and "Ca. Scalindua sp.", which were five orders of magnitude higher than the basal power limit for natural settings (1.9 × 10-19 watts cells-1). Furthermore, the minimum substrate concentrations required for growth (Smin) were calculated to be 3.69 ± 0.21 and 0.09 ± 0.05 μM NO2- for "Ca. B. sinica" and "Ca. Scalindua sp.", respectively. These results match the evidence that "Ca. Scalindua sp." with lower maintenance power requirement and Smin are better adapted to energy-limited natural environments than "Ca. B. sinica", suggesting the importance of these parameters on ecological niche differentiation in natural environments.
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Affiliation(s)
- Satoshi Okabe
- grid.39158.360000 0001 2173 7691Department of Environmental Engineering, Faculty of Engineering, Hokkaido University, North 13, West 8, Sapporo, Hokkaido, 060-8628 Japan
| | - Atsushi Kamigaito
- grid.39158.360000 0001 2173 7691Department of Environmental Engineering, Faculty of Engineering, Hokkaido University, North 13, West 8, Sapporo, Hokkaido, 060-8628 Japan
| | - Kanae Kobayashi
- grid.39158.360000 0001 2173 7691Department of Environmental Engineering, Faculty of Engineering, Hokkaido University, North 13, West 8, Sapporo, Hokkaido, 060-8628 Japan
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18
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Abstract
Microbial growth is a clear example of organization and structure arising in nonequilibrium conditions. Due to the complexity of the microbial metabolic network, elucidating the fundamental principles governing microbial growth remains a challenge. Here, we present a systematic analysis of microbial growth thermodynamics, leveraging an extensive dataset on energy-limited monoculture growth. A consistent thermodynamic framework based on reaction stoichiometry allows us to quantify how much of the available energy microbes can efficiently convert into new biomass while dissipating the remaining energy into the environment and producing entropy. We show that dissipation mechanisms can be linked to the electron donor uptake rate, a fact leading to the central result that the thermodynamic efficiency is related to the electron donor uptake rate by the scaling law [Formula: see text] and to the growth yield by [Formula: see text] These findings allow us to rederive the Pirt equation from a thermodynamic perspective, providing a means to compute its coefficients, as well as a deeper understanding of the relationship between growth rate and yield. Our results provide rather general insights into the relation between mass and energy conversion in microbial growth with potentially wide application, especially in ecology and biotechnology.
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19
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Ortiz M, Leung PM, Shelley G, Jirapanjawat T, Nauer PA, Van Goethem MW, Bay SK, Islam ZF, Jordaan K, Vikram S, Chown SL, Hogg ID, Makhalanyane TP, Grinter R, Cowan DA, Greening C. Multiple energy sources and metabolic strategies sustain microbial diversity in Antarctic desert soils. Proc Natl Acad Sci U S A 2021; 118:e2025322118. [PMID: 34732568 PMCID: PMC8609440 DOI: 10.1073/pnas.2025322118] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/20/2021] [Indexed: 12/11/2022] Open
Abstract
Numerous diverse microorganisms reside in the cold desert soils of continental Antarctica, though we lack a holistic understanding of the metabolic processes that sustain them. Here, we profile the composition, capabilities, and activities of the microbial communities in 16 physicochemically diverse mountainous and glacial soils. We assembled 451 metagenome-assembled genomes from 18 microbial phyla and inferred through Bayesian divergence analysis that the dominant lineages present are likely native to Antarctica. In support of earlier findings, metagenomic analysis revealed that the most abundant and prevalent microorganisms are metabolically versatile aerobes that use atmospheric hydrogen to support aerobic respiration and sometimes carbon fixation. Surprisingly, however, hydrogen oxidation in this region was catalyzed primarily by a phylogenetically and structurally distinct enzyme, the group 1l [NiFe]-hydrogenase, encoded by nine bacterial phyla. Through gas chromatography, we provide evidence that both Antarctic soil communities and an axenic Bacteroidota isolate (Hymenobacter roseosalivarius) oxidize atmospheric hydrogen using this enzyme. Based on ex situ rates at environmentally representative temperatures, hydrogen oxidation is theoretically sufficient for soil communities to meet energy requirements and, through metabolic water production, sustain hydration. Diverse carbon monoxide oxidizers and abundant methanotrophs were also active in the soils. We also recovered genomes of microorganisms capable of oxidizing edaphic inorganic nitrogen, sulfur, and iron compounds and harvesting solar energy via microbial rhodopsins and conventional photosystems. Obligately symbiotic bacteria, including Patescibacteria, Chlamydiae, and predatory Bdellovibrionota, were also present. We conclude that microbial diversity in Antarctic soils reflects the coexistence of metabolically flexible mixotrophs with metabolically constrained specialists.
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Affiliation(s)
- Maximiliano Ortiz
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria 0002, South Africa
| | - Pok Man Leung
- Department of Microbiology, Monash Biomedicine Discovery Institute, Clayton VIC 3800, Australia;
| | - Guy Shelley
- School of Biological Sciences, Monash University, Clayton VIC 3800, Australia
| | - Thanavit Jirapanjawat
- Department of Microbiology, Monash Biomedicine Discovery Institute, Clayton VIC 3800, Australia
| | - Philipp A Nauer
- School of Chemistry, Monash University, Clayton VIC 3800, Australia
| | - Marc W Van Goethem
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria 0002, South Africa
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Sean K Bay
- Department of Microbiology, Monash Biomedicine Discovery Institute, Clayton VIC 3800, Australia
- School of Biological Sciences, Monash University, Clayton VIC 3800, Australia
| | - Zahra F Islam
- Department of Microbiology, Monash Biomedicine Discovery Institute, Clayton VIC 3800, Australia
- School of Biological Sciences, Monash University, Clayton VIC 3800, Australia
| | - Karen Jordaan
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria 0002, South Africa
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile
| | - Surendra Vikram
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria 0002, South Africa
| | - Steven L Chown
- Securing Antarctica's Environmental Future, School of Biological Sciences, Monash University, Clayton VIC 3800, Australia
| | - Ian D Hogg
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria 0002, South Africa
- School of Science, University of Waikato, Hamilton 3240, New Zealand
- Polar Knowledge Canada, Canadian High Arctic Research Station, Cambridge Bay NU X0B 0C0, Canada
| | - Thulani P Makhalanyane
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria 0002, South Africa
| | - Rhys Grinter
- Department of Microbiology, Monash Biomedicine Discovery Institute, Clayton VIC 3800, Australia
| | - Don A Cowan
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria 0002, South Africa;
| | - Chris Greening
- Department of Microbiology, Monash Biomedicine Discovery Institute, Clayton VIC 3800, Australia;
- School of Biological Sciences, Monash University, Clayton VIC 3800, Australia
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20
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Bay SK, Waite DW, Dong X, Gillor O, Chown SL, Hugenholtz P, Greening C. Chemosynthetic and photosynthetic bacteria contribute differentially to primary production across a steep desert aridity gradient. THE ISME JOURNAL 2021; 15:3339-3356. [PMID: 34035443 PMCID: PMC8528921 DOI: 10.1038/s41396-021-01001-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 04/16/2021] [Accepted: 04/28/2021] [Indexed: 02/04/2023]
Abstract
Desert soils harbour diverse communities of aerobic bacteria despite lacking substantial organic carbon inputs from vegetation. A major question is therefore how these communities maintain their biodiversity and biomass in these resource-limiting ecosystems. Here, we investigated desert topsoils and biological soil crusts collected along an aridity gradient traversing four climatic regions (sub-humid, semi-arid, arid, and hyper-arid). Metagenomic analysis indicated these communities vary in their capacity to use sunlight, organic compounds, and inorganic compounds as energy sources. Thermoleophilia, Actinobacteria, and Acidimicrobiia were the most abundant and prevalent bacterial classes across the aridity gradient in both topsoils and biocrusts. Contrary to the classical view that these taxa are obligate organoheterotrophs, genome-resolved analysis suggested they are metabolically flexible, with the capacity to also use atmospheric H2 to support aerobic respiration and often carbon fixation. In contrast, Cyanobacteria were patchily distributed and only abundant in certain biocrusts. Activity measurements profiled how aerobic H2 oxidation, chemosynthetic CO2 fixation, and photosynthesis varied with aridity. Cell-specific rates of atmospheric H2 consumption increased 143-fold along the aridity gradient, correlating with increased abundance of high-affinity hydrogenases. Photosynthetic and chemosynthetic primary production co-occurred throughout the gradient, with photosynthesis dominant in biocrusts and chemosynthesis dominant in arid and hyper-arid soils. Altogether, these findings suggest that the major bacterial lineages inhabiting hot deserts use different strategies for energy and carbon acquisition depending on resource availability. Moreover, they highlight the previously overlooked roles of Actinobacteriota as abundant primary producers and trace gases as critical energy sources supporting productivity and resilience of desert ecosystems.
