1
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Linssen R, de Smit S, Röhring Neé Neubert K, Harnisch F, Ter Heijne A. Revealing cellular (poly)sulphide storage in electrochemically active sulphide oxidising bacteria using rotating disc electrodes. Bioelectrochemistry 2024; 158:108710. [PMID: 38636364 DOI: 10.1016/j.bioelechem.2024.108710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 04/11/2024] [Accepted: 04/12/2024] [Indexed: 04/20/2024]
Abstract
Sulphide oxidising bacteria (SOB) have the potential to be used for bioelectrochemical removal, i.e. oxidation, of sulphide from waste streams. In anaerobic conditions, SOB are able to spatially separate sulphide removal and terminal electron transfer to an electrode and act as a sulphide shuttle. However, it is not fully understood how SOB anaerobically remove sulphide and store charge equivalents, and where in this process sulphur is formed. Therefore, the redox behaviour of sulphide shuttling SOB was investigated at haloalkaline conditions using a glassy carbon rotating disc electrode (RDE) and cyclic voltammetry. Voltammograms of SOB in the absence and presence of sulphide were compared to voltammograms of abiotic sulphur species solutions. Polysulphide and sulphide showed different redox behaviour, with distinct potentials for oxidation of > -0.3 V (vs. Ag/AgCl) for polysulphide and > -0.1 V for sulphide. Comparing biotic to abiotic experiments lead to the hypothesis that SOB formed polysulphides during anaerobic sulphide removal, which stayed sorbed to the cells. With this study, further steps were taken in elucidating the mechanisms of sulphide shuttling by SOB.
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Affiliation(s)
- Rikke Linssen
- Environmental Technology, Wageningen University, P.O. Box 17, Bornse Weilanden 9, 6708 WG, Building Axis z, building nr. 118, 6700 AA Wageningen, the Netherlands
| | - Sanne de Smit
- Environmental Technology, Wageningen University, P.O. Box 17, Bornse Weilanden 9, 6708 WG, Building Axis z, building nr. 118, 6700 AA Wageningen, the Netherlands
| | - Katharina Röhring Neé Neubert
- Department of Microbial Biotechnology, Helmholtz-Centre for Environmental Research GmbH - UFZ, Permoserstrasse 15, 04318 Leipzig, Germany
| | - Falk Harnisch
- Department of Microbial Biotechnology, Helmholtz-Centre for Environmental Research GmbH - UFZ, Permoserstrasse 15, 04318 Leipzig, Germany
| | - Annemiek Ter Heijne
- Environmental Technology, Wageningen University, P.O. Box 17, Bornse Weilanden 9, 6708 WG, Building Axis z, building nr. 118, 6700 AA Wageningen, the Netherlands.
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2
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Fattahi N, Reed J, Heronemus E, Fernando P, Hansen R, Parameswaran P. Polyethylene glycol hydrogel coatings for protection of electroactive bacteria against chemical shocks. Bioelectrochemistry 2024; 156:108595. [PMID: 37976771 DOI: 10.1016/j.bioelechem.2023.108595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 10/25/2023] [Accepted: 10/30/2023] [Indexed: 11/19/2023]
Abstract
Loss of bioelectrochemical activity in low resource environments or from chemical toxin exposure is a significant limitation in microbial electrochemical cells (MxCs), necessitating the development of materials that can stabilize and protect electroactive biofilms. Here, polyethylene glycol (PEG) hydrogels were designed as protective coatings over anodic biofilms, and the effect of the hydrogel coatings on biofilm viability under oligotrophic conditions and ammonia-N (NH4+-N) shocks was investigated. Hydrogel deposition occurred through polymerization of PEG divinyl sulfone and PEG tetrathiol precursor molecules, generating crosslinked PEG coatings with long-term hydrolytic stability between pH values of 3 and 10. Simultaneous monitoring of coated and uncoated electrodes co-located within the same MxC anode chamber confirmed that the hydrogel did not compromise biofilm viability, while the coated anode sustained nearly a 4 × higher current density (0.44 A/m2) compared to the uncoated anode (0.12 A/m2) under oligotrophic conditions. Chemical interactions between NH4+-N and PEG hydrogels revealed that the hydrogels provided a diffusive barrier to NH4+-N transport. This enabled PEG-coated biofilms to generate higher current densities during NH4+-N shocks and faster recovery afterwards. These results indicate that PEG-based coatings can expand the non-ideal chemical environments that electroactive biofilms can reliably operate in.
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Affiliation(s)
- Niloufar Fattahi
- Tim Taylor Department of Chemical Engineering, Kansas State University, Manhattan, KS 66506, USA
| | - Jeffrey Reed
- Tim Taylor Department of Chemical Engineering, Kansas State University, Manhattan, KS 66506, USA
| | - Evan Heronemus
- Department of Civil Engineering, Kansas State University, Manhattan, KS 66506, USA
| | - Priyasha Fernando
- Department of Civil Engineering, Kansas State University, Manhattan, KS 66506, USA
| | - Ryan Hansen
- Tim Taylor Department of Chemical Engineering, Kansas State University, Manhattan, KS 66506, USA.
| | - Prathap Parameswaran
- Department of Civil Engineering, Kansas State University, Manhattan, KS 66506, USA.
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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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Zhao Q, Liu Y, Liao C, Yan X, Tian L, Li T, Li N, Wang X. Reduction of S 0 deposited on electroactive biofilm under an oxidative potential. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 882:163698. [PMID: 37094684 DOI: 10.1016/j.scitotenv.2023.163698] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 04/13/2023] [Accepted: 04/19/2023] [Indexed: 05/03/2023]
Abstract
The inevitable deposition of S0 on the electroactive biofilm (EAB) via anodic sulfide oxidation affects the stability of bioelectrochemical systems (BESs) when an accidental discharge of sulfide occurred, leading to the inhibition of electroacitivity, because the potential of anode (e.g., 0 V versus Ag/AgCl) is ~500 mV more positive than the redox potential of S2-/S0. Here we found that S0 deposited on the EAB can be spontaneously reduced under this oxidative potential independent of microbial community variation, leading to a self-recovery of electroactivity (> 100 % in current density) with biofilm thickening (~210 μm). Transcriptomics of pure culture indicated that Geobacter highly expressed genes involving in S0 metabolism, which had an additional benefit to improve the viability (25 % - 36 %) of bacterial cells in biofilm distant from the anode and the cellular metabolic activity via electron shuttle pair of S0/S2-(Sx2-). Our findings highlighted the importance of spatially heterogeneous metabolism to its stability when EABs encountered with the problem of S0 deposition, and that in turn improved the electroactivity of EABs.
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Affiliation(s)
- Qian Zhao
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Ying Liu
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Chengmei Liao
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Xuejun Yan
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Lili Tian
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Tian Li
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Nan Li
- School of Environmental Science and Engineering, Tianjin University, No. 135 Yaguan Road, Jinnan District, Tianjin 300350, China
| | - Xin Wang
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China.
