1
|
Ni S, Lv W, Ji Z, Wang K, Mei Y, Li Y. Progress of Crude Oil Gasification Technology Assisted by Microorganisms in Reservoirs. Microorganisms 2024; 12:702. [PMID: 38674646 PMCID: PMC11051786 DOI: 10.3390/microorganisms12040702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 03/17/2024] [Accepted: 03/26/2024] [Indexed: 04/28/2024] Open
Abstract
Crude oil gasification bacteria, including fermenting bacteria, hydrocarbon-oxidizing bacteria, reducing bacteria, and methanogenic bacteria, participate in multi-step reactions involving initial activation, intermediate metabolism, and the methanogenesis of crude oil hydrocarbons. These bacteria degrade crude oil into smaller molecules such as hydrogen, carbon dioxide, acetic acid, and formic acid. Ultimately, they convert it into methane, which can be utilized or stored as a strategic resource. However, the current challenges in crude oil gasification include long production cycles and low efficiency. This paper provides a summary of the microbial flora involved in crude oil gasification, the gasification metabolism pathways within reservoirs, and other relevant information. It specifically focuses on analyzing the factors that affect the efficiency of crude oil gasification metabolism and proposes suggestions for improving this efficiency. These studies deepen our understanding of the potential of reservoir ecosystems and provide valuable insights for future reservoir development and management.
Collapse
Affiliation(s)
- Shumin Ni
- University of Chinese Academy of Sciences, Beijing 100049, China; (S.N.); (K.W.); (Y.M.); (Y.L.)
- Institute of Porous Flow & Fluid Mechanics, Chinese Academy of Sciences, Langfang 065007, China;
| | - Weifeng Lv
- Institute of Porous Flow & Fluid Mechanics, Chinese Academy of Sciences, Langfang 065007, China;
- State Key Laboratory of Enhanced Oil Recovery, Research Institute of Petroleum Exploration and Development, CNPC, Beijing 100083, China
| | - Zemin Ji
- Institute of Porous Flow & Fluid Mechanics, Chinese Academy of Sciences, Langfang 065007, China;
| | - Kai Wang
- University of Chinese Academy of Sciences, Beijing 100049, China; (S.N.); (K.W.); (Y.M.); (Y.L.)
- Institute of Porous Flow & Fluid Mechanics, Chinese Academy of Sciences, Langfang 065007, China;
| | - Yuhao Mei
- University of Chinese Academy of Sciences, Beijing 100049, China; (S.N.); (K.W.); (Y.M.); (Y.L.)
- Institute of Porous Flow & Fluid Mechanics, Chinese Academy of Sciences, Langfang 065007, China;
| | - Yushu Li
- University of Chinese Academy of Sciences, Beijing 100049, China; (S.N.); (K.W.); (Y.M.); (Y.L.)
- Institute of Porous Flow & Fluid Mechanics, Chinese Academy of Sciences, Langfang 065007, China;
| |
Collapse
|
2
|
Abdul Halim MF, Fonseca DR, Niehaus TD, Costa KC. Functionally redundant formate dehydrogenases enable formate-dependent growth in Methanococcus maripaludis. J Biol Chem 2024; 300:105550. [PMID: 38072055 PMCID: PMC10805699 DOI: 10.1016/j.jbc.2023.105550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 12/01/2023] [Accepted: 12/02/2023] [Indexed: 01/02/2024] Open
Abstract
Methanogens are essential for the complete remineralization of organic matter in anoxic environments. Most cultured methanogens are hydrogenotrophic, using H2 as an electron donor to reduce CO2 to CH4, but in the absence of H2 many can also use formate. Formate dehydrogenase (Fdh) is essential for formate oxidation, where it transfers electrons for the reduction of coenzyme F420 or to a flavin-based electron bifurcating reaction catalyzed by heterodisulfide reductase (Hdr), the terminal reaction of methanogenesis. Furthermore, methanogens that use formate encode at least two isoforms of Fdh in their genomes, but how these different isoforms participate in methanogenesis is unknown. Using Methanococcus maripaludis, we undertook a biochemical characterization of both Fdh isoforms involved in methanogenesis. Both Fdh1 and Fdh2 interacted with Hdr to catalyze the flavin-based electron bifurcating reaction, and both reduced F420 at similar rates. F420 reduction preceded flavin-based electron bifurcation activity for both enzymes. In a Δfdh1 mutant background, a suppressor mutation was required for Fdh2 activity. Genome sequencing revealed that this mutation resulted in the loss of a specific molybdopterin transferase (moeA), allowing for Fdh2-dependent growth, and the metal content of the proteins suggested that isoforms are dependent on either molybdenum or tungsten for activity. These data suggest that both isoforms of Fdh are functionally redundant, but their activities in vivo may be limited by gene regulation or metal availability under different growth conditions. Together these results expand our understanding of formate oxidation and the role of Fdh in methanogenesis.
Collapse
Affiliation(s)
- Mohd Farid Abdul Halim
- Department of Plant and Microbial Biology, University of Minnesota, Twin Cities, St. Paul, Minnesota, USA
| | - Dallas R Fonseca
- Department of Plant and Microbial Biology, University of Minnesota, Twin Cities, St. Paul, Minnesota, USA
| | - Thomas D Niehaus
- Department of Plant and Microbial Biology, University of Minnesota, Twin Cities, St. Paul, Minnesota, USA
| | - Kyle C Costa
- Department of Plant and Microbial Biology, University of Minnesota, Twin Cities, St. Paul, Minnesota, USA.
| |
Collapse
|
3
|
Hao Z, Zhao L, Liu J, Pu Q, Chen J, Meng B, Feng X. Relative importance of aceticlastic methanogens and hydrogenotrophic methanogens on mercury methylation and methylmercury demethylation in paddy soils. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 906:167601. [PMID: 37832685 DOI: 10.1016/j.scitotenv.2023.167601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 09/28/2023] [Accepted: 10/03/2023] [Indexed: 10/15/2023]
Abstract
The accumulation of methylmercury (MeHg) in paddy soil results from a subtle balance between inorganic mercury (e.g., HgII) methylation and MeHg demethylation. Methanogens not only act as Hg methylators but may also facilitate MeHg demethylation. However, the diverse methanogen flora (e.g., aceticlastic and hydrogenotrophic types) that exists under ambient conditions has not previously been considered. Accordingly, the roles of different types of methanogens in HgII methylation and MeHg degradation in paddy soils were studied using the Hg isotope tracing technique combined with the application of methanogen inhibitors/stimulants. It was found that the response of HgII methylation to methanogen inhibitors or stimulants was site-dependent. Specifically, aceticlastic methanogens were suggested as the potential HgII methylators at the low Hg level background site, whereas hydrogenotrophic methanogens were potentially involved in MeHg production as Hg levels increased. In contrast, both aceticlastic and hydrogenotrophic methanogens facilitated MeHg degradation across the sampling sites. Additionally, competition between hydrogenotrophic and aceticlastic methanogens was observed in Hg-polluted paddy soils, implying that net MeHg production could be alleviated by promoting aceticlastic methanogens or inhibiting hydrogenotrophic methanogens. The findings gained from this study improve the understanding of the role of methanogens in net MeHg formation and link carbon turnover to Hg biogeochemistry in rice paddy ecosystems.
Collapse
Affiliation(s)
- Zhengdong Hao
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lei Zhao
- School of Management Science, Guizhou University of Finance and Economics, Guiyang 550025, China; Guizhou Key Laboratory of Big Data Statistical Analysis (No. [2019]5103), Guiyang 550025, China.
| | - Jiang Liu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Qiang Pu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Ji Chen
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Bo Meng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; University of Chinese Academy of Sciences, Beijing 100049, China
| |
Collapse
|
4
|
Abstract
Methanogenic archaea are the only organisms that produce CH4 as part of their energy-generating metabolism. They are ubiquitous in oxidant-depleted, anoxic environments such as aquatic sediments, anaerobic digesters, inundated agricultural fields, the rumen of cattle, and the hindgut of termites, where they catalyze the terminal reactions in the degradation of organic matter. Methanogenesis is the only metabolism that is restricted to members of the domain Archaea. Here, we discuss the importance of model organisms in the history of methanogen research, including their role in the discovery of the archaea and in the biochemical and genetic characterization of methanogenesis. We also discuss outstanding questions in the field and newly emerging model systems that will expand our understanding of this uniquely archaeal metabolism.
Collapse
Affiliation(s)
- Kyle C. Costa
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, Minnesota, USA
| | | |
Collapse
|
5
|
Wirth R, Bagi Z, Shetty P, Szuhaj M, Cheung TTS, Kovács KL, Maróti G. Inter-kingdom interactions and stability of methanogens revealed by machine-learning guided multi-omics analysis of industrial-scale biogas plants. THE ISME JOURNAL 2023:10.1038/s41396-023-01448-3. [PMID: 37286740 DOI: 10.1038/s41396-023-01448-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 05/23/2023] [Accepted: 05/26/2023] [Indexed: 06/09/2023]
Abstract
Multi-omics analysis is a powerful tool for the detection and study of inter-kingdom interactions, such as those between bacterial and archaeal members of complex biogas-producing microbial communities. In the present study, the microbiomes of three industrial-scale biogas digesters, each fed with different substrates, were analysed using a machine-learning guided genome-centric metagenomics framework complemented with metatranscriptome data. This data permitted us to elucidate the relationship between abundant core methanogenic communities and their syntrophic bacterial partners. In total, we detected 297 high-quality, non-redundant metagenome-assembled genomes (nrMAGs). Moreover, the assembled 16 S rRNA gene profiles of these nrMAGs showed that the phylum Firmicutes possessed the highest copy number, while the representatives of the archaeal domain had the lowest. Further investigation of the three anaerobic microbial communities showed characteristic alterations over time but remained specific to each industrial-scale biogas plant. The relative abundance of various microorganisms as revealed by metagenome data was independent from corresponding metatranscriptome activity data. Archaea showed considerably higher activity than was expected from their abundance. We detected 51 nrMAGs that were present in all three biogas plant microbiomes with different abundances. The core microbiome correlated with the main chemical fermentation parameters, and no individual parameter emerged as a predominant shaper of community composition. Various interspecies H2/electron transfer mechanisms were assigned to hydrogenotrophic methanogens in the biogas plants that ran on agricultural biomass and wastewater. Analysis of metatranscriptome data revealed that methanogenesis pathways were the most active of all main metabolic pathways.
Collapse
Affiliation(s)
- Roland Wirth
- Institute of Plant Biology, Biological Research Centre, Szeged, Hungary
- Department of Biotechnology, University of Szeged, Szeged, Hungary
| | - Zoltán Bagi
- Department of Biotechnology, University of Szeged, Szeged, Hungary
| | - Prateek Shetty
- Institute of Plant Biology, Biological Research Centre, Szeged, Hungary
| | - Márk Szuhaj
- Department of Biotechnology, University of Szeged, Szeged, Hungary
| | | | - Kornél L Kovács
- Department of Biotechnology, University of Szeged, Szeged, Hungary
| | - Gergely Maróti
- Institute of Plant Biology, Biological Research Centre, Szeged, Hungary.
