1
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Guberman-Pfeffer MJ. To be or not to be a cytochrome: electrical characterizations are inconsistent with Geobacter cytochrome 'nanowires'. Front Microbiol 2024; 15:1397124. [PMID: 38633696 PMCID: PMC11021709 DOI: 10.3389/fmicb.2024.1397124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Accepted: 03/21/2024] [Indexed: 04/19/2024] Open
Abstract
Geobacter sulfurreducens profoundly shapes Earth's biogeochemistry by discharging respiratory electrons to minerals and other microbes through filaments of a two-decades-long debated identity. Cryogenic electron microscopy has revealed filaments of redox-active cytochromes, but the same filaments have exhibited hallmarks of organic metal-like conductivity under cytochrome denaturing/inhibiting conditions. Prior structure-based calculations and kinetic analyses on multi-heme proteins are synthesized herein to propose that a minimum of ~7 cytochrome 'nanowires' can carry the respiratory flux of a Geobacter cell, which is known to express somewhat more (≥20) filaments to increase the likelihood of productive contacts. By contrast, prior electrical and spectroscopic structural characterizations are argued to be physiologically irrelevant or physically implausible for the known cytochrome filaments because of experimental artifacts and sample impurities. This perspective clarifies our mechanistic understanding of physiological metal-microbe interactions and advances synthetic biology efforts to optimize those interactions for bioremediation and energy or chemical production.
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2
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Ye Y, Zhang L, Hong X, Chen M, Liu X, Zhou S. Interspecies ecological competition rejuvenates decayed Geobacter electroactive biofilm. THE ISME JOURNAL 2024; 18:wrae118. [PMID: 38916438 PMCID: PMC11227281 DOI: 10.1093/ismejo/wrae118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Revised: 06/05/2024] [Accepted: 06/23/2024] [Indexed: 06/26/2024]
Abstract
Bioelectrochemical systems (BESs) exploit electroactive biofilms (EABs) for promising applications in biosensing, wastewater treatment, energy production, and chemical biosynthesis. However, during the operation of BESs, EABs inevitably decay. Seeking approaches to rejuvenate decayed EABs is critical for the sustainability and practical application of BESs. Prophage induction has been recognized as the primary reason for EAB decay. Herein, we report that introducing a competitive species of Geobacter uraniireducens suspended prophage induction in Geobacter sulfurreducens and thereby rejuvenated the decayed G. sulfurreducens EAB. The transcriptomic profile of G. sulfurreducens demonstrated that the addition of G. uraniireducens significantly affected the expression of metabolism- and stress response system-related genes and in particular suppressed the induction of phage-related genes. Mechanistic analyses revealed that interspecies ecological competition exerted by G. uraniireducens suppressed prophage induction. Our findings not only reveal a novel strategy to rejuvenate decayed EABs, which is significant for the sustainability of BESs, but also provide new knowledge for understanding phage-host interactions from an ecological perspective, with implications for developing therapies to defend against phage attack.
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Affiliation(s)
- Yin Ye
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Lu Zhang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Xiaohui Hong
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Man Chen
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Xing Liu
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Shungui Zhou
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
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3
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Philippon T, Ait-Itto FZ, Monfort A, Barrière F, Behan JA. Fe(III) oxide microparticles modulate extracellular electron transfer in anodic biofilms dominated by bacteria of the Pelobacter genus. Bioelectrochemistry 2023; 151:108394. [PMID: 36739700 DOI: 10.1016/j.bioelechem.2023.108394] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 01/27/2023] [Accepted: 01/28/2023] [Indexed: 02/04/2023]
Abstract
Exo-electrogenic microorganisms have been extensively studied for their ability to transfer electrons with solid surfaces using a large variety of metabolic pathways. Most of the studies on these microorganisms consist in the replacement of solid electron acceptors such as Fe(III) oxides found in nature by electrodes with the objective of generating harvestable current in devices such as microbial fuel cells. In this study we show how the presence of solid ferric oxide (Fe2O3) particles in the inoculum during bio-anode development influences extracellular electron transfer to the electrode. Amplification and sequencing of the 16S rRNA (V4-V5 region) show bacteria and archaea communities with a large predominance of the Pelobacter genus, which is known to be phylogenetically close to the Geobacter genus, regardless of the presence or absence of ferric oxide in the inoculum. Data indicate that the bacteria at the bio-anode surface can preferentially utilize solid ferric oxide as terminal electron acceptors instead of the anode, though extracellular electron transfer to the anode can be restored by removing the particles. Mixed inoculum commonly used to develop bioanodes may produce similar bacterial communities with divergent electrochemical responses due to the presence of alternate electron acceptors, with direct implications for microbial fuel cell performance.
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Affiliation(s)
- Timothé Philippon
- Université de Rennes, CNRS, Institut des Sciences Chimiques de Rennes, UMR 6226, Rennes, France
| | - Fatima-Zahra Ait-Itto
- Université de Rennes, CNRS, Institut des Sciences Chimiques de Rennes, UMR 6226, Rennes, France
| | - Alicia Monfort
- Université de Rennes, CNRS, Institut des Sciences Chimiques de Rennes, UMR 6226, Rennes, France
| | - Frédéric Barrière
- Université de Rennes, CNRS, Institut des Sciences Chimiques de Rennes, UMR 6226, Rennes, France.
| | - James A Behan
- Université de Rennes, CNRS, Institut des Sciences Chimiques de Rennes, UMR 6226, Rennes, France.
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4
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Liu X, Ye Y, Zhang Z, Rensing C, Zhou S, Nealson KH. Prophage Induction Causes Geobacter Electroactive Biofilm Decay. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:6196-6204. [PMID: 36997849 DOI: 10.1021/acs.est.2c08443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Sustaining a metabolically active electroactive biofilm (EAB) is essential for the high efficiency and durable operation of microbial fuel cells (MFCs). However, EABs usually decay during long-term operation, and, until now, the causes remain unknown. Here, we report that lysogenic phages can cause EAB decay in Geobacter sulfurreducens fuel cells. A cross-streak agar assay and bioinformatic analysis revealed the presence of prophages on the G. sulfurreducens genome, and a mitomycin C induction assay revealed the lysogenic to lytic transition of those prophages, resulting in a progressive decay in both current generation and the EAB. Furthermore, the addition of phages purified from decayed EAB resulted in accelerated decay of the EAB, thereafter contributing to a faster decline in current generation; otherwise, deleting prophage-related genes rescued the decay process. Our study provides the first evidence of an interaction between phages and electroactive bacteria and suggests that attack by phages is a primary cause of EAB decay, having significant implications in bioelectrochemical systems.
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Affiliation(s)
- Xing Liu
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Yin Ye
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Zhishuai Zhang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Christopher Rensing
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Shungui Zhou
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Kenneth H Nealson
- Department of Earth Science, University of Southern California, Los Angeles, California 90089, United States
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5
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Howley E, Mangus A, Williams D, Torres CI. Intracytoplasmic membranes develop in Geobacter sulfurreducens under thermodynamically limiting conditions. NPJ Biofilms Microbiomes 2023; 9:18. [PMID: 37029136 PMCID: PMC10082016 DOI: 10.1038/s41522-023-00384-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 03/17/2023] [Indexed: 04/09/2023] Open
Abstract
Geobacter sulfurreducens is an electroactive bacterium capable of reducing metal oxides in the environment and electrodes in engineered systems1,2. Geobacter sp. are the keystone organisms in electrogenic biofilms, as their respiration consumes fermentation products produced by other organisms and reduces a terminal electron acceptor e.g. iron oxide or an electrode. To respire extracellular electron acceptors with a wide range of redox potentials, G. sulfurreducens has a complex network of respiratory proteins, many of which are membrane-bound3-5. We have identified intracytoplasmic membrane (ICM) structures in G. sulfurreducens. This ICM is an invagination of the inner membrane that has folded and organized by an unknown mechanism, often but not always located near the tip of a cell. Using confocal microscopy, we can identify that at least half of the cells contain an ICM when grown on low potential anode surfaces, whereas cells grown at higher potential anode surfaces or using fumarate as electron acceptor had significantly lower ICM frequency. 3D models developed from cryo-electron tomograms show the ICM to be a continuous extension of the inner membrane in contact with the cytoplasmic and periplasmic space. The differential abundance of ICM in cells grown under different thermodynamic conditions supports the hypothesis that it is an adaptation to limited energy availability, as an increase in membrane-bound respiratory proteins could increase electron flux. Thus, the ICM provides extra inner-membrane surface to increase the abundance of these proteins. G. sulfurreducens is the first Thermodesulfobacterium or metal-oxide reducer found to produce ICMs.
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Affiliation(s)
- Ethan Howley
- School for Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ, USA
| | - Anna Mangus
- School for Engineering Mass Transport and Energy, Arizona State University, Tempe, AZ, USA
| | - Dewight Williams
- Eyring Materials Center, Arizona State University, Tempe, AZ, USA
| | - César I Torres
- School for Engineering Mass Transport and Energy, Arizona State University, Tempe, AZ, USA.
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Grozinger L, Heidrich E, Goñi-Moreno Á. An electrogenetic toggle switch model. Microb Biotechnol 2023; 16:546-559. [PMID: 36207818 PMCID: PMC9948229 DOI: 10.1111/1751-7915.14153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 07/29/2022] [Accepted: 09/10/2022] [Indexed: 11/29/2022] Open
Abstract
Synthetic biology uses molecular biology to implement genetic circuits that perform computations. These circuits can process inputs and deliver outputs according to predefined rules that are encoded, often entirely, into genetic parts. However, the field has recently begun to focus on using mechanisms beyond the realm of genetic parts for engineering biological circuits. We analyse the use of electrogenic processes for circuit design and present a model for a merged genetic and electrogenetic toggle switch operating in a biofilm attached to an electrode. Computational simulations explore conditions under which bistability emerges in order to identify the circuit design principles for best switch performance. The results provide a basis for the rational design and implementation of hybrid devices that can be measured and controlled both genetically and electronically.
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Affiliation(s)
- Lewis Grozinger
- School of Computing, Newcastle University, Newcastle Upon Tyne, UK.,Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA/CSIC), Madrid, Spain
| | - Elizabeth Heidrich
- School of Civil Engineering and Geosciences, Newcastle University, Newcastle Upon Tyne, UK
| | - Ángel Goñi-Moreno
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA/CSIC), Madrid, Spain
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7
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Martín-Rodríguez AJ. Respiration-induced biofilm formation as a driver for bacterial niche colonization. Trends Microbiol 2023; 31:120-134. [PMID: 36075785 DOI: 10.1016/j.tim.2022.08.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 08/08/2022] [Accepted: 08/09/2022] [Indexed: 01/27/2023]
Abstract
Depending on their physiology and metabolism, bacteria can carry out diverse redox processes for energy acquisition, which facilitates adaptation to environmental or host-associated niches. Of these processes, respiration, using oxygen or alternative terminal electron acceptors, is energetically the most favorable in heterotrophic bacteria. The biofilm lifestyle, a coordinated multicellular behavior, is ubiquitous in bacteria and is regulated by a variety of intrinsic and extrinsic cues. Respiration of distinct electron acceptors has been shown to induce biofilm formation or dispersal. The notion of biofilm formation regulation by electron acceptor availability and respiration has often been considered species-specific. However, recent evidence suggests that this phenomenon can be strain-specific, even in strains sharing the same functional respiratory pathways, thereby implying subtle regulatory mechanisms. On this basis, I argue that induction of biofilm formation by sensing and respiration of electron acceptors might direct subgroups of redox-specialized strains to occupy certain niches. A palette of respiration and electron-transfer-mediated microbial social interactions within biofilms may broaden ecological opportunities. The strain specificity of this phenomenon represents an important opportunity to identify key molecular mechanisms and their ecophysiological significance, which in turn may lay the ground for applications in areas ranging from biotechnology to the prevention of antimicrobial resistance.