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5
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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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6
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Martinez Ostormujof L, Teychené S, Achouak W, Fochesato S, Bakarat M, Rodriguez‐Ruiz I, Bergel A, Erable B. Systemic Analysis of the Spatiotemporal Changes in Multi‐Species Electroactive Biofilms to Clarify the Gradual Decline of Current Generation in Microbial Anodes. ChemElectroChem 2023. [DOI: 10.1002/celc.202201135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
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7
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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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8
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Gao Y, Xia L, Yao P, Lee HS. Periodic step polarization accelerates electron recovery by electroactive biofilms (EABs). Biotechnol Bioeng 2023; 120:1545-1556. [PMID: 36782377 DOI: 10.1002/bit.28352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 01/08/2023] [Accepted: 02/09/2023] [Indexed: 02/15/2023]
Abstract
Relatively low rate of electron recovery is one of the factors that limit the advancement of bioelectrochemical systems. Here, new periodic polarizations were investigated with electroactive biofilms (EABs) enriched from activated sludge and Geobacter sulfurreducens biofilms. When representative anode potentials (Ea ) were applied, redox centers with midpoint potentials (Emid ) higher than Ea were identified by localized cyclic voltammetry. The electrons held by these redox centers were accessible when Ea was raised to 0.4 V (vs. Ag/AgCl). New periodic polarizations that discharge at 0.4 V recovered electrons faster than normal periodic and fixed-potential polarizations. The best-performing periodic step polarization accelerated electron recovery by 23%-24% and 12%-76% with EABs and G. sulfurreducens biofilms, respectively, compared to the fixed-potential polarization. Quantitative reverse transcription polymerase chain reaction showed an increased abundance of omcZ mRNA transcripts from G. sulfurreducens after periodic step polarization. Therefore, both the rate of energy recovery by EABs and the performance of bioelectrochemical systems can be enhanced by improving the polarization schemes.
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Affiliation(s)
- Yaohuan Gao
- Institute of Global Environmental Change, School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China
| | - Longfei Xia
- Institute of Global Environmental Change, School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China.,Shaanxi Provincial Land Engineering Construction Group, Xi'an, Shaanxi, People's Republic of China
| | - Peiru Yao
- Institute of Global Environmental Change, School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China
| | - Hyung-Sool Lee
- Institute for Environmental and Climate Technology, Korea Institute of Energy Technology (KENTECH), Naju-si, Republic of Korea
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9
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Maximum thickness of non-buffer limited electro-active biofilms decreases at higher anode potentials. Biofilm 2022; 4:100092. [DOI: 10.1016/j.bioflm.2022.100092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 10/13/2022] [Accepted: 11/06/2022] [Indexed: 11/13/2022] Open
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10
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Quek G, Vázquez RJ, McCuskey SR, Kundukad B, Bazan GC. Enabling Electron Injection for Microbial Electrosynthesis with n-Type Conjugated Polyelectrolytes. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2203480. [PMID: 35835449 DOI: 10.1002/adma.202203480] [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: 04/18/2022] [Revised: 06/21/2022] [Indexed: 06/15/2023]
Abstract
Microbial electrosynthesis-using renewable electricity to stimulate microbial metabolism-holds the promise of sustainable chemical production. A key limitation hindering performance is slow electron-transfer rates at biotic-abiotic interfaces. Here a new n-type conjugated polyelectrolyte is rationally designed and synthesized and its use is demonstrated as a soft conductive material to encapsulate electroactive bacteria Shewanella oneidensis MR-1. The self-assembled 3D living biocomposite amplifies current uptake from the electrode ≈674-fold over controls with the same initial number of cells, thereby enabling continuous synthesis of succinate from fumarate. Such functionality is a result of the increased number of bacterial cells having intimate electronic communication with the electrode and a higher current uptake per cell. This is underpinned by the molecular design of the polymer to have an n-dopable conjugated backbone for facile reduction by the electrode and zwitterionic side chains for compatibility with aqueous media. Moreover, direct arylation polycondensation is employed instead of the traditional Stille polymerization to avoid non-biocompatible tin by-products. By demonstrating synergy between living cells with n-type organic semiconductor materials, these results provide new strategies for improving the performance of bioelectrosynthesis technologies.
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Affiliation(s)
- Glenn Quek
- Departments of Chemistry and Chemical & Biomolecular Engineering, Institute for Functional Intelligent Materials (I-FIM), National University of Singapore, Singapore, 119077, Singapore
| | - Ricardo Javier Vázquez
- Departments of Chemistry and Chemical & Biomolecular Engineering, Institute for Functional Intelligent Materials (I-FIM), National University of Singapore, Singapore, 119077, Singapore
| | - Samantha R McCuskey
- Departments of Chemistry and Chemical & Biomolecular Engineering, Institute for Functional Intelligent Materials (I-FIM), National University of Singapore, Singapore, 119077, Singapore
| | - Binu Kundukad
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Guillermo C Bazan
- Departments of Chemistry and Chemical & Biomolecular Engineering, Institute for Functional Intelligent Materials (I-FIM), National University of Singapore, Singapore, 119077, Singapore
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11
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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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12
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In situ continuous electrochemical quantification of bacterial adhesion to electrically polarized metallic surfaces under shear. Biointerphases 2022; 17:021001. [PMID: 35272464 DOI: 10.1116/6.0001585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Biofouling creates significant human and economic losses through infections, corrosion, and drag losses on ships and in oil and food distribution pipelines. Organisms adhered to these surfaces contend with high shear rates and are actively transported to the surface. The metallic surfaces to which these organisms are adhered also conduct charge at various potentials, and the effects of surface charge on adhesion rates are little addressed in the literature. We demonstrate that mass-transport limiting current, chronoamperometry, and cyclic voltammetry can be combined to provide resulting adhesion rates similar to those in the literature. Furthermore, we demonstrate that rotating disk electrodes can be used to study adhesion of bacteria to electrically polarized metallic surfaces under shear. We study the adhesion of Escherichia coli, Bacillus subtilis, and 1μm silica microspheres over a range of shear stress from 0.15 to 37 dyncm-2 or shear rates of 14.7-3730 s-1. Unlike quartz-crystal microbalance, our methodology measures changes in the area instead of mass, simultaneously providing measurements of the protein binding. Our deposition rates agree with those found using optical systems. However, unlike optical systems, our methods apply to a wider range of materials than on-chip flow devices.
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13
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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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14
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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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15
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Dissecting the Structural and Conductive Functions of Nanowires in Geobacter sulfurreducens Electroactive Biofilms. mBio 2021; 13:e0382221. [PMID: 35164556 PMCID: PMC8844916 DOI: 10.1128/mbio.03822-21] [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: 01/09/2023] Open
Abstract
Conductive nanowires are thought to contribute to long-range electron transfer (LET) in Geobacter sulfurreducens anode biofilms. Three types of nanowires have been identified: pili, OmcS, and OmcZ. Previous studies highlighted their conductive function in anode biofilms, yet a structural function also has to be considered. We present here a comprehensive analysis of the function of nanowires in LET by inhibiting the expression of each nanowire. Meanwhile, flagella with poor conductivity were expressed to recover the structural function but not the conductive function of nanowires in the corresponding nanowire mutant strain. The results demonstrated that pili played a structural but not a conductive function in supporting biofilm formation. In contrast, the OmcS nanowire played a conductive but not a structural function in facilitating electron transfer in the biofilm. The OmcZ nanowire played both a structural and a conductive function to contribute to current generation. Expression of the poorly conductive flagellum was shown to enhance biofilm formation, subsequently increasing current generation. These data support a model in which multiheme cytochromes facilitate long-distance electron transfer in G. sulfurreducens biofilms. Our findings also suggest that the formation of a thicker biofilm, which contributed to a higher current generation by G. sulfurreducens, was confined by the biofilm formation deficiency, and this has applications in microbial electrochemical systems. IMPORTANCE The low power generation of microbial fuel cells limits their utility. Many factors can affect power generation, including inefficient electron transfer in the anode biofilm. Thus, understanding the mechanism(s) of electron transfer provides a pathway for increasing the power density of microbial fuel cells. Geobacter sulfurreducens was shown to form a thick biofilm on the anode. Cells far away from the anode reduce the anode through long-range electron transfer. Based on their conductive properties, three types of nanowires have been hypothesized to directly facilitate long-range electron transfer: pili, OmcS, and OmcZ nanowires. However, their structural contributions to electron transfer in anode biofilm have not been elucidated. Based on studies of mutants lacking one or more of these facilitators, our results support a cytochrome-mediated electron transfer process in Geobacter biofilms and highlight the structural contribution of nanowires in anode biofilm formation, which contributes to biofilm formation and current generation, thereby providing a strategy to increase current generation.
