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Cueny RR, Voter AF, McKenzie AM, Morgenstern M, Myers KS, Place MM, Peters JM, Coon JJ, Keck JL. Altering translation allows E. coli to overcome chemically stabilized G-quadruplexes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.12.607615. [PMID: 39185182 PMCID: PMC11343134 DOI: 10.1101/2024.08.12.607615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/27/2024]
Abstract
G-quadruplex (G4) structures can form in guanine-rich DNA or RNA and have been found to modulate cellular processes including replication, transcription, and translation. Many studies on the cellular roles of G4s have focused on eukaryotic systems, with far fewer probing bacterial G4s. Using a chemical-genetic approach, we identified genes in Escherichia coli that are important for growth in G4-stabilizing conditions. Reducing levels of elongation factor Tu or slowing translation elongation with chloramphenicol suppress the effects of G4 stabilization. In contrast, reducing expression of certain translation termination or ribosome recycling proteins is detrimental to growth in G4-stabilizing conditions. Proteomic and transcriptomic analyses demonstrate that ribosome assembly factors and other proteins involved in translation are less abundant in G4-stabilizing conditions. Our integrated systems approach allowed us to propose a model for how RNA G4s can present barriers to E. coli growth and that reducing the rate of translation can compensate for G4-related stress.
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Krukenberg V, Kohtz AJ, Jay ZJ, Hatzenpichler R. Methyl-reducing methanogenesis by a thermophilic culture of Korarchaeia. Nature 2024; 632:1131-1136. [PMID: 39048017 DOI: 10.1038/s41586-024-07829-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 07/15/2024] [Indexed: 07/27/2024]
Abstract
Methanogenesis mediated by archaea is the main source of methane, a strong greenhouse gas, and thus is critical for understanding Earth's climate dynamics. Recently, genes encoding diverse methanogenesis pathways have been discovered in metagenome-assembled genomes affiliated with several archaeal phyla1-7. However, all experimental studies on methanogens are at present restricted to cultured representatives of the Euryarchaeota. Here we show methanogenic growth by a member of the lineage Korarchaeia within the phylum Thermoproteota (TACK superphylum)5-7. Following enrichment cultivation of 'Candidatus Methanodesulfokora washburnenis' strain LCB3, we used measurements of metabolic activity and isotope tracer conversion to demonstrate methanol reduction to methane using hydrogen as an electron donor. Analysis of the archaeon's circular genome and transcriptome revealed unique modifications in the energy conservation pathways linked to methanogenesis, including enzyme complexes involved in hydrogen and sulfur metabolism. The cultivation and characterization of this new group of archaea is critical for a deeper evaluation of the diversity, physiology and biochemistry of methanogens.
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Affiliation(s)
- Viola Krukenberg
- Department of Chemistry and Biochemistry, Center for Biofilm Engineering, and Thermal Biology Institute, Montana State University, Bozeman, MT, USA.
| | - Anthony J Kohtz
- Department of Chemistry and Biochemistry, Center for Biofilm Engineering, and Thermal Biology Institute, Montana State University, Bozeman, MT, USA
| | - Zackary J Jay
- Department of Chemistry and Biochemistry, Center for Biofilm Engineering, and Thermal Biology Institute, Montana State University, Bozeman, MT, USA
| | - Roland Hatzenpichler
- Department of Chemistry and Biochemistry, Center for Biofilm Engineering, and Thermal Biology Institute, Montana State University, Bozeman, MT, USA.
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, USA.
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Chang H, Du B, He K, Yin Q, Wu G. Mechanistic understanding of acclimation and energy metabolism of acetoclastic methanogens under different substrate to microorganism ratios. ENVIRONMENTAL RESEARCH 2024; 252:118911. [PMID: 38604482 DOI: 10.1016/j.envres.2024.118911] [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: 01/18/2024] [Revised: 04/05/2024] [Accepted: 04/08/2024] [Indexed: 04/13/2024]
Abstract
Mechanistic understanding of acetoclastic methanogenesis is pivotal for optimizing anaerobic digestion for efficient methane production. In this study, two different operational modes, continuous flow reactor (CFR) and sequencing batch reactor (SBR), accompanied with solids retention times (SRT) of 10 days (SBR10d and CFR10d) and 25 days (SBR25d and CFR25d) were implemented to elucidate their impacts on microbial communities and energy metabolism of methanogens in acetate-fed systems. Microbial community analysis revealed that the relative abundance of Methanosarcina (16.0%-46.0%) surpassed Methanothrix (3.7%-22.9%) in each reactor. SBRs had the potential to enrich both Methanothrix and Methanosarcina. Compared to SBRs, CFRs had lower total relative abundance of methanogens. Methanosarcina exhibited a superior enrichment in reactors with 10-day SRT, while Methanothrix preferred to be acclimated in reactors with 25-day SRT. The operational mode and SRT were also observed to affect the distribution of acetate-utilizing bacteria, including Pseudomonas, Desulfocurvus, Mesotoga, and Thauera. Regarding enzymes involved in energy metabolism, Ech and Vho/Vht demonstrated higher relative abundances at 10-day SRT compared to 25-day SRT, whereas Fpo and MtrA-H showed higher relative abundances in SBRs than those in CFRs. The relative abundance of genes encoding ATPase harbored by Methanothrix was higher than Methanosarcina at 25-day SRT. Additionally, the relative abundance of V/A-type ATPase (typically for methanogens) was observed higher in SBRs compared to CFRs, while the F-type ATPase (typically for bacteria) exhibited higher relative abundance in CFRs than that in SBRs.
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Affiliation(s)
- Huanhuan Chang
- Civil Engineering, School of Engineering, College of Science and Engineering, University of Galway, Galway H91 TK33, Ireland
| | - Bang Du
- Civil Engineering, School of Engineering, College of Science and Engineering, University of Galway, Galway H91 TK33, Ireland
| | - Kai He
- School of Civil Engineering, Sun Yat-Sen University, Guangzhou 51000, Guangdong, China
| | - Qidong Yin
- School of Civil Engineering, Sun Yat-Sen University, Guangzhou 51000, Guangdong, China
| | - Guangxue Wu
- Civil Engineering, School of Engineering, College of Science and Engineering, University of Galway, Galway H91 TK33, Ireland.
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Mitchell JH, Freedman AH, Delaney JA, Girguis PR. Co-expression analysis reveals distinct alliances around two carbon fixation pathways in hydrothermal vent symbionts. Nat Microbiol 2024; 9:1526-1539. [PMID: 38839975 DOI: 10.1038/s41564-024-01704-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Accepted: 04/19/2024] [Indexed: 06/07/2024]
Abstract
Most autotrophic organisms possess a single carbon fixation pathway. The chemoautotrophic symbionts of the hydrothermal vent tubeworm Riftia pachyptila, however, possess two functional pathways: the Calvin-Benson-Bassham (CBB) and the reductive tricarboxylic acid (rTCA) cycles. How these two pathways are coordinated is unknown. Here we measured net carbon fixation rates, transcriptional/metabolic responses and transcriptional co-expression patterns of Riftia pachyptila endosymbionts by incubating tubeworms collected from the East Pacific Rise at environmental pressures, temperature and geochemistry. Results showed that rTCA and CBB transcriptional patterns varied in response to different geochemical regimes and that each pathway is allied to specific metabolic processes; the rTCA is allied to hydrogenases and dissimilatory nitrate reduction, whereas the CBB is allied to sulfide oxidation and assimilatory nitrate reduction, suggesting distinctive yet complementary roles in metabolic function. Furthermore, our network analysis implicates the rTCA and a group 1e hydrogenase as key players in the physiological response to limitation of sulfide and oxygen. Net carbon fixation rates were also exemplary, and accordingly, we propose that co-activity of CBB and rTCA may be an adaptation for maintaining high carbon fixation rates, conferring a fitness advantage in dynamic vent environments.
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Mei N, Tremblay PL, Wu Y, Zhang T. Proposed mechanisms of electron uptake in metal-corroding methanogens and their potential for CO 2 bioconversion applications. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 923:171384. [PMID: 38432383 DOI: 10.1016/j.scitotenv.2024.171384] [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: 12/18/2023] [Revised: 02/28/2024] [Accepted: 02/28/2024] [Indexed: 03/05/2024]
Abstract
Some methanogens are electrotrophic bio-corroding microbes that can acquire electrons from solid surfaces including metals. In the laboratory, pure cultures of methanogenic cells oxidize iron-based materials including carbon steel, stainless steel, and Fe0. For buried or immersed pipelines or other metallic structures, methanogens are often major components of corroding biofilms with complex interspecies relationships. Models explaining how these microbes acquire electrons from solid donors are multifaceted and include electron transfer via redox mediators such as H2 or by direct contact through membrane proteins. Understanding the electron uptake (EU) routes employed by corroding methanogens is essential to develop efficient strategies for corrosion prevention. It is also beneficial for the development of bioenergy applications relying on methanogenic EU from solid donors such as bioelectromethanogenesis, hybrid photosynthesis, and the acceleration of anaerobic digestion with electroconductive particles. Many methanogenic species carrying out biocorrosion are the same ones forming the extensive abiotic-biological interfaces at the core of these bio-applications. This review will discuss the interactions between corrosive methanogens and metals and how the EU capability of these microbes can be harnessed for different sustainable biotechnologies.
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Affiliation(s)
- Nan Mei
- Institut WUT-AMU, Wuhan University of Technology, Wuhan 430070, PR China
| | - Pier-Luc Tremblay
- Institut WUT-AMU, Wuhan University of Technology, Wuhan 430070, PR China; School of Chemistry, Chemical Engineering, and Life Science, Wuhan University of Technology, Wuhan 430070, PR China; Shaoxing Institute for Advanced Research, Wuhan University of Technology, Shaoxing 312300, PR China; Sanya Science and Education Innovation Park, Wuhan University of Technology, Sanya 572024, PR China
| | - Yuyang Wu
- Institut WUT-AMU, Wuhan University of Technology, Wuhan 430070, PR China
| | - Tian Zhang
- Institut WUT-AMU, Wuhan University of Technology, Wuhan 430070, PR China; School of Chemistry, Chemical Engineering, and Life Science, Wuhan University of Technology, Wuhan 430070, PR China; Shaoxing Institute for Advanced Research, Wuhan University of Technology, Shaoxing 312300, PR China; Sanya Science and Education Innovation Park, Wuhan University of Technology, Sanya 572024, PR China.
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Rasal TA, Mallery CP, Brockley MW, Brown LC, Paczkowski JE, van Kessel JC. Ligand binding determines proteolytic stability of Vibrio LuxR/HapR quorum sensing transcription factors. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.15.580527. [PMID: 38405947 PMCID: PMC10888775 DOI: 10.1101/2024.02.15.580527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
In Vibrio species, quorum sensing signaling culminates in the production of a TetR-type master transcription factor collectively called the LuxR/HapR family, which regulates genes required for colonization and infection of host organisms. These proteins possess a solvent accessible putative ligand binding pocket. However, a native ligand has not been identified, and the role of ligand binding in LuxR/HapR function in Vibrionaceae is unknown. To probe the role of the ligand binding pocket, we utilize the small molecule thiophenesulfonamide inhibitor PTSP (3- p henyl-1-( t hiophen-2-yl s ulfonyl)-1 H - p yrazole) that we previously showed targets LuxR/HapR proteins. Amino acid conservation in the ligand binding pocket determines the specificity and efficacy of PTSP inhibition across Vibrio species. Here, we used structure-function analyses to identify PTSP-interacting residues in the ligand binding pocket of SmcR - the Vibrio vulnificus LuxR/HapR homolog - that are required for PTSP inhibition of SmcR activity in vivo . Forward genetic screening combined with X-ray crystallography structural determination of SmcR bound to PTSP identified substitutions at eight residues that were sufficient to reduce or eliminate PTSP-mediated SmcR inhibition. Small-angle X-ray scattering and computational modeling determined that PTSP drives allosteric unfolding at the N-terminal DNA binding domain. We discovered that SmcR is degraded by the ClpAP protease in the presence of PTSP in vivo ; substitution of key PTSP-interacting residues stabilized or increased SmcR levels in the cell. This mechanism of inhibition is observed for all thiophenesulfonamide compounds tested and against other Vibrio species. We conclude that thiophenesulfonamides specifically bind in the ligand binding pocket of LuxR/HapR proteins, promoting protein degradation and thereby suppressing downstream gene expression, implicating ligand binding as a mediator of LuxR/HapR protein stability and function to govern virulence gene expression in Vibrio pathogens. SIGNIFICANCE LuxR/HapR proteins were discovered in the 1990s as central regulators of quorum sensing gene expression and later discovered to be conserved in all studied Vibrio species. LuxR/HapR homologs regulate a wide range of genes involved in pathogenesis, including but not limited to genes involved in biofilm production and toxin secretion. As archetypal members of the broad class of TetR-type transcription factors, each LuxR/HapR protein has a predicted ligand binding pocket. However, no ligand has been identified for LuxR/HapR proteins that control their function as regulators. Here, we used LuxR/HapR-specific chemical inhibitors to determine that ligand binding drives proteolytic degradation in vivo , the first demonstration of LuxR/HapR function connected to ligand binding for this historical protein family.