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8
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Guberman-Pfeffer MJ. Structural Determinants of Redox Conduction Favor Robustness over Tunability in Microbial Cytochrome Nanowires. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.21.525004. [PMID: 36712098 PMCID: PMC9882360 DOI: 10.1101/2023.01.21.525004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Helical homopolymers of multiheme cytochromes catalyze biogeochemically significant electron transfers with a reported 10 3 -fold variation in conductivity. Herein, classical molecular dynamics and hybrid quantum/classical molecular mechanics are used to elucidate the structural determinants of the redox potentials and conductivities of the tetra-, hexa-, and octaheme outer-membrane cytochromes E, S, and Z, respectively, from Geobacter sulfurreducens . Second-sphere electrostatic interactions acting on minimally polarized heme centers are found to regulate redox potentials over a computed 0.5-V range. However, the energetics of redox conduction are largely robust to the structural diversity: Single-step electronic couplings (⟨H mn ⟩), reaction free energies , and reorganization energies (λ mn ) are always respectively <|0.026|, <|0.26|, and between 0.5 - 1.0 eV. With these conserved parameter ranges, redox conductivity differed by less than a factor of 10 among the 'nanowires' and is sufficient to meet the demands of cellular respiration if 10 2 - 10 3 'nanowires' are expressed. The 'nanowires' are proposed to be differentiated by the protein packaging to interface with a great variety of environments, and not by conductivity, because the rate-limiting electron transfers are elsewhere in the respiratory process. Conducting-probe atomic force microscopy measurements that find conductivities 10 3 -10 6 -fold more than cellular demands are suggested to report on functionality that is either not used or not accessible under physiological conditions. The experimentally measured difference in conductivity between Omc- S and Z is suggested to not be an intrinsic feature of the CryoEM-resolved structures.
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Affiliation(s)
- Matthew J. Guberman-Pfeffer
- Department of Molecular Biophysics and Biochemistry, Yale University, 333 Cedar St., New Haven, CT, 06510
- Microbial Sciences Institute, Yale University, 840 West Campus Drive, West Haven, CT, 06516
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9
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Naaman R, Waldeck DH, Fransson J. New Perspective on Electron Transfer through Molecules. J Phys Chem Lett 2022; 13:11753-11759. [PMID: 36516240 PMCID: PMC9791659 DOI: 10.1021/acs.jpclett.2c03141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 12/09/2022] [Indexed: 06/17/2023]
Abstract
Motivated by experiments which display unusual length and temperature effects for electron transfer in the nanometer length regime, we propose a new approach for describing long-range electron transfer (ET) processes through molecules. We posit that the electron reorganization in the molecules (e.g., the electronic polarization of a macromolecule or organic film by an applied electric potential, or the injected charge generating a dipole moment) should be included in the description. We numerically solve a one-dimensional model for the electron transport, which includes electron-electron interactions explicitly, and we show that it generates a power law distance dependence for electron transport similar to that observed in experiments. The model does not include vibrations explicitly and should be consistent with the weak temperature dependences observed experimentally. This approach emphasizes the need to treat the electronic changes in the molecule(s) more explicitly to understand the behavior.
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Affiliation(s)
- Ron Naaman
- Department
of Chemical and Biological Physics, Weizmann
Institute of Science, Rehovot76100, Israel
| | - David H. Waldeck
- Chemistry
Department, University of Pittsburgh, Pittsburgh, Pennsylvania15260, United States
| | - Jonas Fransson
- Department
of Physics and Astronomy, Uppsala University, Box 516, SE-751 21Uppsala, Sweden
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10
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Deng T, Lin FC, Zink JI, Yu Q. Regulation of Bacterial Behavior by Light and Magnetism Mediated by Mesoporous Silica-Coated MnFe 2O 4@CoFe 2O 4 Nanoparticles. ACS APPLIED MATERIALS & INTERFACES 2022; 14:56007-56017. [PMID: 36509713 DOI: 10.1021/acsami.2c12589] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Unicellular bacterial cells exhibit diverse population behaviors (i.e., aggregation, dispersion, directed assembly, biofilm formation, etc.) to facilitate communication and cooperation. Suitable bacterial behaviors are required for efficient nutrient uptake, cell recycling, and stress response for environmental and industrial application of bacterial populations. However, it remains a great challenge to artificially control bacterial behaviors because of complicated genetic and biochemical mechanisms. In this study, we designed facile mesoporous silica nanoparticle (MSN)-based assemblies to intelligently regulate bacterial behaviors with the help of light and magnetic field. This system was composed of magnetic MSNs, i.e., MnFe2O4@CoFe2O4@MSN modified by photoactive spiropyran (SP), and the chitosan-based polymers ChiPSP, i.e., chitosan grafted by triphenylphosphine and SP. The assembly strongly bound bacterial cells, inducing reversible bacterial aggregation by visible-light irradiation and dark. Moreover, the formed bacterial aggregates could be further governed by a directed magnetic field (DMF) to form microfibers and by an alternating magnetic field (AMF) to form biofilms. This study realized stimulus-triggered regulation of bacterial behaviors by MSNs and implied the great power of chemical strategies in intelligent control of diverse biological processes for environmental and industrial applications.
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Affiliation(s)
- Tian Deng
- Department of Chemistry & Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Fang-Chu Lin
- Department of Chemistry & Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Jeffrey I Zink
- Department of Chemistry & Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Qilin Yu
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, P. R. China
- Department of Chemistry & Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States
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11
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Howley E, Ki D, Krajmalnik-Brown R, Torres CI. Geobacter sulfurreducens' Unique Metabolism Results in Cells with a High Iron and Lipid Content. Microbiol Spectr 2022; 10:e0259322. [PMID: 36301091 PMCID: PMC9769739 DOI: 10.1128/spectrum.02593-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 09/24/2022] [Indexed: 01/07/2023] Open
Abstract
Geobacter sulfurreducens is a ubiquitous iron-reducing bacterium in soils, and in engineered systems, it can respire an electrode to produce measurable electric current. Its unique metabolism, heavily dependent on an extensive network of cytochromes, requires a unique cell composition. In this work, we used metallomics, cell fraction and elemental analyses, and transcriptomics to study and analyze the cell composition of G. sulfurreducens. Elemental composition studies (C, H, O, N, and ash content) showed high C:O and H:O ratios of approximately 1.7:1 and 0.25:1, indicative of more reduced cell composition that is consistent with high lipid content. Our study shows that G. sulfurreducens cells have a large amount of iron (2 ± 0.2 μg/g dry weight) and lipids (32 ± 0.5% dry weight/dry weight) and that this composition does not change whether the cells are grown with a soluble or an insoluble electron acceptor. The high iron concentration, higher than similar microorganisms, is attributed to the production of cytochromes that are abundant in transcriptomic analyses in both solid and soluble electron acceptor growth. The unique cell composition of G. sulfurreducens must be considered when growing this microorganism for lab studies and commercial applications. IMPORTANCE Geobacter sulfurreducens is an electroactive microorganism. In nature, it grows on metallic minerals by transferring electrons to them, effectively "breathing" metals. In a manmade system, it respires an electrode to produce an electric current. It has become a model organism for the study of electroactive organisms. There are potential biotechnological applications of an organism that can bridge the gap between biology and electrical signal and, as a ubiquitous iron reducer in soils around the world, G. sulfurreducens has an impact on the global iron cycle. We measured the concentrations of metals, macromolecules, and basic elements in G. sulfurreducens to define this organism's composition. We also used gene expression data to discuss which proteins those metals could be associated with. We found that G. sulfurreducens has a large amount of lipid and iron compared to other bacteria-these observations are important for future microbiologists and biotechnologists working with the organism.
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Affiliation(s)
- Ethan Howley
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, Arizona, USA
- School for Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona, USA
| | - Dongwon Ki
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, Arizona, USA
- Division of Living and the Built Environment Research, Seoul Institute of Technology, Seoul, South Korea
| | - Rosa Krajmalnik-Brown
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, Arizona, USA
- School for Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona, USA
| | - César I. Torres
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, Arizona, USA
- School for Engineering of Matter Transport and Energy, Arizona State University, Tempe, Arizona, USA
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12
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Zhang Z, Asefaw BK, Xiong Y, Chen H, Tang Y. Evidence and Mechanisms of Selenate Reduction to Extracellular Elemental Selenium Nanoparticles on the Biocathode. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:16259-16270. [PMID: 36239462 DOI: 10.1021/acs.est.2c05145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Intracellular selenium nanoparticles (SeNPs) production is a roadblock to the recovery of selenium from biological water treatment processes because it is energy intensive to break microbial cells and then separate SeNPs. This study provided evidence of significantly more extracellular SeNP production on the biocathode (97-99%) compared to the conventional reactors (1-90%) using transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy. The cathodic microbial community analysis showed that relative abundance of Azospira oryzae, Desulfovibrio, Stenotrophomonas, and Rhodocyclaceae was <1% in the inoculum but enriched to 10-21% for each group when the bioelectrochemical reactor reached a steady state. These four groups of microorganisms simultaneously produce intracellular and extracellular SeNPs in conventional biofilm reactors per literature review but prefer to produce extracellular SeNPs on the cathode. This observation may be explained by the cellular energetics: by producing extracellular SeNPs on the biocathode, microbes do not need to transfer selenate and the electrons from the cathode into the cells, thereby saving energy. Extracellular SeNP production on the biocathode is feasible since we found high concentrations of C-type cytochrome, which is well known for its ability to transfer electrons from electrodes to microbial cells and reduce selenate to SeNPs on the cell membrane.