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Pinck S, Ostormujof LM, Teychené S, Erable B. Microfluidic Microbial Bioelectrochemical Systems: An Integrated Investigation Platform for a More Fundamental Understanding of Electroactive Bacterial Biofilms. Microorganisms 2020; 8:E1841. [PMID: 33238493 PMCID: PMC7700166 DOI: 10.3390/microorganisms8111841] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 11/18/2020] [Accepted: 11/19/2020] [Indexed: 12/31/2022] Open
Abstract
It is the ambition of many researchers to finally be able to close in on the fundamental, coupled phenomena that occur during the formation and expression of electrocatalytic activity in electroactive biofilms. It is because of this desire to understand that bioelectrochemical systems (BESs) have been miniaturized into microBES by taking advantage of the worldwide development of microfluidics. Microfluidics tools applied to bioelectrochemistry permit even more fundamental studies of interactions and coupled phenomena occurring at the microscale, thanks, in particular, to the concomitant combination of electroanalysis, spectroscopic analytical techniques and real-time microscopy that is now possible. The analytical microsystem is therefore much better suited to the monitoring, not only of electroactive biofilm formation but also of the expression and disentangling of extracellular electron transfer (EET) catalytic mechanisms. This article reviews the details of the configurations of microfluidic BESs designed for selected objectives and their microfabrication techniques. Because the aim is to manipulate microvolumes and due to the high modularity of the experimental systems, the interfacial conditions between electrodes and electrolytes are perfectly controlled in terms of physicochemistry (pH, nutrients, chemical effectors, etc.) and hydrodynamics (shear, material transport, etc.). Most of the theoretical advances have been obtained thanks to work carried out using models of electroactive bacteria monocultures, mainly to simplify biological investigation systems. However, a huge virgin field of investigation still remains to be explored by taking advantage of the capacities of microfluidic BESs regarding the complexity and interactions of mixed electroactive biofilms.
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Affiliation(s)
| | | | | | - Benjamin Erable
- Laboratoire de Génie Chimique, Université de Toulouse, CNRS, INPT, UPS, 31432 Toulouse, France; (S.P.); (L.M.O.); (S.T.)
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A chip-based 128-channel potentiostat for high-throughput studies of bioelectrochemical systems: Optimal electrode potentials for anodic biofilms. Biosens Bioelectron 2020; 174:112813. [PMID: 33303324 DOI: 10.1016/j.bios.2020.112813] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 11/04/2020] [Accepted: 11/08/2020] [Indexed: 11/21/2022]
Abstract
The presence of microorganisms performing extracellular electron transfer has been established in many environments. Research to determine their role is moving slowly due to the high cost of potentiostats and the variance of data with small number of replicates. Here, we present a 128-channel potentiostat, connected to a 128 gold electrode array. Whereas the system is able to perform simultaneously 128 (bio)electrochemical measurements with an independent electrical signal input, the present manufacturing of the array limited the number of effective channels for this study to 77. We assessed the impact of 11 electrode potentials ranging from -0.45V to +0.2V vs. Ag/AgCl (7 replicates per potential) on the growth and electrochemical characteristics of anodic electroactive biofilms (EABs) formed by acetate-fed microbial communities. After 7 days of growth, maximum current was reached for electrodes poised at -0.3V, closely followed by -0.25V and -0.1V to +0.1V, a range well-fitting the midpoint potential of minerals naturally reduced by electroactive bacteria such as Geobacter Sulfurreducens. There was no significant difference in apparent midpoint potential of the EABs (-0.35V), suggesting that the mechanism of heterogeneous electron transfer was not affected by the electrode potential. The EABs poised below current plateau potential (≤-0.3V) exhibited slower growth but higher charge transfer parameters. The high-throughput and high reproducibility provided by the array may have a major facilitating impact on the field of electromicrobiology. Key aspects to improve are data processing algorithms to deal with the vast amount of generated data, and manufacturing of the electrode array itself.
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18
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Deng P, Sheng W, Xu A, Li C, Zhang Y, Dai X, Vo R, Kaplan DL, Hsu HH, Jiang X. Bottom-Up Construction of Electrochemically Active Living Filters: From Graphene Oxide Mediated Formation of Bacterial Cables to 3D Assembly of Hierarchical Architectures. ACS APPLIED BIO MATERIALS 2020; 3:7376-7381. [PMID: 35019480 DOI: 10.1021/acsabm.0c01172] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Living composites comprising of both biotic and abiotic modules are shifting the paradigm of materials science, yet challenges remain in effectively converging their distinctive structural and functional attributes. Here we present a bottom-up hybridization strategy to construct functionally coherent, electrochemically active biohybrids with optimal mass/charge transport, mechanical integrity, and biocatalytic performance. This biohybrid can overcome several key limitations of traditional biocarrier designs and demonstrate superior efficiency in metabolizing low-concentration toxic ions with minimal environmental impact. Overall, this work exemplifies a biointegration strategy that complements existing synthetic biology toolsets to further expand the range of material attributes and functionalities.
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Affiliation(s)
- Pu Deng
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, United States.,Thomas Lord Department of Mechanical Engineering & Materials Science, Duke University, Durham, North Carolina 27705, United States
| | - Weiqin Sheng
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, United States.,School of Electronic Information, Hangzhou Dianzi University, Hangzhou 310018, People's Republic of China
| | - Andrew Xu
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, United States
| | - Chunmei Li
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, United States
| | - Yixin Zhang
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, United States
| | - Xiaochuan Dai
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, United States
| | - Richard Vo
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, United States
| | - David L Kaplan
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, United States
| | - Huan-Hsuan Hsu
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, United States
| | - Xiaocheng Jiang
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, United States
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Moß C, Jarmatz N, Hartig D, Schnöing L, Scholl S, Schröder U. Studying the Impact of Wall Shear Stress on the Development and Performance of Electrochemically Active Biofilms. Chempluschem 2020; 85:2298-2307. [PMID: 32975878 DOI: 10.1002/cplu.202000544] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 09/03/2020] [Indexed: 11/06/2022]
Abstract
A laminar flow reactor was designed that provides constant and reproducible growth conditions for the bioelectrochemical observation of electroactive bacteria (EAB). Experiments were performed using four reactors in parallel to enable the comparison of EAB growth behavior and bioelectrochemical performance under different hydrodynamic conditions while simultaneously keeping biological conditions identical. With regard to the moderate flow conditions found in wastewater treatment applications, the wall shear stress was adjusted to a range between 0.4 mPa to 2.9 mPa. Chronoamperometric data indicate that early stage current densities are improved by a moderate increase of the wall shear stress. In the same way, current onset times were increasing slightly towards higher values of the applied wall shear stress. Long-term observations of EAB performance showed a decrease in current density and a leveling of the trend observed for the early stages of biofilm growth.