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Affiliation(s)
- Sean K Bay
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia.
- School of Biological Sciences, Monash University, Clayton, VIC, Australia.
| | - David W Waite
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, QLD, Australia
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Xiyang Dong
- School of Marine Sciences, Sun Yat-Sen University, Zhuhai, China
| | - Osnat Gillor
- Zuckerberg Institute for Water Research, Blaustein Institutes for Desert Research, Ben Gurion University of the Negev, Sde Boker, Israel
| | - Steven L Chown
- School of Biological Sciences, Monash University, Clayton, VIC, Australia
| | - Philip Hugenholtz
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, QLD, Australia
| | - Chris Greening
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia.
- School of Biological Sciences, Monash University, Clayton, VIC, Australia.
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21
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Costa CE, Møller-Hansen I, Romaní A, Teixeira JA, Borodina I, Domingues L. Resveratrol Production from Hydrothermally Pretreated Eucalyptus Wood Using Recombinant Industrial Saccharomyces cerevisiae Strains. ACS Synth Biol 2021; 10:1895-1903. [PMID: 34304554 DOI: 10.1021/acssynbio.1c00120] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Resveratrol is a phenolic compound with strong antioxidant activity, being promising for several applications in health, food, and cosmetics. It is generally extracted from plants or chemically synthesized, in both complex and not sustainable processes, but microbial biosynthesis of resveratrol can counter these drawbacks. In this work, resveratrol production by microbial biosynthesis from lignocellulosic materials was assessed. Three robust industrial Saccharomyces cerevisiae strains known for their thermotolerance and/or resistance to inhibitory compounds were identified as suitable hosts for de novo resveratrol production from glucose and ethanol. Through the CRISPR/Cas9 system, all industrial strains, and a laboratory one, were successfully engineered with the resveratrol biosynthetic pathway via the phenylalanine intermediate. All strains were further screened at 30 °C and 39 °C to evaluate thermotolerance, which is a key feature for Simultaneous Saccharification and Fermentation processes. Ethanol Red RBP showed the best performance at 39 °C, with more than 2.6-fold of resveratrol production in comparison with the other strains. This strain was then used to assess resveratrol production from glucose and ethanol. A maximum resveratrol titer of 187.07 ± 19.88 mg/L was attained from a medium with 2% glucose and 5% ethanol (w/v). Lastly, Ethanol Red RBP produced 151.65 ± 3.84 mg/L resveratrol from 2.95% of cellulose from hydrothermally pretreated Eucalyptus globulus wood, at 39 °C, in a Simultaneous Saccharification and Fermentation process. To the best of our knowledge, this is the first report of lignocellulosic resveratrol production, establishing grounds for the implementation of an integrated lignocellulose-to-resveratrol process in an industrial context.
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Affiliation(s)
- Carlos E. Costa
- Centre of Biological Engineering, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal
| | - Iben Møller-Hansen
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Aloia Romaní
- Centre of Biological Engineering, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal
| | - José A. Teixeira
- Centre of Biological Engineering, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal
| | - Irina Borodina
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Lucília Domingues
- Centre of Biological Engineering, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal
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22
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Hoke KL, Zimmer SL, Roddy AB, Ondrechen MJ, Williamson CE, Buan NR. Reintegrating Biology Through the Nexus of Energy, Information, and Matter. Integr Comp Biol 2021; 61:2082-2094. [PMID: 34374780 DOI: 10.1093/icb/icab174] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Information, energy, and matter are fundamental properties of all levels of biological organization, and life emerges from the continuous flux of matter, energy, and information. This perspective piece defines and explains each of the three pillars of this nexus. We propose that a quantitative characterization of the complex interconversions between matter, energy, and information that comprise this nexus will help us derive biological insights that connect phenomena across different levels of biological organization. We articulate examples from multiple biological scales that highlight how this nexus approach leads to a more complete understanding of the biological system. Metrics of energy, information, and matter can provide a common currency that helps link phenomena across levels of biological organization. The propagation of energy and information through levels of biological organization can result in emergent properties and system-wide changes that impact other hierarchical levels. Deeper consideration of measured imbalances in energy, information, and matter can help researchers identify key factors that influence system function at one scale, highlighting avenues to link phenomena across levels of biological organization and develop predictive models of biological systems.
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Affiliation(s)
- Kim L Hoke
- Department of Biology, Colorado State University, Fort Collins, CO 80523-1878
| | - Sara L Zimmer
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth campus, Duluth, MN 55812
| | - Adam B Roddy
- Institute of Environment, Department of Biological Sciences, Florida International University, Miami, FL 33199
| | - Mary Jo Ondrechen
- Department of Chemistry & Chemical Biology, Northeastern University, Boston, MA 02115
| | | | - Nicole R Buan
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0662
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Ammonia-oxidizing archaea have similar power requirements in diverse marine oxic sediments. ISME JOURNAL 2021; 15:3657-3667. [PMID: 34158628 PMCID: PMC8630020 DOI: 10.1038/s41396-021-01041-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/26/2020] [Revised: 06/09/2021] [Accepted: 06/11/2021] [Indexed: 11/08/2022]
Abstract
Energy/power availability is regarded as one of the ultimate controlling factors of microbial abundance in the deep biosphere, where fewer cells are found in habitats of lower energy availability. A critical assumption driving the proportional relationship between total cell abundance and power availability is that the cell-specific power requirement keeps constant or varies over smaller ranges than other variables, which has yet to be validated. Here we present a quantitative framework to determine the cell-specific power requirement of the omnipresent ammonia-oxidizing archaea (AOA) in eight sediment cores with 3-4 orders of magnitude variations of organic matter flux and oxygen penetration depth. Our results show that despite the six orders of magnitude variations in the rates and power supply of nitrification and AOA abundances across these eight cores, the cell-specific power requirement of AOA from different cores and depths overlaps within the narrow range of 10-19-10-17 W cell-1, where the lower end may represent the basal power requirement of microorganisms persisting in subseafloor sediments. In individual cores, AOA also exhibit similar cell-specific power requirements, regardless of the AOA population size or sediment depth/age. Such quantitative insights establish a relationship between the power supply and the total abundance of AOA, and therefore lay a foundation for a first-order estimate of the standing stock of AOA in global marine oxic sediments.
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24
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Cabau-Peinado O, Straathof AJJ, Jourdin L. A General Model for Biofilm-Driven Microbial Electrosynthesis of Carboxylates From CO 2. Front Microbiol 2021; 12:669218. [PMID: 34149654 PMCID: PMC8211901 DOI: 10.3389/fmicb.2021.669218] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 05/10/2021] [Indexed: 11/13/2022] Open
Abstract
Up to now, computational modeling of microbial electrosynthesis (MES) has been underexplored, but is necessary to achieve breakthrough understanding of the process-limiting steps. Here, a general framework for modeling microbial kinetics in a MES reactor is presented. A thermodynamic approach is used to link microbial metabolism to the electrochemical reduction of an intracellular mediator, allowing to predict cellular growth and current consumption. The model accounts for CO2 reduction to acetate, and further elongation to n-butyrate and n-caproate. Simulation results were compared with experimental data obtained from different sources and proved the model is able to successfully describe microbial kinetics (growth, chain elongation, and product inhibition) and reactor performance (current density, organics titer). The capacity of the model to simulate different system configurations is also shown. Model results suggest CO2 dissolved concentration might be limiting existing MES systems, and highlight the importance of the delivery method utilized to supply it. Simulation results also indicate that for biofilm-driven reactors, continuous mode significantly enhances microbial growth and might allow denser biofilms to be formed and higher current densities to be achieved.
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Affiliation(s)
- Oriol Cabau-Peinado
- Department of Biotechnology, Faculty of Applied Sciences, Delft University of Technology, Delft, Netherlands
| | - Adrie J J Straathof
- Department of Biotechnology, Faculty of Applied Sciences, Delft University of Technology, Delft, Netherlands
| | - Ludovic Jourdin
- Department of Biotechnology, Faculty of Applied Sciences, Delft University of Technology, Delft, Netherlands
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25
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Miri S, Davoodi SM, Karimi Darvanjooghi MH, Brar SK, Rouissi T, Martel R. Precision modelling of co-metabolic biodegradation of recalcitrant aromatic hydrocarbons in conjunction with experimental data. Process Biochem 2021. [DOI: 10.1016/j.procbio.2021.03.026] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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26
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Evolution of default genetic control mechanisms. PLoS One 2021; 16:e0251568. [PMID: 33984070 PMCID: PMC8118313 DOI: 10.1371/journal.pone.0251568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 04/28/2021] [Indexed: 11/19/2022] Open
Abstract
We present a model of the evolution of control systems in a genome under environmental constraints. The model conceptually follows the Jacob and Monod model of gene control. Genes contain control elements which respond to the internal state of the cell as well as the environment to control expression of a coding region. Control and coding regions evolve to maximize a fitness function between expressed coding sequences and the environment. The model was run 118 times to an average of 1.4∙106 ‘generations’ each with a range of starting parameters probed the conditions under which genomes evolved a ‘default style’ of control. Unexpectedly, the control logic that evolved was not significantly correlated to the complexity of the environment. Genetic logic was strongly correlated with genome complexity and with the fraction of genes active in the cell at any one time. More complex genomes correlated with the evolution of genetic controls in which genes were active (‘default on’), and a low fraction of genes being expressed correlated with a genetic logic in which genes were biased to being inactive unless positively activated (‘default off’ logic). We discuss how this might relate to the evolution of the complex eukaryotic genome, which operates in a ‘default off’ mode.