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Affiliation(s)
- Zhiming Zhang
- Department of Civil and Environmental Engineering, FAMU-FSU College of Engineering, Florida State University, 2525 Pottsdamer Street, Tallahassee, Florida32310, United States
| | - Benhur K Asefaw
- Department of Civil and Environmental Engineering, FAMU-FSU College of Engineering, Florida State University, 2525 Pottsdamer Street, Tallahassee, Florida32310, United States
| | - Yi Xiong
- Department of Civil and Environmental Engineering, FAMU-FSU College of Engineering, Florida State University, 2525 Pottsdamer Street, Tallahassee, Florida32310, United States
| | - Huan Chen
- National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, Florida32310, United States
| | - Youneng Tang
- Department of Civil and Environmental Engineering, FAMU-FSU College of Engineering, Florida State University, 2525 Pottsdamer Street, Tallahassee, Florida32310, United States
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13
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Hu Y, Han X, Shi L, Cao B. Electrochemically active biofilm-enabled biosensors: Current status and opportunities for biofilm engineering. Electrochim Acta 2022. [DOI: 10.1016/j.electacta.2022.140917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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14
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Zhu Q, Hou H, Wu Y, Hu J, Liu B, Liang S, Xiao K, Yu W, Yuan S, Yang J, Su X. Deciphering the role of extracellular polymeric substances in the regulation of microbial extracellular electron transfer under low concentrations of tetracycline exposure: Insights from transcriptomic analysis. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 838:156176. [PMID: 35613646 DOI: 10.1016/j.scitotenv.2022.156176] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 04/18/2022] [Accepted: 05/19/2022] [Indexed: 06/15/2023]
Abstract
Low concentrations of antibiotics can regulate the formation of electroactive biofilms, however, the underlying mechanisms, especially the composition and spatial distribution of extracellular polymeric substances (EPS) and their effects on extracellular electron transfer (EET) process, have not been fully deciphered. Here, the response of EPS of Geobacter sulfurreducens biofilm to low concentrations of tetracycline (μg L-1 to mg L-1) was explored, and the impact of such EPS variations on EET efficiency was further elucidated by transcriptomic analysis. Results showed that 0.05 mg L-1 of tetracycline achieved both beneficial quantitative and spatial regulation of redox-active proteins and non-conducting exopolysaccharides in EPS, while higher concentrations induced negative effects. Moreover, 1 mg L-1 of tetracycline upregulated multiple exopolysaccharide biosynthesis-related genes, indicating a stress response for cell-protection, while 0.05 mg L-1 of tetracycline upregulated most direct EET-related gene expressions, resulting in the promoted EET efficiency. Furthermore, 0.05 mg L-1 of tetracycline selectively enriched Geobacter (45.55% vs 19.55% in control, respectively) from mixed inoculum. This research provides a new insight of how antibiotics at low concentrations regulated EET process through modulation of EPS.
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Affiliation(s)
- Qian Zhu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, 1037 Luoyu Road, Wuhan, Hubei 430074, China
| | - Huijie Hou
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, 1037 Luoyu Road, Wuhan, Hubei 430074, China.
| | - Yaqian Wu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, 1037 Luoyu Road, Wuhan, Hubei 430074, China
| | - Jingping Hu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, 1037 Luoyu Road, Wuhan, Hubei 430074, China; State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Bingchuan Liu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, 1037 Luoyu Road, Wuhan, Hubei 430074, China
| | - Sha Liang
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, 1037 Luoyu Road, Wuhan, Hubei 430074, China
| | - Keke Xiao
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, 1037 Luoyu Road, Wuhan, Hubei 430074, China
| | - Wenbo Yu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, 1037 Luoyu Road, Wuhan, Hubei 430074, China
| | - Shushan Yuan
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, 1037 Luoyu Road, Wuhan, Hubei 430074, China
| | - Jiakuan Yang
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, 1037 Luoyu Road, Wuhan, Hubei 430074, China; State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Xintai Su
- School of Environment and Energy, Guangdong Provincial Key Laboratory of Solid Wastes Pollution Control and Recycling, South China University of Technology, Guangzhou, Guangdong 510006, China
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15
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Li W, Yue H, Zhang C, Hu J, Wang Q, Li Y, Zhang S, Chen J, Zhao J. Engineering multiscale polypyrrole/carbon nanotubes interface to boost electron utilization in a bioelectrochemical system coupled with chemical absorption for NO removal. CHEMOSPHERE 2022; 303:134943. [PMID: 35569635 DOI: 10.1016/j.chemosphere.2022.134943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 04/24/2022] [Accepted: 05/09/2022] [Indexed: 06/15/2023]
Abstract
The chemical absorption-bioelectrochemical reduction (CABER) integrated system provides an alternative of good potential for NO removal. The efficient utilization of cathode electrons directly determines the system performance and operating cost. Herein, we synthesize a polypyrrole/carbon nanotubes (PPy/CNTs) composite to engineer a micro-and nanoscale interface with low resistance and high biocompatibility between the cathode and biofilms in the CABER system. The resulting PPy/CNTs biocathodes exhibit 36.4% increase in biomass density, 40.7%-302.6% increase in Faraday efficiency along Fe(III)EDTA reduction, and 204% increase in Fe(II)EDTA-NO reduction rate. The enrichment of functional microorganisms is validated to be a key strengthening factor, as the proportion of which increased from 57.9% to 84.6%. Moreover, for efficient electron transfer and utilization, a low-resistance electron transfer route, "electrode substrate → PPy (→ CNTs) → microbial cells → Fe(III)EDTA or Fe(II)EDTA-NO", is realized in the multiscale conductive networks constructed of PPy/CNTs composite and microbial nanowires.
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Affiliation(s)
- Wei Li
- Key Laboratory of Biomass Chemical Engineering of Ministry of Education, Institute of Industrial Ecology and Environment, College of Chemical and Biological Engineering, Zhejiang University, Yuquan Campus, Hangzhou, 310027, China
| | - Huanyu Yue
- Key Laboratory of Biomass Chemical Engineering of Ministry of Education, Institute of Industrial Ecology and Environment, College of Chemical and Biological Engineering, Zhejiang University, Yuquan Campus, Hangzhou, 310027, China
| | - Chunyan Zhang
- Key Laboratory of Biomass Chemical Engineering of Ministry of Education, Institute of Industrial Ecology and Environment, College of Chemical and Biological Engineering, Zhejiang University, Yuquan Campus, Hangzhou, 310027, China
| | - Junyu Hu
- Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou, 310014, China
| | - Qiaoli Wang
- Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou, 310014, China
| | - Yuanming Li
- College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua, 321004, China
| | - Shihan Zhang
- Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou, 310014, China
| | - Jianmeng Chen
- Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou, 310014, China
| | - Jingkai Zhao
- Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou, 310014, China; College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua, 321004, China.
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16
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17
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Frühauf HM, Stöckl M, Holtmann D. R-based method for quantitative analysis of biofilm thickness by using confocal laser scanning microscopy. Eng Life Sci 2022; 22:464-470. [PMID: 35663481 PMCID: PMC9162930 DOI: 10.1002/elsc.202200008] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 03/17/2022] [Accepted: 03/24/2022] [Indexed: 12/29/2022] Open
Abstract
Microscopy is mostly the method of choice to analyse biofilms. Due to the high local heterogeneity of biofilms, single and punctual analyses only give an incomplete insight into the local distribution of biofilms. In order to retrieve statistically significant results a quantitative method for biofilm thickness measurements was developed based on confocal laser scanning microscopy and the programming language R. The R-script allows the analysis of large image volumes with little hands-on work and outputs statistical information on homogeneity of surface coverage and overall biofilm thickness. The applicability of the script was shown in microbial fuel cell experiments. It was found that Geobacter sulfurreducens responds differently to poised anodes of different material so that the optimum potential for MFC on poised ITO anodes had to be identified with respect to maximum current density, biofilm thickness and MFC start-up time. Thereby, a positive correlation between current density and biofilm thickness was found, but with no direct link to the applied potential. The optimum potential turned out to be +0.1 V versus SHE. The script proved to be a valuable stand-alone tool to quantify biofilm thickness in a statistically valid manner, which is required in many studies.
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Affiliation(s)
- Hanna Marianne Frühauf
- Department of Chemical TechnologyDECHEMA ForschungsinstitutFrankfurt am MainGermany
- Institut für Bioverfahrenstechnik und Pharmazeutische TechnologieTechnische Hochschule MittelhessenGießenGermany
| | - Markus Stöckl
- Department of Chemical TechnologyDECHEMA ForschungsinstitutFrankfurt am MainGermany
| | - Dirk Holtmann
- Institut für Bioverfahrenstechnik und Pharmazeutische TechnologieTechnische Hochschule MittelhessenGießenGermany
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18
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Belleville P, Merlin G, Ramousse J, Deseure J. Characterization of spatiotemporal electroactive anodic biofilm activity distribution using 1D simulations. Sci Rep 2022; 12:5849. [PMID: 35393459 PMCID: PMC8990003 DOI: 10.1038/s41598-022-09596-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 03/14/2022] [Indexed: 11/17/2022] Open
Abstract
Activity distribution limitation in electroactive biofilm remains an unclear phenomenon. Some observations using confocal microscopy have shown notable difference between activity close to the anode and activity at the liquid interface. A numerical model is developed in this work to describe biofilm growth and local biomass segregation in electroactive biofilm. Under our model hypothesis, metabolic activity distribution in the biofilm results from the competition between two limiting factors: acetate diffusion and electronic conduction in the biofilm. Influence of inactive biomass fraction (i.e. non-growing biomass fraction) properties (such as conductivity and density) is simulated to show variation in local biomass distribution. Introducing a dependence of effective diffusion to local density leads to a drastic biomass fraction segregation. Increasing density of inactive fraction reduces significantly acetate diffusion in biofilm, enhances biomass activity on the outer layer (liquid/biofilm interface) and maintains inner core largely inactive. High inactive fraction conductivity enhances biomass activity in the outer layer and enhances current production. Hence, investment in extracellular polymer substance (EPS), anchoring redox components, is benefit for biofilm electroactivity. However, under our model hypothesis it means that conductivity should be two order lower than biofilm conductivity reported in order to observe inner core active biomass segregation.
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Affiliation(s)
- Pierre Belleville
- Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, Grenoble INP Institute of Engineering, LEPMI, 38000, Grenoble, France.,Univ. Savoie Mont-Blanc, CNRS, LOCIE, UMR 5271, Polytech Annecy, Chambéry, bât. Helios, 60 rue du lac Léman, Savoie Technolac, 73370, Le Bourget du Lac, France
| | - Gerard Merlin
- Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, Grenoble INP Institute of Engineering, LEPMI, 38000, Grenoble, France.,Univ. Savoie Mont-Blanc, CNRS, LOCIE, UMR 5271, Polytech Annecy, Chambéry, bât. Helios, 60 rue du lac Léman, Savoie Technolac, 73370, Le Bourget du Lac, France
| | - Julien Ramousse
- Univ. Savoie Mont-Blanc, CNRS, LOCIE, UMR 5271, Polytech Annecy, Chambéry, bât. Helios, 60 rue du lac Léman, Savoie Technolac, 73370, Le Bourget du Lac, France
| | - Jonathan Deseure
- Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, Grenoble INP Institute of Engineering, LEPMI, 38000, Grenoble, France.