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da Silva RJ, Cabo LF, George JL, Cahoon LA, Yang L, Coyne CB, Boyle JP. Human trophoblast stem cells can be used to model placental susceptibility to Toxoplasma gondii and highlight the critical importance of the trophoblast cell surface in pathogen resistance. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.10.566663. [PMID: 37986837 PMCID: PMC10659356 DOI: 10.1101/2023.11.10.566663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
The placenta is a critical barrier against viral, bacterial, and eukaryotic pathogens. For most teratogenic pathogens, the precise molecular mechanisms of placental resistance are still being unraveled. Given the importance to understand these mechanisms and challenges in replicating trophoblast- pathogen interactions using in vitro models, we tested an existing stem-cell derived model of trophoblast development for its relevance to infection with Toxoplasma gondii . We grew human trophoblast stem cells (TS CT ) under conditions leading to either syncytiotrophoblast (TS SYN ) or cytotrophoblast (TS CYT ) and infected them with T. gondii . We evaluated T. gondii proliferation and invasion, cell ultrastructure, as well as for transcriptome changes after infection. TS SYNs cells showed similar ultrastructure compared to primary cells and villous explants when analyzed by TEM and SEM, a resistance to T. gondii adhesion could be visualized on the SEM level. Furthermore, TS SYNs were highly refractory to parasite adhesion and replication, while TS CYT were not. RNA-seq data on mock-treated and infected cells identified differences between cell types as well as how they responded to T. gondii infection. We also evaluated if TS SC -derived SYNs and CYTs had distinct resistance profiles to another vertically transmitted facultative intracellular pathogen, Listeria monocytogenes . We demonstrate that TS SYNs are highly resistant to L. monocytogenes , while TS CYTs are not. Like T. gondii , TS SYN resistance to L. monocytogenes was at the level of bacterial adhesion. Altogether, our data indicate that stem-cell derived trophoblasts recapitulate resistance profiles of primary cells to T. gondii and highlight the critical importance of the placental surface in cell-autonomous resistance to teratogens.
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Khairunisa BH, Heryakusuma C, Ike K, Mukhopadhyay B, Susanti D. Evolving understanding of rumen methanogen ecophysiology. Front Microbiol 2023; 14:1296008. [PMID: 38029083 PMCID: PMC10658910 DOI: 10.3389/fmicb.2023.1296008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2023] [Accepted: 10/12/2023] [Indexed: 12/01/2023] Open
Abstract
Production of methane by methanogenic archaea, or methanogens, in the rumen of ruminants is a thermodynamic necessity for microbial conversion of feed to volatile fatty acids, which are essential nutrients for the animals. On the other hand, methane is a greenhouse gas and its production causes energy loss for the animal. Accordingly, there are ongoing efforts toward developing effective strategies for mitigating methane emissions from ruminant livestock that require a detailed understanding of the diversity and ecophysiology of rumen methanogens. Rumen methanogens evolved from free-living autotrophic ancestors through genome streamlining involving gene loss and acquisition. The process yielded an oligotrophic lifestyle, and metabolically efficient and ecologically adapted descendants. This specialization poses serious challenges to the efforts of obtaining axenic cultures of rumen methanogens, and consequently, the information on their physiological properties remains in most part inferred from those of their non-rumen representatives. This review presents the current knowledge of rumen methanogens and their metabolic contributions to enteric methane production. It also identifies the respective critical gaps that need to be filled for aiding the efforts to mitigate methane emission from livestock operations and at the same time increasing the productivity in this critical agriculture sector.
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Affiliation(s)
| | - Christian Heryakusuma
- Genetics, Bioinformatics, and Computational Biology, Virginia Tech, Blacksburg, VA, United States
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, United States
| | - Kelechi Ike
- Department of Biology, North Carolina Agricultural and Technical State University, Greensboro, NC, United States
| | - Biswarup Mukhopadhyay
- Genetics, Bioinformatics, and Computational Biology, Virginia Tech, Blacksburg, VA, United States
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, United States
- Virginia Tech Carilion School of Medicine, Virginia Tech, Blacksburg, VA, United States
| | - Dwi Susanti
- Microbial Discovery Research, BiomEdit, Greenfield, IN, United States
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Zhou J, Smith JA, Li M, Holmes DE. Methane production by Methanothrix thermoacetophila via direct interspecies electron transfer with Geobacter metallireducens. mBio 2023; 14:e0036023. [PMID: 37306514 PMCID: PMC10470525 DOI: 10.1128/mbio.00360-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 04/13/2023] [Indexed: 06/13/2023] Open
Abstract
Methanothrix is widely distributed in natural and artificial anoxic environments and plays a major role in global methane emissions. It is one of only two genera that can form methane from acetate dismutation and through participation in direct interspecies electron transfer (DIET) with exoelectrogens. Although Methanothrix is a significant member of many methanogenic communities, little is known about its physiology. In this study, transcriptomics helped to identify potential routes of electron transfer during DIET between Geobacter metallireducens and Methanothrix thermoacetophila. Additions of magnetite to cultures significantly enhanced growth by acetoclastic methanogenesis and by DIET, while granular activated carbon (GAC) amendments impaired growth. Transcriptomics suggested that the OmaF-OmbF-OmcF porin complex and the octaheme outer membrane c-type cytochrome encoded by Gmet_0930, were important for electron transport across the outer membrane of G. metallireducens during DIET with Mx. thermoacetophila. Clear differences in the metabolism of Mx. thermoacetophila when grown via DIET or acetate dismutation were not apparent. However, genes coding for proteins involved in carbon fixation, the sheath fiber protein MspA, and a surface-associated quinoprotein, SqpA, were highly expressed in all conditions. Expression of gas vesicle genes was significantly lower in DIET- than acetate-grown cells, possibly to facilitate better contact between membrane-associated redox proteins during DIET. These studies reveal potential electron transfer mechanisms utilized by both Geobacter and Methanothrix during DIET and provide important insights into the physiology of Methanothrix in anoxic environments. IMPORTANCE Methanothrix is a significant methane producer in a variety of methanogenic environments including soils and sediments as well as anaerobic digesters. Its abundance in these anoxic environments has mostly been attributed to its high affinity for acetate and its ability to grow by acetoclastic methanogenesis. However, Methanothrix species can also generate methane by directly accepting electrons from exoelectrogenic bacteria through direct interspecies electron transfer (DIET). Methane production through DIET is likely to further increase their contribution to methane production in natural and artificial environments. Therefore, acquiring a better understanding of DIET with Methanothrix will help shed light on ways to (i) minimize microbial methane production in natural terrestrial environments and (ii) maximize biogas formation by anaerobic digesters treating waste.
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Affiliation(s)
- Jinjie Zhou
- Archaeal Biology Center, Institute for Advanced Study, Shenzhen University, Shenzhen, Guangdong, China
- Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen, Guangdong, China
- Department of Microbiology, University of Massachusetts‐Amherst, Amherst, Massachusetts, USA
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen, Guangdong, China
| | - Jessica A. Smith
- Department of Microbiology, University of Massachusetts‐Amherst, Amherst, Massachusetts, USA
- Department of Biomolecular Sciences, Central Connecticut State University, New Britain, Connecticut, USA
| | - Meng Li
- Archaeal Biology Center, Institute for Advanced Study, Shenzhen University, Shenzhen, Guangdong, China
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen, Guangdong, China
| | - Dawn E. Holmes
- Department of Microbiology, University of Massachusetts‐Amherst, Amherst, Massachusetts, USA
- Department of Physical and Biological Science, Western New England University, Springfield, Massachusetts, USA
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Gallego-López GM, Guzman EC, Knoll LJ, Skala M. Metabolic changes to host cells with Toxoplasma gondii infection. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.10.552811. [PMID: 37609172 PMCID: PMC10441426 DOI: 10.1101/2023.08.10.552811] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Toxoplasma gondii, the causative agent of toxoplasmosis, is an obligate intracellular parasite that infects warm-blooded vertebrates across the world. In humans, seropositivity rates of T. gondii range from 10% to 90%. Despite its prevalence, few studies address how T. gondii infection changes the metabolism of host cells. Here, we investigate how T. gondii manipulates the host cell metabolic environment by monitoring metabolic response over time using non-invasive autofluorescence lifetime imaging of single cells, seahorse metabolic flux analysis, reactive oxygen species (ROS) production, and metabolomics. Autofluorescence lifetime imaging indicates that infected host cells become more oxidized and have an increased proportion of bound NAD(P)H with infection. These findings are consistent with changes in mitochondrial and glycolytic function, decrease of intracellular glucose, fluctuations in lactate and ROS production in infected cells over time. We also examined changes associated with the pre-invasion "kiss and spit" process using autofluorescence lifetime imaging, which similarly showed a more oxidized host cell with an increased proportion of bound NAD(P)H over 48 hours. Glucose metabolic flux analysis indicated that these changes are driven by NADH and NADP+ in T. gondii infection. In sum, metabolic changes in host cells with T. gondii infection were similar during full infection, and kiss and spit. Autofluorescence lifetime imaging can non-invasively monitor metabolic changes in host cells over a microbial infection time-course.
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Affiliation(s)
- Gina M. Gallego-López
- Morgridge Institute for Research, Madison, WI, 53706
- Department of Medical Microbiology & Immunology, University of Wisconsin-Madison, Madison, WI, 53706
| | | | - Laura J. Knoll
- Department of Medical Microbiology & Immunology, University of Wisconsin-Madison, Madison, WI, 53706
| | - Melissa Skala
- Morgridge Institute for Research, Madison, WI, 53706
- Department of Biomedical Engineering, University of Wisconsin- Madison, WI 53706, USA
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Schöne C, Poehlein A, Rother M. Genetic and Physiological Probing of Cytoplasmic Bypasses for the Energy-Converting Methyltransferase Mtr in Methanosarcina acetivorans. Appl Environ Microbiol 2023; 89:e0216122. [PMID: 37347168 PMCID: PMC10370330 DOI: 10.1128/aem.02161-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 06/01/2023] [Indexed: 06/23/2023] Open
Abstract
Methanogenesis is a unique energy metabolism carried out by members of the domain Archaea. Unlike most other methanogens, which reduce CO2 to methane with hydrogen as the electron donor, Methanosarcina acetivorans is able to grow on methylated compounds, on acetate, and on carbon monoxide (CO). These substrates are metabolized via distinct yet overlapping pathways. For the use of any single methanogenic substrate, the membrane-integral, energy-converting N5-methyl-tetrahydrosarcinapterin (H4SPT):coenzyme M (HS-CoM) methyltransferase (Mtr) is required. It was proposed that M. acetivorans can bypass the methyl transfer catalyzed by Mtr via cytoplasmic activities. To address this issue, conversion of different energy substrates by an mtr deletion mutant was analyzed. No significant methyl transfer from H4SPT to HS-CoM could be detected with CO as the electron donor. In contrast, formation of methane and CO2 in the presence of methanol or trimethylamine was indicative of an Mtr bypass in the oxidative direction. As methane thiol and dimethyl sulfide were transiently produced during methylotrophic methanogenesis in the mtr mutant, involvement in this process of methyl sulfide-dependent methyltransferases (Mts) was analyzed in a strain lacking both the Mts system and Mtr. It could be unequivocally demonstrated that the Mts system is not involved in bypassing Mtr, thereby ruling out previous proposals. Conversion of [13C]methanol indicated that in the absence of Mtr M. acetivorans provides the reducing equivalents for methyl-S-CoM reduction to methane by oxidizing (an) intracellular compound(s) to CO2 rather than disproportioning the source of methyl groups. Thus, no in vivo Mtr bypass appears to exist in M. acetivorans. IMPORTANCE Methanogenic archaea possess only a limited number of chemiosmotic coupling sites in their respiratory chains. Among them, N5-methyl-H4SPT:HS-CoM methyltransferase (Mtr) is the most widely distributed. Previous observations led to the conclusion that Methanosarcina acetivorans is able to bypass this reaction via methyl sulfide-dependent methyltransferases (Mts). However, strains lacking Mtr are not able to produce methane from CO. Also, these strains are unable to oxidize methylated substrates to CO2, in contrast to observations in the close relative Methanosarcina barkeri. The results also highlight the sole function of the Mts system in methyl sulfide metabolism. Thus, no in vivo Mtr bypass appears to exist in M. acetivorans.
