1
|
Schwarz IA, Alsaqri B, Lekbach Y, Henry K, Gorman S, Woodard T, Dion L, Real L, Holmes DE, Smith JA, Lovley DR. Lack of physiological evidence for cytochrome filaments functioning as conduits for extracellular electron transfer. mBio 2024; 15:e0069024. [PMID: 38717196 PMCID: PMC11077965 DOI: 10.1128/mbio.00690-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Accepted: 03/08/2024] [Indexed: 05/12/2024] Open
Abstract
Extracellular cytochrome filaments are proposed to serve as conduits for long-range extracellular electron transfer. The primary functional physiological evidence has been the reported inhibition of Geobacter sulfurreducens Fe(III) oxide reduction when the gene for the filament-forming cytochrome OmcS is deleted. Here we report that the OmcS-deficient strain from that original report reduces Fe(III) oxide as well as the wild-type, as does a triple mutant in which the genes for the other known filament-forming cytochromes were also deleted. The triple cytochrome mutant displayed filaments with the same 3 nm diameter morphology and conductance as those produced by Escherichia coli heterologously expressing the G. sulfurreducens PilA pilin gene. Fe(III) oxide reduction was inhibited when the pilin gene in cytochrome-deficient mutants was modified to yield poorly conductive 3 nm diameter filaments. The results are consistent with the concept that 3 nm diameter electrically conductive pili (e-pili) are required for G. sulfurreducens long-range extracellular electron transfer. In contrast, rigorous physiological functional evidence is lacking for cytochrome filaments serving as conduits for long-range electron transport. IMPORTANCE Unraveling microbial extracellular electron transfer mechanisms has profound implications for environmental processes and advancing biological applications. This study on Geobacter sulfurreducens challenges prevailing beliefs on cytochrome filaments as crucial components thought to facilitate long-range electron transport. The discovery of an OmcS-deficient strain's unexpected effectiveness in Fe(III) oxide reduction prompted a reevaluation of the key conduits for extracellular electron transfer. By exploring the impact of genetic modifications on G. sulfurreducens' performance, this research sheds light on the importance of 3-nm diameter electrically conductive pili in Fe(III) oxide reduction. Reassessing these mechanisms is essential for uncovering the true drivers of extracellular electron transfer in microbial systems, offering insights that could revolutionize applications across diverse fields.
Collapse
Affiliation(s)
- Ingrid A. Schwarz
- Department of Biomolecular Sciences, Central Connecticut State University, New Britain, Connecticut, USA
| | - Baha Alsaqri
- Department of Biomolecular Sciences, Central Connecticut State University, New Britain, Connecticut, USA
| | - Yassir Lekbach
- Department of Microbiology, University of Massachusetts Amherst, Amherst, Massachusetts, USA
| | - Kathryn Henry
- Department of Physical and Biological Sciences, Western New England University, Springfield, Massachusetts, USA
| | - Sydney Gorman
- Department of Physical and Biological Sciences, Western New England University, Springfield, Massachusetts, USA
| | - Trevor Woodard
- Department of Microbiology, University of Massachusetts Amherst, Amherst, Massachusetts, USA
| | - Laura Dion
- Department of Physical and Biological Sciences, Western New England University, Springfield, Massachusetts, USA
| | - Lauren Real
- Department of Biomolecular Sciences, Central Connecticut State University, New Britain, Connecticut, USA
| | - Dawn E. Holmes
- Department of Microbiology, University of Massachusetts Amherst, Amherst, Massachusetts, USA
- Department of Physical and Biological Sciences, Western New England University, Springfield, Massachusetts, USA
| | - Jessica A. Smith
- Department of Biomolecular Sciences, Central Connecticut State University, New Britain, Connecticut, USA
- Department of Microbiology, University of Massachusetts Amherst, Amherst, Massachusetts, USA
| | - Derek R. Lovley
- Department of Microbiology, University of Massachusetts Amherst, Amherst, Massachusetts, USA
| |
Collapse
|
2
|
Lin T, Ding W, Zhang D, You Z, Yang Y, Li F, Xu D, Lovley DR, Song H. Expression of filaments of the Geobacter extracellular cytochrome OmcS in Shewanella oneidensis. Biotechnol Bioeng 2024. [PMID: 38555482 DOI: 10.1002/bit.28702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 03/01/2024] [Accepted: 03/11/2024] [Indexed: 04/02/2024]
Abstract
The physiological role of Geobacter sulfurreducens extracellular cytochrome filaments is a matter of debate and the development of proposed electronic device applications of cytochrome filaments awaits methods for large-scale cytochrome nanowire production. Functional studies in G. sulfurreducens are stymied by the broad diversity of redox-active proteins on the outer cell surface and the redundancy and plasticity of extracellular electron transport routes. G. sulfurreducens is a poor chassis for producing cytochrome nanowires for electronics because of its slow, low-yield, anaerobic growth. Here we report that filaments of the G. sulfurreducens cytochrome OmcS can be heterologously expressed in Shewanella oneidensis. Multiple lines of evidence demonstrated that a strain of S. oneidensis, expressing the G. sulfurreducens OmcS gene on a plasmid, localized OmcS on the outer cell surface. Atomic force microscopy revealed filaments with the unique morphology of OmcS filaments emanating from cells. Electron transfer to OmcS appeared to require a functional outer-membrane porin-cytochrome conduit. The results suggest that S. oneidensis, which grows rapidly to high culture densities under aerobic conditions, may be suitable for the development of a chassis for producing cytochrome nanowires for electronics applications and may also be a good model microbe for elucidating cytochrome filament function in anaerobic extracellular electron transfer.
Collapse
Affiliation(s)
- Tong Lin
- Frontiers Science Centre for Synthetic Biology (Ministry of Education), and Key Laboratory of Systems Bioengineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
- College of Life Science, Langfang Normal University, Langfang, Hebei, China
| | - Wenqi Ding
- Frontiers Science Centre for Synthetic Biology (Ministry of Education), and Key Laboratory of Systems Bioengineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
| | - Danni Zhang
- Shenyang National Laboratory for Materials Science, Northeastern University, Shenyang, China
- Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, China
| | - Zixuan You
- Frontiers Science Centre for Synthetic Biology (Ministry of Education), and Key Laboratory of Systems Bioengineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
| | - Yun Yang
- Beijing Advanced Innovation Centre for Biomedical Engineering, Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Engineering Medicine, Beihang University, Beijing, China
| | - Feng Li
- Frontiers Science Centre for Synthetic Biology (Ministry of Education), and Key Laboratory of Systems Bioengineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
| | - Dake Xu
- Shenyang National Laboratory for Materials Science, Northeastern University, Shenyang, China
- Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, China
| | - Derek R Lovley
- Shenyang National Laboratory for Materials Science, Northeastern University, Shenyang, China
- Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, China
| | - Hao Song
- Frontiers Science Centre for Synthetic Biology (Ministry of Education), and Key Laboratory of Systems Bioengineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
| |
Collapse
|
3
|
Lovley DR, Holmes DE. Comment on "Humic acid-dependent respiratory growth of Methanosarcina acetivorans involves pyrroloquinoline quinone" by Yuanxu Song et al. ISME J 2024; 18:wrae020. [PMID: 38366259 PMCID: PMC10945356 DOI: 10.1093/ismejo/wrae020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 12/08/2023] [Accepted: 01/29/2024] [Indexed: 02/18/2024]
Affiliation(s)
- Derek R Lovley
- Department of Microbiology, University of Massachusetts-Amherst, 639 North Pleasant Street, Amherst, MA 01003, United States
| | - Dawn E Holmes
- Department of Microbiology, University of Massachusetts-Amherst, 639 North Pleasant Street, Amherst, MA 01003, United States
- Department of Physical and Biological Science, Western New England University, 1215 Wilbraham Road, Springfield, MA 01119, United States
| |
Collapse
|
4
|
Wang D, Zhou E, Xu D, Lovley DR. Burning question: Are there sustainable strategies to prevent microbial metal corrosion? Microb Biotechnol 2023; 16:2026-2035. [PMID: 37796110 PMCID: PMC10616648 DOI: 10.1111/1751-7915.14347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 09/18/2023] [Indexed: 10/06/2023] Open
Abstract
The global economic burden of microbial corrosion of metals is enormous. Microbial corrosion of iron-containing metals is most extensive under anaerobic conditions. Microbes form biofilms on metal surfaces and can directly extract electrons derived from the oxidation of Fe0 to Fe2+ to support anaerobic respiration. H2 generated from abiotic Fe0 oxidation also serves as an electron donor for anaerobic respiratory microbes. Microbial metabolites accelerate this abiotic Fe0 oxidation. Traditional strategies for curbing microbial metal corrosion include cathodic protection, scrapping, a diversity of biocides, alloys that form protective layers or release toxic metal ions, and polymer coatings. However, these approaches are typically expensive and/or of limited applicability and not environmentally friendly. Biotechnology may provide more effective and sustainable solutions. Biocides produced with microbes can be less toxic to eukaryotes, expanding the environments for potential application. Microbially produced surfactants can diminish biofilm formation by corrosive microbes, as can quorum-sensing inhibitors. Amendments of phages or predatory bacteria have been successful in attacking corrosive microbes in laboratory studies. Poorly corrosive microbes can form biofilms and/or deposit extracellular polysaccharides and minerals that protect the metal surface from corrosive microbes and their metabolites. Nitrate amendments permit nitrate reducers to outcompete highly corrosive sulphate-reducing microbes, reducing corrosion. Investigation of all these more sustainable corrosion mitigation strategies is in its infancy. More study, especially under environmentally relevant conditions, including diverse microbial communities, is warranted.
Collapse
Affiliation(s)
- Di Wang
- Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education)Northeastern UniversityShenyangChina
- Shenyang National Laboratory for Materials ScienceNortheastern UniversityShenyangChina
| | - Enze Zhou
- Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education)Northeastern UniversityShenyangChina
- Shenyang National Laboratory for Materials ScienceNortheastern UniversityShenyangChina
| | - Dake Xu
- Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education)Northeastern UniversityShenyangChina
- Shenyang National Laboratory for Materials ScienceNortheastern UniversityShenyangChina
| | - Derek R. Lovley
- Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education)Northeastern UniversityShenyangChina
- Department of MicrobiologyUniversity of MassachusettsAmherstMassachusettsUSA
| |
Collapse
|
5
|
Abstract
A wide diversity of microorganisms, typically growing as biofilms, has been implicated in corrosion, a multi-trillion dollar a year problem. Aerobic microorganisms establish conditions that promote metal corrosion, but most corrosion has been attributed to anaerobes. Microbially produced organic acids, sulfide and extracellular hydrogenases can accelerate metallic iron (Fe0) oxidation coupled to hydrogen (H2) production, as can respiratory anaerobes consuming H2 as an electron donor. Some bacteria and archaea directly accept electrons from Fe0 to support anaerobic respiration, often with c-type cytochromes as the apparent outer-surface electrical contact with the metal. Functional genetic studies are beginning to define corrosion mechanisms more rigorously. Omics studies are revealing which microorganisms are associated with corrosion, but new strategies for recovering corrosive microorganisms in culture are required to evaluate corrosive capabilities and mechanisms. Interdisciplinary studies of the interactions among microorganisms and between microorganisms and metals in corrosive biofilms show promise for developing new technologies to detect and prevent corrosion. In this Review, we explore the role of microorganisms in metal corrosion and discuss potential ways to mitigate it.
Collapse
Affiliation(s)
- Dake Xu
- Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, China
- Shenyang National Laboratory for Materials Science, Northeastern University, Shenyang, China
| | - Tingyue Gu
- Department of Chemical & Biomolecular Engineering, Ohio University, Athens, OH, USA.
- Department of Biological Sciences, Ohio University, Athens, OH, USA.
- Institute for Corrosion and Multiphase Technology, Ohio University, Athens, OH, USA.
- Institute for Sustainable Energy and the Environment, Ohio University, Athens, OH, USA.
| | - Derek R Lovley
- Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, China
- Department of Microbiology, University of Massachusetts, Amherst, MA, USA
| |
Collapse
|
6
|
Jin Y, Zhou E, Ueki T, Zhang D, Fan Y, Xu D, Wang F, Lovley DR. Accelerated Microbial Corrosion by Magnetite and Electrically Conductive Pili through Direct Fe 0 -to-Microbe Electron Transfer. Angew Chem Int Ed Engl 2023; 62:e202309005. [PMID: 37525962 DOI: 10.1002/anie.202309005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 07/26/2023] [Accepted: 07/31/2023] [Indexed: 08/02/2023]
Abstract
Electrobiocorrosion, the process in which microbes extract electrons from metallic iron (Fe0 ) through direct Fe0 -microbe electrical connections, is thought to contribute to the costly corrosion of iron-containing metals that impacts many industries. However, electrobiocorrosion mechanisms are poorly understood. We report here that electrically conductive pili (e-pili) and the conductive mineral magnetite play an important role in the electron transfer between Fe0 and Geobacter sulfurreducens, the first microbe in which electrobiocorrosion has been rigorously documented. Genetic modification to express poorly conductive pili substantially diminished corrosive pitting and rates of Fe0 -to-microbe electron flux. Magnetite reduced resistance to electron transfer, increasing corrosion currents and intensifying pitting. Studies with mutants suggested that the magnetite promoted electron transfer in a manner similar to the outer-surface c-type cytochrome OmcS. These findings, and the fact that magnetite is a common product of iron corrosion, suggest a potential positive feedback loop of magnetite produced during corrosion further accelerating electrobiocorrosion. The interactions of e-pili, cytochromes, and magnetite demonstrate mechanistic complexities of electrobiocorrosion, but also provide insights into detecting and possibly mitigating this economically damaging process.