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19
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GSU1771 regulates extracellular electron transfer and electroactive biofilm formation in Geobacter sulfurreducens: Genetic and electrochemical characterization. Bioelectrochemistry 2022; 145:108101. [PMID: 35334296 DOI: 10.1016/j.bioelechem.2022.108101] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 03/15/2022] [Accepted: 03/16/2022] [Indexed: 11/21/2022]
Abstract
Type IV pili and the >100c-type cytochromes in Geobacter sulfurreducens are essential for extracellular electron transfer (EET) towards metal oxides and electrodes. A previous report about a mutation in the gsu1771 gene indicated an enhanced reduction of insoluble Fe(III) oxides coupled with increased pilA expression. Herein, a marker-free gsu1771-deficient mutant was constructed and characterized to assess the role of this regulator in EET and the formation of electroactive biofilms. Deleting this gene delayed microbial growth in the acetate/fumarate media (electron donor and acceptor, respectively). However, this mutant reduced soluble and insoluble Fe(III) oxides more efficiently. Heme staining, western blot, and RT-qPCR analyses demonstrated that GSU1771 regulates the transcription of several genes (including pilA) and many c-type cytochromes involved in EET, suggesting the broad regulatory role of this protein. DNA-protein binding assays indicated that GSU1771 directly regulates the transcription of pilA, omcE, omcS, and omcZ. Additionally, gsu1771-deficient mutant biofilms are thicker than wild-type strains. Electrochemical studies revealed that the current produced by this biofilm was markedly higher than the wild-type strains (approximately 100-fold). Thus, demonstrating the role of GSU1771 in the EET pathway and establishing a methodology to develop highly electroactive G. sulfurreducens mutants.
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20
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Rossi R, Baek G, Logan BE. Vapor-Fed Cathode Microbial Electrolysis Cells with Closely Spaced Electrodes Enables Greatly Improved Performance. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:1211-1220. [PMID: 34971515 DOI: 10.1021/acs.est.1c06769] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Hydrogen can be electrochemically produced in microbial electrolysis cells (MECs) by current generated from bacterial anodes with a small added voltage. MECs typically use a liquid catholyte containing a buffer or salts. However, anions in these catholytes result in charge being balanced predominantly by ions other than hydroxide or protons, leading to anode acidification. To enhance only hydroxide ion transport to the anode, we developed a novel vapor-fed MEC configuration lacking a catholyte with closely spaced electrodes and an anion exchange membrane to limit the acidification. This MEC design produced a record-high sustained current density of 43.1 ± 0.6 A/m2 and a H2 production rate of 72 ± 2 LH2/L-d (cell voltage of 0.79 ± 0.00 V). There was minimal impact on MEC performance of increased acetate concentrations, solution conductivity, or anolyte buffer capacity at applied voltages up to 1.1 V, as shown by a nearly constant internal resistance of only 6.8 ± 0.3 mΩ m2. At applied external voltages >1.1 V, the buffer capacity impacted performance, with current densities increasing from 28.5 ± 0.6 A/m2 (20 mM phosphate buffer solution (PBS)) to 51 ± 1 A/m2 (100 mM PBS). These results show that a vapor-fed MEC can produce higher and more stable performance than liquid-fed cathodes by enhancing transport of hydroxide ions to the anode.
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Affiliation(s)
- Ruggero Rossi
- Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Gahyun Baek
- Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Bruce E Logan
- Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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21
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Hu Y, Wang Y, Han X, Shan Y, Li F, Shi L. Biofilm Biology and Engineering of Geobacter and Shewanella spp. for Energy Applications. Front Bioeng Biotechnol 2021; 9:786416. [PMID: 34926431 PMCID: PMC8683041 DOI: 10.3389/fbioe.2021.786416] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 11/18/2021] [Indexed: 01/04/2023] Open
Abstract
Geobacter and Shewanella spp. were discovered in late 1980s as dissimilatory metal-reducing microorganisms that can transfer electrons from cytoplasmic respiratory oxidation reactions to external metal-containing minerals. In addition to mineral-based electron acceptors, Geobacter and Shewanella spp. also can transfer electrons to electrodes. The microorganisms that have abilities to transfer electrons to electrodes are known as exoelectrogens. Because of their remarkable abilities of electron transfer, Geobacter and Shewanella spp. have been the two most well studied groups of exoelectrogens. They are widely used in bioelectrochemical systems (BESs) for various biotechnological applications, such as bioelectricity generation via microbial fuel cells. These applications mostly associate with Geobacter and Shewanella biofilms grown on the surfaces of electrodes. Geobacter and Shewanella biofilms are electrically conductive, which is conferred by matrix-associated electroactive components such as c-type cytochromes and electrically conductive nanowires. The thickness and electroactivity of Geobacter and Shewanella biofilms have a significant impact on electron transfer efficiency in BESs. In this review, we first briefly discuss the roles of planktonic and biofilm-forming Geobacter and Shewanella cells in BESs, and then review biofilm biology with the focus on biofilm development, biofilm matrix, heterogeneity in biofilm and signaling regulatory systems mediating formation of Geobacter and Shewanella biofilms. Finally, we discuss strategies of Geobacter and Shewanella biofilm engineering for improving electron transfer efficiency to obtain enhanced BES performance.
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Affiliation(s)
- Yidan Hu
- Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, China
| | - Yinghui Wang
- Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, China
| | - Xi Han
- Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, China
| | - Yawei Shan
- Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, China
| | - Feng Li
- Key Laboratory of Systems Bioengineering (Ministry of Education), SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
| | - Liang Shi
- Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, China.,State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, China.,Hubei Key Laboratory of Yangtze Catchment Environmental Aquatic Science, China University of Geosciences, Wuhan, China.,State Environmental Protection Key Laboratory of Source Apportionment and Control of Aquatic Pollution, Ministry of Ecology and Environment, Wuhan, China
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22
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Sundaresan V, Do H, Shrout JD, Bohn PW. Electrochemical and spectroelectrochemical characterization of bacteria and bacterial systems. Analyst 2021; 147:22-34. [PMID: 34874024 PMCID: PMC8791413 DOI: 10.1039/d1an01954f] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Microbes, such as bacteria, can be described, at one level, as small, self-sustaining chemical factories. Based on the species, strain, and even the environment, bacteria can be useful, neutral or pathogenic to human life, so it is increasingly important that we be able to characterize them at the molecular level with chemical specificity and spatial and temporal resolution in order to understand their behavior. Bacterial metabolism involves a large number of internal and external electron transfer processes, so it is logical that electrochemical techniques have been employed to investigate these bacterial metabolites. In this mini-review, we focus on electrochemical and spectroelectrochemical methods that have been developed and used specifically to chemically characterize bacteria and their behavior. First, we discuss the latest mechanistic insights and current understanding of microbial electron transfer, including both direct and mediated electron transfer. Second, we summarize progress on approaches to spatiotemporal characterization of secreted factors, including both metabolites and signaling molecules, which can be used to discern how natural or external factors can alter metabolic states of bacterial cells and change either their individual or collective behavior. Finally, we address in situ methods of single-cell characterization, which can uncover how heterogeneity in cell behavior is reflected in the behavior and properties of collections of bacteria, e.g. bacterial communities. Recent advances in (spectro)electrochemical characterization of bacteria have yielded important new insights both at the ensemble and the single-entity levels, which are furthering our understanding of bacterial behavior. These insights, in turn, promise to benefit applications ranging from biosensors to the use of bacteria in bacteria-based bioenergy generation and storage.
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Affiliation(s)
- Vignesh Sundaresan
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46556, USA.
| | - Hyein Do
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Joshua D Shrout
- Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, IN 46556, USA
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN 46556, USA
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Paul W Bohn
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46556, USA.
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
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23
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Fujikawa T, Ogura Y, Ishigami K, Kawano Y, Nagamine M, Hayashi T, Inoue K. Unexpected genomic features of high current density-producing Geobacter sulfurreducens strain YM18. FEMS Microbiol Lett 2021; 368:6362602. [PMID: 34472610 DOI: 10.1093/femsle/fnab119] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 08/31/2021] [Indexed: 12/28/2022] Open
Abstract
Geobacter sulfurreducens produces high current densities and it has been used as a model organism for extracellular electron transfer studies. Nine G. sulfurreducens strains were isolated from biofilms formed on an anode poised at -0.2 V (vs SHE) in a bioelectrochemical system in which river sediment was used as an inoculum. The maximum current density of an isolate, strain YM18 (9.29 A/m2), was higher than that of the strain PCA (5.72 A/m2), the type strain of G. sulfurreducens, and comparable to strain KN400 (8.38 A/m2), which is another high current-producing strain of G. sulfurreducens. Genomic comparison of strains PCA, KN400 and YM18 revealed that omcB, xapD, spc and ompJ, which are known to be important genes for iron reduction and current production in PCA, were not present in YM18. In the PCA and KN400 genomes, two and one region(s) encoding CRISPR/Cas systems were identified, respectively, but they were missing in the YM18 genome. These results indicate that there is genetic variation in the key components involved in extracellular electron transfer among G. sulfurreducens strains.
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Affiliation(s)
- Takashi Fujikawa
- Interdisciplinary Graduate School of Agriculture and Engineering, University of Miyazaki, Miyazaki 889-2192, Japan
| | - Yoshitoshi Ogura
- Division of Microbiology, Department of Infectious Medicine, Kurume University School of Medicine, Kurume 830-0011, Fukuoka, Japan
| | - Koki Ishigami
- Department of Biochemistry and Applied Biosciences, Faculty of Agriculture, University of Miyazaki, Miyazaki 889-2192, Japan
| | - Yoshihiro Kawano
- Department of Biochemistry and Applied Biosciences, Faculty of Agriculture, University of Miyazaki, Miyazaki 889-2192, Japan
| | - Miyuki Nagamine
- Department of Biochemistry and Applied Biosciences, Faculty of Agriculture, University of Miyazaki, Miyazaki 889-2192, Japan
| | - Tetsuya Hayashi
- Department of Bacteriology, Faculty of Medical Sciences, Kyushu University, Fukuoka 812-8285, Japan
| | - Kengo Inoue
- Department of Biochemistry and Applied Biosciences, Faculty of Agriculture, University of Miyazaki, Miyazaki 889-2192, Japan
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24
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Evidence of a Streamlined Extracellular Electron Transfer Pathway from Biofilm Structure, Metabolic Stratification, and Long-Range Electron Transfer Parameters. Appl Environ Microbiol 2021; 87:e0070621. [PMID: 34190605 PMCID: PMC8357294 DOI: 10.1128/aem.00706-21] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
A strain of Geobacter sulfurreducens, an organism capable of respiring solid extracellular substrates, lacking four of five outer membrane cytochrome complexes (extABCD+ strain) grows faster and produces greater current density than the wild type grown under identical conditions. To understand cellular and biofilm modifications in the extABCD+ strain responsible for this increased performance, biofilms grown using electrodes as terminal electron acceptors were sectioned and imaged using electron microscopy to determine changes in thickness and cell density, while parallel biofilms incubated in the presence of nitrogen and carbon isotopes were analyzed using NanoSIMS (nanoscale secondary ion mass spectrometry) to quantify and localize anabolic activity. Long-distance electron transfer parameters were measured for wild-type and extABCD+ biofilms spanning 5-μm gaps. Our results reveal that extABCD+ biofilms achieved higher current densities through the additive effects of denser cell packing close to the electrode (based on electron microscopy), combined with higher metabolic rates per cell compared to the wild type (based on increased rates of 15N incorporation). We also observed an increased rate of electron transfer through extABCD+ versus wild-type biofilms, suggesting that denser biofilms resulting from the deletion of unnecessary multiheme cytochromes streamline electron transfer to electrodes. The combination of imaging, physiological, and electrochemical data confirms that engineered electrogenic bacteria are capable of producing more current per cell and, in combination with higher biofilm density and electron diffusion rates, can produce a higher final current density than the wild type. IMPORTANCE Current-producing biofilms in microbial electrochemical systems could potentially sustain technologies ranging from wastewater treatment to bioproduction of electricity if the maximum current produced could be increased and current production start-up times after inoculation could be reduced. Enhancing the current output of microbial electrochemical systems has been mostly approached by engineering physical components of reactors and electrodes. Here, we show that biofilms formed by a Geobacter sulfurreducens strain producing ∼1.4× higher current than the wild type results from a combination of denser cell packing and higher anabolic activity, enabled by an increased rate of electron diffusion through the biofilms. Our results confirm that it is possible to engineer electrode-specific G. sulfurreducens strains with both faster growth on electrodes and streamlined electron transfer pathways for enhanced current production.