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Affiliation(s)
- Christian Schöne
- Fakultät Biologie, Technische Universität Dresden, Dresden, Germany
| | - Anja Poehlein
- Department of Genomic and Applied Microbiology, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Michael Rother
- Fakultät Biologie, Technische Universität Dresden, Dresden, Germany
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Ferreira D, Venceslau SS, Bernardino R, Preto A, Zhang L, Waldbauer JR, Leavitt WD, Pereira IAC. DsrC is involved in fermentative growth and interacts directly with the FlxABCD-HdrABC complex in Desulfovibrio vulgaris Hildenborough. Environ Microbiol 2023; 25:962-976. [PMID: 36602077 DOI: 10.1111/1462-2920.16335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 12/28/2022] [Indexed: 01/06/2023]
Abstract
DsrC is a key protein in dissimilatory sulfur metabolism, where it works as co-substrate of the dissimilatory sulfite reductase DsrAB. DsrC has two conserved cysteines in a C-terminal arm that are converted to a trisulfide upon reduction of sulfite. In sulfate-reducing bacteria, DsrC is essential and previous works suggested additional functions beyond sulfite reduction. Here, we studied whether DsrC also plays a role during fermentative growth of Desulfovibrio vulgaris Hildenborough, by studying two strains where the functionality of DsrC is impaired by a lower level of expression (IPFG07) and additionally by the absence of one conserved Cys (IPFG09). Growth studies coupled with metabolite and proteomic analyses reveal that fermentation leads to lower levels of DsrC, but impairment of its function results in reduced growth by fermentation and a shift towards more fermentative metabolism during sulfate respiration. In both respiratory and fermentative conditions, there is increased abundance of the FlxABCD-HdrABC complex and Adh alcohol dehydrogenase in IPFG09 versus the wild type, which is reflected in higher production of ethanol. Pull-down experiments confirmed a direct interaction between DsrC and the FlxABCD-HdrABC complex, through the HdrB subunit. Dissimilatory sulfur metabolism, where sulfur compounds are used for energy generation, is a key process in the ecology of anoxic environments, and is more widespread among bacteria than previously believed. Two central proteins for this type of metabolism are DsrAB dissimilatory sulfite reductase and its co-substrate DsrC. Using physiological, proteomic and biochemical studies of Desulfovibrio vulgaris Hildenborough and mutants affected in DsrC functionality, we show that DsrC is also relevant for fermentative growth of this model organism and that it interacts directly with the soluble FlxABCD-HdrABC complex that links the NAD(H) pool with dissimilatory sulfite reduction.
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Affiliation(s)
- Delfim Ferreira
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Sofia S Venceslau
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Raquel Bernardino
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - André Preto
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Lichun Zhang
- Department of the Geophysical Sciences, University of Chicago, Chicago, Illinois, USA
| | - Jacob R Waldbauer
- Department of the Geophysical Sciences, University of Chicago, Chicago, Illinois, USA
| | - William D Leavitt
- Department of Earth Sciences, Dartmouth College, Hanover, New Hampshire, USA
- Department of Chemistry, Dartmouth College, Hanover, New Hampshire, USA
| | - Inês A C Pereira
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
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13
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Downing BE, Gupta D, Nayak DD. The dual role of a multi-heme cytochrome in methanogenesis: MmcA is important for energy conservation and carbon metabolism in Methanosarcina acetivorans. Mol Microbiol 2023; 119:350-363. [PMID: 36660820 DOI: 10.1111/mmi.15029] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 01/05/2023] [Accepted: 01/16/2023] [Indexed: 01/21/2023]
Abstract
Methanogenic archaea belonging to the Order Methanosarcinales conserve energy using an electron transport chain (ETC). In the genetically tractable strain Methanosarcina acetivorans, ferredoxin donates electrons to the ETC via the Rnf (Rhodobacter nitrogen fixation) complex. The Rnf complex in M. acetivorans, unlike its counterpart in Bacteria, contains a multiheme c-type cytochrome (MHC) subunit called MmcA. Early studies hypothesized MmcA is a critical component of Rnf, however recent work posits that the primary role of MmcA is facilitating extracellular electron transport. To explore the physiological role of MmcA, we characterized M. acetivorans mutants lacking either the entire Rnf complex (∆mmcA-rnf) or just the MmcA subunit (∆mmcA). Our data show that MmcA is essential for growth during acetoclastic methanogenesis but neither Rnf nor MmcA is required for methanogenic growth on methylated compounds. On methylated compounds, the absence of MmcA alone leads to a more severe growth defect compared to a Rnf deletion likely due to different strategies for ferredoxin oxidation that arise in each strain. Transcriptomic data suggest that the ∆mmcA mutant might oxidize ferredoxin by upregulating the cytosolic Wood-Ljundahl pathway for acetyl-CoA synthesis, whereas the ∆mmcA-rnf mutant may repurpose the F420 dehydrogenase complex (Fpo) to oxidize ferredoxin coupled to proton translocation. Beyond energy conservation, the deletion of rnf or mmcA leads to global transcriptional changes of genes involved in methanogenesis, carbon assimilation and regulation. Overall, our study provides systems-level insights into the non-overlapping roles of the Rnf bioenergetic complex and the associated MHC, MmcA.
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Affiliation(s)
- Blake E Downing
- Department of Plant and Microbial Biology, University of California, Berkeley, California, USA
| | - Dinesh Gupta
- Department of Molecular and Cell Biology, University of California, Berkeley, California, USA
| | - Dipti D Nayak
- Department of Molecular and Cell Biology, University of California, Berkeley, California, USA
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14
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Choy HL, Gaylord EA, Doering TL. Ergosterol distribution controls surface structure formation and fungal pathogenicity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.17.528979. [PMID: 36824733 PMCID: PMC9949117 DOI: 10.1101/2023.02.17.528979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
Ergosterol, the major sterol in fungal membranes, is critical for defining membrane fluidity and regulating cellular processes. Although ergosterol synthesis has been well defined in model yeast, little is known about sterol organization in the context of fungal pathogenesis. We identified a retrograde sterol transporter, Ysp2, in the opportunistic fungal pathogen Cryptococcus neoformans . We found that the lack of Ysp2 under host-mimicking conditions leads to abnormal accumulation of ergosterol at the plasma membrane, invagination of the plasma membrane, and malformation of the cell wall, which can be functionally rescued by inhibiting ergosterol synthesis with the antifungal drug fluconazole. We also observed that cells lacking Ysp2 mislocalize the cell surface protein Pma1 and have thinner and more permeable capsules. As a result of perturbed ergosterol distribution and its consequences, ysp2 Î" cells cannot survive in physiologically-rele-vant environments such as host phagocytes and are dramatically attenuated in virulence. These findings expand our knowledge of cryptococcal biology and underscore the importance of sterol homeostasis in fungal pathogenesis. IMPORTANCE Cryptococcus neoformans is an opportunistic fungal pathogen that kills over 100,000 people worldwide each year. Only three drugs are available to treat cryptococcosis, and these are variously limited by toxicity, availability, cost, and resistance. Ergosterol is the most abundant sterol in fungi and a key component in modulating membrane behavior. Two of the drugs used for cryptococcal infection, amphotericin B and fluconazole, target this lipid and its synthesis, highlighting its importance as a therapeutic target. We discovered a cryptococcal ergosterol transporter, Ysp2, and demonstrated its key roles in multiple aspects of cryptococcal biology and pathogenesis. These studies demonstrate the role of ergosterol homeostasis in C. neoformans virulence, deepen our understanding of a pathway with proven therapeutic importance, and open a new area of study.
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Affiliation(s)
- Hau Lam Choy
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Elizabeth A. Gaylord
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Tamara L. Doering
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA
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15
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Shen J, Liu Y, Qiao L. Photodriven Chemical Synthesis by Whole-Cell-Based Biohybrid Systems: From System Construction to Mechanism Study. ACS APPLIED MATERIALS & INTERFACES 2023; 15:6235-6259. [PMID: 36702806 DOI: 10.1021/acsami.2c19528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
By simulating natural photosynthesis, the desirable high-value chemical products and clean fuels can be sustainably generated with solar energy. Whole-cell-based photosensitized biohybrid system, which innovatively couples the excellent light-harvesting capacity of semiconductor materials with the efficient catalytic ability of intracellular biocatalysts, is an appealing interdisciplinary creature to realize photodriven chemical synthesis. In this review, we summarize the constructed whole-cell-based biohybrid systems in different application fields, including carbon dioxide fixation, nitrogen fixation, hydrogen production, and other chemical synthesis. Moreover, we elaborate the charge transfer mechanism studies of representative biohybrids, which can help to deepen the current understanding of the synergistic process between photosensitizers and microorganisms, and provide schemes for building novel biohybrids with less electron transfer resistance, advanced productive efficiency, and functional diversity. Further exploration in this field has the prospect of making a breakthrough on the biotic-abiotic interface that will provide opportunities for multidisciplinary research.
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Affiliation(s)
- Jiayuan Shen
- Department of Chemistry, and Shanghai Stomatological Hospital, Fudan University, Shanghai 200000, China
| | - Yun Liu
- Department of Chemistry, and Shanghai Stomatological Hospital, Fudan University, Shanghai 200000, China
| | - Liang Qiao
- Department of Chemistry, and Shanghai Stomatological Hospital, Fudan University, Shanghai 200000, China
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16
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Feng J, Guo X, Cai F, Fu H, Wang J. Model-based driving mechanism analysis for butyric acid production in Clostridium tyrobutyricum. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2022; 15:71. [PMID: 35752796 PMCID: PMC9233315 DOI: 10.1186/s13068-022-02169-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Accepted: 06/13/2022] [Indexed: 11/10/2022]
Abstract
Abstract
Background
Butyric acid, an essential C4 platform chemical, is widely used in food, pharmaceutical, and animal feed industries. Clostridium tyrobutyricum is the most promising microorganism for industrial bio-butyrate production. However, the metabolic driving mechanism for butyrate synthesis was still not profoundly studied.
Results
This study reports a first-generation genome-scale model (GEM) for C. tyrobutyricum, which provides a comprehensive and systematic analysis for the butyrate synthesis driving mechanisms. Based on the analysis in silico, an energy conversion system, which couples the proton efflux with butyryl-CoA transformation by two redox loops of ferredoxin, could be the main driving force for butyrate synthesis. For verifying the driving mechanism, a hydrogenase (HydA) expression was perturbed by inducible regulation and knockout. The results showed that HydA deficiency significantly improved the intracellular NADH/NAD+ rate, decreased acetate accumulation (63.6% in serum bottle and 58.1% in bioreactor), and improved the yield of butyrate (26.3% in serum bottle and 34.5% in bioreactor). It was in line with the expectation based on the energy conversion coupling driving mechanism.
Conclusions
This work show that the first-generation GEM and coupling metabolic analysis effectively promoted in-depth understanding of the metabolic driving mechanism in C. tyrobutyricum and provided a new insight for tuning metabolic flux direction in Clostridium chassis cells.
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17
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Ye J, Wang C, Gao C, Fu T, Yang C, Ren G, Lü J, Zhou S, Xiong Y. Solar-driven methanogenesis with ultrahigh selectivity by turning down H 2 production at biotic-abiotic interface. Nat Commun 2022; 13:6612. [PMID: 36329056 PMCID: PMC9633801 DOI: 10.1038/s41467-022-34423-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Accepted: 10/25/2022] [Indexed: 11/06/2022] Open
Abstract
Integration of methanogens with semiconductors is an effective approach to sustainable solar-driven methanogenesis. However, the H2 production rate by semiconductors largely exceeds that of methanogen metabolism, resulting in abundant H2 as side product. Here, we report that binary metallic active sites (namely, NiCu alloys) are incorporated into the interface between CdS semiconductors and Methanosarcina barkeri. The self-assembled Methanosarcina barkeri-NiCu@CdS exhibits nearly 100% CH4 selectivity with a quantum yield of 12.41 ± 0.16% under light illumination, which not only exceeds the reported biotic-abiotic hybrid systems but also is superior to most photocatalytic systems. Further investigation reveal that the Ni-Cu-Cu hollow sites in NiCu alloys can directly supply hydrogen atoms and electrons through photocatalysis to the Methanosarcina barkeri for methanogenesis via both extracellular and intracellular hydrogen cycles, effectively turning down the H2 production. This work provides important insights into the biotic-abiotic hybrid interface, and offers an avenue for engineering the methanogenesis process.
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Affiliation(s)
- Jie Ye
- grid.256111.00000 0004 1760 2876Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Chao Wang
- grid.256111.00000 0004 1760 2876Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Chao Gao
- grid.59053.3a0000000121679639School of Chemistry and Materials Science, University of Science and Technology of China, Hefei, 230026 China
| | - Tao Fu
- grid.256111.00000 0004 1760 2876Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Chaohui Yang
- grid.256111.00000 0004 1760 2876Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Guoping Ren
- grid.256111.00000 0004 1760 2876Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Jian Lü
- grid.256111.00000 0004 1760 2876Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Shungui Zhou
- grid.256111.00000 0004 1760 2876Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Yujie Xiong
- grid.59053.3a0000000121679639School of Chemistry and Materials Science, University of Science and Technology of China, Hefei, 230026 China
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18
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Duan H, He P, Zhang H, Shao L, Lü F. Metabolic Regulation of Mesophilic Methanosarcina barkeri to Ammonium Inhibition. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:8897-8907. [PMID: 35588324 DOI: 10.1021/acs.est.2c01212] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Undesirable ammonium concentrations can lead to unstable anaerobic digestion processes, and Methanosarcina spp. are the representative methanogens under inhibition. However, no known work seems to exist for directly exploring the detailed metabolic regulation of pure cultured representative Methanosarcina spp. to ammonium inhibition. We used transcriptomics and proteomics to profile the metabolic regulation of Methanosarcina barkeri to 1, 4, and 7 g N/L of total ammoniacal nitrogen (TAN), where free ammonia concentrations were between 1.5 and 36.1 mg N/L. At the initial stages of ammonium inhibition, the genes participating in the acquisition and assimilation of reduced nitrogen sources showed significant upregulation where the minimal fold change of gene transcription was about 2. Apart from nitrogen metabolism, the transcription of some genes in methanogenesis also significantly increased at the initial stages. For example, the genes encoding alternative heterodisulfide reductase subunits (HdrAB), energy-converting hydrogenase subunit (EchC), and methanophenazine-dependent hydrogenase subunits (VhtAC) were significantly upregulated by at least 2.05 times. For the element translocation at the initial stages, the genes participating in the uptake of ferrous iron, potassium ion, and molybdate were significantly upregulated with a minimal fold change of 2.10. As the cultivation proceeded, the gene encoding the cell division protein subunit (FtsH) was significantly upregulated by 13.0 times at 7 g N/L of TAN; meanwhile, an increment in OD600 was observed at the terminal sampling point of 7 g N/L of TAN. The present study explored the metabolic regulation of M. barkeri in stress response, protein synthesis, signal transduction, nitrogen metabolism, methanogenesis, and element translocation. The results would contribute to the understanding of the metabolic effects of ammonium inhibition on methanogens and have significant practical implication in inhibited anaerobic digestion.