- Faculty of Water Sciences, University of Public Service, Baja, Hungary.
| |
Collapse
|
6
|
Interspecies Formate Exchange Drives Syntrophic Growth of Syntrophotalea carbinolica and Methanococcus maripaludis. Appl Environ Microbiol 2022; 88:e0115922. [PMID: 36374033 PMCID: PMC9746305 DOI: 10.1128/aem.01159-22] [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] [Indexed: 11/16/2022] Open
Abstract
The complete remineralization of organic matter in anoxic environments relies on communities of microorganisms that ferment organic acids and alcohols to CH4. This is accomplished through syntrophic association of H2 or formate producing bacteria and methanogenic archaea, where exchange of these intermediates enables growth of both organisms. While these communities are essential to Earth's carbon cycle, our understanding of the dynamics of H2 or formate exchanged is limited. Here, we establish a model partnership between Syntrophotalea carbinolica and Methanococcus maripaludis. Through sequencing a transposon mutant library of M. maripaludis grown with ethanol oxidizing S. carbinolica, we found that genes encoding the F420-dependent formate dehydrogenase (Fdh) and F420-dependent methylene-tetrahydromethanopterin dehydrogenase (Mtd) are important for growth. Competitive growth of M. maripaludis mutants defective in either H2 or formate metabolism verified that, across multiple substrates, interspecies formate exchange was dominant in these communities. Agitation of these cultures to facilitate diffusive loss of H2 to the culture headspace resulted in an even greater competitive advantage for M. maripaludis strains capable of oxidizing formate. Finally, we verified that an M. maripaludis Δmtd mutant had a defect during syntrophic growth. Together, these results highlight the importance of formate exchange for the growth of methanogens under syntrophic conditions. IMPORTANCE In the environment, methane is typically generated by fermentative bacteria and methanogenic archaea working together in a process called syntrophy. Efficient exchange of small molecules like H2 or formate is essential for growth of both organisms. However, difficulties in determining the relative contribution of these intermediates to methanogenesis often hamper efforts to understand syntrophic interactions. Here, we establish a model syntrophic coculture composed of S. carbinolica and the genetically tractable methanogen M. maripaludis. Using mutant strains of M. maripaludis that are defective for either H2 or formate metabolism, we determined that interspecies formate exchange drives syntrophic growth of these organisms. Together, these results advance our understanding of the degradation of organic matter in anoxic environments.
Collapse
|
7
|
Palabikyan H, Ruddyard A, Pomper L, Novak D, Reischl B, Rittmann SKMR. Scale-up of biomass production by Methanococcus maripaludis. Front Microbiol 2022; 13:1031131. [PMID: 36504798 PMCID: PMC9727139 DOI: 10.3389/fmicb.2022.1031131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 10/13/2022] [Indexed: 11/24/2022] Open
Abstract
The development of a sustainable energy economy is one of the great challenges in the current times of climate crisis and growing energy demands. Industrial production of the fifth-generation biofuel methane by microorganisms has the potential to become a crucial biotechnological milestone of the post fossil fuel era. Therefore, reproducible cultivation and scale-up of methanogenic archaea (methanogens) is essential for enabling biomass generation for fundamental studies and for defining peak performance conditions for bioprocess development. This study provides a comprehensive revision of established and optimization of novel methods for the cultivation of the model organism Methanococcus maripaludis S0001. In closed batch mode, 0.05 L serum bottles cultures were gradually replaced by 0.4 L Schott bottle cultures for regular biomass generation, and the time for reaching peak optical density (OD578) values was reduced in half. In 1.5 L reactor cultures, various agitation, harvesting and transfer methods were compared resulting in a specific growth rate of 0.16 h-1 and the highest recorded OD578 of 3.4. Finally, a 300-fold scale-up from serum bottles was achieved by growing M. maripaludis for the first time in a 22 L stainless steel bioreactor with 15 L working volume. Altogether, the experimental approaches described in this study contribute to establishing methanogens as essential organisms in large-scale biotechnology applications, a crucial stage of an urgently needed industrial evolution toward sustainable biosynthesis of energy and high value products.
Collapse
Affiliation(s)
- Hayk Palabikyan
- Archaea Physiology & Biotechnology Group, Department of Functional and Evolutionary Ecology, Universität Wien, Vienna, Austria
| | - Aquilla Ruddyard
- Archaea Physiology & Biotechnology Group, Department of Functional and Evolutionary Ecology, Universität Wien, Vienna, Austria,Arkeon GmbH, Tulln a.d. Donau, Austria
| | - Lara Pomper
- Archaea Physiology & Biotechnology Group, Department of Functional and Evolutionary Ecology, Universität Wien, Vienna, Austria
| | - David Novak
- Department of Biochemistry, Faculty of Science, Masaryk University, Brno, Czechia
| | - Barbara Reischl
- Archaea Physiology & Biotechnology Group, Department of Functional and Evolutionary Ecology, Universität Wien, Vienna, Austria,Arkeon GmbH, Tulln a.d. Donau, Austria
| | - Simon K.-M. R. Rittmann
- Archaea Physiology & Biotechnology Group, Department of Functional and Evolutionary Ecology, Universität Wien, Vienna, Austria,Arkeon GmbH, Tulln a.d. Donau, Austria,*Correspondence: Simon K.-M. R. Rittmann,
| |
Collapse
|
8
|
Li J, Akinyemi TS, Shao N, Chen C, Dong X, Liu Y, Whitman WB. Genetic and Metabolic Engineering of Methanococcus spp. CURRENT RESEARCH IN BIOTECHNOLOGY 2022. [DOI: 10.1016/j.crbiot.2022.11.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
|
9
|
The Fluorescence-Activating and Absorption-Shifting Tag (FAST) Enables Live-Cell Fluorescence Imaging of Methanococcus maripaludis. J Bacteriol 2022; 204:e0012022. [PMID: 35657707 DOI: 10.1128/jb.00120-22] [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] [Indexed: 01/20/2023] Open
Abstract
Live-cell fluorescence imaging of methanogenic archaea has been limited due to the strictly anoxic conditions required for growth and issues with autofluorescence associated with electron carriers in central metabolism. Here, we show that the fluorescence-activating and absorption-shifting tag (FAST) complexed with the fluorogenic ligand 4-hydroxy-3-methylbenzylidene-rhodanine (HMBR) overcomes these issues and displays robust fluorescence in Methanococcus maripaludis. We also describe a mechanism to visualize cells under anoxic conditions using a fluorescence microscope. Derivatives of FAST were successfully applied for protein abundance analysis, subcellular localization analysis, and determination of protein-protein interactions. FAST fusions to both formate dehydrogenase (Fdh) and F420-reducing hydrogenase (Fru) displayed increased fluorescence in cells grown on formate-containing medium, consistent with previous studies suggesting the increased abundance of these proteins in the absence of H2. Additionally, FAST fusions to both Fru and the ATPase associated with the archaellum (FlaI) showed a membrane localization in single cells observed using anoxic fluorescence microscopy. Finally, a split reporter translationally fused to the alpha and beta subunits of Fdh reconstituted a functionally fluorescent molecule in vivo via bimolecular fluorescence complementation. Together, these observations demonstrate the utility of FAST as a tool for studying members of the methanogenic archaea. IMPORTANCE Methanogenic archaea are important members of anaerobic microbial communities where they catalyze essential reactions in the degradation of organic matter. Developing additional tools for studying the cell biology of these organisms is essential to understanding them at a mechanistic level. Here, we show that FAST, in combination with the fluorogenic ligand HMBR, can be used to monitor protein dynamics in live cells of M. maripaludis. The application of FAST holds promise for future studies focused on the metabolism and physiology of methanogenic archaea.
Collapse
|
10
|
Gropp J, Jin Q, Halevy I. Controls on the isotopic composition of microbial methane. SCIENCE ADVANCES 2022; 8:eabm5713. [PMID: 35385305 PMCID: PMC8985922 DOI: 10.1126/sciadv.abm5713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Accepted: 02/15/2022] [Indexed: 06/14/2023]
Abstract
Microbial methane production (methanogenesis) is responsible for more than half of the annual emissions of this major greenhouse gas to the atmosphere. Although the stable isotopic composition of methane is often used to characterize its sources and sinks, strictly empirical descriptions of the isotopic signature of methanogenesis currently limit these attempts. We developed a metabolic-isotopic model of methanogenesis by carbon dioxide reduction, which predicts carbon and hydrogen isotopic fractionations, and clumped isotopologue distributions, as functions of the cell's environment. We mechanistically explain multiple isotopic patterns in laboratory and natural settings and show that these patterns constrain the in situ energetics of methanogenesis. Combining our model with data from environments in which methanogenic activity is energy-limited, we provide predictions for the biomass-specific methanogenesis rates and the associated isotopic effects.
Collapse
Affiliation(s)
- Jonathan Gropp
- Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Qusheng Jin
- Department of Earth Sciences, University of Oregon, Eugene, OR, USA
| | - Itay Halevy
- Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot, Israel
| |
Collapse
|
11
|
Akinyemi TS, Shao N, Lyu Z, Drake IJ, Liu Y, Whitman WB. Tuning Gene Expression by Phosphate in the Methanogenic Archaeon Methanococcus maripaludis. ACS Synth Biol 2021; 10:3028-3039. [PMID: 34665610 DOI: 10.1021/acssynbio.1c00322] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Methanococcus maripaludis is a rapidly growing, hydrogenotrophic, and genetically tractable methanogen with unique capabilities to convert formate and CO2 to CH4. The existence of genome-scale metabolic models and an established, robust system for both large-scale and continuous cultivation make it amenable for industrial applications. However, the lack of molecular tools for differential gene expression has hindered its application as a microbial cell factory to produce biocatalysts and biochemicals. In this study, a library of differentially regulated promoters was designed and characterized based on the pst promoter, which responds to the inorganic phosphate concentration in the growth medium. Gene expression increases by 4- to 6-fold when the medium phosphate drops to growth-limiting concentrations. Hence, this regulated system decouples growth from heterologous gene expression without the need for adding an inducer. The minimal pst promoter is identified and contains a conserved AT-rich region, a factor B recognition element, and a TATA box for phosphate-dependent regulation. Rational changes to the factor B recognition element and start codon had no significant impact on expression; however, changes to the transcription start site and the 5' untranslated region resulted in the differential protein production with regulation remaining intact. Compared to a previous expression system based upon the histone promoter, this regulated expression system resulted in significant improvements in the expression of a key methanogenic enzyme complex, methyl-coenzyme M reductase, and the potentially toxic arginine methyltransferase MmpX.