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Affiliation(s)
- Christopher Moß
- Institute of Environmental and Sustainable Chemistry, Technische Universität Braunschweig, Hagenring 30, 38106, Braunschweig, Germany
| | - Niklas Jarmatz
- Institute for Chemical and Thermal Process Engineering, Technische Universität Braunschweig, Langer Kamp 7, 38106, Braunschweig, Germany
| | - Dave Hartig
- Institute for Chemical and Thermal Process Engineering, Technische Universität Braunschweig, Langer Kamp 7, 38106, Braunschweig, Germany
| | - Lukas Schnöing
- Institute for Chemical and Thermal Process Engineering, Technische Universität Braunschweig, Langer Kamp 7, 38106, Braunschweig, Germany
| | - Stephan Scholl
- Institute for Chemical and Thermal Process Engineering, Technische Universität Braunschweig, Langer Kamp 7, 38106, Braunschweig, Germany
| | - Uwe Schröder
- Institute of Environmental and Sustainable Chemistry, Technische Universität Braunschweig, Hagenring 30, 38106, Braunschweig, Germany
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20
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McCuskey SR, Su Y, Leifert D, Moreland AS, Bazan GC. Living Bioelectrochemical Composites. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1908178. [PMID: 32347632 DOI: 10.1002/adma.201908178] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 02/12/2020] [Accepted: 03/17/2020] [Indexed: 06/11/2023]
Abstract
Composites, in which two or more material elements are combined to provide properties unattainable by single components, have a historical record dating to ancient times. Few include a living microbial community as a key design element. A logical basis for enabling bioelectronic composites stems from the phenomenon that certain microorganisms transfer electrons to external surfaces, such as an electrode. A bioelectronic composite that allows cells to be addressed beyond the confines of an electrode surface can impact bioelectrochemical technologies, including microbial fuel cells for power production and bioelectrosynthesis platforms where microbes produce desired chemicals. It is shown that the conjugated polyelectrolyte CPE-K functions as a conductive matrix to electronically connect a three-dimensional network of Shewanella oneidensis MR-1 to a gold electrode, thereby increasing biocurrent ≈150-fold over control biofilms. These biocomposites spontaneously assemble from solution into an intricate arrangement of cells within a conductive polymer matrix. While increased biocurrent is due to more cells in communication with the electrode, the current extracted per cell is also enhanced, indicating efficient long-range electron transport. Further, the biocomposites show almost an order-of-magnitude lower charge transfer resistance than CPE-K alone, supporting the idea that the electroactive bacteria and the conjugated polyelectrolyte work synergistically toward an effective bioelectronic composite.
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Affiliation(s)
- Samantha R McCuskey
- Department of Chemical Engineering, University of California, Santa Barbara, California, 93106, USA
- Center for Polymers and Organic Solids, University of California, Santa Barbara, California, 93106, USA
| | - Yude Su
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California, 93106, USA
- Center for Polymers and Organic Solids, University of California, Santa Barbara, California, 93106, USA
- Departments of Chemistry and Chemical Engineering, National University of Singapore, Singapore, 119077, Singapore
| | - Dirk Leifert
- Center for Polymers and Organic Solids, University of California, Santa Barbara, California, 93106, USA
| | - Alex S Moreland
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California, 93106, USA
- Center for Polymers and Organic Solids, University of California, Santa Barbara, California, 93106, USA
| | - Guillermo C Bazan
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California, 93106, USA
- Center for Polymers and Organic Solids, University of California, Santa Barbara, California, 93106, USA
- Departments of Chemistry and Chemical Engineering, National University of Singapore, Singapore, 119077, Singapore
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21
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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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22
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Abstract
Electricity-producing bacteria are potential power sources, fermentation platforms, and desalination systems, if current densities could be increased. These organisms form conductive biofilms on electrodes, allowing new cell layers to contribute to current production until a limit is reached, but the biological underpinning of this limit is not well-understood. We investigated the limitation behind this phenomenon using stable isotope probing and nanoscale secondary ion mass spectrometry, showing active cells are restricted to layers closest to the electrode. This metabolic observation fundamentally changes our understanding of electron flow and cell growth within current-producing biofilms and provides constraints on the physical structure of natural communities reliant on this process for growth. We predict improvements in biofilm conductivity will yield higher current-producing systems. Metal-reducing bacteria direct electrons to their outer surfaces, where insoluble metal oxides or electrodes act as terminal electron acceptors, generating electrical current from anaerobic respiration. Geobacter sulfurreducens is a commonly enriched electricity-producing organism, forming thick conductive biofilms that magnify total activity by supporting respiration of cells not in direct contact with electrodes. Hypotheses explaining why these biofilms fail to produce higher current densities suggest inhibition by formation of pH, nutrient, or redox potential gradients; but these explanations are often contradictory, and a lack of direct measurements of cellular growth within biofilms prevents discrimination between these models. To address this fundamental question, we measured the anabolic activity of G. sulfurreducens biofilms using stable isotope probing coupled to nanoscale secondary ion mass spectrometry (nanoSIMS). Our results demonstrate that the most active cells are at the anode surface, and that this activity decreases with distance, reaching a minimum 10 µm from the electrode. Cells nearest the electrode continue to grow at their maximum rate in weeks-old biofilms 80-µm-thick, indicating nutrient or buffer diffusion into the biofilm is not rate-limiting. This pattern, where highest activity occurs at the electrode and declines with each cell layer, is present in thin biofilms (<5 µm) and fully grown biofilms (>20 µm), and at different anode redox potentials. These results suggest a growth penalty is associated with respiring insoluble electron acceptors at micron distances, which has important implications for improving microbial electrochemical devices as well as our understanding of syntrophic associations harnessing the phenomenon of microbial conductivity.
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23
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Reguera G. Microbial nanowires and electroactive biofilms. FEMS Microbiol Ecol 2019; 94:5000162. [PMID: 29931163 DOI: 10.1093/femsec/fiy086] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 05/11/2018] [Indexed: 12/14/2022] Open
Abstract
Geobacter bacteria are the only microorganisms known to produce conductive appendages or pili to electronically connect cells to extracellular electron acceptors such as iron oxide minerals and uranium. The conductive pili also promote cell-cell aggregation and the formation of electroactive biofilms. The hallmark of these electroactive biofilms is electronic heterogeneity, mediated by coordinated interactions between the conductive pili and matrix-associated cytochromes. Collectively, the matrix-associated electron carriers discharge respiratory electrons from cells in multilayered biofilms to electron-accepting surfaces such as iron oxide coatings and electrodes poised at a metabolically oxidizable potential. The presence of pilus nanowires in the electroactive biofilms also promotes the immobilization and reduction of soluble metals, even when present at toxic concentrations. This review summarizes current knowledge about the composition of the electroactive biofilm matrix and the mechanisms that allow the wired Geobacter biofilms to generate electrical currents and participate in metal redox transformations.