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Affiliation(s)
- Haowen Duan
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092, China
| | - Pinjing He
- Institute of Waste Treatment and Reclamation, Tongji University, Shanghai 200092, China
- Shanghai Multi-Source Solid Waste Collaborative Treatment and Energy Engineering Technology Research Center, Shanghai 200092, China
| | - Hua Zhang
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092, China
- Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
| | - Liming Shao
- Institute of Waste Treatment and Reclamation, Tongji University, Shanghai 200092, China
| | - Fan Lü
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092, China
- Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
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19
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Spietz RL, Payne D, Kulkarni G, Metcalf WW, Roden EE, Boyd ES. Investigating Abiotic and Biotic Mechanisms of Pyrite Reduction. Front Microbiol 2022; 13:878387. [PMID: 35615515 PMCID: PMC9124975 DOI: 10.3389/fmicb.2022.878387] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 03/31/2022] [Indexed: 11/16/2022] Open
Abstract
Pyrite (FeS2) has a very low solubility and therefore has historically been considered a sink for iron (Fe) and sulfur (S) and unavailable to biology in the absence of oxygen and oxidative weathering. Anaerobic methanogens were recently shown to reduce FeS2 and assimilate Fe and S reduction products to meet nutrient demands. However, the mechanism of FeS2 mineral reduction and the forms of Fe and S assimilated by methanogens remained unclear. Thermodynamic calculations described herein indicate that H2 at aqueous concentrations as low as 10-10 M favors the reduction of FeS2, with sulfide (HS-) and pyrrhotite (Fe1- x S) as products; abiotic laboratory experiments confirmed the reduction of FeS2 with dissolved H2 concentrations greater than 1.98 × 10-4 M H2. Growth studies of Methanosarcina barkeri provided with FeS2 as the sole source of Fe and S resulted in H2 production but at concentrations too low to drive abiotic FeS2 reduction, based on abiotic laboratory experimental data. A strain of M. barkeri with deletions in all [NiFe]-hydrogenases maintained the ability to reduce FeS2 during growth, providing further evidence that extracellular electron transport (EET) to FeS2 does not involve H2 or [NiFe]-hydrogenases. Physical contact between cells and FeS2 was required for mineral reduction but was not required to obtain Fe and S from dissolution products. The addition of a synthetic electron shuttle, anthraquinone-2,6-disulfonate, allowed for biological reduction of FeS2 when physical contact between cells and FeS2 was prohibited, indicating that exogenous electron shuttles can mediate FeS2 reduction. Transcriptomics experiments revealed upregulation of several cytoplasmic oxidoreductases during growth of M. barkeri on FeS2, which may indicate involvement in provisioning low potential electrons for EET to FeS2. Collectively, the data presented herein indicate that reduction of insoluble FeS2 by M. barkeri occurred via electron transfer from the cell surface to the mineral surface resulting in the generation of soluble HS- and mineral-associated Fe1- x S. Solubilized Fe(II), but not HS-, from mineral-associated Fe1- x S reacts with aqueous HS- yielding aqueous iron sulfur clusters (FeS aq ) that likely serve as the Fe and S source for methanogen growth and activity. FeS aq nucleation and subsequent precipitation on the surface of cells may result in accelerated EET to FeS2, resulting in positive feedback between cell activity and FeS2 reduction.
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Affiliation(s)
- Rachel L. Spietz
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, United States
| | - Devon Payne
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, United States
| | - Gargi Kulkarni
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - William W. Metcalf
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Eric E. Roden
- Department of Geosciences, University of Wisconsin, Madison, WI, United States
| | - Eric S. Boyd
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, United States
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20
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Jin Q, Wu Q, Shapiro BM, McKernan SE. Limited Mechanistic Link Between the Monod Equation and Methanogen Growth: a Perspective from Metabolic Modeling. Microbiol Spectr 2022; 10:e0225921. [PMID: 35238612 PMCID: PMC9045329 DOI: 10.1128/spectrum.02259-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 02/06/2022] [Indexed: 11/20/2022] Open
Abstract
The Monod equation has been widely applied as the general rate law of microbial growth, but its applications are not always successful. By drawing on the frameworks of kinetic and stoichiometric metabolic models and metabolic control analysis, the modeling reported here simulated the growth kinetics of a methanogenic microorganism and illustrated that different enzymes and metabolites control growth rate to various extents and that their controls peak at either very low, intermediate, or very high substrate concentrations. In comparison, with a single term and two parameters, the Monod equation only approximately accounts for the controls of rate-determining enzymes and metabolites at very high and very low substrate concentrations, but neglects the enzymes and metabolites whose controls are most notable at intermediate concentrations. These findings support a limited link between the Monod equation and methanogen growth, and unify the competing views regarding enzyme roles in shaping growth kinetics. The results also preclude a mechanistic derivation of the Monod equation from methanogen metabolic networks and highlight a fundamental challenge in microbiology: single-term expressions may not be sufficient for accurate prediction of microbial growth. IMPORTANCE The Monod equation has been widely applied to predict the rate of microbial growth, but its application is not always successful. Using a novel metabolic modeling approach, we simulated the growth of a methanogen and uncovered a limited mechanistic link between the Monod equation and the methanogen's metabolic network. Specifically, the equation provides an approximation to the controls by rate-determining metabolites and enzymes at very low and very high substrate concentrations, but it is missing the remaining enzymes and metabolites whose controls are most notable at intermediate concentrations. These results support the Monod equation as a useful approximation of growth rates and highlight a fundamental challenge in microbial kinetics: single-term rate expressions may not be sufficient for accurate prediction of microbial growth.
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Affiliation(s)
- Qusheng Jin
- Geobiology Group, University of Oregon, Eugene, Oregon, USA
| | - Qiong Wu
- Geobiology Group, University of Oregon, Eugene, Oregon, USA
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21
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Wang C, Yu J, Ren G, Hu A, Liu X, Chen Y, Ye J, Zhou S, He Z. Self-replicating Biophotoelectrochemistry System for Sustainable CO Methanation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:4587-4596. [PMID: 35290037 DOI: 10.1021/acs.est.1c08340] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Efficient conversion of CO-rich gas to methane (CH4) provides an effective energy solution by taking advantage of existing natural gas infrastructures. However, traditional chemical and biological conversions face different challenges. Herein, an innovative biophotoelectrochemistry (BPEC) system using Methanosarcina barkeri-CdS as a biohybrid catalyst was successfully employed for CO methanation. Compared with CO2-fed BPEC, BPEC-CO significantly extended the CH4 producing time by 1.7-fold and exhibited a higher CH4 yield by 9.5-fold under light irradiation. This superior conversion of CO resulted from the fact that CO could serve as an effective quencher of reactive species along with the photoelectron production. In addition, CO was used as a carbon source either directly or indirectly via the produced CO2 for M. barkeri. Such a process improved the redox activities of membrane-bound proteins for BPEC methanogenesis. These results were consistent with the transcriptomic analyses, in which the genes for the putative CO oxidation and CO2 reduction pathways in M. barkeri were highly expressed, while the gene expression for reactive oxygen species detoxification remained relatively stable under light irradiation. This study has provided the first proof-of-concept evidence for sustainable CO methanation under a mild condition in the self-replicating BPEC system.
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Affiliation(s)
- Chao Wang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Jing Yu
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Guoping Ren
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Andong Hu
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Xing Liu
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Yiping Chen
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Jie Ye
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Shungui Zhou
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Zhen He
- Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States
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22
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Light-driven carbon dioxide reduction to methane by Methanosarcina barkeri in an electric syntrophic coculture. THE ISME JOURNAL 2022; 16:370-377. [PMID: 34341507 PMCID: PMC8776907 DOI: 10.1038/s41396-021-01078-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 07/21/2021] [Accepted: 07/22/2021] [Indexed: 02/07/2023]
Abstract
The direct conversion of CO2 to value-added chemical commodities, thereby storing solar energy, offers a promising option for alleviating both the current energy crisis and global warming. Semiconductor-biological hybrid systems are novel approaches. However, the inherent defects of photocorrosion, photodegradation, and the toxicity of the semiconductor limit the application of these biohybrid systems. We report here that Rhodopseudomonas palustris was able to directly act as a living photosensitizer to drive CO2 to CH4 conversion by Methanosarcina barkeri under illumination after coculturing. Specifically, R. palustris formed a direct electric syntrophic coculture with M. barkeri. Here, R. palustris harvested solar energy, performed anoxygenic photosynthesis using sodium thiosulfate as an electron donor, and transferred electrons extracellularly to M. barkeri to drive methane generation. The methanogenesis of M. barkeri in coculture was a light-dependent process with a production rate of 4.73 ± 0.23 μM/h under light, which is slightly higher than that of typical semiconductor-biohybrid systems (approximately 4.36 μM/h). Mechanistic and transcriptomic analyses showed that electrons were transferred either directly or indirectly (via electron shuttles), subsequently driving CH4 production. Our study suggests that R. palustris acts as a natural photosensitizer that, in coculture with M. barkeri, results in a new way to harvest solar energy that could potentially replace semiconductors in biohybrid systems.
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Chadwick GL, Skennerton CT, Laso-Pérez R, Leu AO, Speth DR, Yu H, Morgan-Lang C, Hatzenpichler R, Goudeau D, Malmstrom R, Brazelton WJ, Woyke T, Hallam SJ, Tyson GW, Wegener G, Boetius A, Orphan VJ. Comparative genomics reveals electron transfer and syntrophic mechanisms differentiating methanotrophic and methanogenic archaea. PLoS Biol 2022; 20:e3001508. [PMID: 34986141 PMCID: PMC9012536 DOI: 10.1371/journal.pbio.3001508] [Citation(s) in RCA: 49] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 04/15/2022] [Accepted: 12/08/2021] [Indexed: 11/25/2022] Open
Abstract
The anaerobic oxidation of methane coupled to sulfate reduction is a microbially mediated process requiring a syntrophic partnership between anaerobic methanotrophic (ANME) archaea and sulfate-reducing bacteria (SRB). Based on genome taxonomy, ANME lineages are polyphyletic within the phylum Halobacterota, none of which have been isolated in pure culture. Here, we reconstruct 28 ANME genomes from environmental metagenomes and flow sorted syntrophic consortia. Together with a reanalysis of previously published datasets, these genomes enable a comparative analysis of all marine ANME clades. We review the genomic features that separate ANME from their methanogenic relatives and identify what differentiates ANME clades. Large multiheme cytochromes and bioenergetic complexes predicted to be involved in novel electron bifurcation reactions are well distributed and conserved in the ANME archaea, while significant variations in the anabolic C1 pathways exists between clades. Our analysis raises the possibility that methylotrophic methanogenesis may have evolved from a methanotrophic ancestor. A comparative genomics study of anaerobic methanotrophic (ANME) archaea reveals the genetic "parts list" associated with the repeated evolutionary transition between methanogenic and methanotrophic metabolism in the archaeal domain of life.