Collapse
Affiliation(s)
- Yuting Jin
- Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials, Ministry of Education), Northeastern University, 110819, Shenyang, China
- Shenyang National Laboratory for Materials Science, Northeastern University, 110819, Shenyang, China
| | - Enze Zhou
- Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials, Ministry of Education), Northeastern University, 110819, Shenyang, China
- Shenyang National Laboratory for Materials Science, Northeastern University, 110819, Shenyang, China
| | - Toshiyuki Ueki
- Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials, Ministry of Education), Northeastern University, 110819, Shenyang, China
- Shenyang National Laboratory for Materials Science, Northeastern University, 110819, Shenyang, China
| | - Danni Zhang
- Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials, Ministry of Education), Northeastern University, 110819, Shenyang, China
- Shenyang National Laboratory for Materials Science, Northeastern University, 110819, Shenyang, China
| | - Yongqiang Fan
- Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials, Ministry of Education), Northeastern University, 110819, Shenyang, China
- Shenyang National Laboratory for Materials Science, Northeastern University, 110819, Shenyang, China
| | - Dake Xu
- Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials, Ministry of Education), Northeastern University, 110819, Shenyang, China
- Shenyang National Laboratory for Materials Science, Northeastern University, 110819, Shenyang, China
| | - Fuhui Wang
- Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials, Ministry of Education), Northeastern University, 110819, Shenyang, China
| | - Derek R Lovley
- Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials, Ministry of Education), Northeastern University, 110819, Shenyang, China
- Shenyang National Laboratory for Materials Science, Northeastern University, 110819, Shenyang, China
| |
Collapse
|
7
|
Smith JA, Holmes DE, Woodard TL, Li Y, Liu X, Wang LY, Meier D, Schwarz IA, Lovley DR. Detrimental impact of the Geobacter metallireducens type VI secretion system on direct interspecies electron transfer. Microbiol Spectr 2023; 11:e0094123. [PMID: 37650614 PMCID: PMC10580878 DOI: 10.1128/spectrum.00941-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 07/02/2023] [Indexed: 09/01/2023] Open
Abstract
Direct interspecies electron transfer (DIET) is important in anaerobic communities of environmental and practical significance. Other than the need for close physical contact for electrical connections, the interactions of DIET partners are poorly understood. Type VI secretion systems (T6SSs) typically kill competitive microbes. Surprisingly, Geobacter metallireducens highly expressed T6SS genes when DIET-based co-cultures were initiated with Geobacter sulfurreducens. T6SS gene expression was lower when the electron shuttle anthraquinone-2,6-disulfonate was added to alleviate the need for interspecies contact. Disruption of hcp, the G. metallireducens gene for the main T6SS needle-tube protein subunit, and the most highly upregulated gene in DIET-grown cells eliminated the long lag periods required for the initiation of DIET. The mutation did not aid DIET in the presence of granular-activated carbon (GAC), consistent with the fact that DIET partners do not make physical contact when electrically connected through conductive materials. The hcp-deficient mutant also established DIET quicker with Methanosarcina barkeri. However, the mutant also reduced Fe(III) oxide faster than the wild-type strain, a phenotype not expected from the loss of the T6SS. Quantitative PCR revealed greater gene transcript abundance for key components of extracellular electron transfer in the hcp-deficient mutant versus the wild-type strain, potentially accounting for the faster Fe(III) oxide reduction and impact on DIET. The results highlight that interspecies interactions beyond electrical connections may influence DIET effectiveness. The unexpected increase in the expression of genes for extracellular electron transport components when hcp was deleted emphasizes the complexities in evaluating the electromicrobiology of highly adaptable Geobacter species. IMPORTANCE Direct interspecies electron transfer is an alternative to the much more intensively studied process of interspecies H2 transfer as a mechanism for microbes to share electrons during the cooperative metabolism of energy sources. DIET is an important process in anaerobic soils and sediments generating methane, a significant greenhouse gas. Facilitating DIET can accelerate and stabilize the conversion of organic wastes to methane biofuel in anaerobic digesters. Therefore, a better understanding of the factors controlling how fast DIET partnerships are established is expected to lead to new strategies for promoting this bioenergy process. The finding that when co-cultured with G. sulfurreducens, G. metallireducens initially expressed a type VI secretion system, a behavior not conducive to interspecies cooperation, illustrates the complexity of establishing syntrophic relationships.
Collapse
Affiliation(s)
- Jessica A. Smith
- Department of Microbiology, University of Massachusetts Amherst, Morrill IV N Science Center, Amherst, Massachusetts, USA
- Department of Biomolecular Sciences, Central Connecticut State University, New Britain, Connecticut, USA
| | - Dawn E. Holmes
- Department of Microbiology, University of Massachusetts Amherst, Morrill IV N Science Center, Amherst, Massachusetts, USA
- Department of Physical and Biological Sciences, Western New England University, Springfield, Massachusetts, USA
| | - Trevor L. Woodard
- Department of Microbiology, University of Massachusetts Amherst, Morrill IV N Science Center, Amherst, Massachusetts, USA
| | - Yang Li
- Department of Microbiology, University of Massachusetts Amherst, Morrill IV N Science Center, Amherst, Massachusetts, USA
- School of Ocean Science and Technology, Dalian University of Technology, Panjin, Liaoning, China
| | - Xinying Liu
- Department of Microbiology, University of Massachusetts Amherst, Morrill IV N Science Center, Amherst, Massachusetts, USA
- College of Environmental Science and Engineering, Beijing Forestry University, Beijing, China
| | - Li-Ying Wang
- Department of Microbiology, University of Massachusetts Amherst, Morrill IV N Science Center, Amherst, Massachusetts, USA
| | - David Meier
- Department of Microbiology, University of Massachusetts Amherst, Morrill IV N Science Center, Amherst, Massachusetts, USA
| | - Ingrid A. Schwarz
- Department of Biomolecular Sciences, Central Connecticut State University, New Britain, Connecticut, USA
| | - Derek R. Lovley
- Department of Microbiology, University of Massachusetts Amherst, Morrill IV N Science Center, Amherst, Massachusetts, USA
| |
Collapse
|
8
|
Lekbach Y, Ueki T, Liu X, Woodard T, Yao J, Lovley DR. Microbial nanowires with genetically modified peptide ligands to sustainably fabricate electronic sensing devices. Biosens Bioelectron 2023; 226:115147. [PMID: 36804664 DOI: 10.1016/j.bios.2023.115147] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 01/23/2023] [Accepted: 02/08/2023] [Indexed: 02/11/2023]
Abstract
Nanowires have substantial potential as the sensor component in electronic sensing devices. However, surface functionalization of traditional nanowire and nanotube materials with short peptides that increase sensor selectivity and sensitivity requires complex chemistries with toxic reagents. In contrast, microorganisms can assemble pilin monomers into protein nanowires with intrinsic conductivity from renewable feedstocks, yielding an electronic material that is robust and stable in applications, but also biodegradable. Here we report that the sensitivity and selectivity of protein nanowire-based sensors can be modified with a simple plug and play genetic approach in which a short peptide sequence, designed to bind the analyte of interest, is incorporated into the pilin protein that is microbially assembled into nanowires. We employed a scalable Escherichia coli chassis to fabricate protein nanowires that displayed either a peptide previously demonstrated to effectively bind ammonia, or a peptide known to bind acetic acid. Sensors comprised of thin films of the nanowires amended with the ammonia-specific peptide had a ca. 100-fold greater response to ammonia than sensors made with unmodified protein nanowires. Protein nanowires with the peptide that binds acetic acid yielded a 4-fold higher response than nanowires without the peptide. The protein nanowire-based sensors had greater responses than previously reported sensors fabricated with other nanomaterials. The results demonstrate that protein nanowires with enhanced sensor response for analytes of interest can be fabricated with a flexible genetic strategy that sustainably eliminates the energy, environmental, and health concerns associated with other common nanomaterials.
Collapse
Affiliation(s)
- Yassir Lekbach
- Department of Microbiology, University of Massachusetts, Amherst, MA, 01003, USA
| | - Toshiyuki Ueki
- Department of Microbiology, University of Massachusetts, Amherst, MA, 01003, USA
| | - Xiaomeng Liu
- Department of Electrical and Computer Engineering University of Massachusetts, Amherst, MA, 01003, USA
| | - Trevor Woodard
- Department of Microbiology, University of Massachusetts, Amherst, MA, 01003, USA
| | - Jun Yao
- Department of Electrical and Computer Engineering University of Massachusetts, Amherst, MA, 01003, USA; Institute for Applied Life Sciences (IALS),University of Massachusetts, Amherst, MA, 01003, USA; Department of Biomedical Engineering, University of Massachusetts, Amherst, MA, 01003, USA
| | - Derek R Lovley
- Department of Microbiology, University of Massachusetts, Amherst, MA, 01003, USA; Institute for Applied Life Sciences (IALS),University of Massachusetts, Amherst, MA, 01003, USA.
| |
Collapse
|
9
|
Lovley DR. Response to Wang et al.: evidence contradicting the cytochrome-only model. Trends Microbiol 2023; 31:548-549. [PMID: 37005158 DOI: 10.1016/j.tim.2023.03.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 03/07/2023] [Accepted: 03/13/2023] [Indexed: 04/03/2023]
|
10
|
Szmuc E, Walker DJF, Kireev D, Akinwande D, Lovley DR, Keitz B, Ellington A. Engineering Geobacter pili to produce metal:organic filaments. Biosens Bioelectron 2023; 222:114993. [PMID: 36525710 DOI: 10.1016/j.bios.2022.114993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 11/15/2022] [Accepted: 12/06/2022] [Indexed: 12/12/2022]
Abstract
The organized self-assembly of conductive biological structures holds promise for creating new bioelectronic devices. In particular, Geobacter sulfurreducens type IVa pili have proven to be a versatile material for fabricating protein nanowire-based devices. To scale the production of conductive pili, we designed a strain of Shewanella oneidensis that heterologously expressed abundant, conductive Geobacter pili when grown aerobically in liquid culture. S. oneidensis expressing a cysteine-modified pilin, designed to enhance the capability to bind to gold, generated conductive pili that self-assembled into biohybrid filaments in the presence of gold nanoparticles. Elemental composition analysis confirmed the filament-metal interactions within the structures, which were several orders of magnitude larger than previously described metal:organic filaments. The results demonstrate that the S. oneidensis chassis significantly advances the possibilities for facile conductive protein nanowire design and fabrication.
Collapse
Affiliation(s)
- Eric Szmuc
- College of Natural Sciences, University of Texas at Austin, Austin, TX, 78712, United States
| | - David J F Walker
- College of Natural Sciences, University of Texas at Austin, Austin, TX, 78712, United States; U.S. Army Engineer Research and Development Center, Environmental Laboratory, University of Texas at Austin, Austin, TX, 78712, United States; Bioconscientia LLC, Austin, TX 78712, United States
| | - Dmitry Kireev
- Cockrell School of Engineering, University of Texas at Austin, Austin, TX, 78712, United States
| | - Deji Akinwande
- Cockrell School of Engineering, University of Texas at Austin, Austin, TX, 78712, United States
| | - Derek R Lovley
- Department of Microbiology, University of Massachusetts-Amherst, Amherst, MA, 01003, United States
| | - Benjamin Keitz
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, 78712, United States
| | - Andrew Ellington
- College of Natural Sciences, University of Texas at Austin, Austin, TX, 78712, United States.