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27
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Diego D, Hannisdal B, Dahle H. On how the power supply shapes microbial survival. Math Biosci 2021; 338:108615. [PMID: 33857526 DOI: 10.1016/j.mbs.2021.108615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 03/29/2021] [Accepted: 04/04/2021] [Indexed: 10/21/2022]
Abstract
Understanding how environmental factors affect microbial survival is an important open problem in microbial ecology. Patterns of microbial community structure have been characterized across a wide range of different environmental settings, but the mechanisms generating these patterns remain poorly understood. Here, we use mathematical modelling to investigate fundamental connections between chemical power supply to a system and patterns of microbial survival. We reveal a complex set of interdependences between power supply and distributions of survival probability across microbial habitats, in a case without interspecific resource competition. We also find that different properties determining power supply, such as substrate fluxes and Gibbs energies of reactions, affect microbial survival in fundamentally different ways. Moreover, we show how simple connections between power supply and growth can give rise to complex patterns of microbial survival across physicochemical gradients, such as pH gradients. Our findings show the importance of taking energy fluxes into account in order to reveal fundamental connections between microbial survival and environmental conditions, and to obtain a better understanding of microbial population dynamics in natural environments.
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Affiliation(s)
- David Diego
- Department of Earth Science, University of Bergen, Allégaten, NO-5007 Bergen, Norway; K.G. Jebsen Centre for Deep Sea Research, Allégaten, NO-5007 Bergen, Norway.
| | - Bjarte Hannisdal
- Department of Earth Science, University of Bergen, Allégaten, NO-5007 Bergen, Norway; K.G. Jebsen Centre for Deep Sea Research, Allégaten, NO-5007 Bergen, Norway
| | - Håkon Dahle
- K.G. Jebsen Centre for Deep Sea Research, Allégaten, NO-5007 Bergen, Norway; Department of Biological Sciences, University of Bergen, Thormøhlens gate 53A, NO-5006 Bergen, Norway; Computational Biology Unit, Department of Informatics, University of Bergen, N-5020 Bergen, Norway
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28
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Tveit AT, Schmider T, Hestnes AG, Lindgren M, Didriksen A, Svenning MM. Simultaneous Oxidation of Atmospheric Methane, Carbon Monoxide and Hydrogen for Bacterial Growth. Microorganisms 2021; 9:microorganisms9010153. [PMID: 33445466 PMCID: PMC7827875 DOI: 10.3390/microorganisms9010153] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 01/06/2021] [Accepted: 01/07/2021] [Indexed: 11/16/2022] Open
Abstract
The second largest sink for atmospheric methane (CH4) is atmospheric methane oxidizing-bacteria (atmMOB). How atmMOB are able to sustain life on the low CH4 concentrations in air is unknown. Here, we show that during growth, with air as its only source for energy and carbon, the recently isolated atmospheric methane-oxidizer Methylocapsa gorgona MG08 (USCα) oxidizes three atmospheric energy sources: CH4, carbon monoxide (CO), and hydrogen (H2) to support growth. The cell-specific CH4 oxidation rate of M. gorgona MG08 was estimated at ~0.7 × 10−18 mol cell−1 h−1, which, together with the oxidation of CO and H2, supplies 0.38 kJ Cmol−1 h−1 during growth in air. This is seven times lower than previously assumed necessary to support bacterial maintenance. We conclude that atmospheric methane-oxidation is supported by a metabolic flexibility that enables the simultaneous harvest of CH4, H2 and CO from air, but the key characteristic of atmospheric CH4 oxidizing bacteria might be very low energy requirements.
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Affiliation(s)
- Alexander Tøsdal Tveit
- Department of Arctic and Marine Biology, UiT, The Arctic University of Norway, 9037 Tromsø, Norway; (T.S.); (A.G.H.); (A.D.); (M.M.S.)
- Correspondence:
| | - Tilman Schmider
- Department of Arctic and Marine Biology, UiT, The Arctic University of Norway, 9037 Tromsø, Norway; (T.S.); (A.G.H.); (A.D.); (M.M.S.)
| | - Anne Grethe Hestnes
- Department of Arctic and Marine Biology, UiT, The Arctic University of Norway, 9037 Tromsø, Norway; (T.S.); (A.G.H.); (A.D.); (M.M.S.)
| | - Matteus Lindgren
- CAGE—Centre for Arctic Gas Hydrate, Environment and Climate, Department of Geosciences, UiT, The Arctic University of Norway, 9010 Tromsø, Norway;
| | - Alena Didriksen
- Department of Arctic and Marine Biology, UiT, The Arctic University of Norway, 9037 Tromsø, Norway; (T.S.); (A.G.H.); (A.D.); (M.M.S.)
| | - Mette Marianne Svenning
- Department of Arctic and Marine Biology, UiT, The Arctic University of Norway, 9037 Tromsø, Norway; (T.S.); (A.G.H.); (A.D.); (M.M.S.)
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29
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Trace gas oxidizers are widespread and active members of soil microbial communities. Nat Microbiol 2021; 6:246-256. [PMID: 33398096 DOI: 10.1038/s41564-020-00811-w] [Citation(s) in RCA: 76] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 10/08/2020] [Indexed: 01/24/2023]
Abstract
Soil microorganisms globally are thought to be sustained primarily by organic carbon sources. Certain bacteria also consume inorganic energy sources such as trace gases, but they are presumed to be rare community members, except within some oligotrophic soils. Here we combined metagenomic, biogeochemical and modelling approaches to determine how soil microbial communities meet energy and carbon needs. Analysis of 40 metagenomes and 757 derived genomes indicated that over 70% of soil bacterial taxa encode enzymes to consume inorganic energy sources. Bacteria from 19 phyla encoded enzymes to use the trace gases hydrogen and carbon monoxide as supplemental electron donors for aerobic respiration. In addition, we identified a fourth phylum (Gemmatimonadota) potentially capable of aerobic methanotrophy. Consistent with the metagenomic profiling, communities within soil profiles from diverse habitats rapidly oxidized hydrogen, carbon monoxide and to a lesser extent methane below atmospheric concentrations. Thermodynamic modelling indicated that the power generated by oxidation of these three gases is sufficient to meet the maintenance needs of the bacterial cells capable of consuming them. Diverse bacteria also encode enzymes to use trace gases as electron donors to support carbon fixation. Altogether, these findings indicate that trace gas oxidation confers a major selective advantage in soil ecosystems, where availability of preferred organic substrates limits microbial growth. The observation that inorganic energy sources may sustain most soil bacteria also has broad implications for understanding atmospheric chemistry and microbial biodiversity in a changing world.
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30
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Jordaan K, Lappan R, Dong X, Aitkenhead IJ, Bay SK, Chiri E, Wieler N, Meredith LK, Cowan DA, Chown SL, Greening C. Hydrogen-Oxidizing Bacteria Are Abundant in Desert Soils and Strongly Stimulated by Hydration. mSystems 2020; 5:e01131-20. [PMID: 33203691 PMCID: PMC7677003 DOI: 10.1128/msystems.01131-20] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 10/29/2020] [Indexed: 01/19/2023] Open
Abstract
How the diverse bacterial communities inhabiting desert soils maintain energy and carbon needs is much debated. Traditionally, most bacteria are thought to persist by using organic carbon synthesized by photoautotrophs following transient hydration events. Recent studies focused on Antarctic desert soils have revealed, however, that some bacteria use atmospheric trace gases, such as hydrogen (H2), to conserve energy and fix carbon independently of photosynthesis. In this study, we investigated whether atmospheric H2 oxidation occurs in four nonpolar desert soils and compared this process to photosynthesis. To do so, we first profiled the distribution, expression, and activities of hydrogenases and photosystems in surface soils collected from the South Australian desert over a simulated hydration-desiccation cycle. Hydrogenase-encoding sequences were abundant in the metagenomes and metatranscriptomes and were detected in actinobacterial, acidobacterial, and cyanobacterial metagenome-assembled genomes. Native dry soil samples mediated H2 oxidation, but rates increased 950-fold following wetting. Oxygenic and anoxygenic phototrophs were also detected in the community but at lower abundances. Hydration significantly stimulated rates of photosynthetic carbon fixation and, to a lesser extent, dark carbon assimilation. Hydrogenase genes were also widespread in samples from three other climatically distinct deserts, the Namib, Gobi, and Mojave, and atmospheric H2 oxidation was also greatly stimulated by hydration at these sites. Together, these findings highlight that H2 is an important, hitherto-overlooked energy source supporting bacterial communities in desert soils. Contrary to our previous hypotheses, however, H2 oxidation occurs simultaneously rather than alternately with photosynthesis in such ecosystems and may even be mediated by some photoautotrophs.IMPORTANCE Desert ecosystems, spanning a third of the earth's surface, harbor remarkably diverse microbial life despite having a low potential for photosynthesis. In this work, we reveal that atmospheric hydrogen serves as a major previously overlooked energy source for a large proportion of desert bacteria. We show that both chemoheterotrophic and photoautotrophic bacteria have the potential to oxidize hydrogen across deserts sampled across four continents. Whereas hydrogen oxidation was slow in native dry deserts, it increased by three orders of magnitude together with photosynthesis following hydration. This study revealed that continual harvesting of atmospheric energy sources may be a major way that desert communities adapt to long periods of water and energy deprivation, with significant ecological and biogeochemical ramifications.