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Affiliation(s)
- Grayson L. Chadwick
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, United States of America
- * E-mail: (GLC); (VJO)
| | - Connor T. Skennerton
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, United States of America
| | - Rafael Laso-Pérez
- Max-Planck Institute for Marine Microbiology, Bremen, Germany
- MARUM, Center for Marine Environmental Science, and Department of Geosciences, University of Bremen, Bremen, Germany
| | - Andy O. Leu
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, Australia
| | - Daan R. Speth
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, United States of America
| | - Hang Yu
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, United States of America
| | - Connor Morgan-Lang
- Graduate Program in Bioinformatics, University of British Columbia, Genome Sciences Centre, Vancouver, British Columbia, Canada
| | - Roland Hatzenpichler
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, United States of America
| | - Danielle Goudeau
- US Department of Energy Joint Genome Institute, Berkeley, California, United States of America
| | - Rex Malmstrom
- US Department of Energy Joint Genome Institute, Berkeley, California, United States of America
| | - William J. Brazelton
- School of Biological Sciences, University of Utah, Salt Lake City, Utah, United States of America
| | - Tanja Woyke
- US Department of Energy Joint Genome Institute, Berkeley, California, United States of America
| | - Steven J. Hallam
- Graduate Program in Bioinformatics, University of British Columbia, Genome Sciences Centre, Vancouver, British Columbia, Canada
- Department of Microbiology & Immunology, University of British Columbia, British Columbia, Canada
- Genome Science and Technology Program, University of British Columbia, Vancouver, British Columbia, Canada
- ECOSCOPE Training Program, University of British Columbia, Vancouver, British Columbia, Canada
- Life Sciences Institute, University of British Columbia, British Columbia, Canada
| | - Gene W. Tyson
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, Australia
| | - Gunter Wegener
- Max-Planck Institute for Marine Microbiology, Bremen, Germany
- MARUM, Center for Marine Environmental Science, and Department of Geosciences, University of Bremen, Bremen, Germany
| | - Antje Boetius
- Max-Planck Institute for Marine Microbiology, Bremen, Germany
- MARUM, Center for Marine Environmental Science, and Department of Geosciences, University of Bremen, Bremen, Germany
- Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, Bremerhaven, Germany
| | - Victoria J. Orphan
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, United States of America
- * E-mail: (GLC); (VJO)
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24
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Svenningsen MS, Svenningsen SL, Sørensen MA, Mitarai N. Existence of log-phase Escherichia coli persisters and lasting memory of a starvation pulse. Life Sci Alliance 2021; 5:5/2/e202101076. [PMID: 34795016 PMCID: PMC8605324 DOI: 10.26508/lsa.202101076] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 11/04/2021] [Accepted: 11/04/2021] [Indexed: 11/24/2022] Open
Abstract
The authors characterize the growth condition dependence of survival of bacteria exposed to lethal antibiotics for a week. 1-h starvation pulse is shown to cause an increase in survival for days. The vast majority of a bacterial population is killed when treated with a lethal concentration of antibiotics. The time scale of this killing is often comparable with the bacterial generation time before the addition of antibiotics. Yet, a small subpopulation typically survives for an extended period. However, the long-term killing dynamics of bacterial cells has not been fully quantified even in well-controlled laboratory conditions. We constructed a week-long killing assay and followed the survival fraction of Escherichia coli K12 exposed to a high concentration of ciprofloxacin. We found that long-term survivors were formed during exponential growth, with some cells surviving at least 7 d. The long-term dynamics contained at least three time scales, which greatly enhances predictions of the population survival time compared with the biphasic extrapolation from the short-term behavior. Furthermore, we observed a long memory effect of a brief starvation pulse, which was dependent on the (p)ppGpp synthase relA. Specifically, 1 h of carbon starvation before antibiotics exposure increased the surviving fraction by nearly 100-fold even after 4 d of ciprofloxacin treatment.
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Affiliation(s)
| | | | | | - Namiko Mitarai
- The Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
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25
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Liu J, Liu F, Yu J, Wang Q, Li Z, Liu K, Xu C, Yu H, Xiao L. Proteomics reveal biomethane production process induced by carbon nanotube. ENVIRONMENTAL RESEARCH 2021; 200:111417. [PMID: 34051197 DOI: 10.1016/j.envres.2021.111417] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 05/11/2021] [Accepted: 05/24/2021] [Indexed: 06/12/2023]
Abstract
Biomethane produced by methanogenic archaea is a main greenhouse resource of terrestrial and marine ecosystems, which strongly affects the global environment change. Conductive materials, especially nano-scale, show considerable intervention on biomethane production potential, but the mechanism is still unclear. Herein, we precisely quantified the absolute abundance of Methanosarcina spp. proteins affected by carbon nanotubes (CNTs) using tandem mass tag (TMT) proteomics technology. Among the 927 detectable proteins, more than three hundred, 304, showed differential expression. Gene Set Enrichment Analysis on KEGG pathways and GO biological processes revealed a trend of decreased protein synthesis induced by CNTs, suggesting these conductive nanomaterials may replace part of the cell structure and function. Interestingly, increased acetoclastic methanogenesis actually came at the expense of reduced protein synthesis in related pathways. CNTs stimulated biomethane production from acetate by stimulating intracellular redox activity and the -COOH oxidation process. These findings enhanced the understanding of the biomethane production process affected by conductive materials.
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Affiliation(s)
- Jian Liu
- Shandong Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou, 253023, PR China
| | - Fanghua Liu
- Key Laboratory of Coastal Biology and Biological Resources Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003, PR China; CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003, PR China
| | - Jiafeng Yu
- Shandong Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou, 253023, PR China.
| | - Quan Wang
- School of Resources and Environmental Engineering, Ludong University, Yantai, 264025, PR China
| | - Zhenkai Li
- School of Resources and Environmental Engineering, Ludong University, Yantai, 264025, PR China
| | - Kui Liu
- Shandong Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou, 253023, PR China
| | - Congmin Xu
- Shandong Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou, 253023, PR China
| | - Hang Yu
- Key Laboratory of Coastal Biology and Biological Resources Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003, PR China
| | - Leilei Xiao
- Key Laboratory of Coastal Biology and Biological Resources Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003, PR China; CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003, PR China.
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26
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Steiniger F, Sorokin DY, Deppenmeier U. Process of energy conservation in the extremely haloalkaliphilic methyl-reducing methanogen Methanonatronarchaeum thermophilum. FEBS J 2021; 289:549-563. [PMID: 34435454 DOI: 10.1111/febs.16165] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 08/05/2021] [Accepted: 08/24/2021] [Indexed: 11/26/2022]
Abstract
The recently isolated methanogen Methanonatronarchaeum thermophilum is an extremely haloalkaliphilic and moderately thermophilic archaeon and belongs to the novel class Methanonatronarchaeia in the phylum Halobacteriota. The knowledge about the physiology and biochemistry of members of the class Methanonatronarchaeia is still limited. It is known that M. thermophilum performs hydrogen or formate-dependent methyl-reducing methanogenesis. Here, we show that the organism was able to grow on all tested C1 -methylated substrates (methanol, trimethylamine, dimethylamine, monomethylamine) in combination with formate or molecular hydrogen. A temporary accumulation of intermediates (dimethylamine or/and monomethylamine) in the medium occurred during the consumption of trimethylamine or dimethylamine. The energy conservation of M. thermophilum was dependent on a respiratory chain consisting of a hydrogenase (VhoGAC), a formate dehydrogenase (FdhGHI), and a heterodisulfide reductase (HdrDE) that were well adapted to the harsh physicochemical conditions in the natural habitat. The experiments revealed the presence of two variants of energy-conserving oxidoreductase systems in the membrane. These included the H2 : heterodisulfide oxidoreductase system, which has already been described in Methanosarcina species, as well as the novel formate: heterodisulfide oxidoreductase system. The latter electron transport chain, which was experimentally proven for the first time, distinguishes the organism from all other known methanogenic archaea and represents a unique feature of the class Methanonatronarchaeia. Experiments with 2-hydroxyphenazine and the inhibitor diphenyleneiodonium chloride indicated that a methanophenazine-like cofactor might function as an electron carrier between the hydrogenase/ formate dehydrogenase and the heterodisulfide reductase.
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Affiliation(s)
- Fabian Steiniger
- Institute of Microbiology and Biotechnology, University of Bonn, Bonn, Germany
| | - Dimitry Y Sorokin
- Research Centre of Biotechnology, Winogradsky Institute of Microbiology, Russian Academy of Sciences, Moscow, Russia.,Department of Biotechnology, Delft University of Technology, Delft, The Netherlands
| | - Uwe Deppenmeier
- Institute of Microbiology and Biotechnology, University of Bonn, Bonn, Germany
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27
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Feldewert C, Lang K, Brune A. The hydrogen threshold of obligately methyl-reducing methanogens. FEMS Microbiol Lett 2021; 367:5895324. [PMID: 32821944 PMCID: PMC7485788 DOI: 10.1093/femsle/fnaa137] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 08/13/2020] [Indexed: 12/11/2022] Open
Abstract
Methanogenesis is the final step in the anaerobic degradation of organic matter. The most important substrates of methanogens are hydrogen plus carbon dioxide and acetate, but also the use of methanol, methylated amines, and aromatic methoxy groups appears to be more widespread than originally thought. Except for most members of the family Methanosarcinaceae, all methylotrophic methanogens require external hydrogen as reductant and therefore compete with hydrogenotrophic methanogens for this common substrate. Since methanogenesis from carbon dioxide consumes four molecules of hydrogen per molecule of methane, whereas methanogenesis from methanol requires only one, methyl-reducing methanogens should have an energetic advantage over hydrogenotrophic methanogens at low hydrogen partial pressures. However, experimental data on their hydrogen threshold is scarce and suffers from relatively high detection limits. Here, we show that the methyl-reducing methanogens Methanosphaera stadtmanae (Methanobacteriales), Methanimicrococcus blatticola (Methanosarcinales), and Methanomassiliicoccus luminyensis (Methanomassiliicoccales) consume hydrogen to partial pressures < 0.1 Pa, which is almost one order of magnitude lower than the thresholds for M. stadtmanae and M. blatticola reported in the only previous study on this topic. We conclude that methylotrophic methanogens should outcompete hydrogenotrophic methanogens for hydrogen and that their activity is limited by the availability of methyl groups.
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Affiliation(s)
- Christopher Feldewert
- Research Group Insect Gut Microbiology and Symbiosis, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Kristina Lang
- Research Group Insect Gut Microbiology and Symbiosis, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Andreas Brune
- Research Group Insect Gut Microbiology and Symbiosis, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
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28
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Roden CA, Dai Y, Seim I, Lee M, Sealfon R, McLaughlin GA, Boerneke MA, Iserman C, Wey SA, Ekena JL, Troyanskaya OG, Weeks KM, You L, Chilkoti A, Gladfelter AS. Double-stranded RNA drives SARS-CoV-2 nucleocapsid protein to undergo phase separation at specific temperatures. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2021. [PMID: 34159327 DOI: 10.1101/2021.06.14.448452] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Betacoronavirus SARS-CoV-2 infections caused the global Covid-19 pandemic. The nucleocapsid protein (N-protein) is required for multiple steps in the betacoronavirus replication cycle. SARS-CoV-2-N-protein is known to undergo liquid-liquid phase separation (LLPS) with specific RNAs at particular temperatures to form condensates. We show that N-protein recognizes at least two separate and distinct RNA motifs, both of which require double-stranded RNA (dsRNA) for LLPS. These motifs are separately recognized by N-protein's two RNA binding domains (RBDs). Addition of dsRNA accelerates and modifies N-protein LLPS in vitro and in cells and controls the temperature condensates form. The abundance of dsRNA tunes N-protein-mediated translational repression and may confer a switch from translation to genome packaging. Thus, N-protein's two RBDs interact with separate dsRNA motifs, and these interactions impart distinct droplet properties that can support multiple viral functions. These experiments demonstrate a paradigm of how RNA structure can control the properties of biomolecular condensates.
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29
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Zhou J, Holmes DE, Tang HY, Lovley DR. Correlation of Key Physiological Properties of Methanosarcina Isolates with Environment of Origin. Appl Environ Microbiol 2021; 87:e0073121. [PMID: 33931421 PMCID: PMC8316034 DOI: 10.1128/aem.00731-21] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Accepted: 04/18/2021] [Indexed: 02/06/2023] Open
Abstract
It is known that the physiology of Methanosarcina species can differ significantly, but the ecological impact of these differences is unclear. We recovered two strains of Methanosarcina from two different ecosystems with a similar enrichment and isolation method. Both strains had the same ability to metabolize organic substrates and participate in direct interspecies electron transfer but also had major physiological differences. Strain DH-1, which was isolated from an anaerobic digester, used H2 as an electron donor. Genome analysis indicated that it lacks an Rnf complex and conserves energy from acetate metabolism via intracellular H2 cycling. In contrast, strain DH-2, a subsurface isolate, lacks hydrogenases required for H2 uptake and cycling and has an Rnf complex for energy conservation when growing on acetate. Further analysis of the genomes of previously described isolates, as well as phylogenetic and metagenomic data on uncultured Methanosarcina in anaerobic digesters and diverse soils and sediments, revealed a physiological dichotomy that corresponded with environment of origin. The physiology of type I Methanosarcina revolves around H2 production and consumption. In contrast, type II Methanosarcina species eschew H2 and have genes for an Rnf complex and the multiheme, membrane-bound c-type cytochrome MmcA, shown to be essential for extracellular electron transfer. The distribution of Methanosarcina species in diverse environments suggests that the type I H2-based physiology is well suited for high-energy environments, like anaerobic digesters, whereas type II Rnf/cytochrome-based physiology is an adaptation to the slower, steady-state carbon and electron fluxes common in organic-poor anaerobic soils and sediments. IMPORTANCE Biogenic methane is a significant greenhouse gas, and the conversion of organic wastes to methane is an important bioenergy process. Methanosarcina species play an important role in methane production in many methanogenic soils and sediments as well as anaerobic waste digesters. The studies reported here emphasize that the genus Methanosarcina is composed of two physiologically distinct groups. This is important to recognize when interpreting the role of Methanosarcina in methanogenic environments, especially regarding H2 metabolism. Furthermore, the finding that type I Methanosarcina species predominate in environments with high rates of carbon and electron flux and that type II Methanosarcina species predominate in lower-energy environments suggests that evaluating the relative abundance of type I and type II Methanosarcina may provide further insights into rates of carbon and electron flux in methanogenic environments.
