1
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Murali R, Gennis RB, Hemp J. Evolution of the cytochrome bd oxygen reductase superfamily and the function of CydAA' in Archaea. THE ISME JOURNAL 2021; 15:3534-3548. [PMID: 34145390 PMCID: PMC8630170 DOI: 10.1038/s41396-021-01019-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 05/06/2021] [Accepted: 05/17/2021] [Indexed: 02/05/2023]
Abstract
Cytochrome bd-type oxygen reductases (cytbd) belong to one of three enzyme superfamilies that catalyze oxygen reduction to water. They are widely distributed in Bacteria and Archaea, but the full extent of their biochemical diversity is unknown. Here we used phylogenomics to identify three families and several subfamilies within the cytbd superfamily. The core architecture shared by all members of the superfamily consists of four transmembrane helices that bind two active site hemes, which are responsible for oxygen reduction. While previously characterized cytochrome bd-type oxygen reductases use quinol as an electron donor to reduce oxygen, sequence analysis shows that only one of the identified families has a conserved quinol binding site. The other families are missing this feature, suggesting that they use an alternative electron donor. Multiple gene duplication events were identified within the superfamily, resulting in significant evolutionary and structural diversity. The CydAA' cytbd, found exclusively in Archaea, is formed by the co-association of two superfamily paralogs. We heterologously expressed CydAA' from Caldivirga maquilingensis and demonstrated that it performs oxygen reduction with quinol as an electron donor. Strikingly, CydAA' is the first isoform of cytbd containing only b-type hemes shown to be active when isolated from membranes, demonstrating that oxygen reductase activity in this superfamily is not dependent on heme d.
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Affiliation(s)
- Ranjani Murali
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.
| | - Robert B Gennis
- Department of Biochemistry, University of Illinois, Urbana-Champaign, Urbana, IL, USA
| | - James Hemp
- The Metrodora Institute, Salt Lake City, UT, USA.
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2
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Dong Y, Shan Y, Xia K, Shi L. The Proposed Molecular Mechanisms Used by Archaea for Fe(III) Reduction and Fe(II) Oxidation. Front Microbiol 2021; 12:690918. [PMID: 34276623 PMCID: PMC8280799 DOI: 10.3389/fmicb.2021.690918] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2021] [Accepted: 06/02/2021] [Indexed: 11/17/2022] Open
Abstract
Iron (Fe) is the fourth most abundant element in the Earth's crust where ferrous Fe [Fe(II)] and ferric Fe [Fe(III)] can be used by archaea for energy conservation. In these archaea-Fe interactions, Fe(III) serves as terminal electron acceptor for anaerobic respiration by a variety of archaea, while Fe(II) serves as electron donor and/or energy sources for archaeal growth. As no Fe is incorporated into the archaeal cells, these redox reactions are referred to as dissimilatory Fe(III) reduction and Fe(II) oxidation, respectively. Dissimilatory Fe(III)-reducing archaea (FeRA) and Fe(II)-oxidizing archaea (FeOA) are widespread on Earth where they play crucial roles in biogeochemical cycling of not only Fe, but also carbon and sulfur. To reduce extracellular Fe(III) (oxyhydr)oxides, some FeRA transfer electrons directly to the Fe(III) (oxyhydr)oxides most likely via multiheme c-type cytochromes (c-Cyts). These multiheme c-Cyts may form the pathways similar to those found in bacteria for transferring electrons from the quinone/quinol pool in the cytoplasmic membrane to the Fe(III) (oxyhydr)oxides external to the archaeal cells. Use of multiheme c-Cyts for extracellular Fe(III) reduction by both Domains of Archaea and Bacteria emphasizes an ancient mechanism of extracellular electron transfer, which is well conserved. Other FeRA, however, reduce Fe(III) (oxyhydr)oxides indirectly via electron shuttles. Similarly, it is proposed that FeOA use pathways to oxidize Fe(II) on the surface of the cytoplasmic membrane and then to transfer the released electrons across the cytoplasmic membrane inward to the O2 and NAD+ in the cytoplasm. In this review, we focus on the latest understandings of the molecular mechanisms used by FeRA and FeOA for Fe(III) reduction and Fe(II) oxidation, respectively.
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Affiliation(s)
- Yiran Dong
- Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, China
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, China
| | - Yawei Shan
- Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, China
| | - Kemin Xia
- Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, China
| | - Liang Shi
- Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, China
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, China
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3
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He Q, Wang S, Hou W, Feng K, Li F, Hai W, Zhang Y, Sun Y, Deng Y. Temperature and microbial interactions drive the deterministic assembly processes in sediments of hot springs. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 772:145465. [PMID: 33571767 DOI: 10.1016/j.scitotenv.2021.145465] [Citation(s) in RCA: 70] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 01/22/2021] [Accepted: 01/24/2021] [Indexed: 06/12/2023]
Abstract
Terrestrial geothermal ecosystems, as a representative of extreme environments, exhibit a variety of geochemical gradients, and their microbes are thought to be under high stress through environmental selection. However, it is still unclear how stochasticity and biotic interactions contribute to the microbial community assembly in hot springs. Here, we investigated the assembly processes and co-occurrence patterns of microbiota (i.e. bacteria and archaea) in both water and sediments sampled from fifteen hot springs in the Tengchong area, Southwestern of China, using 16S rRNA gene sequencing combined with multivariate ecological and statistical methods. These hot springs harbored more specialists than non-geothermal ecosystems, which are well-adapted to the extreme conditions, as shown by extremely high nearest-taxon index (NTI) and narrower niche width. Habitat differentiation led to the differences in microbial diversity, species-interactions, and community assembly between water and sediment communities. The sediment community showed stronger phylogenetic clustering and was primarily governed by heterogeneous selection, while undominated stochastic processes and dispersal limitation were the major assembly processes in the water community. Temperature and ferrous iron were the major factors mediating the balance of stochastic and deterministic assembly processes in sediment communities, as evidenced by how divergences in temperature and ferrous iron increased the proportion of determinism. Microbial interactions in sediments contributed to deterministic community assembly, as indicated by more complex associations and greater responsiveness to environmental change than water community. These findings uncover the ecological processes underlying microbial communities in hot springs, and provide potential insight into understanding the mechanism to maintain microbial diversity in extreme biospheres.