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Affiliation(s)
- Karen Jordaan
- School of Biological Sciences, Monash University, Clayton, VIC, Australia
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
| | - Rachael Lappan
- School of Biological Sciences, Monash University, Clayton, VIC, Australia
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Xiyang Dong
- School of Marine Sciences, Sun Yat-Sen University, Zhuhai, China
| | - Ian J Aitkenhead
- School of Biological Sciences, Monash University, Clayton, VIC, Australia
| | - Sean K Bay
- School of Biological Sciences, Monash University, Clayton, VIC, Australia
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Eleonora Chiri
- School of Biological Sciences, Monash University, Clayton, VIC, Australia
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | | | - Laura K Meredith
- School of Natural Resources and the Environment, University of Arizona, Tucson, Arizona, USA
| | - Don A Cowan
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
| | - Steven L Chown
- School of Biological Sciences, Monash University, Clayton, VIC, Australia
| | - Chris Greening
- School of Biological Sciences, Monash University, Clayton, VIC, Australia
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
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31
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Higgins PM, Cockell CS. A bioenergetic model to predict habitability, biomass and biosignatures in astrobiology and extreme conditions. J R Soc Interface 2020; 17:20200588. [PMID: 33081642 PMCID: PMC7653372 DOI: 10.1098/rsif.2020.0588] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 09/24/2020] [Indexed: 12/23/2022] Open
Abstract
In order to grow, reproduce and evolve life requires a supply of energy and nutrients. Astrobiology has the challenge of studying life on Earth in environments which are poorly characterized or extreme, usually both, and predicting the habitability of extraterrestrial environments. We have developed a general astrobiological model for assessing the energetic and nutrient availability of poorly characterized environments to predict their potential biological productivity. NutMEG (nutrients, maintenance, energy and growth) can be used to estimate how much biomass an environment could host, and how that life might affect the local chemistry. It requires only an overall catabolic reaction and some knowledge of the local environment to begin making estimations, with many more customizable parameters, such as microbial adaptation. In this study, the model was configured to replicate laboratory data on the growth of methanogens. It was used to predict the effect of temperature and energy/nutrient limitation on their microbial growth rates, total biomass levels, and total biosignature production in laboratory-like conditions to explore how it could be applied to astrobiological problems. As temperature rises from 280 to 330 K, NutMEG predicts exponential drops in final biomass ([Formula: see text]) and total methane production ([Formula: see text]) despite an increase in peak growth rates ([Formula: see text]) for a typical methanogen in ideal conditions. This is caused by the increasing cost of microbial maintenance diverting energy away from growth processes. Restricting energy and nutrients exacerbates this trend. With minimal assumptions NutMEG can reliably replicate microbial growth behaviour, but better understanding of the synthesis and maintenance costs life must overcome in different extremes is required to improve its results further. NutMEG can help us assess the theoretical habitability of extraterrestrial environments and predict potential biomass and biosignature production, for example on exoplanets using minimum input parameters to guide observations.
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Affiliation(s)
- P. M. Higgins
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
| | - C. S. Cockell
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
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32
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Bradley JA, Arndt S, Amend JP, Burwicz E, Dale AW, Egger M, LaRowe DE. Widespread energy limitation to life in global subseafloor sediments. SCIENCE ADVANCES 2020; 6:eaba0697. [PMID: 32821818 PMCID: PMC7406382 DOI: 10.1126/sciadv.aba0697] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 06/23/2020] [Indexed: 05/05/2023]
Abstract
Microbial cells buried in subseafloor sediments comprise a substantial portion of Earth's biosphere and control global biogeochemical cycles; however, the rate at which they use energy (i.e., power) is virtually unknown. Here, we quantify organic matter degradation and calculate the power utilization of microbial cells throughout Earth's Quaternary-age subseafloor sediments. Aerobic respiration, sulfate reduction, and methanogenesis mediate 6.9, 64.5, and 28.6% of global subseafloor organic matter degradation, respectively. The total power utilization of the subseafloor sediment biosphere is 37.3 gigawatts, less than 0.1% of the power produced in the marine photic zone. Aerobic heterotrophs use the largest share of global power (54.5%) with a median power utilization of 2.23 × 10-18 watts per cell, while sulfate reducers and methanogens use 1.08 × 10-19 and 1.50 × 10-20 watts per cell, respectively. Most subseafloor cells subsist at energy fluxes lower than have previously been shown to support life, calling into question the power limit to life.
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Affiliation(s)
- J. A. Bradley
- School of Geography, Queen Mary University of London, London, UK
- Department of Geochemistry, GFZ, German Research Centre for Geosciences, Potsdam, Germany
| | - S. Arndt
- Department of Geosciences, Environment and Society, Université Libre de Bruxelles, Brussels, Belgium
| | - J. P. Amend
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, USA
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - E. Burwicz
- GEOMAR, Helmholtz Centre for Ocean Research, Kiel, Germany
| | - A. W. Dale
- GEOMAR, Helmholtz Centre for Ocean Research, Kiel, Germany
| | - M. Egger
- The Ocean Cleanup Foundation, Rotterdam, Netherlands
| | - D. E. LaRowe
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, USA
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33
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Xu B, Ng TCA, Huang S, Ng HY. Effect of quorum quenching on EPS and size-fractioned particles and organics in anaerobic membrane bioreactor for domestic wastewater treatment. WATER RESEARCH 2020; 169:115251. [PMID: 32388050 DOI: 10.1016/j.watres.2019.115251] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 10/10/2019] [Accepted: 10/27/2019] [Indexed: 05/06/2023]
Abstract
Quorum quenching (QQ) has been applied as a promising membrane fouling control strategy for anaerobic membrane bioreactors (AnMBRs). Nevertheless, long-term operation of AnMBRs for real domestic wastewater (DWW) treatment needs to be systematically studied to evaluate comprehensive membrane fouling mechanisms and bioprocess performance. In this study, the impact of QQ on membrane fouling was investigated using a quorum quenching AnMBR (QQAnMBR) deploying a bead-entrapped facultative quorum quenching consortium (FQQ) to treat DWW. FQQ was shown to prolong membrane filtration operation by an average of 75%. Reduced proteins (p < 0.005) and carbohydrates (p < 0.005) in the extracellular polymeric substances (EPS) of mixed liquor (ML) were key differentiators that led to lower cake layer (CL) formation. Additionally, reduced biopolymers production (p < 0.05) in EPS improved sludge dewaterability. The findings suggested that QQ could alter fluorescent microbial metabolites of both EPS and CL as unveiled by excitation-emission matrix spectra pattern. Furthermore, colloidal particles (i.e., particles with size larger than 0.45 μm in ML supernatants) production was retarded by QQ, thereafter, also contributed to the reduced CL formation. Pore blockage was slightly increased by QQ, which might be attributed to pore blockage by large (∼230 nm) and small organic compounds (∼51 nm) in soluble microbial products (SMP). However, QQ had no significant impact on organic concentration of SMP, and QQ was not associated with particle size distribution of biomass. QQ performance was further affirmed through suppressed production of C4-HSL, 3-OXO-C6-HSL, and C6-HSL. The overall AHLs degradability of FQQ was well-maintained even after five membrane service cycles (total operation of 70 d). Moreover, QQ had no compromised impact on treatment performance (i.e., chemical oxygen demand (COD) removal and methane yield). Collectively, this study bridged the knowledge gap to bring forward QQ technology in AnMBR for widespread domestic wastewater treatment application.