| |
Collapse
|
11
|
Liu X, Ueki T, Gao H, Woodard TL, Nevin KP, Fu T, Fu S, Sun L, Lovley DR, Yao J. Microbial biofilms for electricity generation from water evaporation and power to wearables. Nat Commun 2022; 13:4369. [PMID: 35902587 PMCID: PMC9334603 DOI: 10.1038/s41467-022-32105-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 07/18/2022] [Indexed: 11/23/2022] Open
Abstract
Employing renewable materials for fabricating clean energy harvesting devices can further improve sustainability. Microorganisms can be mass produced with renewable feedstocks. Here, we demonstrate that it is possible to engineer microbial biofilms as a cohesive, flexible material for long-term continuous electricity production from evaporating water. Single biofilm sheet (~40 µm thick) serving as the functional component in an electronic device continuously produces power density (~1 μW/cm2) higher than that achieved with thicker engineered materials. The energy output is comparable to that achieved with similar sized biofilms catalyzing current production in microbial fuel cells, without the need for an organic feedstock or maintaining cell viability. The biofilm can be sandwiched between a pair of mesh electrodes for scalable device integration and current production. The devices maintain the energy production in ionic solutions and can be used as skin-patch devices to harvest electricity from sweat and moisture on skin to continuously power wearable devices. Biofilms made from different microbial species show generic current production from water evaporation. These results suggest that we can harness the ubiquity of biofilms in nature as additional sources of biomaterial for evaporation-based electricity generation in diverse aqueous environments. Though water evaporation-driven electricity generation is an attractive sustainable energy production strategy, existing electronic devices suffer from poor performance or is costly. Here, the authors report sustainable biofilms for efficient, low-cost evaporation-based electricity production
Collapse
Affiliation(s)
- Xiaomeng Liu
- Department of Electrical Computer and Engineering, University of Massachusetts, Amherst, MA, USA
| | - Toshiyuki Ueki
- Department of Microbiology, University of Massachusetts, Amherst, MA, USA
| | - Hongyan Gao
- Department of Electrical Computer and Engineering, University of Massachusetts, Amherst, MA, USA
| | - Trevor L Woodard
- Department of Microbiology, University of Massachusetts, Amherst, MA, USA
| | - Kelly P Nevin
- Department of Microbiology, University of Massachusetts, Amherst, MA, USA
| | - Tianda Fu
- Department of Electrical Computer and Engineering, University of Massachusetts, Amherst, MA, USA
| | - Shuai Fu
- Department of Electrical Computer and Engineering, University of Massachusetts, Amherst, MA, USA
| | - Lu Sun
- Department of Electrical Computer and Engineering, University of Massachusetts, Amherst, MA, USA
| | - Derek R Lovley
- Department of Microbiology, University of Massachusetts, Amherst, MA, USA. .,Institute for Applied Life Sciences (IALS), University of Massachusetts, Amherst, MA, USA.
| | - Jun Yao
- Department of Electrical Computer and Engineering, University of Massachusetts, Amherst, MA, USA. .,Institute for Applied Life Sciences (IALS), University of Massachusetts, Amherst, MA, USA. .,Department of Biomedical Engineering, University of Massachusetts, Amherst, MA, USA.
| |
Collapse
|
12
|
Zhou E, Li F, Zhang D, Xu D, Li Z, Jia R, Jin Y, Song H, Li H, Wang Q, Wang J, Li X, Gu T, Homborg AM, Mol JMC, Smith JA, Wang F, Lovley DR. Direct microbial electron uptake as a mechanism for stainless steel corrosion in aerobic environments. Water Res 2022; 219:118553. [PMID: 35561622 DOI: 10.1016/j.watres.2022.118553] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 04/29/2022] [Accepted: 05/03/2022] [Indexed: 06/15/2023]
Abstract
Shewanella oneidensis MR-1 is an attractive model microbe for elucidating the biofilm-metal interactions that contribute to the billions of dollars in corrosion damage to industrial applications each year. Multiple mechanisms for S. oneidensis-enhanced corrosion have been proposed, but none of these mechanisms have previously been rigorously investigated with methods that rule out alternative routes for electron transfer. We found that S. oneidensis grown under aerobic conditions formed thick biofilms (∼50 µm) on stainless steel coupons, accelerating corrosion over sterile controls. H2 and flavins were ruled out as intermediary electron carriers because stainless steel did not reduce riboflavin and previous studies have demonstrated stainless does not generate H2. Strain ∆mtrCBA, in which the genes for the most abundant porin-cytochrome conduit in S. oneidensis were deleted, corroded stainless steel substantially less than wild-type in aerobic cultures. Wild-type biofilms readily reduced nitrate with stainless steel as the sole electron donor under anaerobic conditions, but strain ∆mtrCBA did not. These results demonstrate that S. oneidensis can directly consume electrons from iron-containing metals and illustrate how direct metal-to-microbe electron transfer can be an important route for corrosion, even in aerobic environments.
Collapse
Affiliation(s)
- Enze Zhou
- Shenyang National Laboratory for Materials Science, Northeastern University, Shenyang, 110819, China; Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, 110819, China; Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, Shenyang, 110819, China
| | - Feng Li
- Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin University, Tianjin, 300072, China
| | - Dawei Zhang
- Corrosion and Protection Center, University of Science and Technology Beijing, Beijing, 100083, P. R., China
| | - Dake Xu
- Shenyang National Laboratory for Materials Science, Northeastern University, Shenyang, 110819, China; Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, 110819, China.
| | - Zhong Li
- Shenyang National Laboratory for Materials Science, Northeastern University, Shenyang, 110819, China; Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, 110819, China
| | - Ru Jia
- Department of Chemical and Biomolecular Engineering, Institute for Corrosion and Multiphase Technology, Ohio University, Athens, Ohio, 45701, USA
| | - Yuting Jin
- Shenyang National Laboratory for Materials Science, Northeastern University, Shenyang, 110819, China; Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, 110819, China
| | - Hao Song
- Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin University, Tianjin, 300072, China.
| | - Huabing Li
- Shenyang National Laboratory for Materials Science, Northeastern University, Shenyang, 110819, China
| | - Qiang Wang
- Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, Shenyang, 110819, China
| | - Jianjun Wang
- Shenyang National Laboratory for Materials Science, Northeastern University, Shenyang, 110819, China
| | - Xiaogang Li
- Corrosion and Protection Center, University of Science and Technology Beijing, Beijing, 100083, P. R., China
| | - Tingyue Gu
- Department of Chemical and Biomolecular Engineering, Institute for Corrosion and Multiphase Technology, Ohio University, Athens, Ohio, 45701, USA
| | - Axel M Homborg
- Netherlands Defence Academy, P.O. Box 505, 1780AM, Den Helder, the Netherlands
| | - Johannes M C Mol
- Delft University of Technology, Department of Materials Science and Engineering, Mekelweg 2, 2628CD Delft, the Netherlands
| | - Jessica A Smith
- Department of Biomolecular Sciences, Central Connecticut State University, 1615 Stanley Street, New Britain, CT, 06050, USA
| | - Fuhui Wang
- Shenyang National Laboratory for Materials Science, Northeastern University, Shenyang, 110819, China
| | - Derek R Lovley
- Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, 110819, China
| |
Collapse
|
13
|
|
14
|
Lovley DR. Microbe Profile: Geobacter metallireducens: a model for novel physiologies of biogeochemical and technological significance. Microbiology (Reading) 2022; 168. [PMID: 35171087 DOI: 10.1099/mic.0.001138] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Geobacter metallireducens has served as the initial model for a substantial number of newly recognized microbial physiologies that play an important role in biogeochemical cycling of carbon, metals and nutrients. The strategies used by G. metallireducens for microbial interaction with minerals, contaminants, other microbes and electrodes have led to new technologies for bioremediation, bioenergy conversion and the sustainable production of 'green' electronics.
Collapse
Affiliation(s)
- Derek R Lovley
- Department of Microbiology, University of Massachusetts, Amherst, MA, USA
| |
Collapse
|
15
|
Abstract
In this Quick guide, Derek Lovley introduces microbial nanowires-conductive extracellular appendages made by some bacteria and archaea.
Collapse
Affiliation(s)
- Derek R Lovley
- Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110819, China; Department of Microbiology and Institute for Applied Life Sciences (IALS), University of Massachusetts, Amherst, MA 01003, USA.
| |
Collapse
|
16
|
Lovley DR. Electrotrophy: Other microbial species, iron, and electrodes as electron donors for microbial respirations. Bioresour Technol 2022; 345:126553. [PMID: 34906705 DOI: 10.1016/j.biortech.2021.126553] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 12/06/2021] [Accepted: 12/08/2021] [Indexed: 06/14/2023]
Abstract
Electrotrophy, the growth of microbes on extracellular electron donors, drives important biogeochemical cycles and has practical applications. Studies of Fe(II)-based electrotrophy have provided foundational cytochrome-based mechanistic models for electron transport into cells. Direct electron uptake from other microbial species, Fe(0), or cathodes is of intense interest due to its potential roles in the production and anaerobic oxidation of methane, corrosion, and bioelectrochemical technologies. Other cells or Fe(0) can serve as the sole electron donor supporting the growth of several Geobacter and methanogen strains that are unable to use H2 as an electron donor, providing strong evidence for electrotrophy. Additional evidence for electrotrophy in Geobacter strains and Methanosarcina acetivorans is a requirement for outer-surface c-type cytochromes. However, in most instances claims for electrotrophy in anaerobes are based on indirect inference and the possibility that H2 is actually the electron donor supporting growth has not been rigorously excluded.
Collapse
Affiliation(s)
- Derek R Lovley
- Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110819, China; Department of Microbiology and Institute for Applied Life Sciences (IALS), University of Massachusetts, Amherst, MA, USA.
| |
Collapse
|
17
|
Liang D, Liu X, Woodard TL, Holmes DE, Smith JA, Nevin KP, Feng Y, Lovley DR. Extracellular Electron Exchange Capabilities of Desulfovibrio ferrophilus and Desulfopila corrodens. Environ Sci Technol 2021; 55:16195-16203. [PMID: 34748326 DOI: 10.1021/acs.est.1c04071] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Microbial extracellular electron transfer plays an important role in diverse biogeochemical cycles, metal corrosion, bioelectrochemical technologies, and anaerobic digestion. Evaluation of electron uptake from pure Fe(0) and stainless steel indicated that, in contrast to previous speculation in the literature, Desulfovibrio ferrophilus and Desulfopila corrodens are not able to directly extract electrons from solid-phase electron-donating surfaces. D. ferrophilus grew with Fe(III) as the electron acceptor, but Dp. corrodens did not. D. ferrophilus reduced Fe(III) oxide occluded within porous alginate beads, suggesting that it released a soluble electron shuttle to promote Fe(III) oxide reduction. Conductive atomic force microscopy revealed that the D. ferrophilus pili are electrically conductive and the expression of a gene encoding an aromatics-rich putative pilin was upregulated during growth on Fe(III) oxide. The expression of genes for multi-heme c-type cytochromes was not upregulated during growth with Fe(III) as the electron acceptor, and genes for a porin-cytochrome conduit across the outer membrane were not apparent in the genome. The results suggest that D. ferrophilus has adopted a novel combination of strategies to enable extracellular electron transport, which may be of biogeochemical and technological significance.
Collapse
Affiliation(s)
- Dandan Liang
- Department of Microbiology, University of Massachusetts, Amherst, Massachusetts 01003, United States
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, P. R. China
| | - Xinying Liu
- Department of Microbiology, University of Massachusetts, Amherst, Massachusetts 01003, United States
- College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China
| | - Trevor L Woodard
- Department of Microbiology, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Dawn E Holmes
- Department of Microbiology, University of Massachusetts, Amherst, Massachusetts 01003, United States
- Department of Physical and Biological Sciences, Western New England University, Springfield, Massachusetts 01119-2612, United States
| | - Jessica A Smith
- Department of Microbiology, University of Massachusetts, Amherst, Massachusetts 01003, United States
- Department of Biomolecular Sciences, Central Connecticut State University, New Britain, Connecticut 06053-2490, United States
| | - Kelly P Nevin
- Department of Microbiology, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Yujie Feng
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, P. R. China
| | - Derek R Lovley
- Department of Microbiology, University of Massachusetts, Amherst, Massachusetts 01003, United States
| |
Collapse
|
18
|
Holmes DE, Zhou J, Ueki T, Woodard T, Lovley DR. Mechanisms for Electron Uptake by Methanosarcina acetivorans during Direct Interspecies Electron Transfer. mBio 2021; 12:e0234421. [PMID: 34607451 PMCID: PMC8546582 DOI: 10.1128/mbio.02344-21] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 08/31/2021] [Indexed: 12/13/2022] Open
Abstract
Direct interspecies electron transfer (DIET) between bacteria and methanogenic archaea appears to be an important syntrophy in both natural and engineered methanogenic environments. However, the electrical connections on the outer surface of methanogens and the subsequent processing of electrons for carbon dioxide reduction to methane are poorly understood. Here, we report that the genetically tractable methanogen Methanosarcina acetivorans can grow via DIET in coculture with Geobacter metallireducens serving as the electron-donating partner. Comparison of gene expression patterns in M. acetivorans grown in coculture versus pure-culture growth on acetate revealed that transcripts for the outer-surface multiheme c-type cytochrome MmcA were higher during DIET-based growth. Deletion of mmcA inhibited DIET. The high aromatic amino acid content of M. acetivorans archaellins suggests that they might assemble into electrically conductive archaella. A mutant that could not express archaella was deficient in DIET. However, this mutant grew in DIET-based coculture as well as the archaellum-expressing parental strain in the presence of granular activated carbon, which was previously shown to serve as a substitute for electrically conductive pili as a conduit for long-range interspecies electron transfer in other DIET-based cocultures. Transcriptomic data suggesting that the membrane-bound Rnf, Fpo, and HdrED complexes also play a role in DIET were incorporated into a charge-balanced model illustrating how electrons entering the cell through MmcA can yield energy to support growth from carbon dioxide reduction. The results are the first genetics-based functional demonstration of likely outer-surface electrical contacts for DIET in a methanogen. IMPORTANCE The conversion of organic matter to methane plays an important role in the global carbon cycle and is an effective strategy for converting wastes to a useful biofuel. The reduction of carbon dioxide to methane accounts for approximately a third of the methane produced in anaerobic soils and sediments as well as waste digesters. Potential electron donors for carbon dioxide reduction are H2 or electrons derived from direct interspecies electron transfer (DIET) between bacteria and methanogens. Elucidating the relative importance of these electron donors has been difficult due to a lack of information on the electrical connections on the outer surfaces of methanogens and how they process the electrons received from DIET. Transcriptomic patterns and gene deletion phenotypes reported here provide insight into how a group of Methanosarcina organisms that play an important role in methane production in soils and sediments participate in DIET.