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Affiliation(s)
- Qing He
- CAS Key Laboratory for Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences (CAS), Beijing 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Shang Wang
- CAS Key Laboratory for Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences (CAS), Beijing 100085, China.
| | - Weiguo Hou
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, China
| | - Kai Feng
- CAS Key Laboratory for Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences (CAS), Beijing 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Fangru Li
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, China
| | - Wanming Hai
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, China
| | - Yidi Zhang
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, China
| | - Yuxuan Sun
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, China
| | - Ye Deng
- CAS Key Laboratory for Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences (CAS), Beijing 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, China
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4
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Hart C, Gorman-Lewis D. Energetics of Acidianus ambivalens growth in response to oxygen availability. GEOBIOLOGY 2021; 19:48-62. [PMID: 32902110 DOI: 10.1111/gbi.12413] [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: 05/30/2019] [Revised: 07/30/2020] [Accepted: 08/02/2020] [Indexed: 06/11/2023]
Abstract
All life requires energy to drive metabolic reactions such as growth and cell maintenance; therefore, fluctuations in energy availability can alter microbial activity. There is a gap in our knowledge concerning how energy availability affects the growth of extreme chemolithoautotrophs. Toward this end, we investigated the growth of thermoacidophile Acidianus ambivalens during sulfur oxidation under aerobic to microaerophilic conditions. Calorimetry was used to measure enthalpy (ΔHinc ) of microbial activity, and chemical changes in growth media were measured to calculate Gibbs energy change (ΔGinc ) during incubation. In all experiments, Gibbs energy was primarily dissipated through the release of heat, which suggests enthalpy-driven growth. In microaerophilic conditions, growth was significantly more efficient in terms of biomass yield (defined as C-mol biomass per mole sulfur consumed) and resulted in lower ΔGinc and ΔHinc . ΔGinc in oxygen-limited (OL) and oxygen- and CO2 -limited (OCL) microaerophilic growth conditions resulted in averages of -1.44 × 103 kJ/C-mol and -7.56 × 102 kJ/C-mol, respectively, and average ΔHinc values of -1.11 × 105 kJ/C-mol and -4.43 × 104 kJ/C-mol, respectively. High-oxygen experiments resulted in lower biomass yield values, an increase in ΔGinc to -1.71 × 104 kJ/C-mol, and more exothermic ΔHinc values of -4.71 × 105 kJ/C-mol. The observed inefficiency in high-oxygen conditions may suggest larger maintenance energy demands due to oxidative stresses and a preference for growth in microaerophilic environments.
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Affiliation(s)
- Chloe Hart
- Department of Earth and Space Sciences, University of Washington, Seattle, WA, USA
| | - Drew Gorman-Lewis
- Department of Earth and Space Sciences, University of Washington, Seattle, WA, USA
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5
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Park H, Patel A, Hunt KA, Henson MA, Carlson RP. Artificial consortium demonstrates emergent properties of enhanced cellulosic-sugar degradation and biofuel synthesis. NPJ Biofilms Microbiomes 2020; 6:59. [PMID: 33268782 PMCID: PMC7710750 DOI: 10.1038/s41522-020-00170-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 10/23/2020] [Indexed: 01/03/2023] Open
Abstract
Planktonic cultures, of a rationally designed consortium, demonstrated emergent properties that exceeded the sums of monoculture properties, including a >200% increase in cellobiose catabolism, a >100% increase in glycerol catabolism, a >800% increase in ethanol production, and a >120% increase in biomass productivity. The consortium was designed to have a primary and secondary-resource specialist that used crossfeeding with a positive feedback mechanism, division of labor, and nutrient and energy transfer via necromass catabolism. The primary resource specialist was Clostridium phytofermentans (a.k.a. Lachnoclostridium phytofermentans), a cellulolytic, obligate anaerobe. The secondary-resource specialist was Escherichia coli, a versatile, facultative anaerobe, which can ferment glycerol and byproducts of cellobiose catabolism. The consortium also demonstrated emergent properties of enhanced biomass accumulation when grown as biofilms, which created high cell density communities with gradients of species along the vertical axis. Consortium biofilms were robust to oxic perturbations with E. coli consuming O2, creating an anoxic environment for C. phytofermentans. Anoxic/oxic cycling further enhanced biomass productivity of the biofilm consortium, increasing biomass accumulation ~250% over the sum of the monoculture biofilms. Consortium emergent properties were credited to several synergistic mechanisms. E. coli consumed inhibitory byproducts from cellobiose catabolism, driving higher C. phytofermentans growth and higher cellulolytic enzyme production, which in turn provided more substrate for E. coli. E. coli necromass enhanced C. phytofermentans growth while C. phytofermentans necromass aided E. coli growth via the release of peptides and amino acids, respectively. In aggregate, temporal cycling of necromass constituents increased flux of cellulose-derived resources through the consortium. The study establishes a consortia-based, bioprocessing strategy built on naturally occurring interactions for improved conversion of cellulose-derived sugars into bioproducts.