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Affiliation(s)
- Gemma Reguera
- Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA
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24
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Schrott GD, Bonanni PS, Busalmen JP. Open circuit potentiometry reports on internal redox states of cells in G. Sulfurreducens biofilms. Electrochim Acta 2019. [DOI: 10.1016/j.electacta.2019.02.078] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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25
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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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26
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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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27
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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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Identification of Different Putative Outer Membrane Electron Conduits Necessary for Fe(III) Citrate, Fe(III) Oxide, Mn(IV) Oxide, or Electrode Reduction by Geobacter sulfurreducens. J Bacteriol 2018; 200:JB.00347-18. [PMID: 30038047 PMCID: PMC6148476 DOI: 10.1128/jb.00347-18] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 07/17/2018] [Indexed: 12/14/2022] Open
Abstract
Gram-negative metal-reducing bacteria utilize electron conduits, chains of redox proteins spanning the outer membrane, to transfer electrons to the extracellular surface. Only one pathway for electron transfer across the outer membrane of Geobacter sulfurreducens has been linked to Fe(III) reduction. However, G. sulfurreducens is able to respire a wide array of extracellular substrates. Here we present the first combinatorial genetic analysis of five different electron conduits via creation of new markerless deletion strains and complementation vectors. Multiple conduit gene clusters appear to have overlapping roles, including two that have never been linked to metal reduction. Another recently described cluster (ExtABCD) was the only electron conduit essential during electrode reduction, a substrate of special importance to biotechnological applications of this organism. At least five gene clusters in the Geobacter sulfurreducens genome encode putative “electron conduits” implicated in electron transfer across the outer membrane, each containing a periplasmic multiheme c-type cytochrome, integral outer membrane anchor, and outer membrane redox lipoprotein(s). Markerless single-gene-cluster deletions and all possible multiple-deletion combinations were constructed and grown with soluble Fe(III) citrate, Fe(III) and Mn(IV) oxides, and graphite electrodes poised at +0.24 V and −0.1 V versus the standard hydrogen electrode (SHE). Different gene clusters were necessary for reduction of each electron acceptor. During metal oxide reduction, deletion of the previously described omcBC cluster caused defects, but deletion of additional components in an ΔomcBC background, such as extEFG, were needed to produce defects greater than 50% compared to findings with the wild type. Deletion of all five gene clusters abolished all metal reduction. During electrode reduction, only the ΔextABCD mutant had a severe growth defect at both redox potentials, while this mutation did not affect Fe(III) oxide, Mn(IV) oxide, or Fe(III) citrate reduction. Some mutants containing only one cluster were able to reduce particular terminal electron acceptors better than the wild type, suggesting routes for improvement by targeting specific electron transfer pathways. Transcriptomic comparisons between fumarate and electrode-based growth conditions showed all of these ext clusters to be constitutive, and transcriptional analysis of the triple-deletion strain containing only extABCD detected no significant changes in expression of genes encoding known redox proteins or pilus components. These genetic experiments reveal new outer membrane conduit complexes necessary for growth of G. sulfurreducens, depending on the available extracellular electron acceptor. IMPORTANCE Gram-negative metal-reducing bacteria utilize electron conduits, chains of redox proteins spanning the outer membrane, to transfer electrons to the extracellular surface. Only one pathway for electron transfer across the outer membrane of Geobacter sulfurreducens has been linked to Fe(III) reduction. However, G. sulfurreducens is able to respire a wide array of extracellular substrates. Here we present the first combinatorial genetic analysis of five different electron conduits via creation of new markerless deletion strains and complementation vectors. Multiple conduit gene clusters appear to have overlapping roles, including two that have never been linked to metal reduction. Another recently described cluster (ExtABCD) was the only electron conduit essential during electrode reduction, a substrate of special importance to biotechnological applications of this organism.
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29
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Microbial Electrochemical Technologies for Wastewater Treatment: Principles and Evolution from Microbial Fuel Cells to Bioelectrochemical-Based Constructed Wetlands. WATER 2018. [DOI: 10.3390/w10091128] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Microbial electrochemical technologies (MET) rely on the presence of the metabolic activity of electroactive bacteria for the use of solid-state electrodes for oxidizing different kinds of compound that can lead to the synthesis of chemicals, bioremediation of polluted matrices, the treatment of contaminants of interest, as well as the recovery of energy. Keeping these possibilities in mind, there has been growing interest in the use of electrochemical technologies for wastewater treatment, if possible with simultaneous power generation, since the beginning of the present century. In the last few years, there has been growing interest in exploring the possibility of merging MET with constructed wetlands offering a new option of an intensified wetland system that could maintain a high performance with a lower footprint. Based on that interest, this paper explains the general principles of MET, and the different known extracellular electron transfer mechanisms ruling the interaction between electroactive bacteria and potential solid-state electron acceptors. It also looks at the adoption of those principles for the development of MET set-ups for simultaneous wastewater treatment and power generation, and the challenges that the technology faces. Ultimately, the most recent developments in setups that merge MET with constructed wetlands are presented and discussed.
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30
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Hsu L(HH, Deng P, Zhang Y, Nguyen HN, Jiang X. Nanostructured interfaces for probing and facilitating extracellular electron transfer. J Mater Chem B 2018; 6:7144-7158. [DOI: 10.1039/c8tb01598h] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Probing and facilitating microbial extracellular electron transfer through nanotechnology enabled platforms are transforming bioenergetic, bioelectronic, and other related research areas.
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Affiliation(s)
| | - Pu Deng
- Department of Biomedical Engineering
- Tufts University
- Medford
- USA
| | - Yixin Zhang
- Department of Biomedical Engineering
- Tufts University
- Medford
- USA
| | - Han N. Nguyen
- Department of Biomedical Engineering
- Tufts University
- Medford
- USA
| | - Xiaocheng Jiang
- Department of Biomedical Engineering
- Tufts University
- Medford
- USA
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31
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Dhar BR, Sim J, Ryu H, Ren H, Santo Domingo JW, Chae J, Lee HS. Microbial activity influences electrical conductivity of biofilm anode. WATER RESEARCH 2017; 127:230-238. [PMID: 29055828 PMCID: PMC7321815 DOI: 10.1016/j.watres.2017.10.028] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Revised: 10/11/2017] [Accepted: 10/12/2017] [Indexed: 05/14/2023]
Abstract
This study assessed the conductivity of a Geobacter-enriched biofilm anode in a microbial electrochemical cell (MxC) equipped with two gold anodes (25 mM acetate medium), as different proton gradients were built throughout the biofilm. There was no pH gradient across the biofilm anode at 100 mM phosphate buffer (current density 2.38 A/m2) and biofilm conductivity (Kbio) was as high as 0.87 mS/cm. In comparison, an inner biofilm became acidic at 2.5 mM phosphate buffer in which dead cells were accumulated at ∼80 μm of the inner biofilm anode. At this low phosphate buffer, Kbio significantly decreased by 0.27 mS/cm, together with declined current density of 0.64 A/m2. This work demonstrates that biofilm conductivity depends on the composition of live and dead cells in the conductive biofilm anode.
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Affiliation(s)
- Bipro Ranjan Dhar
- Civil and Environmental Engineering, University of Alberta, 9211-116 Street NW, Edmonton, Alberta, T6G 1H9, Canada; Civil and Environmental Engineering, University of Waterloo, 200 University Avenue, West Waterloo, Ontario, N2L 3G, Canada.
| | - Junyoung Sim
- Civil and Environmental Engineering, University of Waterloo, 200 University Avenue, West Waterloo, Ontario, N2L 3G, Canada.
| | - Hodon Ryu
- National Risk Management Research Laboratory, U.S. Environmental Protection Agency, 26 W. Martin Luther King Drive, Cincinnati, OH 45268, USA.
| | - Hao Ren
- School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, AZ, 85287, USA.
| | - Jorge W Santo Domingo
- National Risk Management Research Laboratory, U.S. Environmental Protection Agency, 26 W. Martin Luther King Drive, Cincinnati, OH 45268, USA.
| | - Junseok Chae
- School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, AZ, 85287, USA.
| | - Hyung-Sool Lee
- Civil and Environmental Engineering, University of Waterloo, 200 University Avenue, West Waterloo, Ontario, N2L 3G, Canada.