Collapse
Affiliation(s)
- 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
| | - Jinjie Zhou
- Department of Microbiology, University of Massachusetts—Amherst, Amherst, Massachusetts, USA
- Institute for Advanced Study, Shenzhen University, Shenzhen, Guangdong, China
| | - Toshiyuki Ueki
- Department of Microbiology, University of Massachusetts—Amherst, Amherst, Massachusetts, USA
| | - Trevor Woodard
- Department of Microbiology, University of Massachusetts—Amherst, Amherst, Massachusetts, USA
| | - Derek R. Lovley
- Department of Microbiology, University of Massachusetts—Amherst, Amherst, Massachusetts, USA
| |
Collapse
|
19
|
Liu X, Walker DJF, Nonnenmann SS, Sun D, Lovley DR. Direct Observation of Electrically Conductive Pili Emanating from Geobacter sulfurreducens. mBio 2021; 12:e0220921. [PMID: 34465020 PMCID: PMC8406130 DOI: 10.1128/mbio.02209-21] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 08/02/2021] [Indexed: 11/20/2022] Open
Abstract
Geobacter sulfurreducens is a model microbe for elucidating the mechanisms for extracellular electron transfer in several biogeochemical cycles, bioelectrochemical applications, and microbial metal corrosion. Multiple lines of evidence previously suggested that electrically conductive pili (e-pili) are an essential conduit for long-range extracellular electron transport in G. sulfurreducens. However, it has recently been reported that G. sulfurreducens does not express e-pili and that filaments comprised of multi-heme c-type cytochromes are responsible for long-range electron transport. This possibility was directly investigated by examining cells, rather than filament preparations, with atomic force microscopy. Approximately 90% of the filaments emanating from wild-type cells had a diameter (3 nm) and conductance consistent with previous reports of e-pili harvested from G. sulfurreducens or heterologously expressed in Escherichia coli from the G. sulfurreducens pilin gene. The remaining 10% of filaments had a morphology consistent with filaments comprised of the c-type cytochrome OmcS. A strain expressing a modified pilin gene designed to yield poorly conductive pili expressed 90% filaments with a 3-nm diameter, but greatly reduced conductance, further indicating that the 3-nm diameter conductive filaments in the wild-type strain were e-pili. A strain in which genes for five of the most abundant outer-surface c-type cytochromes, including OmcS, were deleted yielded only 3-nm-diameter filaments with the same conductance as in the wild type. These results demonstrate that e-pili are the most abundant conductive filaments expressed by G. sulfurreducens, consistent with previous functional studies demonstrating the need for e-pili for long-range extracellular electron transfer. IMPORTANCE Electroactive microbes have significant environmental impacts, as well as applications in bioenergy and bioremediation. The composition, function, and even existence of electrically conductive pili (e-pili) has been one of the most contentious areas of investigation in electromicrobiology, in part because e-pili offer a mechanism for long-range electron transport that does not involve the metal cofactors common in much of biological electron transport. This study demonstrates that e-pili are abundant filaments emanating from Geobacter sulfurreducens, which serves as a model for long-range extracellular electron transfer in direct interspecies electron transfer, dissimilatory metal reduction, microbe-electrode exchange, and corrosion caused by direct electron uptake from Fe(0). The methods described in this study provide a simple strategy for evaluating the distribution of conductive filaments throughout the microbial world with an approach that avoids artifactual production and/or enrichment of filaments that may not be physiologically relevant.
Collapse
Affiliation(s)
- Xinying Liu
- Department of Microbiology, University of Massachusetts—Amherst, Amherst, Massachusetts, USA
- College of Environmental Science and Engineering, Beijing Forestry University, Beijing, China
| | - David J. F. Walker
- Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas, USA
| | - Stephen S. Nonnenmann
- Institute for Applied Life Sciences, university of Massachusetts—Amherst, Amherst, Massachusetts, USA
- Department of Mechanical and Industrial Engineering, University of Massachusetts—Amherst, Amherst, Massachusetts, USA
| | - Dezhi Sun
- College of Environmental Science and Engineering, Beijing Forestry University, Beijing, China
| | - Derek R. Lovley
- Department of Microbiology, University of Massachusetts—Amherst, Amherst, Massachusetts, USA
- Institute for Applied Life Sciences, university of Massachusetts—Amherst, Amherst, Massachusetts, USA
| |
Collapse
|
20
|
Lovley DR, Holmes DE. Electromicrobiology: the ecophysiology of phylogenetically diverse electroactive microorganisms. Nat Rev Microbiol 2021; 20:5-19. [PMID: 34316046 DOI: 10.1038/s41579-021-00597-6] [Citation(s) in RCA: 137] [Impact Index Per Article: 45.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/16/2021] [Indexed: 02/03/2023]
Abstract
Electroactive microorganisms markedly affect many environments in which they establish outer-surface electrical contacts with other cells and minerals or reduce soluble extracellular redox-active molecules such as flavins and humic substances. A growing body of research emphasizes their broad phylogenetic diversity and shows that these microorganisms have key roles in multiple biogeochemical cycles, as well as the microbiome of the gut, anaerobic waste digesters and metal corrosion. Diverse bacteria and archaea have independently evolved cytochrome-based strategies for electron exchange between the outer cell surface and the cell interior, but cytochrome-free mechanisms are also prevalent. Electrically conductive protein filaments, soluble electron shuttles and non-biological conductive materials can substantially extend the electronic reach of microorganisms beyond the surface of the cell. The growing appreciation of the diversity of electroactive microorganisms and their unique electronic capabilities is leading to a broad range of applications.
Collapse
Affiliation(s)
- Derek R Lovley
- Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, China. .,Department of Microbiology, University of Massachusetts, Amherst, MA, USA. .,Institute for Applied Life Sciences (IALS), University of Massachusetts, Amherst, MA, USA.
| | - Dawn E Holmes
- Department of Microbiology, University of Massachusetts, Amherst, MA, USA.,Institute for Applied Life Sciences (IALS), University of Massachusetts, Amherst, MA, USA.,Department of Physical and Biological Sciences, Western New England University, Springfield, MA, USA
| |
Collapse
|
21
|
Abstract
Microbially catalyzed corrosion of metals is a substantial economic concern. Aerobic microbes primarily enhance Fe0 oxidation through indirect mechanisms and their impact appears to be limited compared to anaerobic microbes. Several anaerobic mechanisms are known to accelerate Fe0 oxidation. Microbes can consume H2 abiotically generated from the oxidation of Fe0. Microbial H2 removal makes continued Fe0 oxidation more thermodynamically favorable. Extracellular hydrogenases further accelerate Fe0 oxidation. Organic electron shuttles such as flavins, phenazines, and possibly humic substances may replace H2 as the electron carrier between Fe0 and cells. Direct Fe0-to-microbe electron transfer is also possible. Which of these anaerobic mechanisms predominates in model pure culture isolates is typically poorly documented because of a lack of functional genetic studies. Microbial mechanisms for Fe0 oxidation may also apply to some other metals. An ultimate goal of microbial metal corrosion research is to develop molecular tools to diagnose the occurrence, mechanisms, and rates of metal corrosion to guide the implementation of the most effective mitigation strategies. A systems biology approach that includes innovative isolation and characterization methods, as well as functional genomic investigations, will be required in order to identify the diagnostic features to be gleaned from meta-omic analysis of corroding materials. A better understanding of microbial metal corrosion mechanisms is expected to lead to new corrosion mitigation strategies. The understanding of the corrosion microbiome is clearly in its infancy, but interdisciplinary electrochemical, microbiological, and molecular tools are available to make rapid progress in this field.
Collapse
Affiliation(s)
- Yassir Lekbach
- Shenyang National Laboratory for Materials Science, Northeastern University, Shenyang, China; Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, China
| | - Tao Liu
- College of Ocean Science and Engineering, Shanghai Maritime University, Shanghai, China
| | - Yingchao Li
- Beijing Key Laboratory of Failure, Corrosion and Protection of Oil/Gas Facility Materials, College of New Energy and Materials, China University of Petroleum-Beijing, Beijing, China
| | - Masoumeh Moradi
- Shenyang National Laboratory for Materials Science, Northeastern University, Shenyang, China; Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, China
| | - Wenwen Dou
- Institute of Marine Science and Technology, Shandong University, Qingdao, China
| | - Dake Xu
- Shenyang National Laboratory for Materials Science, Northeastern University, Shenyang, China; Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, China.
| | - Jessica A Smith
- Department of Biomolecular Sciences, Central Connecticut State University, New Britain, CT, United States
| | - Derek R Lovley
- Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, China; Department of Microbiology, University of Massachusetts, Amherst, MA, United States.
| |
Collapse
|
22
|
Sun YL, Montz BJ, Selhorst R, Tang HY, Zhu J, Nevin KP, Woodard TL, Ribbe AE, Russell TP, Nonnenmann SS, Lovley DR, Emrick T. Solvent-Induced Assembly of Microbial Protein Nanowires into Superstructured Bundles. Biomacromolecules 2021; 22:1305-1311. [PMID: 33591727 DOI: 10.1021/acs.biomac.0c01790] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Protein-based electronic biomaterials represent an attractive alternative to traditional metallic and semiconductor materials due to their environmentally benign production and purification. However, major challenges hindering further development of these materials include (1) limitations associated with processing proteins in organic solvents and (2) difficulties in forming higher-order structures or scaffolds with multilength scale control. This paper addresses both challenges, resulting in the formation of one-dimensional bundles composed of electrically conductive protein nanowires harvested from the microbes Geobacter sulfurreducens and Escherichia coli. Processing these bionanowires from common organic solvents, such as hexane, cyclohexane, and DMF, enabled the production of multilength scale structures composed of distinctly visible pili. Transmission electron microscopy revealed striking images of bundled protein nanowires up to 10 μm in length and with widths ranging from 50-500 nm (representing assembly of tens to hundreds of nanowires). Conductive atomic force microscopy confirmed the presence of an appreciable nanowire conductivity in their bundled state. These results greatly expand the possibilities for fabricating a diverse array of protein nanowire-based electronic device architectures.
Collapse
Affiliation(s)
- Yun-Lu Sun
- Department of Microbiology, University of Massachusetts Amherst, Amherst, Massachusetts01003, United States
| | - Brian J Montz
- Department of Polymer Science and Engineering Department, University of Massachusetts Amherst, Amherst, Massachusetts01003, United States
| | - Ryan Selhorst
- Department of Polymer Science and Engineering Department, University of Massachusetts Amherst, Amherst, Massachusetts01003, United States
| | - Hai-Yan Tang
- Department of Microbiology, University of Massachusetts Amherst, Amherst, Massachusetts01003, United States
| | - Jiaxin Zhu
- Department of Mechanical and Industrial Engineering, University of Massachusetts Amherst, Amherst, Massachusetts01003, United States
| | - Kelly P Nevin
- Department of Microbiology, University of Massachusetts Amherst, Amherst, Massachusetts01003, United States
| | - Trevor L Woodard
- Department of Microbiology, University of Massachusetts Amherst, Amherst, Massachusetts01003, United States
| | - Alexander E Ribbe
- Department of Polymer Science and Engineering Department, University of Massachusetts Amherst, Amherst, Massachusetts01003, United States
| | - Thomas P Russell
- Department of Polymer Science and Engineering Department, University of Massachusetts Amherst, Amherst, Massachusetts01003, United States
| | - Stephen S Nonnenmann
- Department of Mechanical and Industrial Engineering, University of Massachusetts Amherst, Amherst, Massachusetts01003, United States
| | - Derek R Lovley
- Department of Microbiology, University of Massachusetts Amherst, Amherst, Massachusetts01003, United States
| | - Todd Emrick
- Department of Polymer Science and Engineering Department, University of Massachusetts Amherst, Amherst, Massachusetts01003, United States
| |
Collapse
|
23
|
Lovley DR, Yao J. Intrinsically Conductive Microbial Nanowires for 'Green' Electronics with Novel Functions. Trends Biotechnol 2021; 39:940-952. [PMID: 33419586 DOI: 10.1016/j.tibtech.2020.12.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Revised: 12/04/2020] [Accepted: 12/07/2020] [Indexed: 10/22/2022]
Abstract
Intrinsically conductive protein nanowires, microbially produced from inexpensive, renewable feedstocks, are a sustainable alternative to traditional nanowire electronic materials, which require high energy inputs and hazardous conditions/chemicals for fabrication and can be highly toxic. Pilin-based nanowires can be tailored for specific functions via the design of synthetic pilin genes to tune wire conductivity or introduce novel functionalities. Other microbially produced nanowire options for electronics may include cytochrome wires, curli fibers, and the conductive fibers of cable bacteria. Proof-of-concept protein nanowire electronics that have been successfully demonstrated include biomedical sensors, neuromorphic devices, and a device that generates electricity from ambient humidity. Further development of applications will require interdisciplinary teams of engineers, biophysicists, and synthetic biologists.