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Affiliation(s)
- Boyan Xu
- Centre for Water Research, Department of Civil and Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, 117576, Singapore
| | - Tze Chiang Albert Ng
- Centre for Water Research, Department of Civil and Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, 117576, Singapore
| | - Shujuan Huang
- Centre for Water Research, Department of Civil and Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, 117576, Singapore
| | - How Yong Ng
- Centre for Water Research, Department of Civil and Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, 117576, Singapore; National University of Singapore Environmental Research Institute, 5A Engineering Drive 1, 117411, Singapore.
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34
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Lip KYF, García-Ríos E, Costa CE, Guillamón JM, Domingues L, Teixeira J, van Gulik WM. Selection and subsequent physiological characterization of industrial Saccharomyces cerevisiae strains during continuous growth at sub- and- supra optimal temperatures. BIOTECHNOLOGY REPORTS (AMSTERDAM, NETHERLANDS) 2020; 26:e00462. [PMID: 32477898 PMCID: PMC7251540 DOI: 10.1016/j.btre.2020.e00462] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 04/22/2020] [Accepted: 04/22/2020] [Indexed: 11/04/2022]
Abstract
A phenotypic screening of 12 industrial yeast strains and the well-studied laboratory strain CEN.PK113-7D at cultivation temperatures between 12 °C and 40 °C revealed significant differences in maximum growth rates and temperature tolerance. From those 12, two strains, one performing best at 12 °C and the other at 40 °C, plus the laboratory strain, were selected for further physiological characterization in well-controlled bioreactors. The strains were grown in anaerobic chemostats, at a fixed specific growth rate of 0.03 h-1 and sequential batch cultures at 12 °C, 30 °C, and 39 °C. We observed significant differences in biomass and ethanol yields on glucose, biomass protein and storage carbohydrate contents, and biomass yields on ATP between strains and cultivation temperatures. Increased temperature tolerance coincided with higher energetic efficiency of cell growth, indicating that temperature intolerance is a result of energy wasting processes, such as increased turnover of cellular components (e.g. proteins) due to temperature induced damage.
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Affiliation(s)
- Ka Ying Florence Lip
- Department of Biotechnology, Delft University of Technology, Delft 2629HZ, the Netherlands
| | - Estéfani García-Ríos
- Food Biotechnology Department, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Valencia, Spain
| | - Carlos E. Costa
- Centre of Biological Engineering, University of Minho, Braga 4710-057, Portugal
| | - José Manuel Guillamón
- Food Biotechnology Department, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Valencia, Spain
| | - Lucília Domingues
- Centre of Biological Engineering, University of Minho, Braga 4710-057, Portugal
| | - José Teixeira
- Centre of Biological Engineering, University of Minho, Braga 4710-057, Portugal
| | - Walter M. van Gulik
- Department of Biotechnology, Delft University of Technology, Delft 2629HZ, the Netherlands
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35
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Sauterey B, Charnay B, Affholder A, Mazevet S, Ferrière R. Co-evolution of primitive methane-cycling ecosystems and early Earth's atmosphere and climate. Nat Commun 2020; 11:2705. [PMID: 32483130 PMCID: PMC7264298 DOI: 10.1038/s41467-020-16374-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 04/28/2020] [Indexed: 01/24/2023] Open
Abstract
The history of the Earth has been marked by major ecological transitions, driven by metabolic innovation, that radically reshaped the composition of the oceans and atmosphere. The nature and magnitude of the earliest transitions, hundreds of million years before photosynthesis evolved, remain poorly understood. Using a novel ecosystem-planetary model, we find that pre-photosynthetic methane-cycling microbial ecosystems are much less productive than previously thought. In spite of their low productivity, the evolution of methanogenic metabolisms strongly modifies the atmospheric composition, leading to a warmer but less resilient climate. As the abiotic carbon cycle responds, further metabolic evolution (anaerobic methanotrophy) may feed back to the atmosphere and destabilize the climate, triggering a transient global glaciation. Although early metabolic evolution may cause strong climatic instability, a low CO:CH4 atmospheric ratio emerges as a robust signature of simple methane-cycling ecosystems on a globally reduced planet such as the late Hadean/early Archean Earth.
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Affiliation(s)
- Boris Sauterey
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Université Paris Sciences et Lettres, CNRS, INSERM, 75005, Paris, France.
- International Center for Interdisciplinary Global Environmental Studies (iGLOBES), CNRS, ENS-PSL University, University of Arizona, Tucson, AZ, 85721, USA.
- Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Univ. Lille, F-75014, Paris, France.
| | - Benjamin Charnay
- LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, 5 place Jules Janssen, 92195, Meudon, France
| | - Antonin Affholder
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Université Paris Sciences et Lettres, CNRS, INSERM, 75005, Paris, France
- International Center for Interdisciplinary Global Environmental Studies (iGLOBES), CNRS, ENS-PSL University, University of Arizona, Tucson, AZ, 85721, USA
- Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Univ. Lille, F-75014, Paris, France
| | - Stéphane Mazevet
- Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Univ. Lille, F-75014, Paris, France
| | - Régis Ferrière
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Université Paris Sciences et Lettres, CNRS, INSERM, 75005, Paris, France
- International Center for Interdisciplinary Global Environmental Studies (iGLOBES), CNRS, ENS-PSL University, University of Arizona, Tucson, AZ, 85721, USA
- Department of Ecology & Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA
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36
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Ciemniecki JA, Newman DK. The Potential for Redox-Active Metabolites To Enhance or Unlock Anaerobic Survival Metabolisms in Aerobes. J Bacteriol 2020; 202:e00797-19. [PMID: 32071098 PMCID: PMC7221258 DOI: 10.1128/jb.00797-19] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Classifying microorganisms as "obligate" aerobes has colloquially implied death without air, leading to the erroneous assumption that, without oxygen, they are unable to survive. However, over the past few decades, more than a few obligate aerobes have been found to possess anaerobic energy conservation strategies that sustain metabolic activity in the absence of growth or at very low growth rates. Similarly, studies emphasizing the aerobic prowess of certain facultative aerobes have sometimes led to underrecognition of their anaerobic capabilities. Yet an inescapable consequence of the affinity both obligate and facultative aerobes have for oxygen is that the metabolism of these organisms may drive this substrate to scarcity, making anoxic survival an essential skill. To illustrate this, we highlight the importance of anaerobic survival strategies for Pseudomonas aeruginosa and Streptomyces coelicolor, representative facultative and obligate aerobes, respectively. Included among these strategies, we describe a role for redox-active secondary metabolites (RAMs), such as phenazines made by P. aeruginosa, in enhancing substrate-level phosphorylation. Importantly, RAMs are made by diverse bacteria, often during stationary phase in the absence of oxygen, and can sustain anoxic survival. We present a hypothesis for how RAMs may enhance or even unlock energy conservation pathways that facilitate the anaerobic survival of both RAM producers and nonproducers.
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Affiliation(s)
- John A Ciemniecki
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA
| | - Dianne K Newman
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, USA
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37
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Meador TB, Schoffelen N, Ferdelman TG, Rebello O, Khachikyan A, Könneke M. Carbon recycling efficiency and phosphate turnover by marine nitrifying archaea. SCIENCE ADVANCES 2020; 6:eaba1799. [PMID: 32426487 PMCID: PMC7209981 DOI: 10.1126/sciadv.aba1799] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 02/25/2020] [Indexed: 05/09/2023]
Abstract
Thaumarchaeotal nitrifiers are among the most abundant organisms in the ocean, but still unknown is the carbon (C) yield from nitrification and the coupling of these fluxes to phosphorus (P) turnover and release of metabolites from the cell. Using a dual radiotracer approach, we found that Nitrosopumilus maritimus fixed roughly 0.3 mol C, assimilated 2 mmol P, and released ca. 10-2 mol C and 10-5 mol P as dissolved organics (DOC and DOP) per mole ammonia respired. Phosphate turnover may influence assimilation fluxes by nitrifiers in the euphotic zone, which parallel those of the dark ocean. Collectively, marine nitrifiers assimilate up to 2 Pg C year-1 and 0.05 Pg P year-1 and thereby recycle roughly 5% of mineralized C and P into marine biomass. Release of roughly 50 Tg DOC and 0.2 Tg DOP by thaumarchaea each year represents a small but fresh input of reduced substrates throughout the ocean.