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32
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Zhang X, Philips J, Roume H, Guo K, Rabaey K, Prévoteau A. Rapid and Quantitative Assessment of Redox Conduction Across Electroactive Biofilms by using Double Potential Step Chronoamperometry. ChemElectroChem 2017. [DOI: 10.1002/celc.201600853] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Xu Zhang
- Center for Microbial Ecology and Technology (cmet); Ghent University; Coupure Links 653 9000 Ghent Belgium
| | - Jo Philips
- Center for Microbial Ecology and Technology (cmet); Ghent University; Coupure Links 653 9000 Ghent Belgium
| | - Hugo Roume
- Center for Microbial Ecology and Technology (cmet); Ghent University; Coupure Links 653 9000 Ghent Belgium
- MetaGenoPolis; INRA; Université Paris-Saclay Domaine de Vilvert; Bâtiment 325 78350 Jouy-en-Josas France
| | - Kun Guo
- Center for Microbial Ecology and Technology (cmet); Ghent University; Coupure Links 653 9000 Ghent Belgium
| | - Korneel Rabaey
- Center for Microbial Ecology and Technology (cmet); Ghent University; Coupure Links 653 9000 Ghent Belgium
| | - Antonin Prévoteau
- Center for Microbial Ecology and Technology (cmet); Ghent University; Coupure Links 653 9000 Ghent Belgium
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33
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Effect of temperature on a miniaturized microbial fuel cell (MFC). MICRO AND NANO SYSTEMS LETTERS 2017. [DOI: 10.1186/s40486-017-0048-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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34
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Yasri NG, Nakhla G. Electrochemical Behavior of Anode-Respiring Bacteria on Doped Carbon Electrodes. ACS APPLIED MATERIALS & INTERFACES 2016; 8:35150-35162. [PMID: 27966869 DOI: 10.1021/acsami.6b09907] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Cultivating anodic respiring bacteria (ARB) on anodes doped with metal-enhanced biological growth and affected higher electocatalytic activity (ECA). The anode doped with calcium sulfide (CaS) proved more favorable for ARB than the magnetite (Fe3O4) or iron(II) sulfide (FeS). Average anodic current densities of 8.4 Am2- (Fe3O4), 11.1 Am2- (FeS), and 22.0 Am2- (CaS) were achieved as compared to that of nondoped carbon (5.1 A m-2). Thus, CaS-doped graphite represents a promising anode material which is suitable for highly efficient bioelectrochemical systems (BES). Electrochemical evaluation during turnover and starvation using simple cycle voltammetry (CV) and derivative cycle voltammetry (DCV) indicated several extracellular electron transfer (EET) pathways characterized with lower potentials for biofilms. However, despite the high affinity of bacteria to iron, their lower ECA was kinetically attributed to the accumulation of self-produced mediators on iron-doped anodes.
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Affiliation(s)
- Nael G Yasri
- Department of Chemical and Biochemical Engineering, University of Western Ontario , London, Ontario N6A 5B9, Canada
| | - George Nakhla
- Department of Chemical and Biochemical Engineering, University of Western Ontario , London, Ontario N6A 5B9, Canada
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35
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Dhar BR, Ryu H, Ren H, Domingo JWS, Chae J, Lee HS. High Biofilm Conductivity Maintained Despite Anode Potential Changes in a Geobacter-Enriched Biofilm. CHEMSUSCHEM 2016; 9:3485-3491. [PMID: 27870324 PMCID: PMC7377214 DOI: 10.1002/cssc.201601007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 08/25/2016] [Indexed: 05/25/2023]
Abstract
This study systematically assessed intracellular electron transfer (IET) and extracellular electron transfer (EET) kinetics with respect to anode potential (Eanode ) in a mixed-culture biofilm anode enriched with Geobacter spp. High biofilm conductivity (0.96-1.24 mS cm-1 ) was maintained during Eanode changes from -0.2 to +0.2 V versus the standard hydrogen electrode (SHE), although the steady-state current density significantly decreased from 2.05 to 0.35 A m-2 in a microbial electrochemical cell. Substantial increase of the Treponema population was observed in the biofilm anode at Eanode =+0.2 V, which reduced intracellular electron-transfer kinetics associated with the maximum specific substrate-utilization rate by a factor of ten. This result suggests that fast EET kinetics can be maintained under dynamic Eanode conditions in a highly conductive biofilm anode as a result of shift of main EET players in the biofilm anode, although Eanode changes can influence IET kinetics.
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Affiliation(s)
- Bipro Ranjan Dhar
- Civil and Environmental Engineering, University of Alberta, 9211-116 Street NW, Edmonton, Alberta, T6G 1H9, Canada
| | - Hodon Ryu
- National Risk Management Research Laboratory, U.S. Environmental Protection Agency, 26 W. Martin Luther King Drive, Cincinnati, OH, 45268, USA
| | - Hao Ren
- School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, AZ, 85287, USA
| | - Jorge W Santo Domingo
- National Risk Management Research Laboratory, U.S. Environmental Protection Agency, 26 W. Martin Luther King Drive, Cincinnati, OH, 45268, USA
| | - Junkseck Chae
- School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, AZ, 85287, USA
| | - Hyung-Sool Lee
- Civil and Environmental Engineering, University of Waterloo, 200 University Avenue, West Waterloo, Ontario, N2L 3G, Canada
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36
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Lusk BG, Parameswaran P, Popat SC, Rittmann BE, Torres CI. The effect of pH and buffer concentration on anode biofilms of Thermincola ferriacetica. Bioelectrochemistry 2016; 112:47-52. [DOI: 10.1016/j.bioelechem.2016.07.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 07/17/2016] [Accepted: 07/18/2016] [Indexed: 11/16/2022]
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Koch C, Harnisch F. What Is the Essence of Microbial Electroactivity? Front Microbiol 2016; 7:1890. [PMID: 27933052 PMCID: PMC5122576 DOI: 10.3389/fmicb.2016.01890] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 11/11/2016] [Indexed: 11/13/2022] Open
Affiliation(s)
- Christin Koch
- Department of Environmental Microbiology, UFZ-Helmholtz Centre for Environmental Research Leipzig, Germany
| | - Falk Harnisch
- Department of Environmental Microbiology, UFZ-Helmholtz Centre for Environmental Research Leipzig, Germany
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38
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Popat SC, Torres CI. Critical transport rates that limit the performance of microbial electrochemistry technologies. BIORESOURCE TECHNOLOGY 2016; 215:265-273. [PMID: 27211921 DOI: 10.1016/j.biortech.2016.04.136] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Revised: 04/26/2016] [Accepted: 04/29/2016] [Indexed: 05/21/2023]
Abstract
Microbial electrochemistry technologies (METs) take advantage of the connection of microorganisms with electrodes. In the classic case of a microbial anode, the maximization of current density produced is often the goal. But, current production is dependent on many transport processes occurring, which can be rate-limiting. These include the fluxes of electron donor and acceptor, the ionic flux, the acidity and alkalinity fluxes at anode and cathode respectively, the electron transport flux at the biofilm, and the reactant/product crossover flux. Associated with these fluxes are inherent concentration gradients that can affect performance. This critical review provides an analysis on how these transport processes have hindered the development of METs, and how MET designs have evolved as more knowledge of these transport limitations is gained. Finally, suggestions are provided on how to design MET systems taking into consideration critical transport processes that are intimately linked to the current produced.
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Affiliation(s)
- Sudeep C Popat
- Swette Center for Environmental Biotechnology, Biodesign Institute, Arizona State University, Tempe, AZ, USA
| | - César I Torres
- Swette Center for Environmental Biotechnology, Biodesign Institute, Arizona State University, Tempe, AZ, USA; School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, USA.
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39
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Steidl RJ, Lampa-Pastirk S, Reguera G. Mechanistic stratification in electroactive biofilms of Geobacter sulfurreducens mediated by pilus nanowires. Nat Commun 2016; 7:12217. [PMID: 27481214 PMCID: PMC4974642 DOI: 10.1038/ncomms12217] [Citation(s) in RCA: 120] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Accepted: 06/09/2016] [Indexed: 01/08/2023] Open
Abstract
Electricity generation by Geobacter sulfurreducens biofilms grown on electrodes involves matrix-associated electron carriers, such as c-type cytochromes. Yet, the contribution of the biofilm's conductive pili remains uncertain, largely because pili-defective mutants also have cytochrome defects. Here we report that a pili-deficient mutant carrying an inactivating mutation in the pilus assembly motor PilB has no measurable defects in cytochrome expression, yet forms anode biofilms with reduced electroactivity and is unable to grow beyond a threshold distance (∼10 μm) from the underlying electrode. The defects are similar to those of a Tyr3 mutant, which produces poorly conductive pili. The results support a model in which the conductive pili permeate the biofilms to wire the cells to the conductive biofilm matrix and the underlying electrode, operating coordinately with cytochromes until the biofilm reaches a threshold thickness that limits the efficiency of the cytochrome pathway but not the functioning of the conductive pili network. The roles played by cytochromes and conductive filamentous appendages (pili) in the electrical conductivity of Geobacter bacterial biofilms are controversial. Here, Steidl et al. present evidence that both mechanisms cooperate in thin biofilms, while pili are important for conductivity across thicker biofilms.