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25
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Xing F, Xi H, Yu Y, Zhou Y. Anode biofilm influence on the toxic response of microbial fuel cells under different operating conditions. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 775:145048. [PMID: 33631591 DOI: 10.1016/j.scitotenv.2021.145048] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 01/03/2021] [Accepted: 01/04/2021] [Indexed: 06/12/2023]
Abstract
The response of microorganisms in microbial fuel cells (MFCs) to toxic compounds under different operating conditions, such as flow rate and culture time, was investigated herein. While it has been reported that MFCs can detect some toxic substances, it is unclear if operating conditions affect MFCs toxicity response. In this study, the toxic response time of MFCs decreased when the flow rate increased from 0.5 mL/min to 2 mL/min and then increased with 5 mL/min. The inhibition rates at 0.5 mL/min, 2 mL/min, and 5 mL/min were 8.4% ± 1.6%, 45.1% ± 5.3%, and 4.9% ± 0.3%, respectively. With the increase of culture time from 7 days to 90 days, the toxic response time of MFCs gradually increased. The inhibition rates at culture times of 7 days, 45 days, and 90 days were 45.1% ± 5.3%, 32.6% ± 6.6%, and 23.2% ± 1.3%, respectively. Increasing the culture time will reduce the sensitivity of MFC. The results showed that MFCs can respond quickly at a flow rate of 2 mL/min after cultivation for 7 days. Under these conditions, the power density can reach 1137.0 ± 65.5 mW/m2, the relative content of Geobacter sp. is 57%, and the ORP of the multilayers changed from -159.2 ± 1.6 mV to -269.9 ± 1.7 mV within 200 μm biofilm thickness. These findings show that increasing the flow rate and shortening the culture time are conducive for the toxicity response of MFCs, which will increase the sensitivity of MFCs in practical applications.
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Affiliation(s)
- Fei Xing
- College of Water Sciences, Beijing Normal University, Beijing 100875, PR China; State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China
| | - Hongbo Xi
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China
| | - Yin Yu
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China.
| | - Yuexi Zhou
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China.
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26
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Controls on Interspecies Electron Transport and Size Limitation of Anaerobically Methane-Oxidizing Microbial Consortia. mBio 2021; 12:mBio.03620-20. [PMID: 33975943 PMCID: PMC8263020 DOI: 10.1128/mbio.03620-20] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
About 382 Tg yr−1 of methane rising through the seafloor is oxidized anaerobically (W. S. Reeburgh, Chem Rev 107:486–513, 2007, https://doi.org/10.1021/cr050362v), preventing it from reaching the atmosphere, where it acts as a strong greenhouse gas. Microbial consortia composed of anaerobic methanotrophic archaea and sulfate-reducing bacteria couple the oxidation of methane to the reduction of sulfate under anaerobic conditions via a syntrophic process. Recent experimental studies and modeling efforts indicate that direct interspecies electron transfer (DIET) is involved in this syntrophy. Here, we explore a fluorescent in situ hybridization-nanoscale secondary ion mass spectrometry data set of large, segregated anaerobic oxidation of methane (AOM) consortia that reveal a decline in metabolic activity away from the archaeal-bacterial interface and use a process-based model to identify the physiological controls on rates of AOM. Simulations reproducing the observational data reveal that ohmic resistance and activation loss are the two main factors causing the declining metabolic activity, where activation loss dominated at a distance of <8 μm. These voltage losses limit the maximum spatial distance between syntrophic partners with model simulations, indicating that sulfate-reducing bacterial cells can remain metabolically active up to ∼30 μm away from the archaeal-bacterial interface. Model simulations further predict that a hybrid metabolism that combines DIET with a small contribution of diffusive exchange of electron donors can offer energetic advantages for syntrophic consortia.
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He X, Chadwick G, Jiménez Otero F, Orphan V, Meile C. Spatially Resolved Electron Transport through Anode‐Respiring
Geobacter sulfurreducens
Biofilms: Controls and Constraints. ChemElectroChem 2021. [DOI: 10.1002/celc.202100111] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Xiaojia He
- Department of Marine Sciences University of Georgia Athens GA USA
| | - Grayson Chadwick
- Division of Geological and Planetary Sciences California Institute of Technology Pasadena CA USA
| | | | - Victoria Orphan
- Division of Geological and Planetary Sciences California Institute of Technology Pasadena CA USA
| | - Christof Meile
- Department of Marine Sciences University of Georgia Athens GA USA
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28
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Desmond-Le Quéméner E, Moscoviz R, Bernet N, Marcus A. Modeling of interspecies electron transfer in anaerobic microbial communities. Curr Opin Biotechnol 2021; 67:49-57. [PMID: 33465544 DOI: 10.1016/j.copbio.2020.12.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 12/19/2020] [Accepted: 12/23/2020] [Indexed: 12/14/2022]
Abstract
Interspecies electron transfer (IET) is a key phenomenon in anaerobic ecosystems, which is traditionally modeled as hydrogen transfer. Recently discovered alternative mediated IET (MIET) or direct IET (DIET) offer exciting alternative mechanisms of microbial partnerships that could lead to new strategies for the improvement of biotechnologies. Here, we analyze mathematical modeling of DIET and MIET in anaerobic ecosystems. Bioenergetics approaches already enable the evaluation of different energy sharing scenarios between microorganisms and give interesting clues on redox mediators and on possible ways of driving microbial communities relying on IET. The modeling of DIET kinetics however is currently only in its infancy. Recent concepts introduced for the modeling of electroactive biofilms should be further exploited. Recent modeling examples confirms the potential of DIET to increase the IET rates compared to H2-MIET, but also point out the need for additional characterizations of biological components supporting IET to improve predictions.
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Affiliation(s)
| | - Roman Moscoviz
- SUEZ, Centre International de Recherche Sur l'Eau et l'Environnement (CIRSEE), Le Pecq, France
| | - Nicolas Bernet
- INRAE, Univ Montpellier, LBE, 102 avenue des Etangs, 11100, Narbonne, France
| | - Andrew Marcus
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, AZ, USA
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The porphyrin ring rather than the metal ion dictates long-range electron transport across proteins suggesting coherence-assisted mechanism. Proc Natl Acad Sci U S A 2020; 117:32260-32266. [PMID: 33288696 DOI: 10.1073/pnas.2008741117] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The fundamental biological process of electron transfer (ET) takes place across proteins with common ET pathways of several nanometers. Recent discoveries push this limit and show long-range extracellular ET over several micrometers. Here, we aim in deciphering how protein-bound intramolecular cofactors can facilitate such long-range ET. In contrast to natural systems, our protein-based platform enables us to modulate important factors associated with ET in a facile manner, such as the type of the cofactor and its quantity within the protein. We choose here the biologically relevant protoporphyrin molecule as the electron mediator. Unlike natural systems having only Fe-containing protoporphyrins, i.e., heme, as electron mediators, we use here porphyrins with different metal centers, or lacking a metal center. We show that the metal redox center has no role in ET and that ET is mediated solely by the conjugated backbone of the molecule. We further discuss several ET mechanisms, accounting to our observations with possible contribution of coherent processes. Our findings contribute to our understanding of the participation of heme molecules in long-range biological ET.
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30
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Rossi R, Logan BE. Impact of external resistance acclimation on charge transfer and diffusion resistance in bench-scale microbial fuel cells. BIORESOURCE TECHNOLOGY 2020; 318:123921. [PMID: 32768279 DOI: 10.1016/j.biortech.2020.123921] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 07/23/2020] [Accepted: 07/24/2020] [Indexed: 06/11/2023]
Abstract
Reducing the external resistance (Rext) for microbial fuel cell (MFC) acclimation can substantially alter the anode performance in terms of charge transfer (RCT), diffusion (Rd) and total anode resistance (RAn). Electrochemical impedance spectroscopy (EIS) was used to quantify anode impedance at different set potentials. Reducing Rext from 50 Ω to 20 Ω during acclimation reduced RCT by 31% (from 6.12 ± 0.09 mΩ m2 to 4.21 ± 0.03 mΩ m2) and Rd by 18% (from 3.4 ± 0.2 mΩ m2 to 2.8 ± 0.1 mΩ m2) at a set anode potential of -115 mV during EIS. Overall RAn decreased by 27%, to 5.13 ± 0.02 mΩ m2 for acclimation at 20 Ω, enabling the anode to achieve 38% higher current densities of 29 ± 1 A m-2. The results show a clear dependence of acclimation procedures and external resistance on kinetic and diffusion components of anode impedance that can impact overall bioelectrochemical performance.
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Affiliation(s)
- Ruggero Rossi
- Department of Civil and Environmental Engineering, Penn State University, University Park, PA 16802, USA
| | - Bruce E Logan
- Department of Civil and Environmental Engineering, Penn State University, University Park, PA 16802, USA.