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Affiliation(s)
- Travis B. Meador
- MARUM Center for Marine Environmental Sciences and Dept. of Geosciences, University of Bremen, Bremen, Germany
- Corresponding author.
| | - Niels Schoffelen
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Timothy G. Ferdelman
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Osmond Rebello
- MARUM Center for Marine Environmental Sciences and Dept. of Geosciences, University of Bremen, Bremen, Germany
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Alexander Khachikyan
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Martin Könneke
- MARUM Center for Marine Environmental Sciences and Dept. of Geosciences, University of Bremen, Bremen, Germany
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38
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Guo JS, Fang F, Yan P, Chen YP. Sludge reduction based on microbial metabolism for sustainable wastewater treatment. BIORESOURCE TECHNOLOGY 2020; 297:122506. [PMID: 31812600 DOI: 10.1016/j.biortech.2019.122506] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 11/21/2019] [Accepted: 11/25/2019] [Indexed: 06/10/2023]
Abstract
Sludge reduction via microbial metabolism does not require extra energy and resource inputs and thus merits attention as an alternative approach for sustainable wastewater treatment. This review presents a summary and analysis of the existing literatures on sludge reduction based on microbial metabolism, as well as interprets these sludge reduction mechanisms using bacterial thermodynamics and stoichiometry. Future efforts should be directed toward using advanced analytical techniques to further reveal sludge reduction mechanisms. The feasibility of coupling sludge reduction and nutrient removal by microorganism metabolism needs to be further evaluated to minimize the effect of sludge reduction on nutrient removal. A comprehensive life cycle assessment of sludge reduction strategies is recommended to effectively confirm their sustainability. Full-scale research is needed to verify the results obtained from bench- and pilot-scale experiments. This review presents the future opportunities and challenges for sludge reduction based on microbial metabolism in the excess sludge disposal.
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Affiliation(s)
- Jin-Song Guo
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China
| | - Fang Fang
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China
| | - Peng Yan
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China.
| | - You-Peng Chen
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China
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INDISIM-Denitrification, an individual-based model for study the denitrification process. J Ind Microbiol Biotechnol 2019; 47:1-20. [PMID: 31691030 DOI: 10.1007/s10295-019-02245-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 10/28/2019] [Indexed: 12/21/2022]
Abstract
Denitrification is one of the key processes of the global nitrogen (N) cycle driven by bacteria. It has been widely known for more than 100 years as a process by which the biogeochemical N-cycle is balanced. To study this process, we develop an individual-based model called INDISIM-Denitrification. The model embeds a thermodynamic model for bacterial yield prediction inside the individual-based model INDISIM and is designed to simulate in aerobic and anaerobic conditions the cell growth kinetics of denitrifying bacteria. INDISIM-Denitrification simulates a bioreactor that contains a culture medium with succinate as a carbon source, ammonium as nitrogen source and various electron acceptors. To implement INDISIM-Denitrification, the individual-based model INDISIM was used to give sub-models for nutrient uptake, stirring and reproduction cycle. Using a thermodynamic approach, the denitrification pathway, cellular maintenance and individual mass degradation were modeled using microbial metabolic reactions. These equations are the basis of the sub-models for metabolic maintenance, individual mass synthesis and reducing internal cytotoxic products. The model was implemented in the open-access platform NetLogo. INDISIM-Denitrification is validated using a set of experimental data of two denitrifying bacteria in two different experimental conditions. This provides an interactive tool to study the denitrification process carried out by any denitrifying bacterium since INDISIM-Denitrification allows changes in the microbial empirical formula and in the energy-transfer-efficiency used to represent the metabolic pathways involved in the denitrification process. The simulator can be obtained from the authors on request.
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40
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Seto M, Noguchi K, Cappellen PV. Potential for Aerobic Methanotrophic Metabolism on Mars. ASTROBIOLOGY 2019; 19:1187-1195. [PMID: 31173512 PMCID: PMC6785171 DOI: 10.1089/ast.2018.1943] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 05/07/2019] [Indexed: 06/09/2023]
Abstract
Observational evidence supports the presence of methane (CH4) in the martian atmosphere on the order of parts per billion by volume (ppbv). Here, we assess whether aerobic methanotrophy is a potentially viable metabolism in the martian upper regolith, by calculating metabolic energy gain rates under assumed conditions of martian surface temperature, pressure, and atmospheric composition. Using kinetic parameters for 19 terrestrial aerobic methanotrophic strains, we show that even under the imposed low temperature and pressure extremes (180-280 K and 6-11 hPa), methane oxidation by oxygen (O2) should in principle be able to generate the minimum energy production rate required to support endogenous metabolism (i.e., cellular maintenance). Our results further indicate that the corresponding metabolic activity would be extremely low, with cell doubling times in excess of 4000 Earth years at the present-day ppbv-level CH4 mixing ratios in the atmosphere of Mars. Thus, while aerobic methanotrophic microorganisms similar to those found on Earth could theoretically maintain their vital functions, they are unlikely to constitute prolific members of hypothetical martian soil communities.
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Affiliation(s)
- Mayumi Seto
- Department of Chemistry, Biology, and Environmental Sciences, Faculty of Science, Nara Women's University, Nara, Japan
| | - Katsuyuki Noguchi
- Department of Chemistry, Biology, and Environmental Sciences, Faculty of Science, Nara Women's University, Nara, Japan
| | - Philippe Van Cappellen
- Ecohydrology Research Group, Department of Earth and Environmental Sciences, Water Institute, University of Waterloo, Waterloo, Canada
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Gogulancea V, González-Cabaleiro R, Li B, Taniguchi D, Jayathilake PG, Chen J, Wilkinson D, Swailes D, McGough AS, Zuliani P, Ofiteru ID, Curtis TP. Individual Based Model Links Thermodynamics, Chemical Speciation and Environmental Conditions to Microbial Growth. Front Microbiol 2019; 10:1871. [PMID: 31456784 PMCID: PMC6700366 DOI: 10.3389/fmicb.2019.01871] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 07/29/2019] [Indexed: 11/13/2022] Open
Abstract
Individual based Models (IbM) must transition from research tools to engineering tools. To make the transition we must aspire to develop large, three dimensional and physically and biologically credible models. Biological credibility can be promoted by grounding, as far as possible, the biology in thermodynamics. Thermodynamic principles are known to have predictive power in microbial ecology. However, this in turn requires a model that incorporates pH and chemical speciation. Physical credibility implies plausible mechanics and a connection with the wider environment. Here, we propose a step toward that ideal by presenting an individual based model connecting thermodynamics, pH and chemical speciation and environmental conditions to microbial growth for 5·105 individuals. We have showcased the model in two scenarios: a two functional group nitrification model and a three functional group anaerobic community. In the former, pH and connection to the environment had an important effect on the outcomes simulated. Whilst in the latter pH was less important but the spatial arrangements and community productivity (that is, methane production) were highly dependent on thermodynamic and reactor coupling. We conclude that if IbM are to attain their potential as tools to evaluate the emergent properties of engineered biological systems it will be necessary to combine the chemical, physical, mechanical and biological along the lines we have proposed. We have still fallen short of our ideals because we cannot (yet) calculate specific uptake rates and must develop the capacity for longer runs in larger models. However, we believe such advances are attainable. Ideally in a common, fast and modular platform. For future innovations in IbM will only be of use if they can be coupled with all the previous advances.
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Affiliation(s)
- Valentina Gogulancea
- School of Engineering, Newcastle University, Newcastle upon Tyne, United Kingdom
- Chemical and Biochemical Department, School of Applied Chemistry and Materials Science, University Politehnica of Bucharest, Bucharest, Romania
| | | | - Bowen Li
- School of Computing, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Denis Taniguchi
- School of Computing, Newcastle University, Newcastle upon Tyne, United Kingdom
| | | | - Jinju Chen
- School of Engineering, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Darren Wilkinson
- School of Mathematics, Statistics and Physics, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - David Swailes
- School of Mathematics, Statistics and Physics, Newcastle University, Newcastle upon Tyne, United Kingdom
| | | | - Paolo Zuliani
- School of Computing, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Irina Dana Ofiteru
- School of Engineering, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Thomas P. Curtis
- School of Engineering, Newcastle University, Newcastle upon Tyne, United Kingdom
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42
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Thomas SC, Tamadonfar KO, Seymour CO, Lai D, Dodsworth JA, Murugapiran SK, Eloe-Fadrosh EA, Dijkstra P, Hedlund BP. Position-Specific Metabolic Probing and Metagenomics of Microbial Communities Reveal Conserved Central Carbon Metabolic Network Activities at High Temperatures. Front Microbiol 2019; 10:1427. [PMID: 31333598 PMCID: PMC6624737 DOI: 10.3389/fmicb.2019.01427] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Accepted: 06/05/2019] [Indexed: 12/02/2022] Open
Abstract
Temperature is a primary driver of microbial community composition and taxonomic diversity; however, it is unclear to what extent temperature affects characteristics of central carbon metabolic pathways (CCMPs) at the community level. In this study, 16S rRNA gene amplicon and metagenome sequencing were combined with 13C-labeled metabolite probing of the CCMPs to assess community carbon metabolism along a temperature gradient (60–95°C) in Great Boiling Spring, NV. 16S rRNA gene amplicon diversity was inversely proportional to temperature, and Archaea were dominant at higher temperatures. KO richness and diversity were also inversely proportional to temperature, yet CCMP genes were similarly represented across the temperature gradient and many individual metagenome-assembled genomes had complete pathways. In contrast, genes encoding cellulosomes and many genes involved in plant matter degradation and photosynthesis were absent at higher temperatures. In situ13C-CO2 production from labeled isotopomer pairs of glucose, pyruvate, and acetate suggested lower relative oxidative pentose phosphate pathway activity and/or fermentation at 60°C, and a stable or decreased maintenance energy demand at higher temperatures. Catabolism of 13C-labeled citrate, succinate, L-alanine, L-serine, and L-cysteine was observed at 85°C, demonstrating broad heterotrophic activity and confirming functioning of the TCA cycle. Together, these results suggest that temperature-driven losses in biodiversity and gene content in geothermal systems may not alter CCMP function or maintenance energy demands at a community level.