Collapse
Affiliation(s)
- Derek R Lovley
- Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110819, China; Department of Microbiology, University of Massachusetts, Amherst, MA, USA; Institute for Applied Life Sciences (IALS), University of Massachusetts, Amherst, MA, USA.
| | - Jun Yao
- Institute for Applied Life Sciences (IALS), University of Massachusetts, Amherst, MA, USA; Department of Electrical and Computer Engineering, University of Massachusetts, Amherst, MA, USA; Department of Biomedical Engineering, University of Massachusetts, Amherst, MA, USA
| |
Collapse
|
24
|
Abstract
Anaerobic digestion was one of the first bioenergy strategies developed, yet the interactions of the microbial community that is responsible for the production of methane are still poorly understood. For example, it has only recently been recognized that the bacteria that oxidize organic waste components can forge electrical connections with methane-producing microbes through biologically produced, protein-based, conductive circuits. This direct interspecies electron transfer (DIET) is faster than interspecies electron exchange via diffusive electron carriers, such as H2. DIET is also more resilient to perturbations such as increases in organic load inputs or toxic compounds. However, with current digester practices DIET rarely predominates. Improvements in anaerobic digestion associated with the addition of electrically conductive materials have been attributed to increased DIET, but experimental verification has been lacking. This deficiency may soon be overcome with improved understanding of the diversity of microbes capable of DIET, which is leading to molecular tools for determining the extent of DIET. Here we review the microbiology of DIET, suggest molecular strategies for monitoring DIET in anaerobic digesters, and propose approaches for re-engineering digester design and practices to encourage DIET.
Collapse
Affiliation(s)
- Zhiqiang Zhao
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China
- Department of Microbiology, University of Massachusetts, Amherst, MA 01003-9298, USA
| | - Yang Li
- School of Ocean Science and Technology, Dalian University of Technology, Panjin 124221, China
- Department of Microbiology, University of Massachusetts, Amherst, MA 01003-9298, USA
| | - Yaobin Zhang
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China
| | - Derek R. Lovley
- Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110819, China
- Department of Microbiology, University of Massachusetts, Amherst, MA 01003-9298, USA
| |
Collapse
|
25
|
Abstract
Direct interspecies electron transfer (DIET) from bacteria to methanogens is a revolutionary concept for syntrophic metabolism in methanogenic soils/sediments and anaerobic digestion. Previous studies have indicated that the potential for DIET is limited to methanogens in the Methanosarcinales, leading to the assumption that an abundance of other types of methanogens, such as Methanobacterium species, indicates a lack of DIET. We report here on a strain of Methanobacterium, designated strain YSL, that grows via DIET in defined cocultures with Geobacter metallireducens. The cocultures formed aggregates, in which cells of strain YSL and G. metallireducens were uniformly dispersed throughout. This close association of the two species is the likely explanation for the ability of a strain of G. metallireducens that could not express electrically conductive pili to grow in coculture with strain YSL. Granular activated carbon promoted the initial formation of the DIET-based cocultures. The discovery of DIET in Methanobacterium, the genus of methanogens that has been the exemplar for interspecies electron transfer via H2, suggests that the capacity for DIET is much more broadly distributed among methanogens than previously considered. More innovative approaches to microbial isolation and characterization are needed in order to better understand how methanogenic communities function.
Collapse
Affiliation(s)
- Shiling Zheng
- Key Laboratory of Coastal Biology and Biological Resources Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China
- Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266237, 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, China
- Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266237, PR China
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
- Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, PR China
| | - Bingchen Wang
- Key Laboratory of Coastal Biology and Biological Resources Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China
| | - Yuechao Zhang
- Key Laboratory of Coastal Biology and Biological Resources Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China
| | - Derek R Lovley
- Electrobiomaterials Institute, Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110819, China
- Department of Microbiology, University of Massachusetts, Amherst, Massachusetts 01003, United States
| |
Collapse
|
26
|
Abstract
Electrically conductive protein nanowires appear to be widespread in the microbial world and are a revolutionary "green" material for the fabrication of electronic devices. Electrically conductive pili (e-pili) assembled from type IV pilin monomers have independently evolved multiple times in microbial history as have electrically conductive archaella (e-archaella) assembled from homologous archaellin monomers. A role for e-pili in long-range (micrometer) extracellular electron transport has been demonstrated in some microbes. The surprising finding of e-pili in syntrophic bacteria and the role of e-pili as conduits for direct interspecies electron transfer have necessitated a reassessment of routes for electron flux in important methanogenic environments, such as anaerobic digesters and terrestrial wetlands. Pilin monomers similar to those found in e-pili may also be a major building block of the conductive "cables" that transport electrons over centimeter distances through continuous filaments of cable bacteria consisting of a thousand cells or more. Protein nanowires harvested from microbes have many functional and sustainability advantages over traditional nanowire materials and have already yielded novel electronic devices for sustainable electricity production, neuromorphic memory, and sensing. e-pili can be mass produced with an Escherichia coli chassis, providing a ready source of material for electronics as well as for studies on the basic mechanisms for long-range electron transport along protein nanowires. Continued exploration is required to better understand the electrification of microbial communities with microbial nanowires and to expand the "green toolbox" of sustainable materials for wiring and powering the emerging "Internet of things."
Collapse
Affiliation(s)
- Derek R Lovley
- Department of Microbiology, University of Massachusetts, Amherst, Massachusetts, USA
- Institute of Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts, USA
| | - Dawn E Holmes
- Department of Microbiology, University of Massachusetts, Amherst, Massachusetts, USA
- Department of Physical and Biological Sciences, Western New England University, Springfield, Massachusetts, USA
| |
Collapse
|
27
|
Ueki T, Walker DJF, Woodard TL, Nevin KP, Nonnenmann SS, Lovley DR. An Escherichia coli Chassis for Production of Electrically Conductive Protein Nanowires. ACS Synth Biol 2020; 9:647-654. [PMID: 32125829 DOI: 10.1021/acssynbio.9b00506] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Geobacter sulfurreducens' pilin-based electrically conductive protein nanowires (e-PNs) are a revolutionary electronic material. They offer novel options for electronic sensing applications and have the remarkable ability to harvest electrical energy from atmospheric humidity. However, technical constraints limit mass cultivation and genetic manipulation of G. sulfurreducens. Therefore, we designed a strain of Escherichia coli to express e-PNs by introducing a plasmid that contained an inducible operon with E. coli genes for type IV pili biogenesis machinery and a synthetic gene designed to yield a peptide monomer that could be assembled into e-PNs. The e-PNs expressed in E. coli and harvested with a simple filtration method had the same diameter (3 nm) and conductance as e-PNs expressed in G. sulfurreducens. These results, coupled with the robustness of E. coli for mass cultivation and the extensive E. coli toolbox for genetic manipulation, greatly expand the opportunities for large-scale fabrication of novel e-PNs.
Collapse
Affiliation(s)
- Toshiyuki Ueki
- Department of Microbiology, University of Massachusetts-Amherst, Amherst, Massachusetts 01003, United States
- Institute for Applied Life Sciences, University of Massachusetts-Amherst, Amherst, Massachusetts 01003, United States
| | - David J. F. Walker
- Department of Microbiology, University of Massachusetts-Amherst, Amherst, Massachusetts 01003, United States
- Institute for Applied Life Sciences, University of Massachusetts-Amherst, Amherst, Massachusetts 01003, United States
| | - Trevor L. Woodard
- Department of Microbiology, University of Massachusetts-Amherst, Amherst, Massachusetts 01003, United States
| | - Kelly P. Nevin
- Department of Microbiology, University of Massachusetts-Amherst, Amherst, Massachusetts 01003, United States
| | - Stephen S. Nonnenmann
- Institute for Applied Life Sciences, University of Massachusetts-Amherst, Amherst, Massachusetts 01003, United States
- Department of Mechanical and Industrial Engineering, University of Massachusetts-Amherst, Amherst, Massachusetts 01003, United States
| | - Derek R. Lovley
- Department of Microbiology, University of Massachusetts-Amherst, Amherst, Massachusetts 01003, United States
- Institute for Applied Life Sciences, University of Massachusetts-Amherst, Amherst, Massachusetts 01003, United States
| |
Collapse
|
28
|
Liu X, Gao H, Ward JE, Liu X, Yin B, Fu T, Chen J, Lovley DR, Yao J. Power generation from ambient humidity using protein nanowires. Nature 2020; 578:550-554. [DOI: 10.1038/s41586-020-2010-9] [Citation(s) in RCA: 201] [Impact Index Per Article: 50.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 11/14/2019] [Indexed: 01/30/2023]
|
29
|
Walker DJF, Nevin KP, Holmes DE, Rotaru AE, Ward JE, Woodard TL, Zhu J, Ueki T, Nonnenmann SS, McInerney MJ, Lovley DR. Syntrophus conductive pili demonstrate that common hydrogen-donating syntrophs can have a direct electron transfer option. ISME J 2020; 14:837-846. [PMID: 31896792 DOI: 10.1038/s41396-019-0575-9] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 12/02/2019] [Accepted: 12/16/2019] [Indexed: 11/09/2022]
Abstract
Syntrophic interspecies electron exchange is essential for the stable functioning of diverse anaerobic microbial communities. Hydrogen/formate interspecies electron transfer (HFIT), in which H2 and/or formate function as diffusible electron carriers, has been considered to be the primary mechanism for electron transfer because most common syntrophs were thought to lack biochemical components, such as electrically conductive pili (e-pili), necessary for direct interspecies electron transfer (DIET). Here we report that Syntrophus aciditrophicus, one of the most intensively studied microbial models for HFIT, produces e-pili and can grow via DIET. Heterologous expression of the putative S. aciditrophicus type IV pilin gene in Geobacter sulfurreducens yielded conductive pili of the same diameter (4 nm) and conductance of the native S. aciditrophicus pili and enabled long-range electron transport in G. sulfurreducens. S. aciditrophicus lacked abundant c-type cytochromes often associated with DIET. Pilin genes likely to yield e-pili were found in other genera of hydrogen/formate-producing syntrophs. The finding that DIET is a likely option for diverse syntrophs that are abundant in many anaerobic environments necessitates a reexamination of the paradigm that HFIT is the predominant mechanism for syntrophic electron exchange within anaerobic microbial communities of biogeochemical and practical significance.
Collapse
Affiliation(s)
- David J F Walker
- Department of Microbiology, University of Massachusetts-Amherst, Amherst, MA, USA.,Institute for Applied Life Sciences, University of Massachusetts-Amherst, Amherst, MA, USA
| | - Kelly P Nevin
- Department of Microbiology, University of Massachusetts-Amherst, Amherst, MA, USA
| | - Dawn E Holmes
- Department of Microbiology, University of Massachusetts-Amherst, Amherst, MA, USA.,Department of Physical and Biological Science, Western New England University, Springfield, MA, USA
| | - Amelia-Elena Rotaru
- Department of Microbiology, University of Massachusetts-Amherst, Amherst, MA, USA.,Department of Biology, University of Southern Denmark, Odense, Denmark
| | - Joy E Ward
- Department of Microbiology, University of Massachusetts-Amherst, Amherst, MA, USA
| | - Trevor L Woodard
- Department of Microbiology, University of Massachusetts-Amherst, Amherst, MA, USA
| | - Jiaxin Zhu
- Department of Mechanical and Industrial Engineering, University of Massachusetts-Amherst, Amherst, MA, USA
| | - Toshiyuki Ueki
- Department of Microbiology, University of Massachusetts-Amherst, Amherst, MA, USA
| | - Stephen S Nonnenmann
- Institute for Applied Life Sciences, University of Massachusetts-Amherst, Amherst, MA, USA.,Department of Mechanical and Industrial Engineering, University of Massachusetts-Amherst, Amherst, MA, USA
| | - Michael J McInerney
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, USA
| | - Derek R Lovley
- Department of Microbiology, University of Massachusetts-Amherst, Amherst, MA, USA. .,Institute for Applied Life Sciences, University of Massachusetts-Amherst, Amherst, MA, USA.
| |
Collapse
|
30
|
Abstract
The study of electrically conductive protein nanowires in Geobacter sulfurreducens has led to new concepts for long-range extracellular electron transport, as well as for the development of sustainable conductive materials and electronic devices with novel functions. Until recently, electrically conductive pili (e-pili), assembled from the PilA pilin monomer, were the only known Geobacter protein nanowires. However, filaments comprised of the multi-heme c-type cytochrome, OmcS, are present in some preparations of G. sulfurreducens outer-surface proteins. The purpose of this review is to evaluate the available evidence on the in vivo expression of e-pili and OmcS filaments and their biological function. Abundant literature demonstrates that G. sulfurreducens expresses e-pili, which are required for long-range electron transport to Fe (III) oxides and through conductive biofilms. In contrast, there is no definitive evidence yet that wild-type G. sulfurreducens express long filaments of OmcS extending from the cells, and deleting the gene for OmcS actually increases biofilm conductivity. The literature does not support the concern that many previous studies on e-pili were mistakenly studying OmcS filaments. For example, heterologous expression of the aromatic-rich pilin monomer of Geobacter metallireducens in G. sulfurreducens increases the conductivity of individual nanowires more than 5,000-fold, whereas expression of an aromatic-poor pilin reduced conductivity more than 1,000-fold. This more than million-fold range in nanowire conductivity was achieved while maintaining the 3-nm diameter characteristic of e-pili. Purification methods that eliminate all traces of OmcS yield highly conductive e-pili, as does heterologous expression of the e-pilin monomer in microbes that do not produce OmcS or any other outer-surface cytochromes. Future studies of G. sulfurreducens expression of protein nanowires need to be cognizant of the importance of maintaining environmentally relevant growth conditions because artificial laboratory culture conditions can rapidly select against e-pili expression. Principles derived from the study of e-pili have enabled identification of non-cytochrome protein nanowires in diverse bacteria and archaea. A similar search for cytochrome appendages is warranted. Both e-pili and OmcS filaments offer design options for the synthesis of protein-based "green" electronics, which may be the primary driving force for the study of these structures in the near future.