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Affiliation(s)
- Heejoon Park
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT, USA.,Center for Biofilm Engineering, Montana State University, Bozeman, MT, USA.,Department of Engineering and Technology, University of North Alabama, Florence, AL, USA
| | - Ayushi Patel
- Department of Chemical Engineering and Institute for Applied Life Sciences, University of Massachusetts, Amherst, MA, USA
| | - Kristopher A Hunt
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT, USA.,Center for Biofilm Engineering, Montana State University, Bozeman, MT, USA.,Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA
| | - Michael A Henson
- Department of Chemical Engineering and Institute for Applied Life Sciences, University of Massachusetts, Amherst, MA, USA
| | - Ross P Carlson
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT, USA. .,Center for Biofilm Engineering, Montana State University, Bozeman, MT, USA.
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6
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Lindsay MR, Amenabar MJ, Fecteau KM, Debes RV, Fernandes Martins MC, Fristad KE, Xu H, Hoehler TM, Shock EL, Boyd ES. Subsurface processes influence oxidant availability and chemoautotrophic hydrogen metabolism in Yellowstone hot springs. GEOBIOLOGY 2018; 16:674-692. [PMID: 30035368 DOI: 10.1111/gbi.12308] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 04/15/2018] [Accepted: 06/20/2018] [Indexed: 06/08/2023]
Abstract
The geochemistry of hot springs and the availability of oxidants capable of supporting microbial metabolisms are influenced by subsurface processes including the separation of hydrothermal fluids into vapor and liquid phases. Here, we characterized the influence of geochemical variation and oxidant availability on the abundance, composition, and activity of hydrogen (H2 )-dependent chemoautotrophs along the outflow channels of two-paired hot springs in Yellowstone National Park. The hydrothermal fluid at Roadside East (RSE; 82.4°C, pH 3.0) is acidic due to vapor-phase input while the fluid at Roadside West (RSW; 68.1°C, pH 7.0) is circumneutral due to liquid-phase input. Most chemotrophic communities exhibited net rates of H2 oxidation, consistent with H2 support of primary productivity, with one chemotrophic community exhibiting a net rate of H2 production. Abundant H2 -oxidizing chemoautotrophs were supported by reduction in oxygen, elemental sulfur, sulfate, and nitrate in RSW and oxygen and ferric iron in RSE; O2 utilizing hydrogenotrophs increased in abundance down both outflow channels. Sequencing of 16S rRNA transcripts or genes from native sediments and dilution series incubations, respectively, suggests that members of the archaeal orders Sulfolobales, Desulfurococcales, and Thermoproteales are likely responsible for H2 oxidation in RSE, whereas members of the bacterial order Thermoflexales and the archaeal order Thermoproteales are likely responsible for H2 oxidation in RSW. These observations suggest that subsurface processes strongly influence spring chemistry and oxidant availability, which in turn select for unique assemblages of H2 oxidizing microorganisms. Therefore, these data point to the role of oxidant availability in shaping the ecology and evolution of hydrogenotrophic organisms.
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Affiliation(s)
- Melody R Lindsay
- Department of Microbiology and Immunology, Montana State University, Bozeman, Montana
| | | | - Kristopher M Fecteau
- School of Molecular Sciences, Arizona State University, Tempe, Arizona
- School of Earth and Space Exploration, Arizona State University, Tempe, Arizona
| | - Randal V Debes
- School of Earth and Space Exploration, Arizona State University, Tempe, Arizona
| | | | | | - Huifang Xu
- Department of Geosciences, University of Wisconsin, Madison, Wisconsin
- NASA Astrobiology Institute, Mountain View, California
| | - Tori M Hoehler
- NASA Ames Research Center, Moffett Field, California
- NASA Astrobiology Institute, Mountain View, California
| | - Everett L Shock
- School of Molecular Sciences, Arizona State University, Tempe, Arizona
- School of Earth and Space Exploration, Arizona State University, Tempe, Arizona
- NASA Astrobiology Institute, Mountain View, California
| | - Eric S Boyd
- Department of Microbiology and Immunology, Montana State University, Bozeman, Montana
- NASA Astrobiology Institute, Mountain View, California
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7
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Hunt KA, Jennings RM, Inskeep WP, Carlson RP. Multiscale analysis of autotroph-heterotroph interactions in a high-temperature microbial community. PLoS Comput Biol 2018; 14:e1006431. [PMID: 30260956 PMCID: PMC6177205 DOI: 10.1371/journal.pcbi.1006431] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 10/09/2018] [Accepted: 08/13/2018] [Indexed: 11/18/2022] Open
Abstract
Interactions among microbial community members can lead to emergent properties, such as enhanced productivity, stability, and robustness. Iron-oxide mats in acidic (pH 2-4), high-temperature (> 65 °C) springs of Yellowstone National Park contain relatively simple microbial communities and are well-characterized geochemically. Consequently, these communities are excellent model systems for studying the metabolic activity of individual populations and key microbial interactions. The primary goals of the current study were to integrate data collected in situ with in silico calculations across process-scales encompassing enzymatic activity, cellular metabolism, community interactions, and ecosystem biogeochemistry, as well as to predict and quantify the functional limits of autotroph-heterotroph interactions. Metagenomic and transcriptomic data were used to reconstruct carbon and energy metabolisms of an important autotroph (Metallosphaera yellowstonensis) and heterotroph (Geoarchaeum sp. OSPB) from the studied Fe(III)-oxide mat communities. Standard and hybrid elementary flux mode and flux balance analyses of metabolic models predicted cellular- and community-level metabolic acclimations to simulated environmental stresses, respectively. In situ geochemical analyses, including oxygen depth-profiles, Fe(III)-oxide deposition rates, stable carbon isotopes and mat biomass concentrations, were combined with cellular models to explore autotroph-heterotroph interactions important to community structure-function. Integration of metabolic modeling with in situ measurements, including the relative population abundance of autotrophs to heterotrophs, demonstrated that Fe(III)-oxide mat communities operate at their maximum total community growth rate (i.e. sum of autotroph and heterotroph growth rates), as opposed to net community growth rate (i.e. total community growth rate subtracting autotroph consumed by heterotroph), as predicted from the maximum power principle. Integration of multiscale data with ecological theory provides a basis for predicting autotroph-heterotroph interactions and community-level cellular organization.