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Affiliation(s)
- Scott C Thomas
- School of Life Sciences, University of Nevada, Las Vegas, NV, United States
| | - Kevin O Tamadonfar
- School of Life Sciences, University of Nevada, Las Vegas, NV, United States
| | - Cale O Seymour
- School of Life Sciences, University of Nevada, Las Vegas, NV, United States
| | - Dengxun Lai
- School of Life Sciences, University of Nevada, Las Vegas, NV, United States
| | - Jeremy A Dodsworth
- Department of Biology, California State University, San Bernardino, CA, United States
| | | | - Emiley A Eloe-Fadrosh
- Department of Energy Joint Genome Institute, Joint Genome Institute, Walnut Creek, CA, United States
| | - Paul Dijkstra
- Department of Biological Sciences, Center of Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, United States
| | - Brian P Hedlund
- School of Life Sciences, University of Nevada, Las Vegas, NV, United States.,Nevada Institute of Personalized Medicine, University of Nevada, Las Vegas, NV, United States
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Defining lower limits of biodegradation: atrazine degradation regulated by mass transfer and maintenance demand in Arthrobacter aurescens TC1. ISME JOURNAL 2019; 13:2236-2251. [PMID: 31073212 PMCID: PMC6776027 DOI: 10.1038/s41396-019-0430-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 04/12/2019] [Accepted: 04/16/2019] [Indexed: 12/31/2022]
Abstract
Exploring adaptive strategies by which microorganisms function and survive in low-energy natural environments remains a grand goal of microbiology, and may help address a prime challenge of the 21st century: degradation of man-made chemicals at low concentrations (“micropollutants”). Here we explore physiological adaptation and maintenance energy requirements of a herbicide (atrazine)-degrading microorganism (Arthrobacter aurescens TC1) while concomitantly observing mass transfer limitations directly by compound-specific isotope fractionation analysis. Chemostat-based growth triggered the onset of mass transfer limitation at residual concentrations of 30 μg L−1 of atrazine with a bacterial population doubling time (td) of 14 days, whereas exacerbated energy limitation was induced by retentostat-based near-zero growth (td = 265 days) at 12 ± 3 μg L−1 residual concentration. Retentostat cultivation resulted in (i) complete mass transfer limitation evidenced by the disappearance of isotope fractionation (ε13C = −0.45‰ ± 0.36‰) and (ii) a twofold decrease in maintenance energy requirement compared with chemostat cultivation. Proteomics revealed that retentostat and chemostat cultivation under mass transfer limitation share low protein turnover and expression of stress-related proteins. Mass transfer limitation effectuated slow-down of metabolism in retentostats and a transition from growth phase to maintenance phase indicating a limit of ≈10 μg L−1 for long-term atrazine degradation. Further studies on other ecosystem-relevant microorganisms will substantiate the general applicability of our finding that mass transfer limitation serves as a trigger for physiological adaptation, which subsequently defines a lower limit of biodegradation.
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Sholes SF, Krissansen-Totton J, Catling DC. A Maximum Subsurface Biomass on Mars from Untapped Free Energy: CO and H 2 as Potential Antibiosignatures. ASTROBIOLOGY 2019; 19:655-668. [PMID: 30950631 DOI: 10.1089/ast.2018.1835] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Whether extant life exists in the martian subsurface is an open question. High concentrations of photochemically produced CO and H2 in the otherwise oxidizing martian atmosphere represent untapped sources of biologically useful free energy. These out-of-equilibrium species diffuse into the regolith, so subsurface microbes could use them as a source of energy and carbon. Indeed, CO oxidation and methanogenesis are relatively simple and evolutionarily ancient metabolisms on Earth. Consequently, assuming CO- or H2-consuming metabolisms would evolve on Mars, the persistence of CO and H2 in the martian atmosphere sets limits on subsurface metabolic activity. In this study, we constrain such maximum subsurface metabolic activity on Mars using a one-dimensional photochemical model with a hypothetical global biological sink on atmospheric CO and H2. We increase the biological sink until the modeled atmospheric composition diverges from observed abundances. We find maximum biological downward subsurface sinks of 1.5 × 108 molecules/(cm2·s) for CO and 1.9 × 108 molecules/(cm2·s1) for H2. These convert to a maximum metabolizing biomass of ≲1027 cells or ≤2 × 1011 kg, equivalent to ≤10-4-10-5 of Earth's biomass, depending on the terrestrial estimate. Diffusion calculations suggest that this upper biomass limit applies to the top few kilometers of the martian crust in communication with the atmosphere at low to mid-latitudes. This biomass limit is more robust than previous estimates because we test multiple possible chemoautotrophic ecosystems over a broad parameter space of tunable model variables using an updated photochemical model with precise atmospheric concentrations and uncertainties from Curiosity. Our results of sparse or absent life in the martian subsurface also demonstrate how the atmospheric redox pairs of CO-O2 and H2-O2 may constitute antibiosignatures, which may be relevant to excluding life on exoplanets.
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Affiliation(s)
- Steven F Sholes
- 1 Department of Earth and Space Sciences, University of Washington, Seattle, Washington
- 2 Astrobiology Program, University of Washington, Seattle, Washington
| | - Joshua Krissansen-Totton
- 1 Department of Earth and Space Sciences, University of Washington, Seattle, Washington
- 2 Astrobiology Program, University of Washington, Seattle, Washington
| | - David C Catling
- 1 Department of Earth and Space Sciences, University of Washington, Seattle, Washington
- 2 Astrobiology Program, University of Washington, Seattle, Washington
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45
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Population dynamics of chemotrophs in anaerobic conditions where the metabolic energy acquisition per redox reaction is limited. J Theor Biol 2019; 467:164-173. [DOI: 10.1016/j.jtbi.2019.01.037] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2018] [Revised: 01/29/2019] [Accepted: 01/31/2019] [Indexed: 11/17/2022]
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Hausmann B, Pelikan C, Rattei T, Loy A, Pester M. Long-Term Transcriptional Activity at Zero Growth of a Cosmopolitan Rare Biosphere Member. mBio 2019; 10:e02189-18. [PMID: 30755506 PMCID: PMC6372793 DOI: 10.1128/mbio.02189-18] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 01/04/2019] [Indexed: 01/05/2023] Open
Abstract
Microbial diversity in the environment is mainly concealed within the rare biosphere (all species with <0.1% relative abundance). While dormancy explains a low-abundance state very well, the mechanisms leading to rare but active microorganisms remain elusive. We used environmental systems biology to genomically and transcriptionally characterize "Candidatus Desulfosporosinus infrequens," a low-abundance sulfate-reducing microorganism cosmopolitan to freshwater wetlands, where it contributes to cryptic sulfur cycling. We obtained its near-complete genome by metagenomics of acidic peat soil. In addition, we analyzed anoxic peat soil incubated under in situ-like conditions for 50 days by Desulfosporosinus-targeted qPCR and metatranscriptomics. The Desulfosporosinus population stayed at a constant low abundance under all incubation conditions, averaging 1.2 × 106 16S rRNA gene copies per cm³ soil. In contrast, transcriptional activity of "Ca. Desulfosporosinus infrequens" increased at day 36 by 56- to 188-fold when minor amendments of acetate, propionate, lactate, or butyrate were provided with sulfate, compared to the no-substrate-control. Overall transcriptional activity was driven by expression of genes encoding ribosomal proteins, energy metabolism, and stress response but not by expression of genes encoding cell growth-associated processes. Since our results did not support growth of these highly active microorganisms in terms of biomass increase or cell division, they had to invest their sole energy for maintenance, most likely counterbalancing acidic pH conditions. This finding explains how a rare biosphere member can contribute to a biogeochemically relevant process while remaining in a zero-growth state over a period of 50 days.IMPORTANCE The microbial rare biosphere represents the largest pool of biodiversity on Earth and constitutes, in sum of all its members, a considerable part of a habitat's biomass. Dormancy or starvation is typically used to explain the persistence of low-abundance microorganisms in the environment. We show that a low-abundance microorganism can be highly transcriptionally active while remaining in a zero-growth state for at least 7 weeks. Our results provide evidence that this zero growth at a high cellular activity state is driven by maintenance requirements. We show that this is true for a microbial keystone species, in particular a cosmopolitan but permanently low-abundance sulfate-reducing microorganism in wetlands that is involved in counterbalancing greenhouse gas emissions. In summary, our results provide an important step forward in understanding time-resolved activities of rare biosphere members relevant for ecosystem functions.