Collapse
Affiliation(s)
- Derek R. Lovley
- Department of Microbiology, Institute for Applied Life Sciences, University of Massachusetts, Amherst, MA, United States
| | | |
Collapse
|
31
|
Ueki T, Walker DJ, Tremblay PL, Nevin KP, Ward JE, Woodard TL, Nonnenmann SS, Lovley DR. Decorating the Outer Surface of Microbially Produced Protein Nanowires with Peptides. ACS Synth Biol 2019; 8:1809-1817. [PMID: 31298834 DOI: 10.1021/acssynbio.9b00131] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The potential applications of electrically conductive protein nanowires (e-PNs) harvested from Geobacter sulfurreducens might be greatly expanded if the outer surface of the wires could be modified to confer novel sensing capabilities or to enhance binding to other materials. We developed a simple strategy for functionalizing e-PNs with surface-exposed peptides. The G. sulfurreducens gene for the monomer that assembles into e-PNs was modified to add peptide tags at the carboxyl terminus of the monomer. Strains of G. sulfurreducens were constructed that fabricated synthetic e-PNs with a six-histidine "His-tag" or both the His-tag and a nine-peptide "HA-tag" exposed on the outer surface. Addition of the peptide tags did not diminish e-PN conductivity. The abundance of HA-tag in e-PNs was controlled by placing expression of the gene for the synthetic monomer with the HA-tag under transcriptional regulation. These studies suggest broad possibilities for tailoring e-PN properties for diverse applications.
Collapse
Affiliation(s)
- Toshiyuki Ueki
- Department of Microbiology, University of Massachusetts—Amherst, Amherst, Massachusetts 01003, United States
- Institute for Applied Life Sciences, University of Massachusetts—Amherst, Amherst, Massachusetts 01003, United States
| | - David J.F. Walker
- Department of Microbiology, University of Massachusetts—Amherst, Amherst, Massachusetts 01003, United States
- Institute for Applied Life Sciences, University of Massachusetts—Amherst, Amherst, Massachusetts 01003, United States
| | - Pier-Luc Tremblay
- Department of Microbiology, University of Massachusetts—Amherst, Amherst, Massachusetts 01003, United States
| | - Kelly P. Nevin
- Department of Microbiology, University of Massachusetts—Amherst, Amherst, Massachusetts 01003, United States
| | - Joy E. Ward
- Department of Microbiology, University of Massachusetts—Amherst, Amherst, Massachusetts 01003, United States
| | - Trevor L. Woodard
- Department of Microbiology, University of Massachusetts—Amherst, Amherst, Massachusetts 01003, United States
| | - Stephen S. Nonnenmann
- Institute for Applied Life Sciences, University of Massachusetts—Amherst, Amherst, Massachusetts 01003, United States
- Department of Mechanical and Industrial Engineering, University of Massachusetts—Amherst, Amherst, Massachusetts 01003, United States
| | - Derek R. Lovley
- Department of Microbiology, University of Massachusetts—Amherst, Amherst, Massachusetts 01003, United States
- Institute for Applied Life Sciences, University of Massachusetts—Amherst, Amherst, Massachusetts 01003, United States
| |
Collapse
|
32
|
Filman DJ, Marino SF, Ward JE, Yang L, Mester Z, Bullitt E, Lovley DR, Strauss M. Cryo-EM reveals the structural basis of long-range electron transport in a cytochrome-based bacterial nanowire. Commun Biol 2019; 2:219. [PMID: 31240257 PMCID: PMC6584659 DOI: 10.1038/s42003-019-0448-9] [Citation(s) in RCA: 91] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Accepted: 04/30/2019] [Indexed: 01/16/2023] Open
Abstract
Electrically conductive pili from Geobacter species, termed bacterial nanowires, are intensely studied for their biological significance and potential in the development of new materials. Using cryo-electron microscopy, we have characterized nanowires from conductive G. sulfurreducens pili preparations that are composed solely of head-to-tail stacked monomers of the six-heme C-type cytochrome OmcS. The unique fold of OmcS - closely wrapped around a continuous stack of hemes that can serve as an uninterrupted path for electron transport - generates a scaffold that supports the unbranched chain of hemes along the central axis of the filament. We present here, at 3.4 Å resolution, the structure of this cytochrome-based filament and discuss its possible role in long-range biological electron transport.
Collapse
Affiliation(s)
- David J. Filman
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115 USA
| | - Stephen F. Marino
- German Federal Institute of Risk Assessment, Unit Bacterial Toxins, Department of Biological Safety, Max-Dohrn-Str. 8–10, Berlin, 10589 Germany
| | - Joy E. Ward
- Department of Microbiology and Institute for Applied Life Sciences, University of Massachusetts, Amherst, MA 01002 USA
| | - Lu Yang
- National Research Council Canada, Montreal Road Ottawa, ON 1200 Canada
| | - Zoltán Mester
- National Research Council Canada, Montreal Road Ottawa, ON 1200 Canada
| | - Esther Bullitt
- Department of Physiology & Biophysics, Boston University School of Medicine, 700 Albany Street, Boston, MA 02118 USA
| | - Derek R. Lovley
- Department of Microbiology and Institute for Applied Life Sciences, University of Massachusetts, Amherst, MA 01002 USA
| | - Mike Strauss
- Department of Anatomy and Cell Biology, McGill University, 3640 University St, Montreal, H3A 2B2 QC Canada
| |
Collapse
|
33
|
Abstract
The concept that anaerobic microorganisms can directly accept electrons from Fe(0) has been controversial because direct metal-microbe electron transfer has previously only been indirectly inferred. Fe(0) oxidation was studied with Geobacter sulfurreducens strain ACL, an autotrophic strain that was previously shown to grow with electrons derived from a graphite cathode as the sole electron donor. Strain ACL grew with Fe(0) as the sole electron donor and fumarate as the electron acceptor. However, it appeared that at least a portion of the electron transfer was via H2 produced nonenzymatically from the oxidation of Fe(0) to Fe(II). H2, which accumulated in abiotic controls, was consumed during the growth of strain ACL, the cells were predominately planktonic, and genes for the uptake hydrogenase were highly expressed. Strain ACLHF was constructed to prevent growth on H2 or formate by deleting the genes for the uptake of hydrogenase and formate dehydrogenases from strain ACL. Strain ACLHF also grew with Fe(0) as the sole electron donor, but H2 accumulated in the culture, and cells heavily colonized Fe(0) surfaces with no visible planktonic growth. Transcriptomics suggested that the outer surface c-type cytochromes OmcS and OmcZ were important during growth of strain ACLHF on Fe(0). Strain ACLHF did not grow on Fe(0) if the gene for either of these cytochromes was deleted. The specific attachment of strain ACLHF to Fe(0), coupled with requirements for known extracellular electrical contacts, suggest that direct metal-microbe electron transfer is the most likely option for Fe(0) serving as an electron donor.IMPORTANCE The anaerobic corrosion of iron structures is expensive to repair and can be a safety and environmental concern. It has been known for over 100 years that the presence of anaerobic respiratory microorganisms can accelerate iron corrosion. Multiple studies have suggested that there are sulfate reducers, methanogens, and acetogens that can directly accept electrons from Fe(0) to support sulfate or carbon dioxide reduction. However, all of the strains studied can also use H2 as an electron donor for growth, which is known to be abiotically produced from Fe(0). Furthermore, no proteins definitely shown to function as extracellular electrical contacts with Fe(0) were identified. The studies described here demonstrate that direct electron transfer from Fe(0) can support anaerobic respiration. They also map out a simple genetic approach to the study of iron corrosion mechanisms in other microorganisms. A better understanding of how microorganisms promote iron corrosion is expected to lead to the development of strategies that can help reduce adverse impacts from this process.
Collapse
Affiliation(s)
- Hai-Yan Tang
- Department of Microbiology, Morrill IV Science Center, 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
| | - Dawn E Holmes
- Department of Microbiology, Morrill IV Science Center, University of Massachusetts Amherst, Amherst, Massachusetts, USA
- Department of Physical and Biological Sciences, Western New England University, Springfield, Massachusetts, USA
| | - Toshiyuki Ueki
- Department of Microbiology, Morrill IV Science Center, University of Massachusetts Amherst, Amherst, Massachusetts, USA
| | - Paola A Palacios
- Department of Microbiology, Morrill IV Science Center, University of Massachusetts Amherst, Amherst, Massachusetts, USA
- Department of Biology, University of Southern Denmark, Odense, Denmark
| | - Derek R Lovley
- Department of Microbiology, Morrill IV Science Center, University of Massachusetts Amherst, Amherst, Massachusetts, USA
| |
Collapse
|
34
|
Liu X, Zhan J, Jing X, Zhou S, Lovley DR. A pilin chaperone required for the expression of electrically conductive
Geobacter sulfurreducens
pili. Environ Microbiol 2019; 21:2511-2522. [DOI: 10.1111/1462-2920.14638] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 04/15/2019] [Accepted: 04/21/2019] [Indexed: 11/30/2022]
Affiliation(s)
- Xing Liu
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and EnvironmentFujian Agriculture and Forestry University Fuzhou China
| | - Ji Zhan
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and EnvironmentFujian Agriculture and Forestry University Fuzhou China
| | - Xianyue Jing
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and EnvironmentFujian Agriculture and Forestry University Fuzhou China
| | - Shungui Zhou
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and EnvironmentFujian Agriculture and Forestry University Fuzhou China
| | - Derek R. Lovley
- Department of MicrobiologyUniversity of Massachusetts Amherst Amherst MA USA
| |
Collapse
|
35
|
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: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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.
Collapse
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
| |
Collapse
|
36
|
Sun YL, Tang HY, Ribbe A, Duzhko V, Woodard TL, Ward JE, Bai Y, Nevin KP, Nonnenmann SS, Russell T, Emrick T, Lovley DR. Conductive Composite Materials Fabricated from Microbially Produced Protein Nanowires. Small 2018; 14:e1802624. [PMID: 30260563 DOI: 10.1002/smll.201802624] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 08/16/2018] [Indexed: 06/08/2023]
Abstract
Protein-based electronic materials have numerous potential advantages with respect to sustainability and biocompatibility over electronic materials that are synthesized using harsh chemical processes and/or which contain toxic components. The microorganism Geobacter sulfurreducens synthesizes electrically conductive protein nanowires (e-PNs) with high aspect ratios (3 nm × 10-30 µm) from renewable organic feedstocks. Here, the integration of G. Sulfurreducens e-PNs into poly(vinyl alcohol) (PVA) as a host polymer matrix is described. The resultant e-PN/PVA composites exhibit conductivities comparable to PVA-based composites containing synthetic nanowires. The relationship between e-PN density and conductivity of the resultant composites is consistent with percolation theory. These e-PNs confer conductivity to the composites even under extreme conditions, with the highest conductivities achieved from materials prepared at pH 1.5 and temperatures greater than 100 °C. These results demonstrate that e-PNs represent viable and sustainable nanowire compositions for the fabrication of electrically conductive composite materials.