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31
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Zhuang Z, Yang G, Mai Q, Guo J, Liu X, Zhuang L. Physiological potential of extracellular polysaccharide in promoting Geobacter biofilm formation and extracellular electron transfer. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 741:140365. [PMID: 32610234 DOI: 10.1016/j.scitotenv.2020.140365] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 06/17/2020] [Accepted: 06/17/2020] [Indexed: 06/11/2023]
Abstract
Geobacter sulfurreducens biofilms have promising applications in renewable energy, pollutant bioremediation, and bioelectronic applications. Genetically manipulating G. sulfurreducens biofilms is an effective strategy to improve the capacity of extracellular electron transfer (EET). Extracellular polysaccharide, a sticky component surrounding microbes, plays an important role in EET. Herein, we constructed a mutant of G. sulfurreducens strain PCA overexpressing the gene GSU1501 (part of the ATP-dependent exporter of the polysaccharide biosynthesis gene operon), designated strain PCA-1501, to increase EET capacity. Experimental results showed that the overexpression of GSU1501 increased extracellular polysaccharide secretion by 25.5%, which promoted the formation of biofilm with higher thickness and viability, as well as the content of extracellular c-type cytochromes. Compared with the control strain, the mutant showed a higher capacity of Fe(III) oxide reduction and current generation (increased by 20.4% and 22.2%, respectively). Interestingly, the overexpression of GSU1501 hindered the pili formation by reducing the transcription level of pilA; a compensatory relationship between extracellular polysaccharide and pili in promoting biofilm formation deserves further investigation. This study provides a feasible method to promote the EET capacity of G. sulfurreducens biofilms, which benefit their bioelectrochemical applications.
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Affiliation(s)
- Zheng Zhuang
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou 511443, China
| | - Guiqin Yang
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou 511443, China
| | - Qijun Mai
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou 511443, China
| | - Junhui Guo
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou 511443, China
| | - Xing Liu
- College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Li Zhuang
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou 511443, China.
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32
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Eshel Y, Peskin U, Amdursky N. Coherence-assisted electron diffusion across the multi-heme protein-based bacterial nanowire. NANOTECHNOLOGY 2020; 31:314002. [PMID: 32259806 DOI: 10.1088/1361-6528/ab8767] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Biological electron transfer (ET) is one of the most studied biochemical processes due to its immense importance in biology. For many years, biological ET was explained using the classical incoherent transport mechanism, i.e. sequential hopping. One of the relatively recent major observations in this field is long-range extracellular ET (EET), where some bacteria were shown to mediate electrons for extremely long distances on the micrometer length scales across individual nanowires. This fascinating finding has resulted in several suggested mechanisms that might explain this intriguing EET. More recently, the structure of a conductive G. sulfurreducens nanowire has been solved, which showed a highly ordered quasi-1D wire of a hexaheme cytochrome protein, named OmcS. Based on this new structure, we suggest here several electron diffusion models for EET, involving either purely hopping or several degrees of mixed hopping and coherent transport, in which the coherent part is due to a local rigidification of the protein structure, associated with a decrease in the local reorganization energy. The effect is demonstrated for two closely packed heme sites as well as for longer chains containing up to several dozens porphyrins. We show that the pure hopping model probably cannot explain the reported conductivity values of the G. sulfurreducens nanowire using conventional values of reorganization energy and electronic coupling. On the other hand, we show that for a wide range of the latter energy values, the mixed hopping-coherent model results in superior electron diffusion compared to the pure hopping model, and especially for long-range coherent transport, involving multiple porphyrin sites.
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Affiliation(s)
- Yoni Eshel
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 3200003, Israel
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33
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Rossi R, Hall DM, Wang X, Regan JM, Logan BE. Quantifying the factors limiting performance and rates in microbial fuel cells using the electrode potential slope analysis combined with electrical impedance spectroscopy. Electrochim Acta 2020. [DOI: 10.1016/j.electacta.2020.136330] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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34
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Heidary N, Kornienko N, Kalathil S, Fang X, Ly KH, Greer HF, Reisner E. Disparity of Cytochrome Utilization in Anodic and Cathodic Extracellular Electron Transfer Pathways of Geobacter sulfurreducens Biofilms. J Am Chem Soc 2020; 142:5194-5203. [PMID: 32066233 PMCID: PMC7082794 DOI: 10.1021/jacs.9b13077] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Indexed: 12/18/2022]
Abstract
Extracellular electron transfer (EET) in microorganisms is prevalent in nature and has been utilized in functional bioelectrochemical systems. EET of Geobacter sulfurreducens has been extensively studied and has been revealed to be facilitated through c-type cytochromes, which mediate charge between the electrode and G. sulfurreducens in anodic mode. However, the EET pathway of cathodic conversion of fumarate to succinate is still under debate. Here, we apply a variety of analytical methods, including electrochemistry, UV-vis absorption and resonance Raman spectroscopy, quartz crystal microbalance with dissipation, and electron microscopy, to understand the involvement of cytochromes and other possible electron-mediating species in the switching between anodic and cathodic reaction modes. By switching the applied bias for a G. sulfurreducens biofilm coupled to investigating the quantity and function of cytochromes, as well as the emergence of Fe-containing particles on the cell membrane, we provide evidence of a diminished role of cytochromes in cathodic EET. This work sheds light on the mechanisms of G. sulfurreducens biofilm growth and suggests the possible existence of a nonheme, iron-involving EET process in cathodic mode.
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Affiliation(s)
- Nina Heidary
- Department
of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United
Kingdom
- Department
of Chemistry, Université de Montréal, Roger-Gaudry Building, Montreal, Quebec H3C 3J7, Canada
| | - Nikolay Kornienko
- Department
of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United
Kingdom
- Department
of Chemistry, Université de Montréal, Roger-Gaudry Building, Montreal, Quebec H3C 3J7, Canada
| | - Shafeer Kalathil
- Department
of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United
Kingdom
| | - Xin Fang
- Department
of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United
Kingdom
| | - Khoa H. Ly
- Department
of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United
Kingdom
- Fakultät
für Chemie und Lebensmittelchemie, Technische Universität Dresden, Dresden 01062, Germany
| | - Heather F. Greer
- Department
of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United
Kingdom
| | - Erwin Reisner
- Department
of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United
Kingdom
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35
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A three-dimensional hybrid electrode with electroactive microbes for efficient electrogenesis and chemical synthesis. Proc Natl Acad Sci U S A 2020; 117:5074-5080. [PMID: 32051251 PMCID: PMC7060665 DOI: 10.1073/pnas.1913463117] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Addressing the global challenge of sustainability calls for cost-effective and eco-friendly pathways to go beyond the existing energy-intense synthetic routes. Biohybrid electrochemical systems integrate electroactive bacteria with synthetic electrodes to leverage the power of biocatalysis for energy conversion and chemical synthesis. This work presents a three-dimensional electrode scaffold to couple the intracellular metabolism with extracellular redox transformations by means of electrochemistry. The large population of bacteria actively metabolizing within the electrode scaffold produces a benchmark current density. The biohybrid electrode can also carry out synthetic reactions within or beyond biochemical pathways driven by solar light. This hierarchical electrode provides a robust and versatile platform to wire bacteria’s intrinsic physiological functionalities with artificial electronics for sustainable energy conversion and chemical production. Integration of electroactive bacteria into electrodes combines strengths of intracellular biochemistry with electrochemistry for energy conversion and chemical synthesis. However, such biohybrid systems are often plagued with suboptimal electrodes, which limits the incorporation and productivity of the bacterial colony. Here, we show that an inverse opal-indium tin oxide electrode hosts a large population of current-producing Geobacter and attains a current density of 3 mA cm−2 stemming from bacterial respiration. Differential gene expression analysis revealed Geobacter’s transcriptional regulations to express more electron-relaying proteins when interfaced with electrodes. The electrode also allows coculturing with Shewanella for syntrophic electrogenesis, which grants the system additional flexibility in converting electron donors. The biohybrid electrode containing Geobacter can also catalyze the reduction of soluble fumarate and heterogenous graphene oxide, with electrons from an external power source or an irradiated photoanode. This biohybrid electrode represents a platform to employ live cells for sustainable power generation and biosynthesis.
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36
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Engel M, Gemünde A, Holtmann D, Müller‐Renno C, Ziegler C, Tippkötter N, Ulber R. Clostridium Acetobutylicum
’s Connecting World: Cell Appendage Formation in Bioelectrochemical Systems. ChemElectroChem 2019. [DOI: 10.1002/celc.201901656] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Mareike Engel
- Bioprocess EngineeringUniversity of Kaiserslautern 67663 Kaiserslautern Germany
| | - André Gemünde
- Bioprocess EngineeringUniversity of Kaiserslautern 67663 Kaiserslautern Germany
| | - Dirk Holtmann
- Industrial BiotechnologyDECHEMA Research Institute 60486 Frankfurt am Main Germany
| | | | - Christiane Ziegler
- Department of PhysicsUniversity of Kaiserslautern 67663 Kaiserslautern Germany
| | - Nils Tippkötter
- Bioprocess EngineeringUniversity of Applied Science Aachen 52428 Jülich Germany
| | - Roland Ulber
- Bioprocess EngineeringUniversity of Kaiserslautern 67663 Kaiserslautern Germany
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37
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Liu X, Zhuo S, Jing X, Yuan Y, Rensing C, Zhou S. Flagella act as Geobacter biofilm scaffolds to stabilize biofilm and facilitate extracellular electron transfer. Biosens Bioelectron 2019; 146:111748. [DOI: 10.1016/j.bios.2019.111748] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 09/22/2019] [Accepted: 09/30/2019] [Indexed: 11/24/2022]
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38
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Mayer F, Enzmann F, Lopez AM, Holtmann D. Performance of different methanogenic species for the microbial electrosynthesis of methane from carbon dioxide. BIORESOURCE TECHNOLOGY 2019; 289:121706. [PMID: 31279320 DOI: 10.1016/j.biortech.2019.121706] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 06/21/2019] [Accepted: 06/26/2019] [Indexed: 06/09/2023]
Abstract
Microbial electrosynthesis (MES) is a promising technology to convert CO2 and electricity into the biofuel methane using methanogens. Until now, most investigations on electro-methanogenesis are "proof-of-principle" studies. In this paper, different strains were quantitatively compared in regard to final methane concentration, yields based on CO2-conversion, productivities as well as Coulombic efficiencies in order to identify suitable organisms for MES. Methanococcus vannielii, Methanococcus maripaludis, Methanolacinia petrolearia, Methanobacterium congolense, and Methanoculleus submarinus were able to produce methane via MES at -700 mV vs. standard hydrogen electrode (SHE). Beside methane also biological H2 production was detected during MES, which might be due to the involvement of hydrogenases. A direct electron transfer pathway is most likely. Obviously, M. maripaludis is the most resource efficient methane producer in microbial electrosynthesis regarding the methane productivity (8.81 ± 0.51 mmol m-2 d-1) and the Coulombic efficiency (58.9 ± 0.8%).
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Affiliation(s)
- Florian Mayer
- DECHEMA-Forschungsinstitut, Industrielle Biotechnologie, Frankfurt am Main, Germany
| | - Franziska Enzmann
- DECHEMA-Forschungsinstitut, Industrielle Biotechnologie, Frankfurt am Main, Germany
| | | | - Dirk Holtmann
- DECHEMA-Forschungsinstitut, Industrielle Biotechnologie, Frankfurt am Main, Germany.