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Affiliation(s)
- Kristopher A. Hunt
- Thermal Biology Institute, Montana State University, Bozeman, Montana, United States of America
- Center for Biofilm Engineering, Montana State University, Bozeman, Montana, United States of America
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, Montana, United States of America
| | - Ryan M. Jennings
- Thermal Biology Institute, Montana State University, Bozeman, Montana, United States of America
- Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, Montana, United States of America
| | - William P. Inskeep
- Thermal Biology Institute, Montana State University, Bozeman, Montana, United States of America
- Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, Montana, United States of America
- * E-mail: (WPI); (RPC)
| | - Ross P. Carlson
- Thermal Biology Institute, Montana State University, Bozeman, Montana, United States of America
- Center for Biofilm Engineering, Montana State University, Bozeman, Montana, United States of America
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, Montana, United States of America
- * E-mail: (WPI); (RPC)
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8
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Hunt KA, Jennings RD, Inskeep WP, Carlson RP. Stoichiometric modelling of assimilatory and dissimilatory biomass utilisation in a microbial community. Environ Microbiol 2016; 18:4946-4960. [PMID: 27387069 PMCID: PMC5629010 DOI: 10.1111/1462-2920.13444] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2016] [Accepted: 06/30/2016] [Indexed: 11/26/2022]
Abstract
Assimilatory and dissimilatory utilisation of autotroph biomass by heterotrophs is a fundamental mechanism for the transfer of nutrients and energy across trophic levels. Metagenome data from a tractable, thermoacidophilic microbial community in Yellowstone National Park was used to build an in silico model to study heterotrophic utilisation of autotroph biomass using elementary flux mode analysis and flux balance analysis. Assimilatory and dissimilatory biomass utilisation was investigated using 29 forms of biomass-derived dissolved organic carbon (DOC) including individual monomer pools, individual macromolecular pools and aggregate biomass. The simulations identified ecologically competitive strategies for utilizing DOC under conditions of varying electron donor, electron acceptor or enzyme limitation. The simulated growth environment affected which form of DOC was the most competitive use of nutrients; for instance, oxygen limitation favoured utilisation of less reduced and fermentable DOC while carbon-limited environments favoured more reduced DOC. Additionally, metabolism was studied considering two encompassing metabolic strategies: simultaneous versus sequential use of DOC. Results of this study bound the transfer of nutrients and energy through microbial food webs, providing a quantitative foundation relevant to most microbial ecosystems.
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Affiliation(s)
- Kristopher A. Hunt
- Center for Biofilm Engineering, Montana State University, Bozeman, MT, USA
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT, USA
- Thermal Biology Institute, Montana State University, Bozeman, MT, USA
| | - Ryan deM. Jennings
- Thermal Biology Institute, Montana State University, Bozeman, MT, USA
- Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, USA
| | - William P. Inskeep
- Thermal Biology Institute, Montana State University, Bozeman, MT, USA
- Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, USA
| | - Ross P. Carlson
- Center for Biofilm Engineering, Montana State University, Bozeman, MT, USA
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT, USA
- Thermal Biology Institute, Montana State University, Bozeman, MT, USA
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9
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Colman DR, Feyhl-Buska J, Robinson KJ, Fecteau KM, Xu H, Shock EL, Boyd ES. Ecological differentiation in planktonic and sediment-associated chemotrophic microbial populations in Yellowstone hot springs. FEMS Microbiol Ecol 2016; 92:fiw137. [PMID: 27306555 DOI: 10.1093/femsec/fiw137] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/12/2016] [Indexed: 01/29/2023] Open
Abstract
Chemosynthetic sediment and planktonic community composition and sizes, aqueous geochemistry and sediment mineralogy were determined in 15 non-photosynthetic hot springs in Yellowstone National Park (YNP). These data were used to evaluate the hypothesis that differences in the availability of dissolved or mineral substrates in the bulk fluids or sediments within springs coincides with ecologically differentiated microbial communities and their populations. Planktonic and sediment-associated communities exhibited differing ecological characteristics including community sizes, evenness and richness. pH and temperature influenced microbial community composition among springs, but within-spring partitioning of taxa into sediment or planktonic communities was widespread, statistically supported (P < 0.05) and could be best explained by the inferred metabolic strategies of the partitioned taxa. Microaerophilic genera of the Aquificales predominated in many of the planktonic communities. In contrast, taxa capable of mineral-based metabolism such as S(o) oxidation/reduction or Fe-oxide reduction predominated in sediment communities. These results indicate that ecological differentiation within thermal spring habitats is common across a range of spring geochemistry and is influenced by the availability of dissolved nutrients and minerals that can be used in metabolism.