Collapse
Affiliation(s)
- Taiwo S. Akinyemi
- Department of Microbiology, University of Georgia, Athens, Georgia 30602, United States
| | - Nana Shao
- Department of Microbiology, University of Georgia, Athens, Georgia 30602, United States
| | - Zhe Lyu
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas 77030, United States
| | - Ian J. Drake
- Corporate Strategic Research, ExxonMobil Research & Engineering Company, Annandale, New Jersey 08801, United States
| | - Yuchen Liu
- Corporate Strategic Research, ExxonMobil Research & Engineering Company, Annandale, New Jersey 08801, United States
| | - William B. Whitman
- Department of Microbiology, University of Georgia, Athens, Georgia 30602, United States
| |
Collapse
|
12
|
Analysis of a Methanogen and an Actinobacterium Dominating the Thermophilic Microbial Community of an Electromethanogenic Biocathode. ACTA ACUST UNITED AC 2021; 2021:8865133. [PMID: 33746613 PMCID: PMC7943316 DOI: 10.1155/2021/8865133] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 02/09/2021] [Accepted: 02/15/2021] [Indexed: 12/13/2022]
Abstract
Electromethanogenesis refers to the bioelectrochemical synthesis of methane from CO2 by biocathodes. In an electromethanogenic system using thermophilic microorganisms, metagenomic analysis along with quantitative real-time polymerase chain reaction and fluorescence in situ hybridization revealed that the biocathode microbiota was dominated by the methanogen Methanothermobacter sp. strain EMTCatA1 and the actinobacterium Coriobacteriaceae sp. strain EMTCatB1. RNA sequencing was used to compare the transcriptome profiles of each strain at the methane-producing biocathodes with those in an open circuit and with the methanogenesis inhibitor 2-bromoethanesulfonate (BrES). For the methanogen, genes related to hydrogenotrophic methanogenesis were highly expressed in a manner similar to those observed under H2-limited conditions. For the actinobacterium, the expression profiles of genes encoding multiheme c-type cytochromes and membrane-bound oxidoreductases suggested that the actinobacterium directly takes up electrons from the electrode. In both strains, various stress-related genes were commonly induced in the open-circuit biocathodes and biocathodes with BrES. This study provides a molecular inventory of the dominant species of an electromethanogenic biocathode with functional insights and therefore represents the first multiomics characterization of an electromethanogenic biocathode.
Collapse
|
13
|
Shalvarjian KE, Nayak DD. Transcriptional regulation of methanogenic metabolism in archaea. Curr Opin Microbiol 2021; 60:8-15. [PMID: 33561735 DOI: 10.1016/j.mib.2021.01.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 01/21/2021] [Accepted: 01/21/2021] [Indexed: 11/25/2022]
Abstract
Methanogenesis is a widespread metabolism of evolutionary and environmental importance that is likely to have originated on early Earth. Microorganisms that perform methanogenesis, termed methanogens, belong exclusively to the domain Archaea. Despite maintaining eukaryotic transcription machinery and homologs of bacterial regulators, archaeal transcription and gene regulation appear to be distinct from either domain. While genes involved in methanogenic metabolism have been identified and characterized, their regulation in response to both extracellular and intracellular signals is less understood. Here, we review recent reports on transcriptional regulation of methanogenesis using two model methanogens, Methanococcus maripaludis and Methanosarcina acetivorans, and highlight directions for future research in this nascent field.
Collapse
Affiliation(s)
- Katie E Shalvarjian
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Dipti D Nayak
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.
| |
Collapse
|
14
|
Kato S, Takashino M, Igarashi K, Mochimaru H, Mayumi D, Tamaki H. An iron corrosion-assisted H 2-supplying system: a culture method for methanogens and acetogens under low H 2 pressures. Sci Rep 2020; 10:19124. [PMID: 33154519 PMCID: PMC7645788 DOI: 10.1038/s41598-020-76267-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Accepted: 10/12/2020] [Indexed: 11/09/2022] Open
Abstract
H2 is an important fermentation intermediate in anaerobic environments. Although H2 occurs at very low partial pressures in the environments, the culture and isolation of H2-utilizing microorganisms is usually carried out under very high H2 pressures, which might have hampered the discovery and understanding of microorganisms adapting to low H2 environments. Here we constructed a culture system designated the "iron corrosion-assisted H2-supplying (iCH) system" by connecting the gas phases of two vials (one for the iron corrosion reaction and the other for culturing microorganisms) to achieve cultures of microorganisms under low H2 pressures. We conducted enrichment cultures for methanogens and acetogens using rice paddy field soil as the microbial source. In the enrichment culture of methanogens under canonical high H2 pressures, only Methanobacterium spp. were enriched. By contrast, Methanocella spp. and Methanoculleus spp., methanogens adapting to low H2 pressures, were specifically enriched in the iCH cultures. We also observed selective enrichment of acetogen species by the iCH system (Acetobacterium spp. and Sporomusa spp.), whereas Clostridium spp. predominated in the high H2 cultures. These results demonstrate that the iCH system facilitates culture of anaerobic microorganisms under low H2 pressures, which will enable the selective culture of microorganisms adapting to low H2 environments.
Collapse
Affiliation(s)
- Souichiro Kato
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2-17-2-1 Tsukisamu-Higashi, Toyohira-ku, Sapporo, Hokkaido, 062-8517, Japan. .,Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Kita-9 Nishi-9, Kita-ku, Sapporo, Hokkaido, 060-8589, Japan.
| | - Motoko Takashino
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2-17-2-1 Tsukisamu-Higashi, Toyohira-ku, Sapporo, Hokkaido, 062-8517, Japan
| | - Kensuke Igarashi
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2-17-2-1 Tsukisamu-Higashi, Toyohira-ku, Sapporo, Hokkaido, 062-8517, Japan
| | - Hanako Mochimaru
- Institute for Geo-Resources and Environment, Geological Survey of Japan, AIST, 1-1-1 Higashi, Tsukuba, 305-8567, Japan
| | - Daisuke Mayumi
- Institute for Geo-Resources and Environment, Geological Survey of Japan, AIST, 1-1-1 Higashi, Tsukuba, 305-8567, Japan
| | - Hideyuki Tamaki
- Bioproduction Research Institute, AIST, 1-1-1 Higashi, Tsukuba, 305-8567, Japan
| |
Collapse
|
15
|
Prathiviraj R, Chellapandi P. Modeling a global regulatory network of Methanothermobacter thermautotrophicus strain ∆H. ACTA ACUST UNITED AC 2020. [DOI: 10.1007/s13721-020-0223-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
|
16
|
Genome Analyses and Genome-Centered Metatranscriptomics of Methanothermobacter wolfeii Strain SIV6, Isolated from a Thermophilic Production-Scale Biogas Fermenter. Microorganisms 2019; 8:microorganisms8010013. [PMID: 31861790 PMCID: PMC7022856 DOI: 10.3390/microorganisms8010013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 12/13/2019] [Accepted: 12/16/2019] [Indexed: 12/18/2022] Open
Abstract
In the thermophilic biogas-producing microbial community, the genus Methanothermobacter was previously described to be frequently abundant. The aim of this study was to establish and analyze the genome sequence of the archaeal strain Methanothermobacter wolfeii SIV6 originating from a thermophilic industrial-scale biogas fermenter and compare it to related reference genomes. The circular chromosome has a size of 1,686,891 bases, featuring a GC content of 48.89%. Comparative analyses considering three completely sequenced Methanothermobacter strains revealed a core genome of 1494 coding sequences and 16 strain specific genes for M. wolfeii SIV6, which include glycosyltransferases and CRISPR/cas associated genes. Moreover, M. wolfeii SIV6 harbors all genes for the hydrogenotrophic methanogenesis pathway and genome-centered metatranscriptomics indicates the high metabolic activity of this strain, with 25.18% of all transcripts per million (TPM) belong to the hydrogenotrophic methanogenesis pathway and 18.02% of these TPM exclusively belonging to the mcr operon. This operon encodes the different subunits of the enzyme methyl-coenzyme M reductase (EC: 2.8.4.1), which catalyzes the final and rate-limiting step during methanogenesis. Finally, fragment recruitment of metagenomic reads from the thermophilic biogas fermenter on the SIV6 genome showed that the strain is abundant (1.2%) within the indigenous microbial community. Detailed analysis of the archaeal isolate M. wolfeii SIV6 indicates its role and function within the microbial community of the thermophilic biogas fermenter, towards a better understanding of the biogas production process and a microbial-based management of this complex process.
Collapse
|
17
|
Hackley RK, Schmid AK. Global Transcriptional Programs in Archaea Share Features with the Eukaryotic Environmental Stress Response. J Mol Biol 2019; 431:4147-4166. [PMID: 31437442 PMCID: PMC7419163 DOI: 10.1016/j.jmb.2019.07.029] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 07/18/2019] [Accepted: 07/18/2019] [Indexed: 01/06/2023]
Abstract
The environmental stress response (ESR), a global transcriptional program originally identified in yeast, is characterized by a rapid and transient transcriptional response composed of large, oppositely regulated gene clusters. Genes induced during the ESR encode core components of stress tolerance, macromolecular repair, and maintenance of homeostasis. In this review, we investigate the possibility for conservation of the ESR across the eukaryotic and archaeal domains of life. We first re-analyze existing transcriptomics data sets to illustrate that a similar transcriptional response is identifiable in Halobacterium salinarum, an archaeal model organism. To substantiate the archaeal ESR, we calculated gene-by-gene correlations, gene function enrichment, and comparison of temporal dynamics. We note reported examples of variation in the ESR across fungi, then synthesize high-level trends present in expression data of other archaeal species. In particular, we emphasize the need for additional high-throughput time series expression data to further characterize stress-responsive transcriptional programs in the Archaea. Together, this review explores an open question regarding features of global transcriptional stress response programs shared across domains of life.
Collapse
Affiliation(s)
- Rylee K Hackley
- Department of Biology, Duke University, Durham, NC 27708, USA; University Program in Genetics and Genomics, Duke University, Durham, NC 27708, USA
| | - Amy K Schmid
- Department of Biology, Duke University, Durham, NC 27708, USA; University Program in Genetics and Genomics, Duke University, Durham, NC 27708, USA; Center for Genomics and Computational Biology, Duke University, Durham, NC 27708, USA.
| |
Collapse
|
18
|
Topçuoğlu BD, Meydan C, Nguyen TB, Lang SQ, Holden JF. Growth Kinetics, Carbon Isotope Fractionation, and Gene Expression in the Hyperthermophile Methanocaldococcus jannaschii during Hydrogen-Limited Growth and Interspecies Hydrogen Transfer. Appl Environ Microbiol 2019; 85:e00180-19. [PMID: 30824444 PMCID: PMC6495749 DOI: 10.1128/aem.00180-19] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 02/15/2019] [Indexed: 11/20/2022] Open
Abstract
Hyperthermophilic methanogens are often H2 limited in hot subseafloor environments, and their survival may be due in part to physiological adaptations to low H2 conditions and interspecies H2 transfer. The hyperthermophilic methanogen Methanocaldococcus jannaschii was grown in monoculture at high (80 to 83 μM) and low (15 to 27 μM) aqueous H2 concentrations and in coculture with the hyperthermophilic H2 producer Thermococcus paralvinellae The purpose was to measure changes in growth and CH4 production kinetics, CH4 fractionation, and gene expression in M. jannaschii with changes in H2 flux. Growth and cell-specific CH4 production rates of M. jannaschii decreased with decreasing H2 availability and decreased further in coculture. However, cell yield (cells produced per mole of CH4 produced) increased 6-fold when M. jannaschii was grown in coculture rather than monoculture. Relative to high H2 concentrations, isotopic fractionation of CO2 to CH4 (εCO2-CH4) was 16‰ larger for cultures grown at low H2 concentrations and 45‰ and 56‰ larger for M. jannaschii growth in coculture on maltose and formate, respectively. Gene expression analyses showed H2-dependent methylene-tetrahydromethanopterin (H4MPT) dehydrogenase expression decreased and coenzyme F420-dependent methylene-H4MPT dehydrogenase expression increased with decreasing H2 availability and in coculture growth. In coculture, gene expression decreased for membrane-bound ATP synthase and hydrogenase. The results suggest that H2 availability significantly affects the CH4 and biomass production and CH4 fractionation by hyperthermophilic methanogens in their native habitats.IMPORTANCE Hyperthermophilic methanogens and H2-producing heterotrophs are collocated in high-temperature subseafloor environments, such as petroleum reservoirs, mid-ocean ridge flanks, and hydrothermal vents. Abiotic flux of H2 can be very low in these environments, and there is a gap in our knowledge about the origin of CH4 in these habitats. In the hyperthermophile Methanocaldococcus jannaschii, growth yields increased as H2 flux, growth rates, and CH4 production rates decreased. The same trend was observed increasingly with interspecies H2 transfer between M. jannaschii and the hyperthermophilic H2 producer Thermococcus paralvinellae With decreasing H2 availability, isotopic fractionation of carbon during methanogenesis increased, resulting in isotopically more negative CH4 with a concomitant decrease in H2-dependent methylene-tetrahydromethanopterin dehydrogenase gene expression and increase in F420-dependent methylene-tetrahydromethanopterin dehydrogenase gene expression. The significance of our research is in understanding the nature of hyperthermophilic interspecies H2 transfer and identifying biogeochemical and molecular markers for assessing the physiological state of methanogens and possible source of CH4 in natural environments.