Collapse
Affiliation(s)
- Yun-Lu Sun
- Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Hai-Yan Tang
- Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Alexander Ribbe
- Polymer Science and Engineering Department, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Volodimyr Duzhko
- Polymer Science and Engineering Department, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Trevor L Woodard
- Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Joy E Ward
- Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Ying Bai
- Polymer Science and Engineering Department, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Kelly P Nevin
- Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Stephen S Nonnenmann
- Department of Mechanical and Industrial Engineering, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Thomas Russell
- Polymer Science and Engineering Department, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Todd Emrick
- Polymer Science and Engineering Department, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Derek R Lovley
- Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| |
Collapse
|
37
|
Holmes DE, Orelana R, Giloteaux L, Wang LY, Shrestha P, Williams K, Lovley DR, Rotaru AE. Potential for Methanosarcina to Contribute to Uranium Reduction during Acetate-Promoted Groundwater Bioremediation. Microb Ecol 2018; 76:660-667. [PMID: 29500492 PMCID: PMC6132540 DOI: 10.1007/s00248-018-1165-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 02/16/2018] [Indexed: 05/06/2023]
Abstract
Previous studies of acetate-promoted bioremediation of uranium-contaminated aquifers focused on Geobacter because no other microorganisms that can couple the oxidation of acetate with U(VI) reduction had been detected in situ. Monitoring the levels of methyl CoM reductase subunit A (mcrA) transcripts during an acetate-injection field experiment demonstrated that acetoclastic methanogens from the genus Methanosarcina were enriched after 40 days of acetate amendment. The increased abundance of Methanosarcina corresponded with an accumulation of methane in the groundwater. In order to determine whether Methanosarcina species could be participating in U(VI) reduction in the subsurface, cell suspensions of Methanosarcina barkeri were incubated in the presence of U(VI) with acetate provided as the electron donor. U(VI) was reduced by metabolically active M. barkeri cells; however, no U(VI) reduction was observed in inactive controls. These results demonstrate that Methanosarcina species could play an important role in the long-term bioremediation of uranium-contaminated aquifers after depletion of Fe(III) oxides limits the growth of Geobacter species. The results also suggest that Methanosarcina have the potential to influence uranium geochemistry in a diversity of anaerobic sedimentary environments.
Collapse
Affiliation(s)
- Dawn E Holmes
- Department of Physical and Biological Science, Western New England University, Springfield, MA, USA.
- Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, USA.
| | - Roberto Orelana
- Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, USA
| | - Ludovic Giloteaux
- Department of Molecular Biology and Genetics, College of Agriculture and Life Sciences, Cornell University, Ithaca, NY, USA
| | - Li-Ying Wang
- Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, USA
| | - Pravin Shrestha
- Energy Biosciences Institute, University of California Berkeley, Berkeley, CA, USA
| | | | - Derek R Lovley
- Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, USA
| | | |
Collapse
|
38
|
Ueki T, Nevin KP, Woodard TL, Aklujkar MA, Holmes DE, Lovley DR. Construction of a Geobacter Strain With Exceptional Growth on Cathodes. Front Microbiol 2018; 9:1512. [PMID: 30057572 PMCID: PMC6053493 DOI: 10.3389/fmicb.2018.01512] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 06/18/2018] [Indexed: 12/13/2022] Open
Abstract
Insoluble extracellular electron donors are important sources of energy for anaerobic respiration in biogeochemical cycling and in diverse practical applications. The previous lack of a genetically tractable model microorganism that could be grown to high densities under anaerobic conditions in pure culture with an insoluble extracellular electron donor has stymied efforts to better understand this form of respiration. We report here on the design of a strain of Geobacter sulfurreducens, designated strain ACL, which grows as thick (ca. 35 μm) confluent biofilms on graphite cathodes poised at -500 mV (versus Ag/AgCl) with fumarate as the electron acceptor. Sustained maximum current consumption rates were >0.8 A/m2, which is >10-fold higher than the current consumption of the wild-type strain. The improved function on the cathode was achieved by introducing genes for an ATP-dependent citrate lyase, completing the complement of enzymes needed for a reverse TCA cycle for the synthesis of biosynthetic precursors from carbon dioxide. Strain ACL provides an important model organism for elucidating the mechanisms for effective anaerobic growth with an insoluble extracellular electron donor and may offer unique possibilities as a chassis for the introduction of synthetic metabolic pathways for the production of commodities with electrons derived from electrodes.
Collapse
Affiliation(s)
- Toshiyuki Ueki
- Morrill Science Center IV, Department of Microbiology, University of Massachusetts, Amherst, MA, United States
| | - Kelly P Nevin
- Morrill Science Center IV, Department of Microbiology, University of Massachusetts, Amherst, MA, United States
| | - Trevor L Woodard
- Morrill Science Center IV, Department of Microbiology, University of Massachusetts, Amherst, MA, United States
| | - Muktak A Aklujkar
- Morrill Science Center IV, Department of Microbiology, University of Massachusetts, Amherst, MA, United States
| | - Dawn E Holmes
- Morrill Science Center IV, Department of Microbiology, University of Massachusetts, Amherst, MA, United States.,Department of Physical and Biological Sciences, Western New England University, Springfield, MA, United States
| | - Derek R Lovley
- Morrill Science Center IV, Department of Microbiology, University of Massachusetts, Amherst, MA, United States
| |
Collapse
|
39
|
Ueki T, DiDonato LN, Lovley DR. Toward establishing minimum requirements for extracellular electron transfer in Geobacter sulfurreducens. FEMS Microbiol Lett 2017; 364:3796320. [PMID: 28472266 DOI: 10.1093/femsle/fnx093] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 05/03/2017] [Indexed: 11/12/2022] Open
Abstract
The highly redundant pathways for extracellular electron transfer in Geobacter sulfurreducens must be simplified for this microorganism to serve as an effective chassis for applications such as the development of sensors and biocomputing. Five homologs of the periplasmic c-type cytochromes, PpcA-E, offer the possibility of multiple routes of electron transfer across the periplasm. The presence of a large number of outer membrane c-type cytochromes allows G. sulfurreducens to adapt to disruption of an electron transfer pathway in the outer membrane. A strain in which genes for all five periplasmic cytochromes, PpcA-E, were deleted did not reduce Fe(III). Introducing ppcA under the control of an IPTG-inducible system in the quintuple deletion strain yielded a strain that reduced Fe(III) only in the presence of IPTG. A strain lacking known major outer membrane cytochromes, OmcB, OmcE, OmcS and OmcT, and putative functional homologs of OmcB, did not reduce Fe(III). Introduction of omcB in this septuple deletion strain restored the ability to reduce Fe(III). These results demonstrate that it is possible to trim redundancy from the extracellular electron transfer pathways in G. sulfurreducens in order to construct strains with defined extracellular electron transfer routes.
Collapse
|
40
|
Affiliation(s)
- Derek R. Lovley
- Department of Microbiology, University of Massachusetts, Amherst, Massachusetts 01003
| |
Collapse
|
41
|
Abstract
The growing ubiquity of electronic devices is increasingly consuming substantial energy and rare resources for materials fabrication, as well as creating expansive volumes of toxic waste. This is not sustainable. Electronic biological materials (e-biologics) that are produced with microbes, or designed with microbial components as the guide for synthesis, are a potential green solution. Some e-biologics can be fabricated from renewable feedstocks with relatively low energy inputs, often while avoiding the harsh chemicals used for synthesizing more traditional electronic materials. Several are completely free of toxic components, can be readily recycled, and offer unique features not found in traditional electronic materials in terms of size, performance, and opportunities for diverse functionalization. An appropriate investment in the concerted multidisciplinary collaborative research required to identify and characterize e-biologics and to engineer materials and devices based on e-biologics could be rewarded with a new "green age" of sustainable electronic materials and devices.
Collapse
Affiliation(s)
- Derek R Lovley
- Department of Microbiology, University of Massachusetts, Amherst, Massachusetts, USA
| |
Collapse
|
42
|
Butler CS, Lovley DR. How to Sustainably Feed a Microbe: Strategies for Biological Production of Carbon-Based Commodities with Renewable Electricity. Front Microbiol 2016; 7:1879. [PMID: 27965629 PMCID: PMC5124563 DOI: 10.3389/fmicb.2016.01879] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 11/08/2016] [Indexed: 11/15/2022] Open
Abstract
As interest and application of renewable energy grows, strategies are needed to align the asynchronous supply and demand. Microbial metabolisms are a potentially sustainable mechanism for transforming renewable electrical energy into biocommodities that are easily stored and transported. Acetogens and methanogens can reduce carbon dioxide to organic products including methane, acetic acid, and ethanol. The library of biocommodities is expanded when engineered metabolisms of acetogens are included. Typically, electrochemical systems are employed to integrate renewable energy sources with biological systems for production of carbon-based commodities. Within these systems, there are three prevailing mechanisms for delivering electrons to microorganisms for the conversion of carbon dioxide to reduce organic compounds: (1) electrons can be delivered to microorganisms via H2 produced separately in a electrolyzer, (2) H2 produced at a cathode can convey electrons to microorganisms supported on the cathode surface, and (3) a cathode can directly feed electrons to microorganisms. Each of these strategies has advantages and disadvantages that must be considered in designing full-scale processes. This review considers the evolving understanding of each of these approaches and the state of design for advancing these strategies toward viability.
Collapse
Affiliation(s)
- Caitlyn S Butler
- Civil and Environmental Engineering, University of Massachusetts Amherst, MA, USA
| | - Derek R Lovley
- Microbiology, University of Massachusetts Amherst, MA, USA
| |
Collapse
|
43
|
Malvankar NS, Rotello VM, Tuominen MT, Lovley DR. Reply to 'Measuring conductivity of living Geobacter sulfurreducens biofilms'. Nat Nanotechnol 2016; 11:913-914. [PMID: 27821844 DOI: 10.1038/nnano.2016.191] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Affiliation(s)
- Nikhil S Malvankar
- Department of Molecular Biophysics and Biochemistry, Microbial Sciences Institute, Yale University, Connecticut 06516, USA
| | - Vincent M Rotello
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - Mark T Tuominen
- Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - Derek R Lovley
- Department of Microbiology, University of Massachusetts, Amherst, Massachusetts 01003, USA
| |
Collapse
|
44
|
Lovley DR. Happy together: microbial communities that hook up to swap electrons. ISME J 2016; 11:327-336. [PMID: 27801905 DOI: 10.1038/ismej.2016.136] [Citation(s) in RCA: 168] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 08/29/2016] [Accepted: 09/04/2016] [Indexed: 12/22/2022]
Abstract
The discovery of direct interspecies electron transfer (DIET) and cable bacteria has demonstrated that microbial cells can exchange electrons over long distances (μm-cm) through electrical connections. For example, in the presence of cable bacteria electrons are rapidly transported over centimeter distances, coupling the oxidation of reduced sulfur compounds in anoxic sediments to oxygen reduction in overlying surficial sediments. Bacteria and archaea wired for DIET are found in anaerobic methane-producing and methane-consuming communities. Electrical connections between gut microbes and host cells have also been proposed. Iterative environmental and defined culture studies on methanogenic communities revealed the importance of electrically conductive pili and c-type cytochromes in natural electrical grids, and demonstrated that conductive carbon materials and magnetite can substitute for these biological connectors to facilitate DIET. This understanding has led to strategies to enhance and stabilize anaerobic digestion. Key unknowns warranting further investigation include elucidation of the archaeal electrical connections facilitating DIET-based methane production and consumption; and the mechanisms for long-range electron transfer through cable bacteria. A better understanding of mechanisms for cell-to-cell electron transfer could facilitate the hunt for additional electrically connected microbial communities with omics approaches and could advance spin-off applications such as the development of sustainable bioelectronics materials and bioelectrochemical technologies.
Collapse
Affiliation(s)
- Derek R Lovley
- Department of Microbiology, Morrill IV N Science Center, University of Massachusetts, Amherst, MA, USA
| |
Collapse
|
45
|
Dang Y, Holmes DE, Zhao Z, Woodard TL, Zhang Y, Sun D, Wang LY, Nevin KP, Lovley DR. Enhancing anaerobic digestion of complex organic waste with carbon-based conductive materials. Bioresour Technol 2016; 220:516-522. [PMID: 27611035 DOI: 10.1016/j.biortech.2016.08.114] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 08/29/2016] [Accepted: 08/30/2016] [Indexed: 06/06/2023]
Abstract
The aim of this work was to study the methanogenic metabolism of dog food, a food waste surrogate, in laboratory-scale reactors with different carbon-based conductive materials. Carbon cloth, carbon felt, and granular activated carbon all permitted higher organic loading rates and promoted faster recovery of soured reactors than the control reactors. Microbial community analysis revealed that specific and substantial enrichments of Sporanaerobacter and Methanosarcina were present on the carbon cloth surface. These results, and the known ability of Sporanaerobacter species to transfer electrons to elemental sulfur, suggest that Sporanaerobacter species can participate in direct interspecies electron transfer with Methanosarcina species when carbon cloth is available as an electron transfer mediator.