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Affiliation(s)
- Daniel R Colman
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA
| | - Jayme Feyhl-Buska
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA
| | - Kirtland J Robinson
- School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA
| | | | - Huifang Xu
- Department of Geosciences, University of Wisconsin, Madison, WI 53706, USA NASA Astrobiology Institute, Mountain View, CA 94035, USA School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287, USA
| | - Everett L Shock
- School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA NASA Astrobiology Institute, Mountain View, CA 94035, USA School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287, USA
| | - Eric S Boyd
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA NASA Astrobiology Institute, Mountain View, CA 94035, USA School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287, USA
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10
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Jay ZJ, Beam JP, Kozubal MA, Jennings RD, Rusch DB, Inskeep WP. The distribution, diversity and function of predominant Thermoproteales in high-temperature environments of Yellowstone National Park. Environ Microbiol 2016; 18:4755-4769. [PMID: 27130276 DOI: 10.1111/1462-2920.13366] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 04/25/2016] [Indexed: 12/01/2022]
Abstract
High-temperature environments (> 70°C) contain diverse and abundant members of the crenarchaeal order Thermoproteales. However, a comprehensive study of the distribution and function of diverse members of this group across different habitat types has not been conducted. Consequently, the goals of this study were to determine the distribution of different Thermoproteales genera across geochemically distinct geothermal habitats of Yellowstone National Park, and to identify key functional attributes of major genera that correlate with environmental parameters. Curated sequence assemblies belonging to five genera were characterized in replicate samples of 11 high-temperature communities ranging in pH from 3 to 9. Thermocladium, Vulcanisaeta and Caldivirga spp. were the primary Thermoproteales populations present in low pH (pH < 5) habitats, whereas Thermoproteus populations were found in mildly-acidic (pH 5-6) sulfur sediments, and Pyrobaculum populations were confined to higher pH (pH > 6) sulfur sediments and/or filamentous 'streamer' communities. Metabolic reconstruction and comparative genomics among assemblies show that these populations are primarily chemoorganotrophs that utilize different electron acceptors depending on geochemical conditions. The presence of potential CO2 fixation pathways in some Thermoproteales populations appears to be linked with NiFe hydrogenases, which combined with high levels of H2 in many sulfidic systems, may provide the energy required to fix inorganic C.
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Affiliation(s)
- Zackary J Jay
- Department of Land Resources and Environmental Sciences and Thermal Biology Institute, Montana State University, Bozeman, MT, 59175-3120, USA
| | - Jacob P Beam
- Department of Land Resources and Environmental Sciences and Thermal Biology Institute, Montana State University, Bozeman, MT, 59175-3120, USA
| | - Mark A Kozubal
- Department of Land Resources and Environmental Sciences and Thermal Biology Institute, Montana State University, Bozeman, MT, 59175-3120, USA
| | - Ryan deM Jennings
- Department of Land Resources and Environmental Sciences and Thermal Biology Institute, Montana State University, Bozeman, MT, 59175-3120, USA
| | - Douglas B Rusch
- Center for Genomics and Bioinformatics, Indiana University, Bloomington, IN, USA
| | - William P Inskeep
- Department of Land Resources and Environmental Sciences and Thermal Biology Institute, Montana State University, Bozeman, MT, 59175-3120, USA
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11
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Renslow RS, Lindemann SR, Song HS. A Generalized Spatial Measure for Resilience of Microbial Systems. Front Microbiol 2016; 7:443. [PMID: 27092116 PMCID: PMC4823267 DOI: 10.3389/fmicb.2016.00443] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 03/18/2016] [Indexed: 11/29/2022] Open
Abstract
The emergent property of resilience is the ability of a system to return to an original state after a disturbance. Resilience may be used as an early warning system for significant or irreversible community transition; that is, a community with diminishing or low resilience may be close to catastrophic shift in function or an irreversible collapse. Typically, resilience is quantified using recovery time, which may be difficult or impossible to directly measure in microbial systems. A recent study in the literature showed that under certain conditions, a set of spatial-based metrics termed recovery length, can be correlated to recovery time, and thus may be a reasonable alternative measure of resilience. However, this spatial metric of resilience is limited to use for step-change perturbations. Building upon the concept of recovery length, we propose a more general form of the spatial metric of resilience that can be applied to any shape of perturbation profiles (for example, either sharp or smooth gradients). We termed this new spatial measure “perturbation-adjusted spatial metric of resilience” (PASMORE). We demonstrate the applicability of the proposed metric using a mathematical model of a microbial mat.