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39
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Lebedev N, Stroud RM, Yates MD, Tender LM. Spatially Resolved Chemical Analysis of Geobacter sulfurreducens Cell Surface. ACS NANO 2019; 13:4834-4842. [PMID: 30943001 DOI: 10.1021/acsnano.9b02032] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Geobacter sulfurreducens is of interest for the highest efficiency of power generation and extremely long extracellular electron transfer (EET) between the bacterium and electrodes. Despite more than 15 years of intensive molecular biological research, there is still no clear answer which molecules are responsible for these processes. In the present work, we look at the problem from another (atomic) perspective and identify the location and shape of the compounds that are known to be conductive, particularly those containing Fe atoms. By using highly sophisticated energy dispersive X-ray spectroscopy combined with high-angle annular dark-field transmission electron microscopy enabling detection, identification, and localization of chemical compounds on the surface at nearly atomic spatial resolution, we analyze Fe spatial distribution within the G. sulfurreducens community. We discover the presence of small Fe-containing particles on the surface of the bacterium cells. The size of the particles (diameter 5.6 nm) is highly reproducible and comparable with the size of a single protein. The particles cover about 2% of the cell surface, which is similar to that expected for molecular conductors responsible for electron transfer through the bacterium cell wall. We find that G. sulfurreducens filaments ("bacterial molecular wires") also contain Fe atoms in their bundles. We observe that the bacterium enable changing the distance between the Fe-containing bundles in the filaments from separated to attached (the latter is needed for the efficient electron transfer between the Fe-containing particles), depending on the bacterium metabolic activity and attachment to extracellular substrates. These results are consistent with the recently published research about the role of Fe atoms in protein molecular conductance ( Phys. Chem. Chem. Phys. , 2018 , 20 , 14072 - 14081 ) and show what type of Fe-containing particles are involved in the bacterial extracellular communication. They can be used for the design and construction of artificial biomolecular wires and bioinorganic interfaces.
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Affiliation(s)
- Nikolai Lebedev
- Center for Bio/Molecular Science and Engineering , U.S. Naval Research Laboratory , Washington , DC 20375 , United States
| | - Rhonda M Stroud
- Materials Science and Technology Division , U.S. Naval Research Laboratory , Washington , DC 20375 , United States
| | - Matthew D Yates
- Center for Bio/Molecular Science and Engineering , U.S. Naval Research Laboratory , Washington , DC 20375 , United States
| | - Leonard Martin Tender
- Center for Bio/Molecular Science and Engineering , U.S. Naval Research Laboratory , Washington , DC 20375 , United States
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40
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Chen Z, Zhang Y, Luo Q, Wang L, Liu S, Peng Y, Wang H, Shen L, Li Q, Wang Y. Maghemite (γ-Fe 2O 3) nanoparticles enhance dissimilatory ferrihydrite reduction by Geobacter sulfurreducens: Impacts on iron mineralogical change and bacterial interactions. J Environ Sci (China) 2019; 78:193-203. [PMID: 30665638 DOI: 10.1016/j.jes.2018.09.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 09/21/2018] [Accepted: 09/21/2018] [Indexed: 06/09/2023]
Abstract
Microbially mediated bioreduction of iron oxyhydroxide plays an important role in the biogeochemical cycle of iron. Geobacter sulfurreducens is a representative dissimilatory iron-reducing bacterium that assembles electrically conductive pili and cytochromes. The impact of supplementation with γ-Fe2O3 nanoparticles (NPs) (0.2 and 0.6 g) on the G. sulfurreducens-mediated reduction of ferrihydrite was investigated. In the overall performance of microbial ferrihydrite reduction mediated by γ-Fe2O3 NPs, stronger reduction was observed in the presence of direct contact with γ-Fe2O3 NPs than with indirect contact. Compared to the production of Fe(II) derived from biotic modification with ferrihydrite alone, increases greater than 1.6- and 1.4-fold in the production of Fe(II) were detected in the biotic modifications in which direct contact with 0.2 g and 0.6 g γ-Fe2O3 NPs, respectively, occurred. X-ray diffraction analysis indicated that magnetite was a unique representative iron mineral in ferrihydrite when active G. sulfurreducens cells were in direct contact with γ-Fe2O3 NPs. Because of the sorption of biogenic Fe(II) onto γ-Fe2O3 NPs instead of ferrihydrite, the addition of γ-Fe2O3 NPs could also contribute to increased duration of ferrihydrite reduction by preventing ferrihydrite surface passivation. Additionally, electron microscopy analysis confirmed that the direct addition of γ-Fe2O3 NPs stimulated the electrically conductive pili and cytochromes to stretch, facilitating long-range electron transfer between the cells and ferrihydrite. The obtained findings provide a more comprehensive understanding of the effects of iron oxide NPs on soil biogeochemistry.
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Affiliation(s)
- Zheng Chen
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361001, China. E-mail: ; Department of Environmental Science, School of Environmental Science and Engineering, Tan Kah Kee College, Xiamen University, Zhangzhou 363105, China; Key Laboratory of Measurement and Control System for Coastal Environment, Fuqing Branch of Fujian Normal University, Fuqing 350300, China; Zhejiang Provincial Key Laboratory of Watershed Science and Health, School of Public Health and Management, Wenzhou Medical University, Wenzhou 325035, China
| | - Yaxian Zhang
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361001, China. E-mail:
| | - Qingliu Luo
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361001, China. E-mail:
| | - Liuying Wang
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361001, China. E-mail:
| | - Shurui Liu
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361001, China. E-mail:
| | - Yajuan Peng
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361001, China. E-mail:
| | - Haitao Wang
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361001, China. E-mail:
| | - Liang Shen
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361001, China. E-mail:
| | - Qingbiao Li
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361001, China. E-mail:
| | - Yuanpeng Wang
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361001, China. E-mail: .
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41
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Huerta-Miranda GA, Arroyo-Escoto AI, Burgos X, Juárez K, Miranda-Hernández M. Influence of the major pilA transcriptional regulator in electrochemical responses of Geobacter sulfureducens PilR-deficient mutant biofilm formed on FTO electrodes. Bioelectrochemistry 2019; 127:145-153. [PMID: 30825658 DOI: 10.1016/j.bioelechem.2019.02.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 02/12/2019] [Accepted: 02/13/2019] [Indexed: 11/29/2022]
Abstract
Geobacter sulfurreducens is a model organism for understanding the role of bacterial structures in extracellular electron transfer mechanism (EET). This kind of bacteria relies on different structures such as type IV pili and over 100 c-type cytochromes to perform EET towards soluble and insoluble electron acceptors, including electrodes. To our knowledge, this work is the first electrochemical study comparing a G. sulfurreducens PilR-deficient mutant and wild type biofilms developed on fluorine-doped tin oxide (FTO) electrodes. Open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), were used to evaluate the electroactive properties of biofilms grown without externally imposed potential. Parallel studies of Confocal Laser Scanning Microscopy (CLSM) correlated with the electrochemical results. PilR is a transcriptional regulator involved in the expression of a wide variety of genes, including pilA (pilus structural protein) relevant c-type cytochromes and some other genes involved in biofilm formation and EET processes. Our findings suggest that PilR-deficient mutant forms a thinner (CLSM analysis) and less conductive biofilm (EIS analysis) than wild type, exhibiting different and irreversible redox processes at the interface (CV analysis). Additionally, this work reinforces some of the remarkable features described in previous reports about this G. sulfurreducens mutant.
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Affiliation(s)
- G A Huerta-Miranda
- Instituto de Energías Renovables, Universidad Nacional Autónoma de México, Priv. Xochicalco, 62580 Temixco, Morelos, Mexico
| | - A I Arroyo-Escoto
- Instituto de Energías Renovables, Universidad Nacional Autónoma de México, Priv. Xochicalco, 62580 Temixco, Morelos, Mexico; Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001. Col. Chamilpa, Cuernavaca, Morelos, Mexico
| | - X Burgos
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001. Col. Chamilpa, Cuernavaca, Morelos, Mexico
| | - K Juárez
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001. Col. Chamilpa, Cuernavaca, Morelos, Mexico.
| | - M Miranda-Hernández
- Instituto de Energías Renovables, Universidad Nacional Autónoma de México, Priv. Xochicalco, 62580 Temixco, Morelos, Mexico.
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Jones AAD, Buie CR. Continuous shear stress alters metabolism, mass-transport, and growth in electroactive biofilms independent of surface substrate transport. Sci Rep 2019; 9:2602. [PMID: 30796283 PMCID: PMC6385357 DOI: 10.1038/s41598-019-39267-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 12/28/2018] [Indexed: 11/09/2022] Open
Abstract
Electroactive bacteria such as Geobacter sulfurreducens and Shewanella onedensis produce electrical current during their respiration; this has been exploited in bioelectrochemical systems. These bacteria form thicker biofilms and stay more active than soluble-respiring bacteria biofilms because their electron acceptor is always accessible. In bioelectrochemical systems such as microbial fuel cells, corrosion-resistant metals uptake current from the bacteria, producing power. While beneficial for engineering applications, collecting current using corrosion resistant metals induces pH stress in the biofilm, unlike the naturally occurring process where a reduced metal combines with protons released during respiration. To reduce pH stress, some bioelectrochemical systems use forced convection to enhance mass transport of both nutrients and byproducts; however, biofilms’ small pore size limits convective transport, thus, reducing pH stress in these systems remains a challenge. Understanding how convection is necessary but not sufficient for maintaining biofilm health requires decoupling mass transport from momentum transport (i.e. fluidic shear stress). In this study we use a rotating disc electrode to emulate a practical bioelectrochemical system, while decoupling mass transport from shear stress. This is the first study to isolate the metabolic and structural changes in electroactive biofilms due to shear stress. We find that increased shear stress reduces biofilm development time while increasing its metabolic rate. Furthermore, we find biofilm health is negatively affected by higher metabolic rates over long-term growth due to the biofilm’s memory of the fluid flow conditions during the initial biofilm development phases. These results not only provide guidelines for improving performance of bioelectrochemical systems, but also reveal features of biofilm behavior. Results of this study suggest that optimized reactors may initiate operation at high shear to decrease development time before decreasing shear for steady-state operation. Furthermore, this biofilm memory discovered will help explain the presence of channels within biofilms observed in other studies.