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Affiliation(s)
- Jinjie Zhou
- Department of Microbiology, University of Massachusetts-Amherst, Amherst, Massachusetts, USA
- School of Bioengineering, Dalian University of Technology, Dalian, Liaoning, China
| | - Dawn E. Holmes
- Department of Microbiology, University of Massachusetts-Amherst, Amherst, Massachusetts, USA
- Department of Physical and Biological Science, Western New England University, Springfield, Massachusetts, USA
| | - Hai-Yan Tang
- Department of Microbiology, University of Massachusetts-Amherst, Amherst, Massachusetts, USA
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waster Resource Utilization, Nanjing Agricultural University, Nanjing, China
| | - Derek R. Lovley
- Department of Microbiology, University of Massachusetts-Amherst, Amherst, Massachusetts, USA
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30
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Harris RL, Schuerger AC, Wang W, Tamama Y, Garvin ZK, Onstott TC. Transcriptional response to prolonged perchlorate exposure in the methanogen Methanosarcina barkeri and implications for Martian habitability. Sci Rep 2021; 11:12336. [PMID: 34117335 PMCID: PMC8196204 DOI: 10.1038/s41598-021-91882-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 05/28/2021] [Indexed: 02/05/2023] Open
Abstract
Observations of trace methane (CH4) in the Martian atmosphere are significant to the astrobiology community given the overwhelming contribution of biological methanogenesis to atmospheric CH4 on Earth. Previous studies have shown that methanogenic Archaea can generate CH4 when incubated with perchlorates, highly oxidizing chaotropic salts which have been found across the Martian surface. However, the regulatory mechanisms behind this remain completely unexplored. In this study we performed comparative transcriptomics on the methanogen Methanosarcina barkeri, which was incubated at 30˚C and 0˚C with 10-20 mM calcium-, magnesium-, or sodium perchlorate. Consistent with prior studies, we observed decreased CH4 production and apparent perchlorate reduction, with the latter process proceeding by heretofore essentially unknown mechanisms. Transcriptomic responses of M. barkeri to perchlorates include up-regulation of osmoprotectant transporters and selection against redox-sensitive amino acids. Increased expression of methylamine methanogenesis genes suggest competition for H2 with perchlorate reduction, which we propose is catalyzed by up-regulated molybdenum-containing enzymes and maintained by siphoning diffused H2 from energy-conserving hydrogenases. Methanogenesis regulatory patterns suggest Mars' freezing temperatures alone pose greater constraints to CH4 production than perchlorates. These findings increase our understanding of methanogen survival in extreme environments and confers continued consideration of a potential biological contribution to Martian CH4.
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Affiliation(s)
- Rachel L Harris
- Department of Geosciences, Princeton University, Princeton, NJ, USA.
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA.
| | - Andrew C Schuerger
- Department of Plant Pathology, University of Florida, Gainesville, FL, USA
| | - Wei Wang
- Lewis-Sigler Institute for Integrative Genomics, Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Yuri Tamama
- Department of Geosciences, Princeton University, Princeton, NJ, USA
| | - Zachary K Garvin
- Department of Geosciences, Princeton University, Princeton, NJ, USA
| | - Tullis C Onstott
- Department of Geosciences, Princeton University, Princeton, NJ, USA
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31
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Gao K, Lu Y. Putative Extracellular Electron Transfer in Methanogenic Archaea. Front Microbiol 2021; 12:611739. [PMID: 33828536 PMCID: PMC8019784 DOI: 10.3389/fmicb.2021.611739] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 03/03/2021] [Indexed: 11/14/2022] Open
Abstract
It has been suggested that a few methanogens are capable of extracellular electron transfers. For instance, Methanosarcina barkeri can directly capture electrons from the coexisting microbial cells of other species. Methanothrix harundinacea and Methanosarcina horonobensis retrieve electrons from Geobacter metallireducens via direct interspecies electron transfer (DIET). Recently, Methanobacterium, designated strain YSL, has been found to grow via DIET in the co-culture with Geobacter metallireducens. Methanosarcina acetivorans can perform anaerobic methane oxidation and respiratory growth relying on Fe(III) reduction through the extracellular electron transfer. Methanosarcina mazei is capable of electromethanogenesis under the conditions where electron-transfer mediators like H2 or formate are limited. The membrane-bound multiheme c-type cytochromes (MHC) and electrically-conductive cellular appendages have been assumed to mediate the extracellular electron transfer in bacteria like Geobacter and Shewanella species. These molecules or structures are rare but have been recently identified in a few methanogens. Here, we review the current state of knowledge for the putative extracellular electron transfers in methanogens and highlight the opportunities and challenges for future research.
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Affiliation(s)
- Kailin Gao
- College of Urban and Environmental Sciences, Peking University, Beijing, China
| | - Yahai Lu
- College of Urban and Environmental Sciences, Peking University, Beijing, China
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32
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Anaerobic Production of Isoprene by Engineered Methanosarcina Species Archaea. Appl Environ Microbiol 2021; 87:AEM.02417-20. [PMID: 33452028 DOI: 10.1128/aem.02417-20] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 12/25/2020] [Indexed: 01/14/2023] Open
Abstract
Isoprene is a valuable petrochemical used for a wide variety of consumer goods, such as adhesives and synthetic rubber. We were able to achieve a high yield of renewable isoprene by taking advantage of the naturally high-flux mevalonate lipid synthesis pathway in anaerobic methane-producing archaea (methanogens). Our study illustrates that by genetically manipulating Methanosarcina species methanogens, it is possible to create organisms that grow by producing the hemiterpene isoprene. Mass balance measurements show that engineered methanogens direct up to 4% of total carbon flux to isoprene, demonstrating that methanogens produce higher isoprene yields than engineered yeast, bacteria, or cyanobacteria, and from inexpensive feedstocks. Expression of isoprene synthase resulted in increased biomass and changes in gene expression that indicate that isoprene synthesis depletes membrane precursors and redirects electron flux, enabling isoprene to be a major metabolic product. Our results demonstrate that methanogens are a promising engineering chassis for renewable isoprene synthesis.IMPORTANCE A significant barrier to implementing renewable chemical technologies is high production costs relative to those for petroleum-derived products. Existing technologies using engineered organisms have difficulty competing with petroleum-derived chemicals due to the cost of feedstocks (such as glucose), product extraction, and purification. The hemiterpene monomer isoprene is one such chemical that cannot currently be produced using cost-competitive renewable biotechnologies. To reduce the cost of renewable isoprene, we have engineered methanogens to synthesize it from inexpensive feedstocks such as methane, methanol, acetate, and carbon dioxide. The "isoprenogen" strains we developed have potential to be used for industrial production of inexpensive renewable isoprene.
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33
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Sorokin DY, Messina E, Smedile F, La Cono V, Hallsworth JE, Yakimov MM. Carbohydrate‐dependent sulfur respiration in halo(alkali)philic archaea. Environ Microbiol 2021; 23:3789-3808. [DOI: 10.1111/1462-2920.15421] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 01/03/2021] [Accepted: 02/01/2021] [Indexed: 12/16/2022]
Affiliation(s)
- Dimitry Y. Sorokin
- Winogradsky Institute of Microbiology, Research Centre of Biotechnology Russian Academy of Sciences Moscow Russia
- Department of Biotechnology Delft University of Technology Delft The Netherlands
| | - Enzo Messina
- Institute of Biological Resources and Marine Biotechnology, IRBIM‐CNR Messina Italy
| | - Francesco Smedile
- Institute of Biological Resources and Marine Biotechnology, IRBIM‐CNR Messina Italy
| | - Violetta La Cono
- Institute of Biological Resources and Marine Biotechnology, IRBIM‐CNR Messina Italy
| | - John E. Hallsworth
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast Belfast, Northern Ireland BT9 5DL UK
| | - Michail M. Yakimov
- Institute of Biological Resources and Marine Biotechnology, IRBIM‐CNR Messina Italy
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34
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Agne M, Appel L, Seelmann C, Boll M. Enoyl-Coenzyme A Respiration via Formate Cycling in Syntrophic Bacteria. mBio 2021; 13:e0374021. [PMID: 35100874 PMCID: PMC8805022 DOI: 10.1128/mbio.03740-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 01/03/2022] [Indexed: 11/23/2022] Open
Abstract
Syntrophic bacteria play a key role in the anaerobic conversion of biological matter to methane. They convert short-chain fatty acids or alcohols to H2, formate, and acetate that serve as substrates for methanogenic archaea. Many syntrophic bacteria can also grow with unsaturated fatty acids such as crotonate without a syntrophic partner, and the reducing equivalents derived from the oxidation of one crotonate to two acetate are regenerated by the reduction of a second crotonate. However, it has remained unresolved how the oxidative and reductive catabolic branches are interconnected and how energy may be conserved in the reductive branch. Here, we provide evidence that during axenic growth of the syntrophic model organism Syntrophus aciditrophicus with crotonate, the NAD+-dependent oxidation of 3-hydroxybutyryl-CoA to acetoacetyl-CoA is coupled to the reduction of crotonyl-CoA via formate cycling. In this process, the intracellular formate generated by a NAD+-regenerating CO2 reductase is taken up by a periplasmic, membrane-bound formate dehydrogenase that in concert with a membrane-bound electron-transferring flavoprotein (ETF):methylmenaquinone oxidoreductase, ETF, and an acyl-CoA dehydrogenase reduces intracellular enoyl-CoA to acyl-CoA. This novel type of energy metabolism, referred to as enoyl-CoA respiration, generates a proton motive force via a methylmenaquinone-dependent redox-loop. As a result, the beneficial syntrophic cooperation of fermenting bacteria and methanogenic archaea during growth with saturated fatty acids appears to turn into a competition for formate and/or H2 during growth with unsaturated fatty acids. IMPORTANCE The syntrophic interaction of fermenting bacteria and methanogenic archaea is important for the global carbon cycle. As an example, it accomplishes the conversion of biomass-derived saturated fatty acid fermentation intermediates into methane. In contrast, unsaturated fatty acid intermediates such as crotonate may serve as growth substrate for the fermenting partner alone. Thereby, the reducing equivalents generated during the oxidation of one crotonate to two acetate are regenerated by reduction of a second crotonate to butyrate. Here, we show that the oxidative and reductive branches of this pathway are connected via formate cycling involving an energy-conserving redox-loop. We refer to this previously unknown type of energy metabolism as to enoyl-CoA respiration with acyl-CoA dehydrogenases serving as cytoplasmic terminal reductases.
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Affiliation(s)
- Michael Agne
- Faculty of Biology–Microbiology, Albert-Ludwigs-Universität Freiburg, Freiburg im Breisgau, Germany
- Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, Freiburg, Germany
| | - Lena Appel
- Faculty of Biology–Microbiology, Albert-Ludwigs-Universität Freiburg, Freiburg im Breisgau, Germany
| | - Carola Seelmann
- Faculty of Biology–Microbiology, Albert-Ludwigs-Universität Freiburg, Freiburg im Breisgau, Germany
| | - Matthias Boll
- Faculty of Biology–Microbiology, Albert-Ludwigs-Universität Freiburg, Freiburg im Breisgau, Germany
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Ferry JG. Methanosarcina acetivorans: A Model for Mechanistic Understanding of Aceticlastic and Reverse Methanogenesis. Front Microbiol 2020; 11:1806. [PMID: 32849414 PMCID: PMC7399021 DOI: 10.3389/fmicb.2020.01806] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 07/09/2020] [Indexed: 11/13/2022] Open
Abstract
Acetate-utilizing methanogens are responsible for approximately two-thirds of the one billion metric tons of methane produced annually in Earth's anaerobic environments. Methanosarcina acetivorans has emerged as a model organism for the mechanistic understanding of aceticlastic methanogenesis and reverse methanogenesis applicable to understanding the methane and carbon cycles in nature. It has the largest genome in the Archaea, supporting a metabolic complexity that enables a remarkable ability for adapting to environmental opportunities and challenges. Biochemical investigations have revealed an aceticlastic pathway capable of fermentative and respiratory energy conservation that explains how Ms. acetivorans is able to grow and compete in the environment. The mechanism of respiratory energy conservation also plays a role in overcoming endothermic reactions that are key to reversing methanogenesis.