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Affiliation(s)
- Ryan S Renslow
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland WA, USA
| | - Stephen R Lindemann
- Biological Sciences Division, Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland WA, USA
| | - Hyun-Seob Song
- Biological Sciences Division, Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland WA, USA
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Beam JP, Bernstein HC, Jay ZJ, Kozubal MA, Jennings RD, Tringe SG, Inskeep WP. Assembly and Succession of Iron Oxide Microbial Mat Communities in Acidic Geothermal Springs. Front Microbiol 2016; 7:25. [PMID: 26913020 PMCID: PMC4753309 DOI: 10.3389/fmicb.2016.00025] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 01/11/2016] [Indexed: 11/25/2022] Open
Abstract
Biomineralized ferric oxide microbial mats are ubiquitous features on Earth, are common in hot springs of Yellowstone National Park (YNP, WY, USA), and form due to direct interaction between microbial and physicochemical processes. The overall goal of this study was to determine the contribution of different community members to the assembly and succession of acidic high-temperature Fe(III)-oxide mat ecosystems. Spatial and temporal changes in Fe(III)-oxide accretion and the abundance of relevant community members were monitored over 70 days using sterile glass microscope slides incubated in the outflow channels of two acidic geothermal springs (pH = 3–3.5; temperature = 68–75°C) in YNP. Hydrogenobaculum spp. were the most abundant taxon identified during early successional stages (4–40 days), and have been shown to oxidize arsenite, sulfide, and hydrogen coupled to oxygen reduction. Iron-oxidizing populations of Metallosphaera yellowstonensis were detected within 4 days, and reached steady-state levels within 14–30 days, corresponding to visible Fe(III)-oxide accretion. Heterotrophic archaea colonized near 30 days, and emerged as the dominant functional guild after 70 days and in mature Fe(III)-oxide mats (1–2 cm thick). First-order rate constants of Fe(III)-oxide accretion ranged from 0.046 to 0.05 day−1, and in situ microelectrode measurements showed that the oxidation of Fe(II) is limited by the diffusion of O2 into the Fe(III)-oxide mat. The formation of microterracettes also implicated O2 as a major variable controlling microbial growth and subsequent mat morphology. The assembly and succession of Fe(III)-oxide mat communities follows a repeatable pattern of colonization by lithoautotrophic organisms, and the subsequent growth of diverse organoheterotrophs. The unique geochemical signatures and micromorphology of extant biomineralized Fe(III)-oxide mats are also useful for understanding other Fe(II)-oxidizing systems.
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Affiliation(s)
- Jacob P Beam
- Department of Land Resources and Environmental Sciences, Thermal Biology Institute, Montana State University Bozeman, MT, USA
| | - Hans C Bernstein
- Department of Chemical and Biological Engineering, Center for Biofilm Engineering, Montana State UniversityBozeman, MT, USA; Biodetection Science and Biological Science Division, Pacific Northwest National LaboratoryRichland, WA, USA
| | - Zackary J Jay
- Department of Land Resources and Environmental Sciences, Thermal Biology Institute, Montana State UniversityBozeman, MT, USA; Department of Chemical and Biological Engineering, Center for Biofilm Engineering, Montana State UniversityBozeman, MT, USA
| | - Mark A Kozubal
- Department of Land Resources and Environmental Sciences, Thermal Biology Institute, Montana State University Bozeman, MT, USA
| | - Ryan deM Jennings
- Department of Land Resources and Environmental Sciences, Thermal Biology Institute, Montana State University Bozeman, MT, USA
| | - Susannah G Tringe
- United States Department of Energy Joint Genome Institute Walnut Creek, CA, USA
| | - William P Inskeep
- Department of Land Resources and Environmental Sciences, Thermal Biology Institute, Montana State University Bozeman, MT, USA
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Beam JP, Jay ZJ, Schmid MC, Rusch DB, Romine MF, M Jennings RD, Kozubal MA, Tringe SG, Wagner M, Inskeep WP. Ecophysiology of an uncultivated lineage of Aigarchaeota from an oxic, hot spring filamentous 'streamer' community. THE ISME JOURNAL 2016; 10:210-24. [PMID: 26140529 PMCID: PMC4681859 DOI: 10.1038/ismej.2015.83] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Revised: 04/09/2015] [Accepted: 04/17/2015] [Indexed: 12/22/2022]
Abstract
The candidate archaeal phylum 'Aigarchaeota' contains microorganisms from terrestrial and subsurface geothermal ecosystems. The phylogeny and metabolic potential of Aigarchaeota has been deduced from several recent single-cell amplified genomes; however, a detailed description of their metabolic potential and in situ transcriptional activity is absent. Here, we report a comprehensive metatranscriptome-based reconstruction of the in situ metabolism of Aigarchaeota in an oxic, hot spring filamentous 'streamer' community. Fluorescence in situ hybridization showed that these newly discovered Aigarchaeota are filamentous, which is consistent with the presence and transcription of an actin-encoding gene. Aigarchaeota filaments are intricately associated with other community members, which include both bacteria (for example, filamentous Thermocrinis spp.) and archaea. Metabolic reconstruction of genomic and metatranscriptomic data suggests that this aigarchaeon is an aerobic, chemoorganoheterotroph with autotrophic potential. A heme copper oxidase complex was identified in the environmental genome assembly and highly transcribed in situ. Potential electron donors include acetate, fatty acids, amino acids, sugars and aromatic compounds, which may originate from extracellular polymeric substances produced by other microorganisms shown to exist in close proximity and/or autochthonous dissolved organic carbon (OC). Transcripts related to genes specific to each of these potential electron donors were identified, indicating that this aigarchaeon likely utilizes several OC substrates. Characterized members of this lineage cannot synthesize heme, and other cofactors and vitamins de novo, which suggests auxotrophy. We propose the name Candidatus 'Calditenuis aerorheumensis' for this aigarchaeon, which describes its filamentous morphology and its primary electron acceptor, oxygen.