Collapse
Affiliation(s)
- Begüm D Topçuoğlu
- Department of Microbiology, University of Massachusetts, Amherst, Massachusetts, USA
| | - Cem Meydan
- Institute for Computational Biomedicine, Weill Cornell Medical College, New York, New York, USA
| | - Tran B Nguyen
- School of the Earth, Ocean, and Environment, University of South Carolina, Columbia, South Carolina, USA
| | - Susan Q Lang
- School of the Earth, Ocean, and Environment, University of South Carolina, Columbia, South Carolina, USA
| | - James F Holden
- Department of Microbiology, University of Massachusetts, Amherst, Massachusetts, USA
| |
Collapse
|
19
|
Perona-Vico E, Blasco-Gómez R, Colprim J, Puig S, Bañeras L. [NiFe]-hydrogenases are constitutively expressed in an enriched Methanobacterium sp. population during electromethanogenesis. PLoS One 2019; 14:e0215029. [PMID: 30973887 PMCID: PMC6459506 DOI: 10.1371/journal.pone.0215029] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 03/25/2019] [Indexed: 01/18/2023] Open
Abstract
Electromethanogenesis is the bioreduction of carbon dioxide (CO2) to methane (CH4) utilizing an electrode as electron donor. Some studies have reported the active participation of Methanobacterium sp. in electron capturing, although no conclusive results are available. In this study, we aimed at determining short-time changes in the expression levels of [NiFe]-hydrogenases (Eha, Ehb and Mvh), heterodisulfide reductase (Hdr), coenzyme F420-reducing [NiFe]-hydrogenase (Frh), and hydrogenase maturation protein (HypD), according to the electron flow in independently connected carbon cloth cathodes poised at– 800 mV vs. standard hydrogen electrode (SHE). Amplicon massive sequencing of cathode biofilm confirmed the presence of an enriched Methanobacterium sp. population (>70% of sequence reads), which remained in an active state (78% of cDNA reads), tagging this archaeon as the main methane producer in the system. Quantitative RT-PCR determinations of ehaB, ehbL, mvhA, hdrA, frhA, and hypD genes resulted in only slight (up to 1.5 fold) changes for four out of six genes analyzed when cells were exposed to open (disconnected) or closed (connected) electric circuit events. The presented results suggested that suspected mechanisms for electron capturing were not regulated at the transcriptional level in Methanobacterium sp. for short time exposures of the cells to connected-disconnected circuits. Additional tests are needed in order to confirm proteins that participate in electron capturing in Methanobacterium sp.
Collapse
Affiliation(s)
- Elisabet Perona-Vico
- Molecular Microbial Ecology Group, Institute of Aquatic Ecology, University of Girona, Girona, Spain
- * E-mail: (LB); (EPV)
| | | | - Jesús Colprim
- LEQUiA, Institute of the Environment, University of Girona, Girona, Spain
| | - Sebastià Puig
- LEQUiA, Institute of the Environment, University of Girona, Girona, Spain
| | - Lluis Bañeras
- Molecular Microbial Ecology Group, Institute of Aquatic Ecology, University of Girona, Girona, Spain
- * E-mail: (LB); (EPV)
| |
Collapse
|
20
|
Quitzke V, Fersch J, Seyhan D, Rother M. Selenium-dependent gene expression in Methanococcus maripaludis: Involvement of the transcriptional regulator HrsM. Biochim Biophys Acta Gen Subj 2018; 1862:2441-2450. [DOI: 10.1016/j.bbagen.2018.03.030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 03/28/2018] [Accepted: 03/29/2018] [Indexed: 01/23/2023]
|
21
|
Dong N, Bu F, Zhou Q, Khanal SK, Xie L. Performance and microbial community of hydrogenotrophic methanogenesis under thermophilic and extreme-thermophilic conditions. BIORESOURCE TECHNOLOGY 2018; 266:454-462. [PMID: 30005412 DOI: 10.1016/j.biortech.2018.05.105] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 05/29/2018] [Accepted: 05/30/2018] [Indexed: 06/08/2023]
Abstract
In this study, hydrogenotrophic methanogenesis with respect to methanogenic activity and microbial structures under extreme-thermophilic conditions were examined, and compared with the conventional thermophilic condition. The hydrogenotrophic methanogens were successfully acclimated to the temperatures of 55, 65 and 70 °C. Although acclimation was slower at 65 and 70 °C, hydrogenotrophic methanogenesis remained fairly stable. High-throughput sequencing using 16S rRNA analysis showed that the higher temperatures resulted in single archaea community dominated by hydrogenotrophic Methanothermobacter. Moreover, the syntrophic bacteria changed from Coprothermobacter and Thermodesulfovibrio at 55 °C to Thermodesulfovibrio at 70 °C. Specific hydrogenotrophic methanogenic rate at 70 °C was 98.6 ± 4.2 Nml CH4/g VS/hr, which was over 4-folds higher than that 8at 55 °C. The lag phase under extreme-thermophilic conditions was longer than thermophilic condition, which was probably due to the archaeal structure with low diversity. Extreme-thermophilic condition resulted in a shift in methanogenesis pathway from acetoclastic methanogenesis to hydrogenotrophic methanogenesis with the enrichment of Methanothermobacter thermautotrophicus.
Collapse
Affiliation(s)
- Nanshi Dong
- State Key Laboratory of Pollution Control and Resource Reuse, Key Laboratory of Yangtze River Water Environment, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, PR China
| | - Fan Bu
- State Key Laboratory of Pollution Control and Resource Reuse, Key Laboratory of Yangtze River Water Environment, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, PR China
| | - Qi Zhou
- State Key Laboratory of Pollution Control and Resource Reuse, Key Laboratory of Yangtze River Water Environment, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, PR China
| | - Samir Kumar Khanal
- Department of Molecular Biosciences and Bioengineering (MBBE), University of Hawai'i at Mānoa, 1955 East-West Road, Agricultural Science Building 218, Honolulu, HI 96822, USA
| | - Li Xie
- State Key Laboratory of Pollution Control and Resource Reuse, Key Laboratory of Yangtze River Water Environment, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China.
| |
Collapse
|
22
|
Liu P, Lu Y. Concerted Metabolic Shifts Give New Insights Into the Syntrophic Mechanism Between Propionate-Fermenting Pelotomaculum thermopropionicum and Hydrogenotrophic Methanocella conradii. Front Microbiol 2018; 9:1551. [PMID: 30038609 PMCID: PMC6046458 DOI: 10.3389/fmicb.2018.01551] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 06/21/2018] [Indexed: 11/13/2022] Open
Abstract
Microbial syntrophy is a thermodynamically-based cooperation between microbial partners that share the small amounts of free energy for anaerobic growth. To gain insights into the mechanism by which syntrophic microorganisms coordinate their metabolism, we constructed cocultures of propionate-oxidizing Pelotomaculum thermopropionicum and hydrogenotrophic Methanocella conradii and compared them to monocultures. Transcriptome analysis was performed on these cultures using strand-specific mRNA sequencing (RNA-Seq). The results showed that in coculture both P. thermopropionicum and M. conradii significantly upregulated the expression of genes involved in catabolism but downregulated those for anabolic biosynthesis. Specifically, genes coding for the methylmalonyl-CoA pathway in P. thermopropionicum and key genes for methanogenesis in M. conradii were substantially upregulated in coculture compared to monoculture. The putative flavin-based electron bifurcation/confurcation systems in both organisms were also upregulated in coculture. Formate dehydrogenase encoding genes in both organisms were markedly upregulated, indicating that formate was produced and utilized by P. thermopropionicum and M. conradii, respectively. The inhibition of syntrophic activity by formate and 2-bromoethanesulphonate (2-BES) but not H2/CO2 also suggested that formate production was used by P. thermopropionicum for the recycling of intracellular redox mediators. Finally, flagellum-induced signal transduction and amino acids exchange was upregulated for syntrophic interactions. Together, our study suggests that syntrophic organisms employ multiple strategies including global metabolic shift, utilization of electron bifurcation/confurcation and employing formate as an alternate electron carrier to optimize their metabolisms for syntrophic growth.
Collapse
Affiliation(s)
- Pengfei Liu
- College of Urban and Environmental Sciences, Peking University, Beijing, China
| | - Yahai Lu
- College of Urban and Environmental Sciences, Peking University, Beijing, China
| |
Collapse
|
23
|
A Flexible System for Cultivation of Methanococcus and Other Formate-Utilizing Methanogens. ARCHAEA-AN INTERNATIONAL MICROBIOLOGICAL JOURNAL 2017; 2017:7046026. [PMID: 29348732 PMCID: PMC5733999 DOI: 10.1155/2017/7046026] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 08/24/2017] [Indexed: 11/17/2022]
Abstract
Many hydrogenotrophic methanogens use either H2 or formate as the major electron donor to reduce CO2 for methane production. The conventional cultivation of these organisms uses H2 and CO2 as the substrate with frequent replenishment of gas during growth. H2 is explosive and requires an expensive gassing system to handle safely. Formate is as an ideal alternative substrate from the standpoints of both economy and safety but leads to large changes in the culture pH during growth. Here, we report that glycylglycine is an inexpensive and nontoxic buffer suitable for growth of Methanococcus maripaludis and Methanothermococcus okinawensis. This cultivation system is suitable for growth on liquid as well as solid medium in serum bottles. Moreover, it allows cultivation of liter scale cultures without expensive fermentation equipment. This formate cultivation system provides an inexpensive and flexible alternative for the growth of formate-utilizing, hydrogenotrophic methanogens.