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Affiliation(s)
- James G Ferry
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, United States
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Ye J, Ren G, Kang L, Zhang Y, Liu X, Zhou S, He Z. Efficient Photoelectron Capture by Ni Decoration in Methanosarcina barkeri-CdS Biohybrids for Enhanced Photocatalytic CO 2-to-CH 4 Conversion. iScience 2020; 23:101287. [PMID: 32623335 PMCID: PMC7334578 DOI: 10.1016/j.isci.2020.101287] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 05/19/2020] [Accepted: 06/13/2020] [Indexed: 01/08/2023] Open
Abstract
Semi-artificial photosynthesis (biohybrid) provides an intriguing opportunity for efficient CO2-to-CH4 conversion. However, creating a desirable semiconductor in biohybrids remains a great challenge. Here, by doping Ni into CdS nanoparticles, we have successfully developed the Methanosarcina barkeri-Ni:CdS biohybrids. The CH4 yield by the M. barkeri-Ni(0.75%):CdS biohybrids was approximately 250% higher than that by the M. barkeri-CdS biohybrids. The suitable Ni dopants serve as an effective electron sink, which accelerates the photoelectron transfer in biohybrids. In addition, Ni doping changes the metabolic status of M. barkeri and results in a higher expression of a series of proteins for electron transfer, energy conversion, and CO2 fixation. These increased proteins can promote the photoelectron capture by M. barkeri and injection into cells, which trigger a higher intracellular reduction potential to drive the reduction of CO2 to CH4. Our discovery will offer a promising strategy for the optimization of biohybrids in the solar-to-chemical conversion. M. barkeri-Ni:CdS biohybrids were successfully developed for CO2 reduction A highest QE of 2.08% was achieved by the M. barkeri-Ni(0.75%):CdS biohybrids Ni dopants effectively suppressed the electron-hole recombination in biohybrids Ni doping changed the metabolic status of M. barkeri in biohybrids
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Affiliation(s)
- Jie Ye
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Guoping Ren
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Li Kang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Yiyun Zhang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Xing Liu
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Shungui Zhou
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Zhen He
- Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA
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Chen J, Wade MJ, Dolfing J, Soyer OS. Increasing sulfate levels show a differential impact on synthetic communities comprising different methanogens and a sulfate reducer. J R Soc Interface 2020; 16:20190129. [PMID: 31064258 PMCID: PMC6544901 DOI: 10.1098/rsif.2019.0129] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Methane-producing microbial communities are of ecological and biotechnological interest. Syntrophic interactions among sulfate reducers and aceto/hydrogenotrophic and obligate hydrogenotrophic methanogens form a key component of these communities, yet, the impact of these different syntrophic routes on methane production and their stability against sulfate availability are not well understood. Here, we construct model synthetic communities using a sulfate reducer and two types of methanogens representing different methanogenesis routes. We find that tri-cultures with both routes increase methane production by almost twofold compared to co-cultures and are stable in the absence of sulfate. With increasing sulfate, system stability and productivity decreases and does so faster in communities with aceto/hydrogenotrophic methanogens despite the continued presence of acetate. We show that this is due to a shift in the metabolism of these methanogens towards co-utilization of hydrogen with acetate. These findings indicate the important role of hydrogen dynamics in the stability and productivity of syntrophic communities.
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Affiliation(s)
- Jing Chen
- 1 School of Life Sciences, University of Warwick , Coventry CV4 7AL , UK
| | - Matthew J Wade
- 3 School of Engineering, Newcastle University , Newcastle NE1 7RU , UK.,4 School of Mathematics and Statistics, McMaster University , Hamilton, Ontario , Canada L8S 4K1
| | - Jan Dolfing
- 3 School of Engineering, Newcastle University , Newcastle NE1 7RU , UK
| | - Orkun S Soyer
- 1 School of Life Sciences, University of Warwick , Coventry CV4 7AL , UK.,2 Warwick Integrative Synthetic Biology Centre (WISB), University of Warwick , Coventry CV4 7AL , UK
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Chatzidionysiou K, Svenungsson E, Faustini F. Could severe COVID-19 be considered a complementopathy? Lupus Sci Med 2020; 7:e000415. [PMID: 32430402 PMCID: PMC7246101 DOI: 10.1136/lupus-2020-000415] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 05/13/2020] [Indexed: 02/05/2023]
Affiliation(s)
- Katerina Chatzidionysiou
- Rheumatology Unit, Karolinska University Hospital, Karolinska Institutet Department of Medicine Solna, Stockholm, Sweden
| | - Elisabet Svenungsson
- Rheumatology Unit, Karolinska University Hospital, Karolinska Institutet Department of Medicine Solna, Stockholm, Sweden
| | - Francesca Faustini
- Rheumatology Unit, Karolinska University Hospital, Karolinska Institutet Department of Medicine Solna, Stockholm, Sweden
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It does not always take two to tango: "Syntrophy" via hydrogen cycling in one bacterial cell. ISME JOURNAL 2020; 14:1561-1570. [PMID: 32203116 PMCID: PMC7242416 DOI: 10.1038/s41396-020-0627-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Revised: 02/18/2020] [Accepted: 02/26/2020] [Indexed: 11/10/2022]
Abstract
Interspecies hydrogen transfer in anoxic ecosystems is essential for the complete microbial breakdown of organic matter to methane. Acetogenic bacteria are key players in anaerobic food webs and have been considered as prime candidates for hydrogen cycling. We have tested this hypothesis by mutational analysis of the hydrogenase in the model acetogen Acetobacterium woodii. Hydrogenase-deletion mutants no longer grew on H2 + CO2 or organic substrates such as fructose, lactate, or ethanol. Heterotrophic growth could be restored by addition of molecular hydrogen to the culture, indicating that hydrogen is an intermediate in heterotrophic growth. Indeed, hydrogen production from fructose was detected in a stirred-tank reactor. The mutant grew well on organic substrates plus caffeate, an alternative electron acceptor that does not require molecular hydrogen but NADH as reductant. These data are consistent with the notion that molecular hydrogen is produced from organic substrates and then used as reductant for CO2 reduction. Surprisingly, hydrogen cycling in A. woodii is different from the known modes of interspecies or intraspecies hydrogen cycling. Our data are consistent with a novel type of hydrogen cycling that connects an oxidative and reductive metabolic module in one bacterial cell, “intracellular syntrophy.”
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Wang H, Byrne JM, Liu P, Liu J, Dong X, Lu Y. Redox cycling of Fe(II) and Fe(III) in magnetite accelerates aceticlastic methanogenesis by Methanosarcina mazei. ENVIRONMENTAL MICROBIOLOGY REPORTS 2020; 12:97-109. [PMID: 31876088 DOI: 10.1111/1758-2229.12819] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2019] [Accepted: 12/20/2019] [Indexed: 06/10/2023]
Abstract
It has been recently shown that magnetite nanoparticles (nanoFe3 O4 ) can facilitate methanogenic syntrophy but the effect of magnetite on methanogenesis alone remains elusive. Here we show that aceticlastic methanogenesis by Methanosarcina mazei is accelerated by magnetite and is correlated with the redox cycling of structural Fe(II) and Fe(III) in the mineral. An enrichment and its closest pure culture relative, Ms. mazei zm-15, both obtained from a natural wetland of the Tibetan plateau were tested in this experiment. The Fe(II) to Fe(III) ratios in magnetite, as measured by multiple approaches, show an initial increase in both the methanogenic cultures and the blank preparations containing no microbes. The Fe(II)/Fe(III) ratio then displays a distinct decline followed by an increase towards the end of incubation only in the enrichment and pure culture cultivations. This redox cycling of magnetite is in accordance with the stimulation of aceticlastic methanogenesis. Microscopic observation reveals the precipitation of nanoFe3 O4 on methanogen cell surface. The genomic analysis predicts that in addition to electron transfer components essential for aceticlastic methanogenesis, Ms. mazei zm-15 contains an outer-surface multiheme c-type cytochrome (MHC) and a few function-unknown surface proteins that harbour monoheme motif. We hypothesize that the redox cycling of nanoFe3 O4 delivers a positive influence via the MHC to the membrane electron transfer chain and hence promote the aceticlastic methanogenesis.
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Affiliation(s)
- Hui Wang
- College of Urban and Environmental Sciences, Peking University, Beijing, 100871, China
| | - James M Byrne
- Geomicrobiology, Center for Applied Geosciences, University of Tuebingen, Sigwartstrasse, 10, 70726, Tuebingen, Germany
| | - Pengfei Liu
- Department of Soil and Crop Sciences, Colorado State University, 80521, Fort Collins, CO, USA
| | - Juan Liu
- College of Environmental Sciences and Engineering, Peking University, Beijing, 100871, China
| | - Xiuzhu Dong
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Yahai Lu
- College of Urban and Environmental Sciences, Peking University, Beijing, 100871, China
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He P, Duan H, Han W, Liu Y, Shao L, Lü F. Responses of Methanosarcina barkeri to acetate stress. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:289. [PMID: 31890017 PMCID: PMC6913021 DOI: 10.1186/s13068-019-1630-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 12/05/2019] [Indexed: 05/30/2023]
Abstract
BACKGROUND Anaerobic digestion of easily degradable biowaste can lead to the accumulation of volatile fatty acids, which will cause environmental stress to the sensitive methanogens consequently. The metabolic characteristics of methanogens under acetate stress can affect the overall performance of mixed consortia. Nevertheless, there exist huge gaps in understanding the responses of the dominant methanogens to the stress, e.g., Methanosarcinaceae. Such methanogens are resistant to environmental deterioration and able to utilize multiple carbon sources. In this study, transcriptomic and proteomic analyses were conducted to explore the responses of Methanosarcina barkeri strain MS at different acetate concentrations of 10, 25, and 50 mM. RESULTS The trend of OD600 and the regulation of the specific genes in 50 mM acetate, indicated that high concentration of acetate promoted the acclimation of M. barkeri to acetate stress. Acetate stress hindered the regulation of quorum sensing and thereby eliminated the advantages of cell aggregation, which was beneficial to resist stress. Under acetate stress, M. barkeri allocated more resources to enhance the uptake of iron to maintain the integrities of electron-transport chains and other essential biological processes. Comparing with the initial stages of different acetate concentrations, most of the genes participating in acetoclastic methanogenesis did not show significantly different expressions except hdrB1C1, an electron-bifurcating heterodisulfide reductase participating in energy conversion and improving thermodynamic efficiency. Meanwhile, vnfDGHK and nifDHK participating in nitrogen fixation pathway were upregulated. CONCLUSION In this work, transcriptomic and proteomic analyses are combined to reveal the responses of M. barkeri to acetate stress in terms of central metabolic pathways, which provides basic clues for exploring the responses of other specific methanogens under high organics load. Moreover, the results can also be used to gain insights into the complex interactions and geochemical cycles among natural or engineered populations. Furthermore, these findings also provide the potential for designing effective and robust anaerobic digesters with high organic loads.
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Affiliation(s)
- Pinjing He
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai, 200092 China
- Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092 China
- Institute of Waste Treatment and Reclamation, Tongji University, Shanghai, 200092 China
| | - Haowen Duan
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai, 200092 China
| | - Wenhao Han
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai, 200092 China
| | - Yang Liu
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai, 200092 China
| | - Liming Shao
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai, 200092 China
- Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092 China
- Institute of Waste Treatment and Reclamation, Tongji University, Shanghai, 200092 China
| | - Fan Lü
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai, 200092 China
- Institute of Waste Treatment and Reclamation, Tongji University, Shanghai, 200092 China
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Fu B, Jin X, Conrad R, Liu H, Liu H. Competition Between Chemolithotrophic Acetogenesis and Hydrogenotrophic Methanogenesis for Exogenous H 2/CO 2 in Anaerobically Digested Sludge: Impact of Temperature. Front Microbiol 2019; 10:2418. [PMID: 31749772 PMCID: PMC6842956 DOI: 10.3389/fmicb.2019.02418] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 10/07/2019] [Indexed: 11/13/2022] Open
Abstract
Anaerobic digestion is a widely applied technology for sewage sludge treatment. Hydrogen and CO2 are important degradation products, which serve as substrates for both hydrogenotrophic methanogenesis and chemolithotrophic acetogenesis. In order to understand the competition between these processes for H2/CO2, sludge samples were incubated under H2/CO2 headspace at different temperatures, and analyzed with respect to turnover of H2, CO2, CH4 and acetate including their δ13C values. At 15°C, 13C-depleted acetate (δ13C of -41 to -43‰) and transient acetate accumulation were observed under H2/CO2, and CH4 accumulated with δ13C values increasing from -53 to -33‰. The copy numbers of the fhs gene, which is characteristic for acetogenic bacteria, were at 15°C one order of magnitude higher in the H2/CO2 incubations than the N2 control. At 30°C, however, acetate did not accumulate in the H2/CO2 incubation and the δ13C of CH4 was very low (-100 to -77‰). At 50°C, isotopically enriched acetate was transiently formed and subsequently consumed followed by the production of 13C-depleted CH4. Collectively, the results indicate a high contribution of chemolithotrophic acetogenesis to H2/CO2 utilization at 15°C and 50°C, while H2/CO2 was mainly consumed by hydrogenotrophic methanogenesis at 30°C. Fermentative production and methanogenic consumption of acetate were active at 50°C.
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Affiliation(s)
- Bo Fu
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environmental and Civil Engineering, Jiangnan University, Wuxi, China.,Department of Biogeochemistry, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany.,Jiangsu Collaborative Innovation Center of Technology and Material of Water Treatment, Suzhou, China
| | - Xin Jin
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environmental and Civil Engineering, Jiangnan University, Wuxi, China
| | - Ralf Conrad
- Department of Biogeochemistry, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Hongbo Liu
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environmental and Civil Engineering, Jiangnan University, Wuxi, China.,Jiangsu Collaborative Innovation Center of Technology and Material of Water Treatment, Suzhou, China
| | - He Liu
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environmental and Civil Engineering, Jiangnan University, Wuxi, China.,Jiangsu Collaborative Innovation Center of Technology and Material of Water Treatment, Suzhou, China
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Energy Conservation and Hydrogenase Function in Methanogenic Archaea, in Particular the Genus Methanosarcina. Microbiol Mol Biol Rev 2019; 83:83/4/e00020-19. [PMID: 31533962 DOI: 10.1128/mmbr.00020-19] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The biological production of methane is vital to the global carbon cycle and accounts for ca. 74% of total methane emissions. The organisms that facilitate this process, methanogenic archaea, belong to a large and phylogenetically diverse group that thrives in a wide range of anaerobic environments. Two main subgroups exist within methanogenic archaea: those with and those without cytochromes. Although a variety of metabolisms exist within this group, the reduction of growth substrates to methane using electrons from molecular hydrogen is, in a phylogenetic sense, the most widespread methanogenic pathway. Methanogens without cytochromes typically generate methane by the reduction of CO2 with electrons derived from H2, formate, or secondary alcohols, generating a transmembrane ion gradient for ATP production via an Na+-translocating methyltransferase (Mtr). These organisms also conserve energy with a novel flavin-based electron bifurcation mechanism, wherein the endergonic reduction of ferredoxin is facilitated by the exergonic reduction of a disulfide terminal electron acceptor coupled to either H2 or formate oxidation. Methanogens that utilize cytochromes have a broader substrate range, and can convert acetate and methylated compounds to methane, in addition to the ability to reduce CO2 Cytochrome-containing methanogens are able to supplement the ion motive force generated by Mtr with an H+-translocating electron transport system. In both groups, enzymes known as hydrogenases, which reversibly interconvert protons and electrons to molecular hydrogen, play a central role in the methanogenic process. This review discusses recent insight into methanogen metabolism and energy conservation mechanisms with a particular focus on the genus Methanosarcina.