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Affiliation(s)
- Jacob P Beam
- Thermal Biology Institute and Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, USA
| | - Zackary J Jay
- Thermal Biology Institute and Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, USA
| | - Markus C Schmid
- Divison of Microbial Ecology, University of Vienna, Vienna, Austria
| | - Douglas B Rusch
- Center for Genomics and Bioinformatics, Indiana University, Bloomington, IN, USA
| | | | - Ryan de M Jennings
- Thermal Biology Institute and Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, USA
| | - Mark A Kozubal
- Thermal Biology Institute and Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, USA
- Sustainable Bioproducts LLC, Bozeman, MT, USA
| | | | - Michael Wagner
- Divison of Microbial Ecology, University of Vienna, Vienna, Austria
| | - William P Inskeep
- Thermal Biology Institute and Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, USA
- Pacific Northwest National Laboratory, Richland, WA, USA
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Moran JJ, Doll CG, Bernstein HC, Renslow RS, Cory AB, Hutchison JR, Lindemann SR, Fredrickson JK. Spatially tracking (13) C-labelled substrate (bicarbonate) accumulation in microbial communities using laser ablation isotope ratio mass spectrometry. ENVIRONMENTAL MICROBIOLOGY REPORTS 2014; 6:786-791. [PMID: 25155264 DOI: 10.1111/1758-2229.12211] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Accepted: 08/05/2014] [Indexed: 06/03/2023]
Abstract
Microbial mats are characterized by extensive metabolic interactions, rapidly changing internal geochemical gradients, and prevalent microenvironments within tightly constrained physical structures. We present laser ablation isotope ratio mass spectrometry (LA-IRMS) as a culture-independent, spatially specific technology for tracking the accumulation of (13) C-labelled substrate into heterogeneous microbial mat communities. This study demonstrates the novel LA-IRMS approach by tracking labeled bicarbonate incorporation into a cyanobacteria-dominated microbial mat system. The spatial resolution of 50 μm was sufficient for distinguishing different mat strata and the approach effectively identified regions of greatest label incorporation. Sample preparation for LA-IRMS is straightforward and the spatial selectivity of LA-IRMS minimizes the volume of mat consumed, leaving material for complimentary analyses. We present analysis of DNA extracted from a sample post-ablation and suggest pigments, lipids or other biomarkers could similarly be extracted following ablation. LA-IRMS is well positioned to spatially resolve the accumulation of any (13) C-labelled substrate provided to a mat, making this a versatile tool for studying carbon transfer and interspecies exchanges within the limited spatial confines of such systems.
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Affiliation(s)
- James J Moran
- Signatures Science and Technology Division, National Security Directorate, Pacific Northwest National Laboratory, Richland, WA, 99352, USA
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15
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Bernstein HC, Kesaano M, Moll K, Smith T, Gerlach R, Carlson RP, Miller CD, Peyton BM, Cooksey KE, Gardner RD, Sims RC. Direct measurement and characterization of active photosynthesis zones inside wastewater remediating and biofuel producing microalgal biofilms. BIORESOURCE TECHNOLOGY 2014; 156:206-215. [PMID: 24508901 DOI: 10.1016/j.biortech.2014.01.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Revised: 12/30/2013] [Accepted: 01/02/2014] [Indexed: 06/03/2023]
Abstract
Microalgal biofilm based technologies are of keen interest due to their high biomass concentrations and ability to utilize light and CO2. While photoautotrophic biofilms have long been used for wastewater remediation, biofuel production represents a relatively new and under-represented focus area. However, the direct measurement and characterization of fundamental parameters required for industrial control are challenging due to biofilm heterogeneity. This study evaluated oxygenic photosynthesis and respiration on two distinct microalgal biofilms cultured using a novel rotating algal biofilm reactor operated at field- and laboratory-scales. Clear differences in oxygenic photosynthesis and respiration were observed based on different culturing conditions, microalgal composition, light intensity and nitrogen availability. The cultures were also evaluated as potential biofuel synthesis strategies. Nitrogen depletion was not found to have the same effect on lipid accumulation compared to traditional planktonic microalgal studies. Physiological characterizations of these microalgal biofilms identify fundamental parameters needed to understand and control process optimization.
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Affiliation(s)
- Hans C Bernstein
- Center for Biofilm Engineering, Montana State University, Bozeman, MT 59717, United States; Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT 59717, United States; Chemical and Biological Signature Science, Pacific Northwest National Laboratories, Richland, WA 99352, United States
| | - Maureen Kesaano
- Department of Biological Engineering, Utah State University, Logan, UT 84322, United States
| | - Karen Moll
- Center for Biofilm Engineering, Montana State University, Bozeman, MT 59717, United States; Department of Microbiology, Montana State University, Bozeman, MT 59717, United States
| | - Terence Smith
- Department of Biological Engineering, Utah State University, Logan, UT 84322, United States
| | - Robin Gerlach
- Center for Biofilm Engineering, Montana State University, Bozeman, MT 59717, United States; Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT 59717, United States
| | - Ross P Carlson
- Center for Biofilm Engineering, Montana State University, Bozeman, MT 59717, United States; Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT 59717, United States
| | - Charles D Miller
- Department of Biological Engineering, Utah State University, Logan, UT 84322, United States
| | - Brent M Peyton
- Center for Biofilm Engineering, Montana State University, Bozeman, MT 59717, United States; Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT 59717, United States
| | - Keith E Cooksey
- Environmental Biotechnology Consultants, Manhattan, MT 59741, United States
| | - Robert D Gardner
- Center for Biofilm Engineering, Montana State University, Bozeman, MT 59717, United States; Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT 59717, United States.
| | - Ronald C Sims
- Department of Biological Engineering, Utah State University, Logan, UT 84322, United States.