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Affiliation(s)
- A-Andrew D Jones
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.,Department of Chemical Engineering and Department of Mechanical & Industrial Engineering, Northeastern University, Boston, MA, 02115, USA
| | - Cullen R Buie
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
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Zhang X, Prévoteau A, Louro RO, Paquete CM, Rabaey K. Periodic polarization of electroactive biofilms increases current density and charge carriers concentration while modifying biofilm structure. Biosens Bioelectron 2018; 121:183-191. [DOI: 10.1016/j.bios.2018.08.045] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 08/19/2018] [Accepted: 08/20/2018] [Indexed: 10/28/2022]
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Jiang Z, Zhang D, Zhou L, Deng D, Duan M, Liu Y. Enhanced catalytic capability of electroactive biofilm modified with different kinds of carbon nanotubes. Anal Chim Acta 2018; 1035:51-59. [DOI: 10.1016/j.aca.2018.06.077] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2018] [Revised: 06/14/2018] [Accepted: 06/29/2018] [Indexed: 11/28/2022]
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45
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Zeng X, Borole AP, Pavlostathis SG. Processes and electron flow in a microbial electrolysis cell bioanode fed with furanic and phenolic compounds. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2018; 25:35981-35989. [PMID: 29558790 DOI: 10.1007/s11356-018-1747-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 03/13/2018] [Indexed: 06/08/2023]
Abstract
Furanic and phenolic compounds are problematic compounds resulting from the pretreatment of lignocellulosic biomass for biofuel production. Microbial electrolysis cell (MEC) is a promising technology to convert furanic and phenolic compounds to renewable H2. The objective of the research presented here was to elucidate the processes and electron equivalents flow during the conversion of two furanic (furfural, FF; 5-hydroxymethyl furfural, HMF) and three phenolic (syringic acid, SA; vanillic acid, VA; 4-hydroxybenzoic acid, HBA) compounds in the MEC bioanode. Cyclic voltammograms of the bioanode demonstrated that purely electrochemical reactions in the biofilm attached to the electrode were negligible. Instead, microbial reactions related to the biotransformation of the five parent compounds (i.e., fermentation followed by exoelectrogenesis) were the primary processes resulting in the electron equivalents flow in the MEC bioanode. A mass-based framework of substrate utilization and electron flow was developed to quantify the distribution of the electron equivalents among the bioanode processes, including biomass growth for each of the five parent compounds. Using input parameters of anode efficiency and biomass observed yield coefficients, it was estimated that more than 50% of the SA, FF, and HMF electron equivalents were converted to current. In contrast, only 12 and 9% of VA and HBA electron equivalents, respectively, resulted in current production, while 76 and 79% remained as fermentation end products not further utilized in exoelectrogenesis. For all five compounds, it was estimated that 10% of the initially added electron equivalents were used for fermentative biomass synthesis, while 2 to 13% were used for exoelectrogenic biomass synthesis. The proposed mass-based framework provides a foundation for the simulation of bioanode processes to guide the optimization of MECs converting biomass-derived waste streams to renewable H2.
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Affiliation(s)
- Xiaofei Zeng
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA, 30332-0512, USA
| | - Abhijeet P Borole
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
- Bredesen Center for Interdisciplinary Research and Education, The University of Tennessee, Knoxville, TN, 37996, USA
| | - Spyros G Pavlostathis
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA, 30332-0512, USA.
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Wehner J, Brombacher L, Brown J, Junghans C, Çaylak O, Khalak Y, Madhikar P, Tirimbò G, Baumeier B. Electronic Excitations in Complex Molecular Environments: Many-Body Green's Functions Theory in VOTCA-XTP. J Chem Theory Comput 2018; 14:6253-6268. [PMID: 30404449 PMCID: PMC6293448 DOI: 10.1021/acs.jctc.8b00617] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Many-body Green's functions theory within the GW approximation and the Bethe-Salpeter Equation (BSE) is implemented in the open-source VOTCA-XTP software, aiming at the calculation of electronically excited states in complex molecular environments. Based on Gaussian-type atomic orbitals and making use of resolution of identity techniques, the code is designed specifically for nonperiodic systems. Application to a small molecule reference set successfully validates the methodology and its implementation for a variety of excitation types covering an energy range from 2 to 8 eV in single molecules. Further, embedding each GW-BSE calculation into an atomistically resolved surrounding, typically obtained from Molecular Dynamics, accounts for effects originating from local fields and polarization. Using aqueous DNA as a prototypical system, different levels of electrostatic coupling between the regions in this GW-BSE/MM setup are demonstrated. Particular attention is paid to charge-transfer (CT) excitations in adenine base pairs. It is found that their energy is extremely sensitive to the specific environment and to polarization effects. The calculated redshift of the CT excitation energy compared to a nucelobase dimer treated in vacuum is of the order of 1 eV, which matches expectations from experimental data. Predicted lowest CT energies are below that of a single nucleobase excitation, indicating the possibility of an initial (fast) decay of such an UV excited state into a binucleobase CT exciton. The results show that VOTCA-XTP's GW-BSE/MM is a powerful tool to study a wide range of types of electronic excitations in complex molecular environments.
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Affiliation(s)
- Jens Wehner
- Max Planck Institute for Polymer Research , Ackermannweg 10 , D-55128 Mainz , Germany.,Department of Mathematics and Computer Science & Institute for Complex Molecular Systems , Eindhoven University of Technology , P.O. Box 513, 5600MB Eindhoven , The Netherlands
| | - Lothar Brombacher
- Max Planck Institute for Polymer Research , Ackermannweg 10 , D-55128 Mainz , Germany
| | - Joshua Brown
- Department of Electrical Computer and Energy Engineering , University of Colorado Boulder , 425 UCB, Boulder , Colorado 80309 , United States.,Renewable and Sustainable Energy Institute , University of Colorado Boulder , 4001 Discovery Drive , Boulder , Colorado 80303 , United States
| | - Christoph Junghans
- Computer, Computational, and Statistical Sciences Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Onur Çaylak
- Department of Mathematics and Computer Science & Institute for Complex Molecular Systems , Eindhoven University of Technology , P.O. Box 513, 5600MB Eindhoven , The Netherlands
| | - Yuriy Khalak
- Department of Mathematics and Computer Science & Institute for Complex Molecular Systems , Eindhoven University of Technology , P.O. Box 513, 5600MB Eindhoven , The Netherlands
| | - Pranav Madhikar
- Department of Mathematics and Computer Science & Institute for Complex Molecular Systems , Eindhoven University of Technology , P.O. Box 513, 5600MB Eindhoven , The Netherlands
| | - Gianluca Tirimbò
- Department of Mathematics and Computer Science & Institute for Complex Molecular Systems , Eindhoven University of Technology , P.O. Box 513, 5600MB Eindhoven , The Netherlands
| | - Björn Baumeier
- Department of Mathematics and Computer Science & Institute for Complex Molecular Systems , Eindhoven University of Technology , P.O. Box 513, 5600MB Eindhoven , The Netherlands
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Golden J, Yates MD, Halsted M, Tender L. Application of electrochemical surface plasmon resonance (ESPR) to the study of electroactive microbial biofilms. Phys Chem Chem Phys 2018; 20:25648-25656. [PMID: 30289415 DOI: 10.1039/c8cp03898h] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Electrochemical surface plasmon resonance (ESPR) monitors faradaic processes optically by the change in refractive index that occurs with a change in redox state at the electrode surface. Here we apply ESPR to investigate the anode-grown Geobacter sulfurreducens biofilm (GSB), a model system used to study electroactive microbial biofilms (EABFs) which perform electrochemical reactions using electrodes as metabolic electron acceptors or donors. A substantial body of evidence indicates that electron transfer reactions among hemes of c-type cytochromes (c-Cyt) play major roles in the extracellular electron transfer (EET) pathways that connect intracellular metabolic processes of cells in an EABF to the electrode surface. The results reported here reveal that when the potential of the electrode is changed from relatively oxidizing (0.40 V vs. SHE) to reducing (-0.55 V vs. SHE) and then back to oxidizing, 70% of c-Cyt residing closest to the biofilm/electrode (within hundreds of nm from the electrode surface) appear to remain trapped in the reduced state, requiring as long as 12 hours to be re-oxidized. c-Cyt storing electrons cannot contribute to EET, yet turnover current resulting from cellular oxidation of acetate coupled with EET to the electrode surface is unaffected. This suggests that a relatively small fraction of c-Cyt residing closest to the biofilm/electrode interface is involved in EET while the majority store electrons. The results also reveal that biomass density at the biofilm/electrode interface increases rapidly during lag phase, reaching its maximum value at the onset of exponential biofilm growth when turnover current begins to rapidly increase.
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Affiliation(s)
- Joel Golden
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, Washington DC, 20375, USA.
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Zarabadi MP, Charette SJ, Greener J. Flow-Based Deacidification of Geobacter sulfurreducens
Biofilms Depends on Nutrient Conditions: a Microfluidic Bioelectrochemical Study. ChemElectroChem 2018. [DOI: 10.1002/celc.201800968] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Mir Pouyan Zarabadi
- Département de Chimie Faculté des sciences et de génie; Université Laval; Québec City, QC Canada
| | - Steve J. Charette
- Institut de Biologie Intégrative et des Systèmes; Université Laval; Québec City, QC Canada
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec; Québec City, QC Canada
- Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de génie; Université Laval; Québec City, QC Canada
| | - Jesse Greener
- Département de Chimie Faculté des sciences et de génie; Université Laval; Québec City, QC Canada
- CHU de Québec centre de recherche; Université Laval; 10 rue de l'Espinay Québec, QC Canada
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49
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Bacterial electroactivity and viability depends on the carbon nanotube-coated sponge anode used in a microbial fuel cell. Bioelectrochemistry 2018. [DOI: 10.1016/j.bioelechem.2018.02.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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50
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Park JH, Park JH, Je Seong H, Sul WJ, Jin KH, Park HD. Metagenomic insight into methanogenic reactors promoting direct interspecies electron transfer via granular activated carbon. BIORESOURCE TECHNOLOGY 2018; 259:414-422. [PMID: 29597150 DOI: 10.1016/j.biortech.2018.03.050] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2017] [Revised: 03/06/2018] [Accepted: 03/09/2018] [Indexed: 06/08/2023]
Abstract
To provide insight into direct interspecies electron transfer via granular activated carbon (GAC), the effect of GAC supplementation on anaerobic digestion was evaluated. Compared to control samples, the GAC supplementation increased the total amount of methane production and its production rate by 31% and 72%, respectively. 16S rDNA sequencing analysis revealed a shift in the archaeal community composition; the Methanosarcina proportion decreased 17%, while the Methanosaeta proportion increased 5.6%. Metagenomic analyses based on shotgun sequencing demonstrated that the abundance of pilA and omcS genes belonging to Geobacter species decreased 69.4% and 29.4%, respectively. Furthermore, the analyses suggested a carbon dioxide reduction pathway rather than an acetate decarboxylation pathway for methane formation. Taken together, these results suggest that GAC improved methane production performance by shifting the microbial community and altering functional genes associated with direct interspecies electron transfer via conductive materials.
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Affiliation(s)
- Jeong-Hoon Park
- Department of Civil, Environmental and Architectural Engineering, Korea University, Seoul 02841, South Korea
| | - Jong-Hun Park
- Department of Civil, Environmental and Architectural Engineering, Korea University, Seoul 02841, South Korea
| | - Hoon Je Seong
- Department of Systems Biotechnology, Chung-Ang University, Anseong 17546, South Korea
| | - Woo Jun Sul
- Department of Systems Biotechnology, Chung-Ang University, Anseong 17546, South Korea
| | - Kang-Hyun Jin
- Department of Civil, Environmental and Architectural Engineering, Korea University, Seoul 02841, South Korea
| | - Hee-Deung Park
- Department of Civil, Environmental and Architectural Engineering, Korea University, Seoul 02841, South Korea; KU-KIST Green School, Graduate School of Energy and Environment, Korea University, Seoul 02841, South Korea.
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