Collapse
|
24
|
Gilmore SP, Henske JK, Sexton JA, Solomon KV, Seppälä S, Yoo JI, Huyett LM, Pressman A, Cogan JZ, Kivenson V, Peng X, Tan Y, Valentine DL, O'Malley MA. Genomic analysis of methanogenic archaea reveals a shift towards energy conservation. BMC Genomics 2017; 18:639. [PMID: 28826405 PMCID: PMC5563889 DOI: 10.1186/s12864-017-4036-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 08/08/2017] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND The metabolism of archaeal methanogens drives methane release into the environment and is critical to understanding global carbon cycling. Methanogenesis operates at a very low reducing potential compared to other forms of respiration and is therefore critical to many anaerobic environments. Harnessing or altering methanogen metabolism has the potential to mitigate global warming and even be utilized for energy applications. RESULTS Here, we report draft genome sequences for the isolated methanogens Methanobacterium bryantii, Methanosarcina spelaei, Methanosphaera cuniculi, and Methanocorpusculum parvum. These anaerobic, methane-producing archaea represent a diverse set of isolates, capable of methylotrophic, acetoclastic, and hydrogenotrophic methanogenesis. Assembly and analysis of the genomes allowed for simple and rapid reconstruction of metabolism in the four methanogens. Comparison of the distribution of Clusters of Orthologous Groups (COG) proteins to a sample of genomes from the RefSeq database revealed a trend towards energy conservation in genome composition of all methanogens sequenced. Further analysis of the predicted membrane proteins and transporters distinguished differing energy conservation methods utilized during methanogenesis, such as chemiosmotic coupling in Msar. spelaei and electron bifurcation linked to chemiosmotic coupling in Mbac. bryantii and Msph. cuniculi. CONCLUSIONS Methanogens occupy a unique ecological niche, acting as the terminal electron acceptors in anaerobic environments, and their genomes display a significant shift towards energy conservation. The genome-enabled reconstructed metabolisms reported here have significance to diverse anaerobic communities and have led to proposed substrate utilization not previously reported in isolation, such as formate and methanol metabolism in Mbac. bryantii and CO2 metabolism in Msph. cuniculi. The newly proposed substrates establish an important foundation with which to decipher how methanogens behave in native communities, as CO2 and formate are common electron carriers in microbial communities.
Collapse
Affiliation(s)
- Sean P Gilmore
- Department of Chemical Engineering, University of California, Santa Barbara, California, USA
| | - John K Henske
- Department of Chemical Engineering, University of California, Santa Barbara, California, USA
| | - Jessica A Sexton
- Department of Chemical Engineering, University of California, Santa Barbara, California, USA
| | - Kevin V Solomon
- Department of Chemical Engineering, University of California, Santa Barbara, California, USA.,Present Address: Agricultural & Biological Engineering, Purdue University, West Lafayette, Indiana, USA
| | - Susanna Seppälä
- Department of Chemical Engineering, University of California, Santa Barbara, California, USA.,Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Hørsholm, Denmark
| | - Justin I Yoo
- Department of Chemical Engineering, University of California, Santa Barbara, California, USA
| | - Lauren M Huyett
- Department of Chemical Engineering, University of California, Santa Barbara, California, USA
| | - Abe Pressman
- Department of Chemical Engineering, University of California, Santa Barbara, California, USA
| | - James Z Cogan
- Biology Program, College of Creative Studies, University of California, Santa Barbara, California, USA
| | - Veronika Kivenson
- Department of Earth Science and Marine Science Institute, University of California, Santa Barbara, California, USA
| | - Xuefeng Peng
- Department of Chemical Engineering, University of California, Santa Barbara, California, USA.,Department of Earth Science and Marine Science Institute, University of California, Santa Barbara, California, USA
| | - YerPeng Tan
- California NanoScience Institute, University of California, Santa Barbara, California, USA
| | - David L Valentine
- Department of Earth Science and Marine Science Institute, University of California, Santa Barbara, California, USA
| | - Michelle A O'Malley
- Department of Chemical Engineering, University of California, Santa Barbara, California, USA.
| |
Collapse
|
25
|
Susanti D, Loganathan U, Mukhopadhyay B. A Novel F420-dependent Thioredoxin Reductase Gated by Low Potential FAD: A TOOL FOR REDOX REGULATION IN AN ANAEROBE. J Biol Chem 2016; 291:23084-23100. [PMID: 27590343 DOI: 10.1074/jbc.m116.750208] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Indexed: 12/18/2022] Open
Abstract
A recent report suggested that the thioredoxin-dependent metabolic regulation, which is widespread in all domains of life, existed in methanogenic archaea about 3.5 billion years ago. We now show that the respective electron delivery enzyme (thioredoxin reductase, TrxR), although structurally similar to flavin-containing NADPH-dependent TrxRs (NTR), lacked an NADPH-binding site and was dependent on reduced coenzyme F420 (F420H2), a stronger reductant with a mid-point redox potential (E'0) of -360 mV; E'0 of NAD(P)H is -320 mV. Because F420 is a deazaflavin, this enzyme was named deazaflavin-dependent flavin-containing thioredoxin reductase (DFTR). It transferred electrons from F420H2 to thioredoxin via protein-bound flavin; Km values for thioredoxin and F420H2 were 6.3 and 28.6 μm, respectively. The E'0 of DFTR-bound flavin was approximately -389 mV, making electron transfer from NAD(P)H or F420H2 to flavin endergonic. However, under high partial pressures of hydrogen prevailing on early Earth and present day deep-sea volcanoes, the potential for the F420/F420H2 pair could be as low as -425 mV, making DFTR efficient. The presence of DFTR exclusively in ancient methanogens and mostly in the early Earth environment of deep-sea volcanoes and DFTR's characteristics suggest that the enzyme developed on early Earth and gave rise to NTR. A phylogenetic analysis revealed six more novel-type TrxR groups and suggested that the broader flavin-containing disulfide oxidoreductase family is more diverse than previously considered. The unprecedented structural similarities between an F420-dependent enzyme (DFTR) and an NADPH-dependent enzyme (NTR) brought new thoughts to investigations on F420 systems involved in microbial pathogenesis and antibiotic production.
Collapse
Affiliation(s)
| | | | - Biswarup Mukhopadhyay
- From the Department of Biochemistry, .,Biocomplexity Institute, and.,Virginia Tech Carilion School of Medicine, Virginia Tech, Blacksburg, Virginia 24061
| |
Collapse
|
26
|
Browne P, Tamaki H, Kyrpides N, Woyke T, Goodwin L, Imachi H, Bräuer S, Yavitt JB, Liu WT, Zinder S, Cadillo-Quiroz H. Genomic composition and dynamics among Methanomicrobiales predict adaptation to contrasting environments. ISME JOURNAL 2016; 11:87-99. [PMID: 27552639 DOI: 10.1038/ismej.2016.104] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Revised: 06/13/2016] [Accepted: 06/22/2016] [Indexed: 11/09/2022]
Abstract
Members of the order Methanomicrobiales are abundant, and sometimes dominant, hydrogenotrophic (H2-CO2 utilizing) methanoarchaea in a broad range of anoxic habitats. Despite their key roles in greenhouse gas emissions and waste conversion to methane, little is known about the physiological and genomic bases for their widespread distribution and abundance. In this study, we compared the genomes of nine diverse Methanomicrobiales strains, examined their pangenomes, reconstructed gene flow and identified genes putatively mediating their success across different habitats. Most strains slowly increased gene content whereas one, Methanocorpusculum labreanum, evidenced genome downsizing. Peat-dwelling Methanomicrobiales showed adaptations centered on improved transport of scarce inorganic nutrients and likely use H+ rather than Na+ transmembrane chemiosmotic gradients during energy conservation. In contrast, other Methanomicrobiales show the potential to concurrently use Na+ and H+ chemiosmotic gradients. Analyses also revealed that the Methanomicrobiales lack a canonical electron bifurcation system (MvhABGD) known to produce low potential electrons in other orders of hydrogenotrophic methanogens. Additional putative differences in anabolic metabolism suggest that the dynamics of interspecies electron transfer from Methanomicrobiales syntrophic partners can also differ considerably. Altogether, these findings suggest profound differences in electron trafficking in the Methanomicrobiales compared with other hydrogenotrophs, and warrant further functional evaluations.
Collapse
Affiliation(s)
- Patrick Browne
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
| | - Hideyuki Tamaki
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Ibaraki, Japan
| | - Nikos Kyrpides
- Department of Energy, Joint Genome Institute, Walnut Creek, CA, USA
| | - Tanja Woyke
- Department of Energy, Joint Genome Institute, Walnut Creek, CA, USA
| | | | - Hiroyuki Imachi
- Department of Subsurface Geobiological Analysis and Research, Japan Agency for Marine-Earth Science and Technology, Yokosuka, Kanagawa, Japan
| | - Suzanna Bräuer
- Department of Biology, Appalachian State University, Boone, NC, USA
| | - Joseph B Yavitt
- Department of Natural Resources, Cornell University, Ithaca, NY, USA
| | - Wen-Tso Liu
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Stephen Zinder
- Department of Microbiology, Cornell University, Ithaca, NY, USA
| | - Hinsby Cadillo-Quiroz
- School of Life Sciences, Arizona State University, Tempe, AZ, USA.,Swette Center for Environmental Biotechnology at the Biodesign Institute, Arizona State University, Tempe, AZ, USA
| |
Collapse
|
27
|
Lyu Z, Jain R, Smith P, Fetchko T, Yan Y, Whitman WB. Engineering the Autotroph Methanococcus maripaludis for Geraniol Production. ACS Synth Biol 2016; 5:577-81. [PMID: 26886063 DOI: 10.1021/acssynbio.5b00267] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The rapid autotrophic growth of the methanogenic archaeon Methanococcus maripaludis on H2 and CO2 makes it an attractive microbial chassis to inexpensively produce biochemicals. To explore this potential, a synthetic gene encoding geraniol synthase (GES) derived from Ocimum basilicum was cloned into a M. maripaludis expression vector under selection for puromycin resistance. Recombinant expression of GES in M. maripaludis during autotrophic growth on H2/CO2 or formate yielded geraniol at 2.8 and 4.0 mg g(-1) of dry weight, respectively. The yield of geraniol decreased 2-3-fold when organic carbon sources were added to stimulate heterotrophic growth. In the absence of puromycin, geraniol production during autotrophic growth on formate increased to 4.6 mg g(-1) of dry weight. A conceptual model centered on the autotrophic acetyl coenzyme A biosynthetic pathway identified strategies to divert more autotrophic carbon flux to geraniol production.
Collapse
Affiliation(s)
- Zhe Lyu
- Department of Microbiology, ‡College of Engineering, and §Department of Biochemistry and Molecular
Biology, University of Georgia, Athens, Georgia 30602, United States
| | - Rachit Jain
- Department of Microbiology, ‡College of Engineering, and §Department of Biochemistry and Molecular
Biology, University of Georgia, Athens, Georgia 30602, United States
| | - Peyton Smith
- Department of Microbiology, ‡College of Engineering, and §Department of Biochemistry and Molecular
Biology, University of Georgia, Athens, Georgia 30602, United States
| | - Travis Fetchko
- Department of Microbiology, ‡College of Engineering, and §Department of Biochemistry and Molecular
Biology, University of Georgia, Athens, Georgia 30602, United States
| | - Yajun Yan
- Department of Microbiology, ‡College of Engineering, and §Department of Biochemistry and Molecular
Biology, University of Georgia, Athens, Georgia 30602, United States
| | - William B. Whitman
- Department of Microbiology, ‡College of Engineering, and §Department of Biochemistry and Molecular
Biology, University of Georgia, Athens, Georgia 30602, United States
| |
Collapse
|
28
|
Physiology, Biochemistry, and Applications of F420- and Fo-Dependent Redox Reactions. Microbiol Mol Biol Rev 2016; 80:451-93. [PMID: 27122598 DOI: 10.1128/mmbr.00070-15] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
5-Deazaflavin cofactors enhance the metabolic flexibility of microorganisms by catalyzing a wide range of challenging enzymatic redox reactions. While structurally similar to riboflavin, 5-deazaflavins have distinctive and biologically useful electrochemical and photochemical properties as a result of the substitution of N-5 of the isoalloxazine ring for a carbon. 8-Hydroxy-5-deazaflavin (Fo) appears to be used for a single function: as a light-harvesting chromophore for DNA photolyases across the three domains of life. In contrast, its oligoglutamyl derivative F420 is a taxonomically restricted but functionally versatile cofactor that facilitates many low-potential two-electron redox reactions. It serves as an essential catabolic cofactor in methanogenic, sulfate-reducing, and likely methanotrophic archaea. It also transforms a wide range of exogenous substrates and endogenous metabolites in aerobic actinobacteria, for example mycobacteria and streptomycetes. In this review, we discuss the physiological roles of F420 in microorganisms and the biochemistry of the various oxidoreductases that mediate these roles. Particular focus is placed on the central roles of F420 in methanogenic archaea in processes such as substrate oxidation, C1 pathways, respiration, and oxygen detoxification. We also describe how two F420-dependent oxidoreductase superfamilies mediate many environmentally and medically important reactions in bacteria, including biosynthesis of tetracycline and pyrrolobenzodiazepine antibiotics by streptomycetes, activation of the prodrugs pretomanid and delamanid by Mycobacterium tuberculosis, and degradation of environmental contaminants such as picrate, aflatoxin, and malachite green. The biosynthesis pathways of Fo and F420 are also detailed. We conclude by considering opportunities to exploit deazaflavin-dependent processes in tuberculosis treatment, methane mitigation, bioremediation, and industrial biocatalysis.