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Carbon dioxide fixation by Metallosphaera yellowstonensis and acidothermophilic iron-oxidizing microbial communities from Yellowstone National Park. Appl Environ Microbiol 2014; 80:2665-71. [PMID: 24532073 DOI: 10.1128/aem.03416-13] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The fixation of inorganic carbon has been documented in all three domains of life and results in the biosynthesis of diverse organic compounds that support heterotrophic organisms. The primary aim of this study was to assess carbon dioxide fixation in high-temperature Fe(III)-oxide mat communities and in pure cultures of a dominant Fe(II)-oxidizing organism (Metallosphaera yellowstonensis strain MK1) originally isolated from these environments. Protein-encoding genes of the complete 3-hydroxypropionate/4-hydroxybutyrate (3-HP/4-HB) carbon dioxide fixation pathway were identified in M. yellowstonensis strain MK1. Highly similar M. yellowstonensis genes for this pathway were identified in metagenomes of replicate Fe(III)-oxide mats, as were genes for the reductive tricarboxylic acid cycle from Hydrogenobaculum spp. (Aquificales). Stable-isotope ((13)CO2) labeling demonstrated CO2 fixation by M. yellowstonensis strain MK1 and in ex situ assays containing live Fe(III)-oxide microbial mats. The results showed that strain MK1 fixes CO2 with a fractionation factor of ∼2.5‰. Analysis of the (13)C composition of dissolved inorganic C (DIC), dissolved organic C (DOC), landscape C, and microbial mat C showed that mat C is from both DIC and non-DIC sources. An isotopic mixing model showed that biomass C contains a minimum of 42% C of DIC origin, depending on the fraction of landscape C that is present. The significance of DIC as a major carbon source for Fe(III)-oxide mat communities provides a foundation for examining microbial interactions that are dependent on the activity of autotrophic organisms (i.e., Hydrogenobaculum and Metallosphaera spp.) in simplified natural communities.
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Beam JP, Jay ZJ, Kozubal MA, Inskeep WP. Niche specialization of novel Thaumarchaeota to oxic and hypoxic acidic geothermal springs of Yellowstone National Park. ISME JOURNAL 2013; 8:938-51. [PMID: 24196321 DOI: 10.1038/ismej.2013.193] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 09/06/2013] [Accepted: 09/17/2013] [Indexed: 11/09/2022]
Abstract
Novel lineages of the phylum Thaumarchaeota are endemic to thermal habitats, and may exhibit physiological capabilities that are not yet observed in members of this phylum. The primary goals of this study were to conduct detailed phylogenetic and functional analyses of metagenome sequence assemblies of two different thaumarchaeal populations found in high-temperature (65-72 °C), acidic (pH~3) iron oxide and sulfur sediment environments of Yellowstone National Park (YNP). Metabolic reconstruction was coupled with detailed geochemical measurements of each geothermal habitat and reverse-transcriptase PCR to confirm the in situ activity of these populations. Phylogenetic analyses of ribosomal and housekeeping proteins place these archaea near the root of the thaumarchaeal branch. Metabolic reconstruction suggests that these populations are chemoorganotrophic and couple growth with the reduction of oxygen or nitrate in iron oxide habitats, or sulfur in hypoxic sulfur sediments. The iron oxide population has the potential for growth via the oxidation of sulfide to sulfate using a novel reverse sulfate reduction pathway. Possible carbon sources include aromatic compounds (for example, 4-hydroxyphenylacetate), complex carbohydrates (for example, starch), oligopeptides and amino acids. Both populations contain a type III ribulose bisphosphate carboxylase/oxygenase used for carbon dioxide fixation or adenosine monophosphate salvage. No evidence for the oxidation of ammonia was obtained from de novo sequence assemblies. Our results show that thermoacidophilic Thaumarchaeota from oxic iron mats and hypoxic sulfur sediments exhibit different respiratory machinery depending on the presence of oxygen versus sulfide, represent deeply rooted lineages within the phylum Thaumarchaeota and are endemic to numerous sites in YNP.
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Affiliation(s)
- Jacob P Beam
- Thermal Biology Institute and Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, USA
| | - Zackary J Jay
- Thermal Biology Institute and Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, USA
| | - Mark A Kozubal
- Thermal Biology Institute and Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, USA
| | - William P Inskeep
- Thermal Biology Institute and Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, USA
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18
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Predominant Acidilobus-like populations from geothermal environments in yellowstone national park exhibit similar metabolic potential in different hypoxic microbial communities. Appl Environ Microbiol 2013; 80:294-305. [PMID: 24162572 DOI: 10.1128/aem.02860-13] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
High-temperature (>70°C) ecosystems in Yellowstone National Park (YNP) provide an unparalleled opportunity to study chemotrophic archaea and their role in microbial community structure and function under highly constrained geochemical conditions. Acidilobus spp. (order Desulfurococcales) comprise one of the dominant phylotypes in hypoxic geothermal sulfur sediment and Fe(III)-oxide environments along with members of the Thermoproteales and Sulfolobales. Consequently, the primary goals of the current study were to analyze and compare replicate de novo sequence assemblies of Acidilobus-like populations from four different mildly acidic (pH 3.3 to 6.1) high-temperature (72°C to 82°C) environments and to identify metabolic pathways and/or protein-encoding genes that provide a detailed foundation of the potential functional role of these populations in situ. De novo assemblies of the highly similar Acidilobus-like populations (>99% 16S rRNA gene identity) represent near-complete consensus genomes based on an inventory of single-copy genes, deduced metabolic potential, and assembly statistics generated across sites. Functional analysis of coding sequences and confirmation of gene transcription by Acidilobus-like populations provide evidence that they are primarily chemoorganoheterotrophs, generating acetyl coenzyme A (acetyl-CoA) via the degradation of carbohydrates, lipids, and proteins, and auxotrophic with respect to several external vitamins, cofactors, and metabolites. No obvious pathways or protein-encoding genes responsible for the dissimilatory reduction of sulfur were identified. The presence of a formate dehydrogenase (Fdh) and other protein-encoding genes involved in mixed-acid fermentation supports the hypothesis that Acidilobus spp. function as degraders of complex organic constituents in high-temperature, mildly acidic, hypoxic geothermal systems.
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