Collapse
Affiliation(s)
- Yan Dang
- Department of Microbiology, University of Massachusetts Amherst, Morril IV N Science Center, Amherst, MA 01003, USA; Beijing Key Laboratory for Source Control Technology of Water Pollution, College of Environmental Science & Engineering, Beijing Forestry University, 35 Tsinghua East Road, Beijing 100083, China.
| | - Dawn E Holmes
- Department of Microbiology, University of Massachusetts Amherst, Morril IV N Science Center, Amherst, MA 01003, USA; Department of Physical and Biological Sciences, Western New England University, 1215 Wilbraham Rd, Springfield, MA 01119, USA
| | - Zhiqiang Zhao
- Department of Microbiology, University of Massachusetts Amherst, Morril IV N Science Center, Amherst, MA 01003, USA; Key Laboratory of Industrial Ecology and Environmental Engineering (Dalian University of Technology), Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China
| | - Trevor L Woodard
- Department of Microbiology, University of Massachusetts Amherst, Morril IV N Science Center, Amherst, MA 01003, USA
| | - Yaobin Zhang
- Department of Microbiology, University of Massachusetts Amherst, Morril IV N Science Center, Amherst, MA 01003, USA; Key Laboratory of Industrial Ecology and Environmental Engineering (Dalian University of Technology), Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China
| | - Dezhi Sun
- Department of Microbiology, University of Massachusetts Amherst, Morril IV N Science Center, Amherst, MA 01003, USA; Beijing Key Laboratory for Source Control Technology of Water Pollution, College of Environmental Science & Engineering, Beijing Forestry University, 35 Tsinghua East Road, Beijing 100083, China
| | - Li-Ying Wang
- Department of Microbiology, University of Massachusetts Amherst, Morril IV N Science Center, Amherst, MA 01003, USA
| | - Kelly P Nevin
- Department of Microbiology, University of Massachusetts Amherst, Morril IV N Science Center, Amherst, MA 01003, USA
| | - Derek R Lovley
- Department of Microbiology, University of Massachusetts Amherst, Morril IV N Science Center, Amherst, MA 01003, USA
| |
Collapse
|
46
|
Ueki T, Nevin KP, Woodard TL, Lovley DR. Genetic switches and related tools for controlling gene expression and electrical outputs of Geobacter sulfurreducens. J Ind Microbiol Biotechnol 2016; 43:1561-1575. [PMID: 27659960 DOI: 10.1007/s10295-016-1836-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2016] [Accepted: 09/11/2016] [Indexed: 01/04/2023]
Abstract
Physiological studies and biotechnology applications of Geobacter species have been limited by a lack of genetic tools. Therefore, potential additional molecular strategies for controlling metabolism were explored. When the gene for citrate synthase, or acetyl-CoA transferase, was placed under the control of a LacI/IPTG regulator/inducer system, cells grew on acetate only in the presence of IPTG. The TetR/AT system could also be used to control citrate synthase gene expression and acetate metabolism. A strain that required IPTG for growth on D-lactate was constructed by placing the gene for D-lactate dehydrogenase under the control of the LacI/IPTG system. D-Lactate served as an inducer in a strain in which a D-lactate responsive promoter and transcription repressor were used to control citrate synthase expression. Iron- and potassium-responsive systems were successfully incorporated to regulate citrate synthase expression and growth on acetate. Linking the appropriate degradation tags on the citrate synthase protein made it possible to control acetate metabolism with either the endogenous ClpXP or exogenous Lon protease and tag system. The ability to control current output from Geobacter biofilms and the construction of an AND logic gate for acetate metabolism suggested that the tools developed may be applicable for biosensor and biocomputing applications.
Collapse
Affiliation(s)
- Toshiyuki Ueki
- Department of Microbiology, University of Massachusetts, Morrill Science Center IV North, 639 North Pleasant Street, Amherst, MA, 01003, USA.
| | - Kelly P Nevin
- Department of Microbiology, University of Massachusetts, Morrill Science Center IV North, 639 North Pleasant Street, Amherst, MA, 01003, USA
| | - Trevor L Woodard
- Department of Microbiology, University of Massachusetts, Morrill Science Center IV North, 639 North Pleasant Street, Amherst, MA, 01003, USA
| | - Derek R Lovley
- Department of Microbiology, University of Massachusetts, Morrill Science Center IV North, 639 North Pleasant Street, Amherst, MA, 01003, USA
| |
Collapse
|
47
|
Tan Y, Adhikari RY, Malvankar NS, Pi S, Ward JE, Woodard TL, Nevin KP, Xia Q, Tuominen MT, Lovley DR. Synthetic Biological Protein Nanowires with High Conductivity. Small 2016; 12:4481-4485. [PMID: 27409066 DOI: 10.1002/smll.201601112] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 06/11/2016] [Indexed: 06/06/2023]
Abstract
Genetic modification to add tryptophan to PilA, the monomer for the electrically conductive pili of Geobacter sulfurreducens, yields conductive protein filaments 2000-fold more conductive than the wild-type pili while cutting the diameter in half to 1.5 nm.
Collapse
Affiliation(s)
- Yang Tan
- Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Ramesh Y Adhikari
- Department of Physics, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Nikhil S Malvankar
- Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, 01003, USA
- Department of Physics, University of Massachusetts Amherst, Amherst, MA, 01003, USA
- Department of Molecular Biophysics and Biochemistry, Microbial Sciences Institute, Yale University, New Haven, CT, 06516, USA
| | - Shuang Pi
- Department of Electrical and Computer Engineering, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Joy E Ward
- Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Trevor L Woodard
- Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Kelly P Nevin
- Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Qiangfei Xia
- Department of Electrical and Computer Engineering, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Mark T Tuominen
- Department of Physics, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Derek R Lovley
- Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| |
Collapse
|
48
|
Holmes DE, Dang Y, Walker DJF, Lovley DR. The electrically conductive pili of Geobacter species are a recently evolved feature for extracellular electron transfer. Microb Genom 2016; 2:e000072. [PMID: 28348867 DOI: 10.1099/mgen.0.000072] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 05/31/2016] [Indexed: 12/14/2022] Open
Abstract
The electrically conductive pili (e-pili) of Geobactersulfurreducens have environmental and practical significance because they can facilitate electron transfer to insoluble Fe(III) oxides; to other microbial species; and through electrically conductive biofilms. E-pili conductivity has been attributed to the truncated PilA monomer, which permits tight packing of aromatic amino acids to form a conductive path along the length of e-pili. In order to better understand the evolution and distribution of e-pili in the microbial world, type IVa PilA proteins from various Gram-negative and Gram-positive bacteria were examined with a particular emphasis on Fe(III)-respiring bacteria. E-pilin genes are primarily restricted to a tight phylogenetic group in the order Desulfuromonadales. The downstream gene in all but one of the Desulfuromonadales that possess an e-pilin gene is a gene previously annotated as 'pilA-C' that has characteristics suggesting that it may encode an outer-membrane protein. Other genes associated with pilin function are clustered with e-pilin and 'pilA-C' genes in the Desulfuromonadales. In contrast, in the few bacteria outside the Desulfuromonadales that contain e-pilin genes, the other genes required for pilin function may have been acquired through horizontal gene transfer. Of the 95 known Fe(III)-reducing micro-organisms for which genomes are available, 80 % lack e-pilin genes, suggesting that e-pili are just one of several mechanisms involved in extracellular electron transport. These studies provide insight into where and when e-pili are likely to contribute to extracellular electron transport processes that are biogeochemically important and involved in bioenergy conversions.
Collapse
Affiliation(s)
- Dawn E Holmes
- 1Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, USA.,2Department of Physical and Biological Sciences, Western New England University, Springfield, MA, USA
| | - Yan Dang
- 1Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, USA
| | - David J F Walker
- 1Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, USA
| | - Derek R Lovley
- 1Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, USA
| |
Collapse
|
49
|
Tan Y, Adhikari RY, Malvankar NS, Ward JE, Nevin KP, Woodard TL, Smith JA, Snoeyenbos-West OL, Franks AE, Tuominen MT, Lovley DR. The Low Conductivity of Geobacter uraniireducens Pili Suggests a Diversity of Extracellular Electron Transfer Mechanisms in the Genus Geobacter. Front Microbiol 2016; 7:980. [PMID: 27446021 PMCID: PMC4923279 DOI: 10.3389/fmicb.2016.00980] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 06/07/2016] [Indexed: 11/30/2022] Open
Abstract
Studies on the mechanisms for extracellular electron transfer in Geobacter species have primarily focused on Geobacter sulfurreducens, but the poor conservation of genes for some electron transfer components within the Geobacter genus suggests that there may be a diversity of extracellular electron transport strategies among Geobacter species. Examination of the gene sequences for PilA, the type IV pilus monomer, in Geobacter species revealed that the PilA sequence of Geobacter uraniireducens was much longer than that of G. sulfurreducens. This is of interest because it has been proposed that the relatively short PilA sequence of G. sulfurreducens is an important feature conferring conductivity to G. sulfurreducens pili. In order to investigate the properties of the G. uraniireducens pili in more detail, a strain of G. sulfurreducens that expressed pili comprised the PilA of G. uraniireducens was constructed. This strain, designated strain GUP, produced abundant pili, but generated low current densities and reduced Fe(III) very poorly. At pH 7, the conductivity of the G. uraniireducens pili was 3 × 10-4 S/cm, much lower than the previously reported 5 × 10-2 S/cm conductivity of G. sulfurreducens pili at the same pH. Consideration of the likely voltage difference across pili during Fe(III) oxide reduction suggested that G. sulfurreducens pili can readily accommodate maximum reported rates of respiration, but that G. uraniireducens pili are not sufficiently conductive to be an effective mediator of long-range electron transfer. In contrast to G. sulfurreducens and G. metallireducens, which require direct contact with Fe(III) oxides in order to reduce them, G. uraniireducens reduced Fe(III) oxides occluded within microporous beads, demonstrating that G. uraniireducens produces a soluble electron shuttle to facilitate Fe(III) oxide reduction. The results demonstrate that Geobacter species may differ substantially in their mechanisms for long-range electron transport and that it is important to have information beyond a phylogenetic affiliation in order to make conclusions about the mechanisms by which Geobacter species are transferring electrons to extracellular electron acceptors.
Collapse
Affiliation(s)
- Yang Tan
- Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, USA
| | - Ramesh Y Adhikari
- Department of Physics, University of Massachusetts Amherst Amherst, MA, USA
| | - Nikhil S Malvankar
- Department of Microbiology, University of Massachusetts Amherst,Amherst, MA, USA; Department of Physics, University of Massachusetts AmherstAmherst, MA, USA; Department of Molecular Biophysics and Biochemistry, Microbial Sciences Institute, Yale UniversityNew Haven, CT, USA
| | - Joy E Ward
- Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, USA
| | - Kelly P Nevin
- Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, USA
| | - Trevor L Woodard
- Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, USA
| | - Jessica A Smith
- Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, USA
| | | | - Ashley E Franks
- Department of Microbiology, University of Massachusetts Amherst,Amherst, MA, USA; Department of Physiology, Anatomy and Microbiology, La Trobe UniversityMelbourne, VIC, Australia
| | - Mark T Tuominen
- Department of Physics, University of Massachusetts Amherst Amherst, MA, USA
| | - Derek R Lovley
- Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, USA
| |
Collapse
|
50
|
Zhao Z, Zhang Y, Holmes DE, Dang Y, Woodard TL, Nevin KP, Lovley DR. Potential enhancement of direct interspecies electron transfer for syntrophic metabolism of propionate and butyrate with biochar in up-flow anaerobic sludge blanket reactors. Bioresour Technol 2016; 209:148-56. [PMID: 26967338 DOI: 10.1016/j.biortech.2016.03.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Revised: 02/27/2016] [Accepted: 03/01/2016] [Indexed: 05/16/2023]
Abstract
Promoting direct interspecies electron transfer (DIET) to enhance syntrophic metabolism may be a strategy for accelerating the conversion of organic wastes to methane, but microorganisms capable of metabolizing propionate and butyrate via DIET under methanogenic conditions have yet to be identified. In an attempt to establish methanogenic communities metabolizing propionate or butyrate with DIET, enrichments were initiated with up-flow anaerobic sludge blanket (UASB), similar to those that were previously reported to support communities that metabolized ethanol with DIET that relied on direct biological electrical connections. In the absence of any amendments, microbial communities enriched were dominated by microorganisms closely related to pure cultures that are known to metabolize propionate or butyrate to acetate with production of H2. When biochar was added to the reactors there was a substantial enrichment on the biochar surface of 16S rRNA gene sequences closely related to Geobacter and Methanosaeta species known to participate in DIET.
Collapse
Affiliation(s)
- Zhiqiang Zhao
- Department of Microbiology, University of Massachusetts, Amherst, MA 01003-9298, USA; Key Laboratory of Industrial Ecology and Environmental Engineering (Dalian University of Technology), Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China
| | - Yaobin Zhang
- Department of Microbiology, University of Massachusetts, Amherst, MA 01003-9298, USA; Key Laboratory of Industrial Ecology and Environmental Engineering (Dalian University of Technology), Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China.
| | - Dawn E Holmes
- Department of Microbiology, University of Massachusetts, Amherst, MA 01003-9298, USA; Physical and Biological Sciences, Western New England University, Springfield, MA, USA
| | - Yan Dang
- Department of Microbiology, University of Massachusetts, Amherst, MA 01003-9298, USA; Beijing Key Lab for Source Control Technology of Water Pollution, Beijing Forestry University, 35 Tsinghua East Road, Beijing 100083, China
| | - Trevor L Woodard
- Department of Microbiology, University of Massachusetts, Amherst, MA 01003-9298, USA
| | - Kelly P Nevin
- Department of Microbiology, University of Massachusetts, Amherst, MA 01003-9298, USA
| | - Derek R Lovley
- Department of Microbiology, University of Massachusetts, Amherst, MA 01003-9298, USA
| |
Collapse
|