Collapse
|
29
|
Effects of growth conditions on archaellation and N-glycosylation in Methanococcus maripaludis. Microbiology (Reading) 2016; 162:339-350. [DOI: 10.1099/mic.0.000221] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
|
30
|
Response of a rice paddy soil methanogen to syntrophic growth as revealed by transcriptional analyses. Appl Environ Microbiol 2015; 80:4668-76. [PMID: 24837392 DOI: 10.1128/aem.01259-14] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Members of Methanocellales are widespread in paddy field soils and play the key role in methane production. These methanogens feature largely in these organisms’ adaptation to low H2 and syntrophic growth with anaerobic fatty acid oxidizers. The adaptive mechanisms, however, remain unknown. In the present study, we determined the transcripts of 21 genes involved in the key steps of methanogenesis and acetate assimilation of Methanocella conradii HZ254, a strain recently isolated from paddy field soil. M. conradii was grown in monoculture and syntrophically with Pelotomaculum thermopropionicum (a propionate syntroph) or Syntrophothermus lipocalidus (a butyrate syntroph). Comparison of the relative transcript abundances showed that three hydrogenase-encoding genes and all methanogenesis-related genes tested were upregulated in cocultures relative to monoculture. The genes encoding formylmethanofuran dehydrogenase (Fwd), heterodisulfide reductase (Hdr), and the membrane-bound energy-converting hydrogenase (Ech) were the most upregulated among the evaluated genes. The expression of the formate dehydrogenase (Fdh)-encoding gene also was significantly upregulated. In contrast, an acetate assimilation gene was downregulated in cocultures. The genes coding for Fwd, Hdr, and the D subunit of F420-nonreducing hydrogenase (Mvh) form a large predicted transcription unit; therefore, the Mvh/Hdr/Fwd complex, capable of mediating the electron bifurcation and connecting the first and last steps of methanogenesis, was predicted to be formed in M. conradii. We propose that Methanocella methanogens cope with low H2 and syntrophic growth by (i) stabilizing the Mvh/Hdr/Fwd complex and (ii) activating formatedependent methanogenesis.
Collapse
|
31
|
Thioredoxin targets fundamental processes in a methane-producing archaeon, Methanocaldococcus jannaschii. Proc Natl Acad Sci U S A 2014; 111:2608-13. [PMID: 24505058 DOI: 10.1073/pnas.1324240111] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Thioredoxin (Trx), a small redox protein, controls multiple processes in eukaryotes and bacteria by changing the thiol redox status of selected proteins. The function of Trx in archaea is, however, unexplored. To help fill this gap, we have investigated this aspect in methanarchaea--strict anaerobes that produce methane, a fuel and greenhouse gas. Bioinformatic analyses suggested that Trx is nearly universal in methanogens. Ancient methanogens that produce methane almost exclusively from H2 plus CO2 carried approximately two Trx homologs, whereas nutritionally versatile members possessed four to eight. Due to its simplicity, we studied the Trx system of Methanocaldococcus jannaschii--a deeply rooted hyperthermophilic methanogen growing only on H2 plus CO2. The organism carried two Trx homologs, canonical Trx1 that reduced insulin and accepted electrons from Escherichia coli thioredoxin reductase and atypical Trx2. Proteomic analyses with air-oxidized extracts treated with reduced Trx1 revealed 152 potential targets representing a range of processes--including methanogenesis, biosynthesis, transcription, translation, and oxidative response. In enzyme assays, Trx1 activated two selected targets following partial deactivation by O2, validating proteomics observations: methylenetetrahydromethanopterin dehydrogenase, a methanogenesis enzyme, and sulfite reductase, a detoxification enzyme. The results suggest that Trx assists methanogens in combating oxidative stress and synchronizing metabolic activities with availability of reductant, making it a critical factor in the global carbon cycle and methane emission. Because methanogenesis developed before the oxygenation of Earth, it seems possible that Trx functioned originally in metabolic regulation independently of O2, thus raising the question whether a complex biological system of this type evolved at least 2.5 billion years ago.
Collapse
|
32
|
Abstract
The ability of organisms to sense and respond to their environment is essential to their survival. This is no different for members of the third domain of life, the Archaea. Archaea are found in diverse and often extreme habitats. However, their ability to sense and respond to their environment at the level of gene expression has been understudied when compared to bacteria and eukaryotes. Over the last decade, the field has expanded, and a variety of unique and interesting regulatory schemes have been unraveled. In this review, the current state of knowledge of archaeal transcription regulation is explored.
Collapse
|
33
|
Yoon SH, Turkarslan S, Reiss DJ, Pan M, Burn JA, Costa KC, Lie TJ, Slagel J, Moritz RL, Hackett M, Leigh JA, Baliga NS. A systems level predictive model for global gene regulation of methanogenesis in a hydrogenotrophic methanogen. Genome Res 2013; 23:1839-51. [PMID: 24089473 PMCID: PMC3814884 DOI: 10.1101/gr.153916.112] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Methanogens catalyze the critical methane-producing step (called methanogenesis) in the anaerobic decomposition of organic matter. Here, we present the first predictive model of global gene regulation of methanogenesis in a hydrogenotrophic methanogen, Methanococcus maripaludis. We generated a comprehensive list of genes (protein-coding and noncoding) for M. maripaludis through integrated analysis of the transcriptome structure and a newly constructed Peptide Atlas. The environment and gene-regulatory influence network (EGRIN) model of the strain was constructed from a compendium of transcriptome data that was collected over 58 different steady-state and time-course experiments that were performed in chemostats or batch cultures under a spectrum of environmental perturbations that modulated methanogenesis. Analyses of the EGRIN model have revealed novel components of methanogenesis that included at least three additional protein-coding genes of previously unknown function as well as one noncoding RNA. We discovered that at least five regulatory mechanisms act in a combinatorial scheme to intercoordinate key steps of methanogenesis with different processes such as motility, ATP biosynthesis, and carbon assimilation. Through a combination of genetic and environmental perturbation experiments we have validated the EGRIN-predicted role of two novel transcription factors in the regulation of phosphate-dependent repression of formate dehydrogenase—a key enzyme in the methanogenesis pathway. The EGRIN model demonstrates regulatory affiliations within methanogenesis as well as between methanogenesis and other cellular functions.
Collapse
Affiliation(s)
- Sung Ho Yoon
- Institute for Systems Biology, Seattle, Washington 98109, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
34
|
Riede S, Boguhn J, Breves G. Studies on potential effects of fumaric acid on rumen microbial fermentation, methane production and microbial community. Arch Anim Nutr 2013; 67:368-80. [DOI: 10.1080/1745039x.2013.830518] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
|
35
|
VhuD facilitates electron flow from H2 or formate to heterodisulfide reductase in Methanococcus maripaludis. J Bacteriol 2013; 195:5160-5. [PMID: 24039260 DOI: 10.1128/jb.00895-13] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Flavin-based electron bifurcation has recently been characterized as an essential energy conservation mechanism that is utilized by hydrogenotrophic methanogenic Archaea to generate low-potential electrons in an ATP-independent manner. Electron bifurcation likely takes place at the flavin associated with the α subunit of heterodisulfide reductase (HdrA). In Methanococcus maripaludis the electrons for this reaction come from either formate or H2 via formate dehydrogenase (Fdh) or Hdr-associated hydrogenase (Vhu). However, how these enzymes bind to HdrA to deliver electrons is unknown. Here, we present evidence that the δ subunit of hydrogenase (VhuD) is central to the interaction of both enzymes with HdrA. When M. maripaludis is grown under conditions where both Fdh and Vhu are expressed, these enzymes compete for binding to VhuD, which in turn binds to HdrA. Under these conditions, both enzymes are fully functional and are bound to VhuD in substoichiometric quantities. We also show that Fdh copurifies specifically with VhuD in the absence of other hydrogenase subunits. Surprisingly, in the absence of Vhu, growth on hydrogen still occurs; we show that this involves F420-reducing hydrogenase. The data presented here represent an initial characterization of specific protein interactions centered on Hdr in a hydrogenotrophic methanogen that utilizes multiple electron donors for growth.
Collapse
|
36
|
Random mutagenesis identifies factors involved in formate-dependent growth of the methanogenic archaeon Methanococcus maripaludis. Mol Genet Genomics 2013; 288:413-24. [PMID: 23801407 DOI: 10.1007/s00438-013-0756-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 05/31/2013] [Indexed: 01/25/2023]
Abstract
Methane is a key intermediate in the carbon cycle and biologically produced by methanogenic archaea. Most methanogens are able to conserve energy by reducing CO2 to methane using molecular hydrogen as electron donor (hydrogenotrophic methanogenesis), but several hydrogenotrophic methanogens can also use formate as electron donor for methanogenesis. Formate dehydrogenase (Fdh) oxidizes formate to CO2 and is involved in funneling reducing equivalents into the methanogenic pathway, but details on other factors relevant for formate-dependent physiology of methanogens are not available. To learn more about the factors involved in formate-dependent growth of Methanococcus maripaludis strain JJ, we used a recently developed system for random in vitro mutagenesis, which is based on a modified insect transposable element to create 2,865 chromosomal transposon mutants and screened them for impaired growth on formate. Of 12 M. maripaludis transposon-induced mutants exhibiting this phenotype, the transposon insertion sites in the chromosome were mapped. Among the genes, apparently affecting formate-dependent growth were those encoding archaeal transcription factor S, a regulator of ion transport, and carbon monoxide dehydrogenase/acetyl-CoA synthase. Interestingly, in seven of the mutants, transposons were localized in a 10.2 kb region where Fdh1, one of two Fdh isoforms in the organism, is encoded. Two transcription start sites within the 10.2 kb region could be mapped, and quantification of transcripts revealed that transposon insertion in this region diminished fdhA1 expression due to polar effects.