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Affiliation(s)
- Bela Hausmann
- Research Network Chemistry meets Microbiology, Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, University of Vienna, Vienna, Austria
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Claus Pelikan
- Research Network Chemistry meets Microbiology, Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, University of Vienna, Vienna, Austria
| | - Thomas Rattei
- Research Network Chemistry meets Microbiology, Department of Microbiology and Ecosystem Science, Division of Computational Systems Biology, University of Vienna, Vienna, Austria
| | - Alexander Loy
- Research Network Chemistry meets Microbiology, Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, University of Vienna, Vienna, Austria
| | - Michael Pester
- Department of Biology, University of Konstanz, Konstanz, Germany
- Department of Microorganisms, Leibniz Institute DSMZ, Braunschweig, Germany
- Institute of Microbiology, Technical University of Braunschweig, Braunschweig, Germany
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47
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Bonk F, Popp D, Weinrich S, Sträuber H, Becker D, Kleinsteuber S, Harms H, Centler F. Determination of Microbial Maintenance in Acetogenesis and Methanogenesis by Experimental and Modeling Techniques. Front Microbiol 2019; 10:166. [PMID: 30800108 PMCID: PMC6375858 DOI: 10.3389/fmicb.2019.00166] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 01/22/2019] [Indexed: 11/21/2022] Open
Abstract
For biogas-producing continuous stirred tank reactors, an increase in dilution rate increases the methane production rate as long as substrate input can be converted fully. However, higher dilution rates necessitate higher specific microbial growth rates, which are assumed to have a strong impact on the apparent microbial biomass yield due to cellular maintenance. To test this, we operated two reactors at 37°C in parallel at dilution rates of 0.18 and 0.07 days-1 (hydraulic retention times of 5.5 and 14 days, doubling times of 3.9 and 9.9 days in steady state) with identical inoculum and a mixture of volatile fatty acids as sole carbon sources. We evaluated the performance of the Anaerobic Digestion Model No. 1 (ADM1), a thermodynamic black box approach (TBA), and dynamic flux balance analysis (dFBA), to describe the experimental observations. All models overestimated the impact of dilution rate on the apparent microbial biomass yield when using default parameter values. Based on our analysis, a maintenance coefficient value below 0.2 kJ per carbon mole of microbial biomass per hour should be used for the TBA, corresponding to 0.12 mmol ATP per gram dry weight per hour for dFBA, which strongly deviates from the value of 9.8 kJ Cmol h-1 that has been suggested to apply to all anaerobic microorganisms at 37°C. We hypothesized that a decrease in dilution rate might select taxa with minimized maintenance expenditure. However, no major differences in the dominating taxa between the reactors were observed based on amplicon sequencing of 16S rRNA genes and terminal restriction fragment length polymorphism analysis of mcrA genes. Surprisingly, Methanosaeta dominated over Methanosarcina even at a dilution rate of 0.18 days-1, which contradicts previous model expectations. Furthermore, only 23-49% of the bacterial reads could be assigned to known syntrophic fatty acid oxidizers, indicating that unknown members of this functional group remain to be discovered. In conclusion, microbial maintenance was found to be much lower for acetogenesis and methanogenesis than previously assumed, likely due to the exceptionally low growth rates in anaerobic digestion. This finding might also be relevant for other microbial systems operating at similarly low growth rates.
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Affiliation(s)
- Fabian Bonk
- Department of Environmental Microbiology, UFZ-Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - Denny Popp
- Department of Environmental Microbiology, UFZ-Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - Sören Weinrich
- Biochemical Conversion Department, DBFZ-Deutsches Biomasseforschungszentrum gGmbH, Leipzig, Germany
| | - Heike Sträuber
- Department of Environmental Microbiology, UFZ-Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - Daniela Becker
- Department of Environmental Microbiology, UFZ-Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - Sabine Kleinsteuber
- Department of Environmental Microbiology, UFZ-Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - Hauke Harms
- Department of Environmental Microbiology, UFZ-Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - Florian Centler
- Department of Environmental Microbiology, UFZ-Helmholtz Centre for Environmental Research, Leipzig, Germany
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Bradley JA, Amend JP, LaRowe DE. Survival of the fewest: Microbial dormancy and maintenance in marine sediments through deep time. GEOBIOLOGY 2019; 17:43-59. [PMID: 30248245 PMCID: PMC6585783 DOI: 10.1111/gbi.12313] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 07/17/2018] [Accepted: 08/21/2018] [Indexed: 06/01/2023]
Abstract
Microorganisms buried in marine sediments are known to endure starvation over geologic timescales. However, the mechanisms of how these microorganisms cope with prolonged energy limitation is unknown and therefore yet to be captured in a quantitative framework. Here, we present a novel mathematical model that considers (a) the physiological transitions between the active and dormant states of microorganisms, (b) the varying requirement for maintenance power between these phases, and (c) flexibility in the provenance (i.e., source) of energy from exogenous and endogenous catabolism. The model is applied to sediments underlying the oligotrophic South Pacific Gyre where microorganisms endure ultra-low fluxes of energy for tens of millions of years. Good fits between model simulations and measurements of cellular carbon and organic carbon concentrations are obtained and are interpreted as follows: (a) the unfavourable microbial habitat in South Pacific Gyre sediments triggers rapid mortality and a transition to dormancy; (b) there is minimal biomass growth, and organic carbon consumption is dominated by catabolism to support maintenance activities rather than new biomass synthesis; (c) the amount of organic carbon that microorganisms consume for maintenance activities is equivalent to approximately 2% of their carbon biomass per year; and (d) microorganisms must rely solely on exogenous rather than endogenous catabolism to persist in South Pacific Gyre sediments over long timescales. This leads us to the conclusion that under oligotrophic conditions, the fitness of an organism is determined by its ability to simply stay alive, rather than to grow. This modelling framework is designed to be flexible for application to other sites and habitats, and thus serves as a new quantitative tool for determining the habitability of and an ultimate limit for life in any environment.
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Affiliation(s)
- James A. Bradley
- Department of Earth SciencesUniversity of Southern CaliforniaLos AngelesCalifornia
| | - Jan P. Amend
- Department of Earth SciencesUniversity of Southern CaliforniaLos AngelesCalifornia
- Department of Biological SciencesUniversity of Southern CaliforniaLos AngelesCalifornia
| | - Douglas E. LaRowe
- Department of Earth SciencesUniversity of Southern CaliforniaLos AngelesCalifornia
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Abstract
We propose a model whereby microscopic tunnels form in basalt glass in response to a natural proton flux from seawater into the glass. This flux is generated by the alteration of the glass as protons from water replace cations in the glass. In our proton gradient model, cells are gateways through which protons enter and alter the glass and through which cations leave the glass. In the process, tunnels are formed, and cells derive energy from the proton and ion fluxes. Proton flux from seawater into basalt glass would have occurred on Earth as soon as water accumulated on the surface and would have preceded biological redox catalysis. Tunnels in modern basalts are similar to tunnels in Archean basalts, which may be our earliest physical evidence of life. Proton gradients like those described in this paper certainly exist on other planetary bodies where silicate rocks are exposed to acidic to slightly alkaline water.
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Affiliation(s)
- Martin R Fisk
- 1 College of Earth, Ocean, and Atmospheric Sciences, Oregon State University , Corvallis, Oregon, USA
| | - Radu Popa
- 2 Department of Biological Sciences, University of Southern California , Los Angeles, California, USA
| | - David Wacey
- 3 Centre for Microscopy, Characterisation and Analysis, The University of Western Australia , Perth, Australia
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Methanogens: pushing the boundaries of biology. Emerg Top Life Sci 2018; 2:629-646. [PMID: 33525834 PMCID: PMC7289024 DOI: 10.1042/etls20180031] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 10/23/2018] [Accepted: 10/24/2018] [Indexed: 01/15/2023]
Abstract
Methanogens are anaerobic archaea that grow by producing methane gas. These microbes and their exotic metabolism have inspired decades of microbial physiology research that continues to push the boundary of what we know about how microbes conserve energy to grow. The study of methanogens has helped to elucidate the thermodynamic and bioenergetics basis of life, contributed our understanding of evolution and biodiversity, and has garnered an appreciation for the societal utility of studying trophic interactions between environmental microbes, as methanogens are important in microbial conversion of biogenic carbon into methane, a high-energy fuel. This review discusses the theoretical basis for energy conservation by methanogens and identifies gaps in methanogen biology that may be filled by undiscovered or yet-to-be engineered organisms.
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