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Affiliation(s)
- Rebecca J Steidl
- Department of Microbiology and Molecular Genetics, Michigan State University, 567 Wilson Road, Rm 6190, Biomedical and Physical Science building, East Lansing, Michigan 48824, USA
| | - Sanela Lampa-Pastirk
- Department of Microbiology and Molecular Genetics, Michigan State University, 567 Wilson Road, Rm 6190, Biomedical and Physical Science building, East Lansing, Michigan 48824, USA
| | - Gemma Reguera
- Department of Microbiology and Molecular Genetics, Michigan State University, 567 Wilson Road, Rm 6190, Biomedical and Physical Science building, East Lansing, Michigan 48824, USA
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40
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Ren H, Tian H, Gardner CL, Ren TL, Chae J. A miniaturized microbial fuel cell with three-dimensional graphene macroporous scaffold anode demonstrating a record power density of over 10,000 W m(-3) . NANOSCALE 2016; 8:3539-47. [PMID: 26804041 DOI: 10.1039/c5nr07267k] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A microbial fuel cell (MFC) is a bio-inspired renewable energy converter which directly converts biomass into electricity. This is accomplished via the unique extracellular electron transfer (EET) of a specific species of microbe called the exoelectrogen. Many studies have attempted to improve the power density of MFCs, yet the reported power density is still nearly two orders of magnitude lower than other power sources/converters. Such a low performance can primarily be attributed to two bottlenecks: (i) ineffective electron transfer from microbes located far from the anode and (ii) an insufficient buffer supply to the biofilm. This work takes a novel approach to mitigate these two bottlenecks by integrating a three-dimensional (3D) macroporous graphene scaffold anode in a miniaturized MFC. This implementation has delivered the highest power density reported to date in all MFCs of over 10,000 W m(-3). The miniaturized configuration offers a high surface area to volume ratio and improved mass transfer of biomass and buffers. The 3D graphene macroporous scaffold warrants investigation due to its high specific surface area, high porosity, and excellent conductivity and biocompatibility which facilitates EET and alleviates acidification in the biofilm. Consequently, the 3D scaffold houses an extremely thick and dense biofilm from the Geobacter-enriched culture, delivering an areal/volumetric current density of 15.51 A m(-2)/31,040 A m(-3) and a power density of 5.61 W m(-2)/11,220 W m(-3), a 3.3 fold increase when compared to its planar two-dimensional (2D) control counterparts.
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Affiliation(s)
- Hao Ren
- School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, AZ 85287, USA.
| | - He Tian
- Institute of Microelectronics & Tsinghua National Laboratory for Information Science and Technology (TNList), Tsinghua University, Beijing, 10084, P. R. China.
| | - Cameron L Gardner
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ 85287, USA
| | - Tian-Ling Ren
- Institute of Microelectronics & Tsinghua National Laboratory for Information Science and Technology (TNList), Tsinghua University, Beijing, 10084, P. R. China.
| | - Junseok Chae
- School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, AZ 85287, USA.
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41
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Commault AS, Lear G, Weld RJ. Maintenance of Geobacter -dominated biofilms in microbial fuel cells treating synthetic wastewater. Bioelectrochemistry 2015; 106:150-8. [DOI: 10.1016/j.bioelechem.2015.04.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2014] [Revised: 04/19/2015] [Accepted: 04/22/2015] [Indexed: 11/24/2022]
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42
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Yates MD, Golden JP, Roy J, Strycharz-Glaven SM, Tsoi S, Erickson JS, El-Naggar MY, Calabrese Barton S, Tender LM. Thermally activated long range electron transport in living biofilms. Phys Chem Chem Phys 2015; 17:32564-70. [PMID: 26611733 DOI: 10.1039/c5cp05152e] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Microbial biofilms grown utilizing electrodes as metabolic electron acceptors or donors are a new class of biomaterials with distinct electronic properties. Here we report that electron transport through living electrode-grown Geobacter sulfurreducens biofilms is a thermally activated process with incoherent redox conductivity. The temperature dependency of this process is consistent with electron-transfer reactions involving hemes of c-type cytochromes known to play important roles in G. sulfurreducens extracellular electron transport. While incoherent redox conductivity is ubiquitous in biological systems at molecular-length scales, it is unprecedented over distances it appears to occur through living G. sulfurreducens biofilms, which can exceed 100 microns in thickness.
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Affiliation(s)
- Matthew D Yates
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, Washington, DC 20375, USA.
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43
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Wu B, Yu H, Lin C, Feng C, Wei C. The Use of Accumulated Charge Density of a Bioanode to Estimate Maximum Current in a Bioelectrochemical System. ChemElectroChem 2015. [DOI: 10.1002/celc.201500139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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44
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GEMM-I riboswitches from Geobacter sense the bacterial second messenger cyclic AMP-GMP. Proc Natl Acad Sci U S A 2015; 112:5383-8. [PMID: 25848022 DOI: 10.1073/pnas.1419328112] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cyclic dinucleotides are an expanding class of signaling molecules that control many aspects of bacterial physiology. A synthase for cyclic AMP-GMP (cAG, also referenced as 3'-5', 3'-5' cGAMP) called DncV is associated with hyperinfectivity of Vibrio cholerae but has not been found in many bacteria, raising questions about the prevalence and function of cAG signaling. We have discovered that the environmental bacterium Geobacter sulfurreducens produces cAG and uses a subset of GEMM-I class riboswitches (GEMM-Ib, Genes for the Environment, Membranes, and Motility) as specific receptors for cAG. GEMM-Ib riboswitches regulate genes associated with extracellular electron transfer; thus cAG signaling may control aspects of bacterial electrophysiology. These findings expand the role of cAG beyond organisms that harbor DncV and beyond pathogenesis to microbial geochemistry, which is important to environmental remediation and microbial fuel cell development. Finally, we have developed an RNA-based fluorescent biosensor for live-cell imaging of cAG. This selective, genetically encodable biosensor will be useful to probe the biochemistry and cell biology of cAG signaling in diverse bacteria.
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45
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Jiang X, Hu J, Lieber AM, Jackan CS, Biffinger JC, Fitzgerald LA, Ringeisen BR, Lieber CM. Nanoparticle facilitated extracellular electron transfer in microbial fuel cells. NANO LETTERS 2014; 14:6737-6742. [PMID: 25310721 DOI: 10.1021/nl503668q] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Microbial fuel cells (MFCs) have been the focus of substantial research interest due to their potential for long-term, renewable electrical power generation via the metabolism of a broad spectrum of organic substrates, although the low power densities have limited their applications to date. Here, we demonstrate the potential to improve the power extraction by exploiting biogenic inorganic nanoparticles to facilitate extracellular electron transfer in MFCs. Simultaneous short-circuit current recording and optical imaging on a nanotechnology-enabled platform showed substantial current increase from Shewanella PV-4 after the formation of cell/iron sulfide nanoparticle aggregates. Detailed characterization of the structure and composition of the cell/nanoparticle interface revealed crystalline iron sulfide nanoparticles in intimate contact with and uniformly coating the cell membrane. In addition, studies designed to address the fundamental mechanisms of charge transport in this hybrid system showed that charge transport only occurred in the presence of live Shewanella, and moreover demonstrated that the enhanced current output can be attributed to improved electron transfer at cell/electrode interface and through the cellular-networks. Our approach of interconnecting and electrically contacting bacterial cells through biogenic nanoparticles represents a unique and promising direction in MFC research and has the potential to not only advance our fundamental knowledge about electron transfer processes in these biological systems but also overcome a key limitation in MFCs by constructing an electrically connected, three-dimensional cell network from the bottom-up.