Collapse
|
37
|
Lovastatin in Aspergillus terreus: fermented rice straw extracts interferes with methane production and gene expression in Methanobrevibacter smithii. BIOMED RESEARCH INTERNATIONAL 2013; 2013:604721. [PMID: 23710454 PMCID: PMC3655455 DOI: 10.1155/2013/604721] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Revised: 03/27/2013] [Accepted: 03/27/2013] [Indexed: 12/26/2022]
Abstract
Lovastatin, a natural byproduct of some fungi, is able to inhibit HMG-CoA (3-hydroxy-3methyl glutaryl CoA) reductase. This is a key enzyme involved in isoprenoid synthesis and essential for cell membrane formation in methanogenic Archaea. In this paper, experiments were designed to test the hypothesis that lovastatin secreted by Aspergillus terreus in fermented rice straw extracts (FRSE) can inhibit growth and CH4 production in Methanobrevibacter smithii (a test methanogen). By HPLC analysis, 75% of the total lovastatin in FRSE was in the active hydroxyacid form, and in vitro studies confirmed that this had a stronger effect in reducing both growth and CH4 production in M. smithii compared to commercial lovastatin. Transmission electron micrographs revealed distorted morphological divisions of lovastatin- and FRSE-treated M. smithii cells, supporting its role in blocking normal cell membrane synthesis. Real-time PCR confirmed that both commercial lovastatin and FRSE increased (P < 0.01) the expression of HMG-CoA reductase gene (hmg). In addition, expressions of other gene transcripts in M. smithii. with a key involvement in methanogenesis were also affected. Experimental confirmation that CH4 production is inhibited by lovastatin in A. terreus-fermented rice straw paves the way for its evaluation as a feed additive for mitigating CH4 production in ruminants.
Collapse
|
38
|
Contribution of transcriptomics to systems-level understanding of methanogenic Archaea. ARCHAEA-AN INTERNATIONAL MICROBIOLOGICAL JOURNAL 2013; 2013:586369. [PMID: 23533330 PMCID: PMC3600222 DOI: 10.1155/2013/586369] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Revised: 12/24/2012] [Accepted: 01/23/2013] [Indexed: 01/25/2023]
Abstract
Methane-producing Archaea are of interest due to their contribution to atmospheric change and for their roles in technological applications including waste treatment and biofuel production. Although restricted to anaerobic environments, methanogens are found in a wide variety of habitats, where they commonly live in syntrophic relationships with bacterial partners. Owing to tight thermodynamic constraints of methanogenesis alone or in syntrophic metabolism, methanogens must carefully regulate their catabolic pathways including the regulation of RNA transcripts. The transcriptome is a dynamic and important control point in microbial systems. This paper assesses the impact of mRNA (transcriptome) studies on the understanding of methanogenesis with special consideration given to how methanogenesis is regulated to cope with nutrient limitation, environmental variability, and interactions with syntrophic partners. In comparison with traditional microarray-based transcriptome analyses, next-generation high-throughput RNA sequencing is greatly advantageous in assessing transcription start sites, the extent of 5′ untranslated regions, operonic structure, and the presence of small RNAs. We are still in the early stages of understanding RNA regulation but it is already clear that determinants beyond transcript abundance are highly relevant to the lifestyles of methanogens, requiring further study.
Collapse
|
39
|
Abstract
UNLABELLED Hydrogenotrophic methanogenic Archaea require reduced ferredoxin as an anaplerotic source of electrons for methanogenesis. H(2) oxidation by the hydrogenase Eha provides these electrons, consistent with an H(2) requirement for growth. Here we report the identification of alternative pathways of ferredoxin reduction in Methanococcus maripaludis that operate independently of Eha to stimulate methanogenesis. A suppressor mutation that increased expression of the glycolytic enzyme glyceraldehyde-3-phosphate:ferredoxin oxidoreductase resulted in a strain capable of H(2)-independent ferredoxin reduction and growth with formate as the sole electron donor. In this background, it was possible to eliminate all seven hydrogenases of M. maripaludis. Alternatively, carbon monoxide oxidation by carbon monoxide dehydrogenase could also generate reduced ferredoxin that feeds into methanogenesis. In either case, the reduced ferredoxin generated was inefficient at stimulating methanogenesis, resulting in a slow growth phenotype. As methanogenesis is limited by the availability of reduced ferredoxin under these conditions, other electron donors, such as reduced coenzyme F(420), should be abundant. Indeed, when F(420)-reducing hydrogenase was reintroduced into the hydrogenase-free mutant, the equilibrium of H(2) production via an F(420)-dependent formate:H(2) lyase activity shifted markedly toward H(2) compared to the wild type. IMPORTANCE Hydrogenotrophic methanogens are thought to require H(2) as a substrate for growth and methanogenesis. Here we show alternative pathways in methanogenic metabolism that alleviate this H(2) requirement and demonstrate, for the first time, a hydrogenotrophic methanogen that is capable of growth in the complete absence of H(2). The demonstration of alternative pathways in methanogenic metabolism suggests that this important group of organisms is metabolically more versatile than previously thought.
Collapse
|
40
|
Effects of H2 and formate on growth yield and regulation of methanogenesis in Methanococcus maripaludis. J Bacteriol 2013; 195:1456-62. [PMID: 23335420 DOI: 10.1128/jb.02141-12] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Hydrogenotrophic methanogenic Archaea are defined by an H2 requirement for growth. Despite this requirement, many hydrogenotrophs are also capable of growth with formate as an electron donor for methanogenesis. While certain responses of these organisms to hydrogen availability have been characterized, responses to formate starvation have not been reported. Here we report that during continuous culture of Methanococcus maripaludis under defined nutrient conditions, growth yields relative to methane production decreased markedly with either H2 excess or formate excess. Analysis of the growth yields of several mutants suggests that this phenomenon occurs independently of the storage of intracellular carbon or a transcriptional response to methanogenesis. Using microarray analysis, we found that the expression of genes encoding coenzyme F420-dependent steps of methanogenesis, including one of two formate dehydrogenases, increased with H2 starvation but with formate occurred at high levels regardless of limitation or excess. One gene, encoding H2-dependent methylene-tetrahydromethanopterin dehydrogenase, decreased in expression with either H2 limitation or formate limitation. Expression of genes for the second formate dehydrogenase, molybdenum-dependent formylmethanofuran dehydrogenase, and molybdenum transport increased specifically with formate limitation. Of the two formate dehydrogenases, only the first could support growth on formate in batch culture where formate was in excess.
Collapse
|
41
|
Rowe AR, Mansfeldt CB, Heavner GL, Richardson RE. Methanospirillum respiratory mRNA biomarkers correlate with hydrogenotrophic methanogenesis rate during growth and competition for hydrogen in an organochlorine-respiring mixed culture. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:372-381. [PMID: 23153046 DOI: 10.1021/es303061y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Molecular biomarkers hold promise for inferring rates of key metabolic activities in complex microbial systems. However, few studies have assessed biomarker levels for simultaneously occurring (and potentially competing) respirations. In this study, methanogenesis biomarkers for Methanospirillum hungatei were developed, tested, and compared to Dehalococcoides mccartyi biomarkers in a well-characterized mixed culture. Proteomic analyses of mixed culture samples (n = 4) confirmed expression of many M. hungatei methanogenesis enzymes. The mRNAs for two oxidoreductases detected were explored as quantitative biomarkers of hydrogenotrophic methanogenesis: a coenzyme F(420)-reducing hydrogenase (FrcA) and an iron sulfur protein (MvrD). As shown previously in D. mccartyi, M. hungatei transcript levels correlated linearly with measured (R = 0.97 for FrcA, R = 0.91 for MvrD; n = 7) or calculated respiration rate (R = 0.81 for FrcA, R = 0.62 for MvrD; n = 35) across two orders of magnitude on a log-log scale. The average abundance of MvrD transcripts was consistently two orders of magnitude lower than FrcA, regardless of experimental condition. In experiments where M. hungatei was competing for hydrogen with D. mccartyi, transcripts for the key respiratory hydrogenase HupL were generally less abundant per mL than FrcA and more abundant than MvrD. With no chlorinated electron acceptor added, HupL transcripts fell below both targets. These biomarkers hold promise for the prediction of in situ rates of respiration for these microbes, even when growing in mixed culture and utilizing a shared substrate which has important implications for both engineered and environmental systems. However, the differences in overall biomarker abundances suggest that the strength of any particular mRNA biomarker relies upon empirically established quantitative trends under a range of pertinent conditions.
Collapse
Affiliation(s)
- Annette R Rowe
- Field of Microbiology, Cornell University, Ithaca, New York, United States.
| | | | | | | |
Collapse
|
42
|
Microwave radiation and reactor design influence microbial communities during methane fermentation. ACTA ACUST UNITED AC 2012; 39:1397-405. [DOI: 10.1007/s10295-012-1141-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 04/25/2012] [Indexed: 01/19/2023]
Abstract
Abstract
The effect of reactor design and method of heating on the efficiency of methane fermentation and composition of microbial communities, especially methanogenic Archaea, were determined. The research was carried out using submerge- and trickling-bed reactors fed with wastewater and the heat supply into the reactors included a convection heating method and microwave radiation. The polymerase chain reaction-denaturing gradient gel electrophoresis and relative real-time PCR were used in order to assess the biofilm communities. The best fermentation results and the highest abundance of methanogenic Archaea in biomass were observed in microwave heated trickling-bed reactors. The research proved that in reactors of identical design, the application of microwaves enabled a higher fermentation efficiency to be obtained and simultaneously increased the diversity of methanogenic Archaea communities that favors process stability. All the identified sequences of Archaea belonged to Methanosarcina sp., suggesting that species from this genera are susceptible to non-thermal effects of microwaves. There were no effects from microwaves on the bacterial communities in both types of reactors, however, the bacterial species composition varied in the reactors of different design.
Collapse
|
43
|
Abstract
Methanococcus maripaludis grown syntrophically with Desulfovibrio vulgaris was compared with M. maripaludis monocultures grown under hydrogen limitation using transcriptional, proteomic and metabolite analyses. These measurements indicate a decrease in transcript abundance for energy-consuming biosynthetic functions in syntrophically grown M. maripaludis, with an increase in transcript abundance for genes involved in the energy-generating central pathway for methanogenesis. Compared with growth in monoculture under hydrogen limitation, the response of paralogous genes, such as those coding for hydrogenases, often diverged, with transcripts of one variant increasing in relative abundance, whereas the other was little changed or significantly decreased in abundance. A common theme was an apparent increase in transcripts for functions using H2 directly as reductant, versus those using the reduced deazaflavin (coenzyme F420). The greater importance of direct reduction by H2 was supported by improved syntrophic growth of a deletion mutant in an F420-dependent dehydrogenase of M. maripaludis. These data suggest that paralogous genes enable the methanogen to adapt to changing substrate availability, sustaining it under environmental conditions that are often near the thermodynamic threshold for growth. Additionally, the discovery of interspecies alanine transfer adds another metabolic dimension to this environmentally relevant mutualism.
Collapse
|
44
|
Oza JP, Sowers KR, Perona JJ. Linking energy production and protein synthesis in hydrogenotrophic methanogens. Biochemistry 2012; 51:2378-89. [PMID: 22401293 DOI: 10.1021/bi300106p] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Hydrogenotrophic methanogens possessing the hydrogen-dependent dehydrogenase Hmd also encode paralogs of this protein whose function is poorly understood. Here we present biochemical evidence that the two inactive Hmd paralogs of Methanocaldococcus jannaschii, HmdII and HmdIII, form binary and ternary complexes with several components of the protein translation apparatus. HmdII and HmdIII, but not the active dehydrogenase Hmd, bind with micromolar binding affinities to a number of tRNAs and form ternary complexes with tRNA(Pro) and prolyl-tRNA synthetase (ProRS). Fluorescence spectroscopy experiments also suggest that binding of HmdII and ProRS involves distinct binding determinants on the tRNA. These biochemical data suggest the possibility of a regulatory link between energy production and protein translation pathways that may allow a rapid cellular response to altered environmental conditions.