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Baffert C, Kpebe A, Avilan L, Brugna M. Hydrogenases and H 2 metabolism in sulfate-reducing bacteria of the Desulfovibrio genus. Adv Microb Physiol 2019; 74:143-189. [PMID: 31126530 DOI: 10.1016/bs.ampbs.2019.03.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Hydrogen metabolism plays a central role in sulfate-reducing bacteria of the Desulfovibrio genus and is based on hydrogenases that catalyze the reversible conversion of protons into dihydrogen. These metabolically versatile microorganisms possess a complex hydrogenase system composed of several enzymes of both [FeFe]- and [NiFe]-type that can vary considerably from one Desulfovibrio species to another. This review covers the molecular and physiological aspects of hydrogenases and H2 metabolism in Desulfovibrio but focuses particularly on our model bacterium Desulfovibrio fructosovorans. The search of hydrogenase genes in more than 30 sequenced genomes provides an overview of the distribution of these enzymes in Desulfovibrio. Our discussion will consider the significance of the involvement of electron-bifurcation in H2 metabolism.
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Affiliation(s)
- Carole Baffert
- Aix-Marseille University, CNRS, BIP, 31 Chemin Joseph Aiguier, 13402 Marseille, France
| | - Arlette Kpebe
- Aix-Marseille University, CNRS, BIP, 31 Chemin Joseph Aiguier, 13402 Marseille, France
| | - Luisana Avilan
- Aix-Marseille University, CNRS, BIP, 31 Chemin Joseph Aiguier, 13402 Marseille, France
| | - Myriam Brugna
- Aix-Marseille University, CNRS, BIP, 31 Chemin Joseph Aiguier, 13402 Marseille, France
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45
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Fu L, Zhou T, Wang J, You L, Lu Y, Yu L, Zhou S. NanoFe 3O 4 as Solid Electron Shuttles to Accelerate Acetotrophic Methanogenesis by Methanosarcina barkeri. Front Microbiol 2019; 10:388. [PMID: 30891017 PMCID: PMC6411705 DOI: 10.3389/fmicb.2019.00388] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 02/13/2019] [Indexed: 12/13/2022] Open
Abstract
Magnetite nanoparticles (nanoFe3O4) have been reported to facilitate direct interspecies electron transfer (DIET) between syntrophic bacteria and methanogens thereby improving syntrophic methanogenesis. However, whether or how nanoFe3O4 affects acetotrophic methanogenesis remain unknown. Herein, we demonstrate the unique role of nanoFe3O4 in accelerating methane production from direct acetotrophic methanogenesis in Methanosarcina-enriched cultures, which was further confirmed by pure cultures of Methanosarcina barkeri. Compared with other nanomaterials of higher electrical conductivity such as carbon nanotubes and graphite, nanoFe3O4 with mixed valence Fe(II) and Fe(III) had the most significant stimulatory effect on methane production, suggesting its redox activity rather than electrical conductivity led to enhanced methanogenesis by M. barkeri. Cell morphology and spectroscopy analysis revealed that nanoFe3O4 penetrated into the cell membrane and cytoplasm of M. barkeri. These results provide the unprecedented possibility that nanoFe3O4 in the cell membrane of methanogens serve as electron shuttles to facilitate intracellular electron transfer and thus enhance methane production. This work has important implications not only for understanding the mechanisms of mineral-methanogen interaction but also for optimizing engineered methanogenic processes.
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Affiliation(s)
- Li Fu
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China.,College of Urban and Environmental Sciences, Peking University, Beijing, China
| | - Ting Zhou
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Jingyuan Wang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Lexing You
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Yahai Lu
- College of Urban and Environmental Sciences, Peking University, Beijing, China
| | - Linpeng Yu
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Shungui Zhou
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
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Abstract
Hydrogenases are metal-containing biocatalysts that reversibly convert protons and electrons to hydrogen gas. This reaction can contribute in different ways to the generation of the proton motive force (PMF) of a cell. One means of PMF generation involves reduction of protons on the inside of the cytoplasmic membrane, releasing H2 gas, which being without charge is freely diffusible across the cytoplasmic membrane, where it can be re-oxidized to release protons. A second route of PMF generation couples transfer of electrons derived from H2 oxidation to quinone reduction and concomitant proton uptake at the membrane-bound heme cofactor. This redox-loop mechanism, as originally formulated by Mitchell, requires a second, catalytically distinct, enzyme complex to re-oxidize quinol and release the protons outside the cell. A third way of generating PMF is also by electron transfer to quinones but on the outside of the membrane while directly drawing protons through the entire membrane. The cofactor-less membrane subunits involved are proposed to operate by a conformational mechanism (redox-linked proton pump). Finally, PMF can be generated through an electron bifurcation mechanism, whereby an exergonic reaction is tightly coupled with an endergonic reaction. In all cases the protons can be channelled back inside through a F1F0-ATPase to convert the 'energy' stored in the PMF into the universal cellular energy currency, ATP. New and exciting discoveries employing these mechanisms have recently been made on the bioenergetics of hydrogenases, which will be discussed here and placed in the context of their contribution to energy conservation.
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Affiliation(s)
- Constanze Pinske
- Institute of Biology/Microbiology, Martin-Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, 06120 Halle/Saale, Germany
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Fu B, Jin X, Conrad R, Liu H, Liu H. Competition Between Chemolithotrophic Acetogenesis and Hydrogenotrophic Methanogenesis for Exogenous H 2/CO 2 in Anaerobically Digested Sludge: Impact of Temperature. Front Microbiol 2019; 10:2418. [PMID: 31749772 DOI: 10.3389/fmicb.2019.02418/full] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 10/07/2019] [Indexed: 05/21/2023] Open
Abstract
Anaerobic digestion is a widely applied technology for sewage sludge treatment. Hydrogen and CO2 are important degradation products, which serve as substrates for both hydrogenotrophic methanogenesis and chemolithotrophic acetogenesis. In order to understand the competition between these processes for H2/CO2, sludge samples were incubated under H2/CO2 headspace at different temperatures, and analyzed with respect to turnover of H2, CO2, CH4 and acetate including their δ13C values. At 15°C, 13C-depleted acetate (δ13C of -41 to -43‰) and transient acetate accumulation were observed under H2/CO2, and CH4 accumulated with δ13C values increasing from -53 to -33‰. The copy numbers of the fhs gene, which is characteristic for acetogenic bacteria, were at 15°C one order of magnitude higher in the H2/CO2 incubations than the N2 control. At 30°C, however, acetate did not accumulate in the H2/CO2 incubation and the δ13C of CH4 was very low (-100 to -77‰). At 50°C, isotopically enriched acetate was transiently formed and subsequently consumed followed by the production of 13C-depleted CH4. Collectively, the results indicate a high contribution of chemolithotrophic acetogenesis to H2/CO2 utilization at 15°C and 50°C, while H2/CO2 was mainly consumed by hydrogenotrophic methanogenesis at 30°C. Fermentative production and methanogenic consumption of acetate were active at 50°C.
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Affiliation(s)
- Bo Fu
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environmental and Civil Engineering, Jiangnan University, Wuxi, China
- Department of Biogeochemistry, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
- Jiangsu Collaborative Innovation Center of Technology and Material of Water Treatment, Suzhou, China
| | - Xin Jin
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environmental and Civil Engineering, Jiangnan University, Wuxi, China
| | - Ralf Conrad
- Department of Biogeochemistry, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Hongbo Liu
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environmental and Civil Engineering, Jiangnan University, Wuxi, China
- Jiangsu Collaborative Innovation Center of Technology and Material of Water Treatment, Suzhou, China
| | - He Liu
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environmental and Civil Engineering, Jiangnan University, Wuxi, China
- Jiangsu Collaborative Innovation Center of Technology and Material of Water Treatment, Suzhou, China
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Methanogens: pushing the boundaries of biology. Emerg Top Life Sci 2018; 2:629-646. [PMID: 33525834 PMCID: PMC7289024 DOI: 10.1042/etls20180031] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 10/23/2018] [Accepted: 10/24/2018] [Indexed: 01/15/2023]
Abstract
Methanogens are anaerobic archaea that grow by producing methane gas. These microbes and their exotic metabolism have inspired decades of microbial physiology research that continues to push the boundary of what we know about how microbes conserve energy to grow. The study of methanogens has helped to elucidate the thermodynamic and bioenergetics basis of life, contributed our understanding of evolution and biodiversity, and has garnered an appreciation for the societal utility of studying trophic interactions between environmental microbes, as methanogens are important in microbial conversion of biogenic carbon into methane, a high-energy fuel. This review discusses the theoretical basis for energy conservation by methanogens and identifies gaps in methanogen biology that may be filled by undiscovered or yet-to-be engineered organisms.
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Holmes DE, Rotaru AE, Ueki T, Shrestha PM, Ferry JG, Lovley DR. Electron and Proton Flux for Carbon Dioxide Reduction in Methanosarcina barkeri During Direct Interspecies Electron Transfer. Front Microbiol 2018; 9:3109. [PMID: 30631315 PMCID: PMC6315138 DOI: 10.3389/fmicb.2018.03109] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 11/30/2018] [Indexed: 11/13/2022] Open
Abstract
Direct interspecies electron transfer (DIET) is important in diverse methanogenic environments, but how methanogens participate in DIET is poorly understood. Therefore, the transcriptome of Methanosarcina barkeri grown via DIET in co-culture with Geobacter metallireducens was compared with its transcriptome when grown via H2 interspecies transfer (HIT) with Pelobacter carbinolicus. Notably, transcripts for the F420H2 dehydrogenase, Fpo, and the heterodisulfide reductase, HdrABC, were more abundant during growth on DIET. A model for CO2 reduction was developed from these results in which electrons delivered to methanophenazine in the cell membrane are transferred to Fpo. The external proton gradient necessary to drive the otherwise thermodynamically unfavorable reverse electron transport for Fpo-catalyzed F420 reduction is derived from protons released from G. metallireducens metabolism. Reduced F420 is a direct electron donor in the carbon dioxide reduction pathway and also serves as the electron donor for the proposed HdrABC-catalyzed electron bifurcation reaction in which reduced ferredoxin (also required for carbon dioxide reduction) is generated with simultaneous reduction of CoM-S-S-CoB. Expression of genes for putative redox-active proteins predicted to be localized on the outer cell surface was higher during growth on DIET, but further analysis will be required to identify the electron transfer route to methanophenazine. The results indicate that the pathways for electron and proton flux for CO2 reduction during DIET are substantially different than for HIT and suggest that gene expression patterns may also be useful for determining whether Methanosarcina are directly accepting electrons from other extracellular electron donors, such as corroding metals or electrodes.
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Affiliation(s)
- Dawn E. Holmes
- Department of Microbiology, University of Massachusetts, Amherst, MA, United States
- Department of Physical and Biological Sciences, Western New England University, Springfield, MA, United States
| | - Amelia-Elena Rotaru
- Department of Microbiology, University of Massachusetts, Amherst, MA, United States
- Department of Biology, University of Southern Denmark, Odense, Denmark
| | - Toshiyuki Ueki
- Department of Microbiology, University of Massachusetts, Amherst, MA, United States
| | - Pravin M. Shrestha
- Department of Microbiology, University of Massachusetts, Amherst, MA, United States
- Assembly Biosciences, San Francisco, CA, United States
| | - James G. Ferry
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, United States
| | - Derek R. Lovley
- Department of Microbiology, University of Massachusetts, Amherst, MA, United States
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Abstract
Two recent studies (T. D. Mand, G. Kulkarni, and W. W. Metcalf, J. Bacteriol 200:e00342-18, 2018, https://doi.org/10.1128/JB.00342-18, and G. Kulkarni, T. D. Mand, and W. W. Metcalf, mBio 9:e01256-18, 2018, https://doi.org/10.1128/mBio.01256-18) analyzed an impressive array of hydrogenase-deficient mutant strains of Methanosarcina barkeri not only to describe H2-based growth but also to demonstrate the conservation of energy with intracellular hydrogen cycling, a novel strategy for creating a proton motive force to support ATP synthesis.
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