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Affiliation(s)
- Xiaocheng Jiang
- Department of Chemistry and Chemical Biology and ‡Division of Engineering and Applied Sciences, Harvard University , Cambridge, Massachusetts 02138, United States
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46
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Jayasinghe N, Franks A, Nevin KP, Mahadevan R. Metabolic modeling of spatial heterogeneity of biofilms in microbial fuel cells reveals substrate limitations in electrical current generation. Biotechnol J 2014; 9:1350-61. [PMID: 25113946 DOI: 10.1002/biot.201400068] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 07/24/2014] [Accepted: 08/11/2014] [Indexed: 11/06/2022]
Abstract
Microbial fuel cells (MFCs) have been proposed as an alternative energy resource for the conversion of organic compounds to electricity. In an MFC, microorganisms such as Geobacter sulfurreducens form an anode-associated biofilm that can completely oxidize organic matter (electron donor) to carbon dioxide with direct electron transfer to the anode (electron acceptor). Mathematical models are useful in analyzing biofilm processes; however, existing models rely on Nernst-Monod type expressions, and evaluate extracellular processes separated from the intracellular metabolism of the microorganism. Thus, models that combine both extracellular and intracellular components, while addressing spatial heterogeneity, are essential for improved representation of biofilm processes. The goal of this work is to develop a model that integrates genome-scale metabolic models with the model of biofilm environment. This integrated model shows the variations of electrical current production and biofilm thickness under the presence/absence of NH4 in the bulk solution, and under varying maintenance energy demands. Further, sensitivity analysis suggested that conductivity is not limiting electrical current generation and that increasing cell density can lead to enhanced current generation. In addition, the modeling results also highlight instances such as the transformation into respiring cells, where the mechanism of electrical current generation during biofilm development is not yet clearly understood.
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Affiliation(s)
- Nadeera Jayasinghe
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON, Canada
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47
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Microbial nanowires for bioenergy applications. Curr Opin Biotechnol 2014; 27:88-95. [DOI: 10.1016/j.copbio.2013.12.003] [Citation(s) in RCA: 202] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 11/22/2013] [Accepted: 12/06/2013] [Indexed: 11/23/2022]
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48
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Virdis B, Millo D, Donose BC, Batstone DJ. Real-time measurements of the redox states of c-type cytochromes in electroactive biofilms: a confocal resonance Raman Microscopy study. PLoS One 2014; 9:e89918. [PMID: 24587123 PMCID: PMC3934938 DOI: 10.1371/journal.pone.0089918] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Accepted: 01/28/2014] [Indexed: 11/19/2022] Open
Abstract
Confocal Resonance Raman Microscopy (CRRM) was used to probe variations of redox state of c-type cytochromes embedded in living mixed-culture electroactive biofilms exposed to different electrode polarizations, under potentiostatic and potentiodynamic conditions. In the absence of the metabolic substrate acetate, the redox state of cytochromes followed the application of reducing and oxidizing electrode potentials. Real-time monitoring of the redox state of cytochromes during cyclic voltammetry (CV) in a potential window where cytochromes reduction occurs, evidenced a measurable time delay between the oxidation of redox cofactors probed by CV at the electrode interface, and oxidation of distal cytochromes probed by CRRM. This delay was used to tentatively estimate the diffusivity of electrons through the biofilm. In the presence of acetate, the resonance Raman spectra of young (10 days, j = 208±49 µA cm−2) and mature (57 days, j = 267±73 µA cm−2) biofilms show that cytochromes remained oxidized homogeneously even at layers as far as 70 µm from the electrode, implying the existence of slow metabolic kinetics that do not result in the formation of a redox gradient inside the biofilm during anode respiration. However, old biofilms (80 days, j = 190±37 µA cm−2) with thickness above 100 µm were characterized by reduced catalytic activity compared to the previous developing stages. The cytochromes in these biofilm were mainly in the reduced redox state, showing that only aged mixed-culture biofilms accumulate electrons during anode respiration. These results differ substantially from recent observations in pure Geobacter sulfurreducens electroactive biofilms, in which accumulation of reduced cytochromes is already observed in thinner biofilms, thus suggesting different bottlenecks in current production for mixed-culture and G. sulfurreducens biofilms.
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Affiliation(s)
- Bernardino Virdis
- Centre for Microbial Electrosynthesis (CEMES), The University of Queensland, Brisbane, Queensland, Australia
- Advanced Water Management Centre (AWMC), The University of Queensland, Brisbane, Queensland, Australia
- * E-mail:
| | - Diego Millo
- Biomolecular Spectroscopy/LaserLaB Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Bogdan C. Donose
- Centre for Microbial Electrosynthesis (CEMES), The University of Queensland, Brisbane, Queensland, Australia
- Advanced Water Management Centre (AWMC), The University of Queensland, Brisbane, Queensland, Australia
| | - Damien J. Batstone
- Advanced Water Management Centre (AWMC), The University of Queensland, Brisbane, Queensland, Australia
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49
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Schrott GD, Ordoñez MV, Robuschi L, Busalmen JP. Physiological stratification in electricity-producing biofilms of Geobacter sulfurreducens. CHEMSUSCHEM 2014; 7:598-603. [PMID: 24307451 DOI: 10.1002/cssc.201300605] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 09/27/2013] [Indexed: 06/02/2023]
Abstract
The elucidation of mechanisms and limitations in electrode respiration by electroactive biofilms is significant for the development of rapidly emerging clean energy production and wastewater treatment technologies. In Geobacter sulfurreducens biofilms, the controlling steps in current production are thought to be the metabolic activity of cells, but still remain to be determined. By quantifying the DNA, RNA, and protein content during the long-term growth of biofilms on polarized graphite electrodes, we show in this work that current production becomes independent of DNA accumulation immediately after a maximal current is achieved. Indeed, the mean respiratory rate of biofilms rapidly decreases after this point, which indicates the progressive accumulation of cells that do not contribute to current production or contribute to a negligible extent. These results support the occurrence of physiological stratification within biofilms as a consequence of respiratory limitations imposed by limited biofilm conductivity.
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Affiliation(s)
- Germán David Schrott
- División Electroquímica y Corrosión INTEMA-CONICET-UNMdP, Juan B Justo 4302, B7608FDQ, Mar del Plata (Argentina).
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50
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Torres CI. On the importance of identifying, characterizing, and predicting fundamental phenomena towards microbial electrochemistry applications. Curr Opin Biotechnol 2014; 27:107-14. [PMID: 24441074 DOI: 10.1016/j.copbio.2013.12.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 12/04/2013] [Accepted: 12/16/2013] [Indexed: 11/18/2022]
Abstract
The development of microbial electrochemistry research toward technological applications has increased significantly in the past years, leading to many process configurations. This short review focuses on the need to identify and characterize the fundamental phenomena that control the performance of microbial electrochemical cells (MXCs). Specifically, it discusses the importance of recent efforts to discover and characterize novel microorganisms for MXC applications, as well as recent developments to understand transport limitations in MXCs. As we increase our understanding of how MXCs operate, it is imperative to continue modeling efforts in order to effectively predict their performance, design efficient MXC technologies, and implement them commercially. Thus, the success of MXC technologies largely depends on the path of identifying, understanding, and predicting fundamental phenomena that determine MXC performance.
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Affiliation(s)
- César Iván Torres
- Swette Center for Environmental Biotechnology, Biodesign Institute, Arizona State University, 1001 S McAllister Avenue, Tempe, AZ 85287-5701, USA; School for Engineering of Matter Transport and Energy, Arizona State University, 501 E. Tyler Mall ECG 301, Tempe, AZ 85287, USA.
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