Collapse
Affiliation(s)
- Javin P Oza
- Interdepartmental Program in Biomolecular Science and Engineering, University of California, Santa Barbara, Santa Barbara, California 93106-9510, United States
| | | | | |
Collapse
|
45
|
Stock T, Selzer M, Connery S, Seyhan D, Resch A, Rother M. Disruption and complementation of the selenocysteine biosynthesis pathway reveals a hierarchy of selenoprotein gene expression in the archaeon Methanococcus maripaludis. Mol Microbiol 2011; 82:734-47. [PMID: 21992107 DOI: 10.1111/j.1365-2958.2011.07850.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Proteins containing selenocysteine are found in members of all three domains of life, Bacteria, Eukarya and Archaea. A dedicated tRNA (tRNA(sec)) serves as a scaffold for selenocysteine synthesis. However, sequence and secondary structures differ in tRNA(sec) from the different domains. An Escherichia coli strain lacking the gene for tRNA(sec) could only be complemented with the homologue from Methanococcus maripaludis when a single base in the anticodon loop was exchanged demonstrating that this base is a crucial determinant for archaeal tRNA(sec) to function in E. coli. Complementation in trans of M. maripaludis JJ mutants lacking tRNA(sec) , O-phosphoseryl-tRNA(sec) kinase or O-phosphoseryl-tRNA(sec) :selenocysteine synthase with the corresponding genes from M. maripaludis S2 restored the mutant's ability to synthesize selenoproteins. However, only partial restoration of the wild-type selenoproteome was observed as only selenocysteine-containing formate dehydrogenase was synthesized. Quantification of transcripts showed that disrupting the pathway of selenocysteine synthesis leads to downregulation of selenoprotein gene expression, concomitant with upregulation of a selenium-independent backup system, which is not re-adjusted upon complementation. This transcriptional arrest was independent of selenophosphate but depended on the 'history' of the mutants and was inheritable, which suggests that a stable genetic switch may cause the resulting hierarchy of selenoproteins synthesized.
Collapse
Affiliation(s)
- Tilmann Stock
- Institut für Molekulare Biowissenschaften, Johann Wolfgang Goethe-Universität, Frankfurt am Main, Germany
| | | | | | | | | | | |
Collapse
|
46
|
Enoki M, Shinzato N, Sato H, Nakamura K, Kamagata Y. Comparative proteomic analysis of Methanothermobacter themautotrophicus ΔH in pure culture and in co-culture with a butyrate-oxidizing bacterium. PLoS One 2011; 6:e24309. [PMID: 21904627 PMCID: PMC3164167 DOI: 10.1371/journal.pone.0024309] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Accepted: 08/06/2011] [Indexed: 11/21/2022] Open
Abstract
To understand the physiological basis of methanogenic archaea living on interspecies H2 transfer, the protein expression of a hydrogenotrophic methanogen, Methanothermobacter thermautotrophicus strain ΔH, was investigated in both pure culture and syntrophic coculture with an anaerobic butyrate oxidizer Syntrophothermus lipocalidus strain TGB-C1 as an H2 supplier. Comparative proteomic analysis showed that global protein expression of methanogen cells in the model coculture was substantially different from that of pure cultured cells. In brief, in syntrophic coculture, although methanogenesis-driven energy generation appeared to be maintained by shifting the pathway to the alternative methyl coenzyme M reductase isozyme I and cofactor F420-dependent process, the machinery proteins involved in carbon fixation, amino acid synthesis, and RNA/DNA metabolisms tended to be down-regulated, indicating restrained cell growth rather than vigorous proliferation. In addition, our proteome analysis revealed that α subunits of proteasome were differentially acetylated between the two culture conditions. Since the relevant modification has been suspected to regulate proteolytic activity of the proteasome, the global protein turnover rate could be controlled under syntrophic growth conditions. To our knowledge, the present study is the first report on N-acetylation of proteasome subunits in methanogenic archaea. These results clearly indicated that physiological adaptation of hydrogenotrophic methanogens to syntrophic growth is more complicated than that of hitherto proposed.
Collapse
Affiliation(s)
- Miho Enoki
- Research Institute of Biological Resources, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
- Marine Biotechnology Institute, Kamaishi, Iwate, Japan
| | - Naoya Shinzato
- Research Institute of Biological Resources, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
- Tropical Biosphere Research Center, University of the Ryukyus, Nishihara-cho, Okinawa, Japan
- * E-mail:
| | - Hiroaki Sato
- Research Institute for Environmental Management Technology, National Institute of Advanced Industrial Science and Technology (AIST), Japan
| | - Kohei Nakamura
- Research Institute of Biological Resources, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
- Faculty of Applied Biological Sciences, Gifu University, Gifu, Gifu, Japan
| | - Yoichi Kamagata
- Research Institute of Biological Resources, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
- Research Institute of Genome-Based Biofactory, National Institute of Advanced Industrial Science and Technology (AIST), Toyohira-ku, Sapporo, Japan
| |
Collapse
|
47
|
Yoon SH, Reiss DJ, Bare JC, Tenenbaum D, Pan M, Slagel J, Moritz RL, Lim S, Hackett M, Menon AL, Adams MWW, Barnebey A, Yannone SM, Leigh JA, Baliga NS. Parallel evolution of transcriptome architecture during genome reorganization. Genome Res 2011; 21:1892-904. [PMID: 21750103 DOI: 10.1101/gr.122218.111] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Assembly of genes into operons is generally viewed as an important process during the continual adaptation of microbes to changing environmental challenges. However, the genome reorganization events that drive this process are also the roots of instability for existing operons. We have determined that there exists a statistically significant trend that correlates the proportion of genes encoded in operons in archaea to their phylogenetic lineage. We have further characterized how microbes deal with operon instability by mapping and comparing transcriptome architectures of four phylogenetically diverse extremophiles that span the range of operon stabilities observed across archaeal lineages: a photoheterotrophic halophile (Halobacterium salinarum NRC-1), a hydrogenotrophic methanogen (Methanococcus maripaludis S2), an acidophilic and aerobic thermophile (Sulfolobus solfataricus P2), and an anaerobic hyperthermophile (Pyrococcus furiosus DSM 3638). We demonstrate how the evolution of transcriptional elements (promoters and terminators) generates new operons, restores the coordinated regulation of translocated, inverted, and newly acquired genes, and introduces completely novel regulation for even some of the most conserved operonic genes such as those encoding subunits of the ribosome. The inverse correlation (r=-0.92) between the proportion of operons with such internally located transcriptional elements and the fraction of conserved operons in each of the four archaea reveals an unprecedented view into varying stages of operon evolution. Importantly, our integrated analysis has revealed that organisms adapted to higher growth temperatures have lower tolerance for genome reorganization events that disrupt operon structures.
Collapse
Affiliation(s)
- Sung Ho Yoon
- Institute for Systems Biology, Seattle, Washington 98109, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
48
|
Leigh JA, Albers SV, Atomi H, Allers T. Model organisms for genetics in the domain Archaea: methanogens, halophiles, Thermococcales and Sulfolobales. FEMS Microbiol Rev 2011; 35:577-608. [PMID: 21265868 DOI: 10.1111/j.1574-6976.2011.00265.x] [Citation(s) in RCA: 157] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The tree of life is split into three main branches: eukaryotes, bacteria, and archaea. Our knowledge of eukaryotic and bacteria cell biology has been built on a foundation of studies in model organisms, using the complementary approaches of genetics and biochemistry. Archaea have led to some exciting discoveries in the field of biochemistry, but archaeal genetics has been slow to get off the ground, not least because these organisms inhabit some of the more inhospitable places on earth and are therefore believed to be difficult to culture. In fact, many species can be cultivated with relative ease and there has been tremendous progress in the development of genetic tools for both major archaeal phyla, the Euryarchaeota and the Crenarchaeota. There are several model organisms available for methanogens, halophiles, and thermophiles; in the latter group, there are genetic systems for Sulfolobales and Thermococcales. In this review, we present the advantages and disadvantages of working with each archaeal group, give an overview of their different genetic systems, and direct the neophyte archaeologist to the most appropriate model organism.
Collapse
Affiliation(s)
- John A Leigh
- Department of Microbiology, University of Washington, Seattle, WA, USA
| | | | | | | |
Collapse
|
49
|
Abstract
Methanogenic archaea are a unique group of strictly anaerobic microorganisms characterized by their ability, and dependence, to convert simple C1 and C2 compounds to methane for growth. The major models for studying the biology of methanogens are members of the Methanococcus and Methanosarcina species. Recent development of sophisticated tools for molecular analysis and for genetic manipulation allows investigating not only their metabolism but also their cell cycle, and their interaction with the environment in great detail. One aspect of such analyses is assessment and dissection of methanoarchaeal gene regulation, for which, at present, only a handful of cases have been investigated thoroughly, partly due to the great methodological effort required. However, it becomes more and more evident that many new regulatory paradigms can be unraveled in this unique archaeal group. Here, we report both molecular and physiological/genetic methods to assess gene regulation in Methanococcus maripaludis and Methanosarcina acetivorans, which should, however, be applicable for other methanogens as well.
Collapse
Affiliation(s)
- Michael Rother
- Institut fu¨ r Molekulare Biowissenschaften, Molekulare Mikrobiologie & Bioenergetik, Johann Wolfgang Goethe-Universita¨t, Frankfurt am Main, Germany
| | | | | |
Collapse
|
50
|
Bull AT. The renaissance of continuous culture in the post-genomics age. J Ind Microbiol Biotechnol 2010; 37:993-1021. [PMID: 20835748 DOI: 10.1007/s10295-010-0816-4] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Accepted: 08/11/2010] [Indexed: 01/08/2023]
Abstract
The development of continuous culture techniques 60 years ago and the subsequent formulation of theory and the diversification of experimental systems revolutionised microbiology and heralded a unique period of innovative research. Then, progressively, molecular biology and thence genomics and related high-information-density omics technologies took centre stage and microbial growth physiology in general faded from educational programmes and research funding priorities alike. However, there has been a gathering appreciation over the past decade that if the claims of systems biology are going to be realised, they will have to be based on rigorously controlled and reproducible microbial and cell growth platforms. This revival of continuous culture will be long lasting because its recognition as the growth system of choice is firmly established. The purpose of this review, therefore, is to remind microbiologists, particularly those new to continuous culture approaches, of the legacy of what I call the first age of continuous culture, and to explore a selection of researches that are using these techniques in this post-genomics age. The review looks at the impact of continuous culture across a comprehensive range of microbiological research and development. The ability to establish (quasi-) steady state conditions is a frequently stated advantage of continuous cultures thereby allowing environmental parameters to be manipulated without causing concomitant changes in the specific growth rate. However, the use of continuous cultures also enables the critical study of specified transition states and chemical, physical or biological perturbations. Such dynamic analyses enhance our understanding of microbial ecology and microbial pathology for example, and offer a wider scope for innovative drug discovery; they also can inform the optimization of batch and fed-batch operations that are characterized by sequential transitions states.
Collapse
Affiliation(s)
- Alan T Bull
- School of Biosciences, University of Kent, Canterbury, Kent CT27NJ, UK.
| |
Collapse
|