51
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Chen M, Zhou X, Liu X, Zeng RJ, Zhang F, Ye J, Zhou S. Facilitated extracellular electron transfer of Geobacter sulfurreducens biofilm with in situ formed gold nanoparticles. Biosens Bioelectron 2018; 108:20-26. [PMID: 29494884 DOI: 10.1016/j.bios.2018.02.030] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 02/07/2018] [Accepted: 02/11/2018] [Indexed: 11/19/2022]
Abstract
The conductivity of a biofilm is the key factor for the high current density of a bioelectrochemical system (BES). Most previous works have focused on electrode modification, but, this only benefits the microorganisms that directly contact the electrode. The low conductivity of biofilm limits the current density of the BES. In this work, gold nanoparticles (Au-NPs) were successfully fabricated in situ into a Geobacter sulfurreducens biofilm to increase the conductivity. 20 ppm NaAuCl4 (the precursor) was slowly dropped into the anode chamber at a rate of 1.3 mL/h in a continuous-flow three-electrode BES. The Au(III) was transformed to Au-NPs, which then precipitated in the biofilm via biological mineralization. The current density of the anode increased by 40%. Meanwhile, the removal percentage of the organic substrate (acetate) was enhanced 2.2 times, from 24.7% to 53.3%, after the in situ fabrication of Au-NPs. This method greatly lowered the charge transfer resistance of the anode and enhanced the anodic limiting current. Our results proved that the current density and organic removal rate of the G. sulfurreducens biofilm in the anode were effectively enhanced by in situ Au-NP fabrication. This work not only provides a simple and effective strategy for enhancing the electricity generation of BES with conductive NP fabrication, but also improves the understanding of the extracellular electron transfer (EET) of exoelectrogens.
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Affiliation(s)
- Man Chen
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Xiaofang Zhou
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Xing Liu
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Raymond Jianxiong Zeng
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Fang Zhang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Jie Ye
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 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, Fujian 350002, China.
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52
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Yates MD, Eddie BJ, Lebedev N, Kotloski NJ, Strycharz-Glaven SM, Tender LM. On the relationship between long-distance and heterogeneous electron transfer in electrode-grown Geobacter sulfurreducens biofilms. Bioelectrochemistry 2018; 119:111-118. [DOI: 10.1016/j.bioelechem.2017.09.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Revised: 09/12/2017] [Accepted: 09/14/2017] [Indexed: 02/05/2023]
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53
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Zhou L, Li T, An J, Liao C, Li N, Wang X. Subminimal inhibitory concentration (sub-MIC) of antibiotic induces electroactive biofilm formation in bioelectrochemical systems. WATER RESEARCH 2017; 125:280-287. [PMID: 28866443 DOI: 10.1016/j.watres.2017.08.059] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 08/03/2017] [Accepted: 08/28/2017] [Indexed: 06/07/2023]
Abstract
Electroactive biofilms (EABs) generated from mixed inocula are attractive due to their unique direct extracellular electron transfer abilities and potential use in water pollution control. In this study, for the first time, we identified a chemical that can be used for EAB regulation (both inhibition and promotion). We confirmed that tobramycin, an antibiotic previously demonstrated to inhibit the activity of EABs, is an agonist of EAB formation at subminimal inhibitory concentrations (sub-MICs). Compared to the control, at tobramycin concentrations of 0.05 (1/80 MIC) and 0.1 mg/L (1/40 MIC), the time required to reach 3 A/m2 was shorter, and the limiting current densities increased by 17%. The enhanced EAB activity was primarily attributed to the 50% increase in biomass density from 289 ± 21 to 434 ± 12 μg protein/cm2 and the increased biofilm thickness from 28 ± 1 to 37 ± 0.5 μm. Geobacter species in the microbial communities were selectively increased from 76% to 82%, and their abundance was estimated to increase by 1.63-fold. The accelerated growth was further confirmed using the model strain G. sulfurreducens PCA. Transcriptomic analysis revealed that 0.05 mg/L of tobramycin led to a significant upregulation of genes related to cytochromes and the type IV pilus, suggesting a possible mechanism for the observed current enhancement. These findings extend our knowledge of the regulation of EAB formation by antibiotics and the selective enrichment of Geobacter from a mixed culture, with broader implications on the potential impact of trace antibiotics on the dissimilatory metal reduction process in water environment.
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Affiliation(s)
- Lean Zhou
- 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
| | - Jingkun An
- School of Environmental Science and Engineering, Tianjin University, No. 92 Weijin Road, Nankai District, Tianjin, 300072, 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
| | - Nan Li
- School of Environmental Science and Engineering, Tianjin University, No. 92 Weijin Road, Nankai District, Tianjin, 300072, 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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54
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Schmidt I, Pieper A, Wichmann H, Bunk B, Huber K, Overmann J, Walla PJ, Schröder U. In Situ Autofluorescence Spectroelectrochemistry for the Study of Microbial Extracellular Electron Transfer. ChemElectroChem 2017. [DOI: 10.1002/celc.201700675] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Igor Schmidt
- Institute of Environmental and Sustainable Chemistry; Technische Universität Braunschweig; 38106 Braunschweig Germany
| | - Alexander Pieper
- Department of Biophysical Chemistry, Institute for Physical and Theoretical Chemistry; Technische Universität Braunschweig; 38106 Braunschweig, Germany
| | - Hilke Wichmann
- Institute of Environmental and Sustainable Chemistry; Technische Universität Braunschweig; 38106 Braunschweig Germany
| | - Boyke Bunk
- Department Microbial Ecology and Diversity Research; Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures; 38124 Braunschweig Germany
| | - Katharina Huber
- Department Microbial Ecology and Diversity Research; Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures; 38124 Braunschweig Germany
| | - Jörg Overmann
- Department Microbial Ecology and Diversity Research; Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures; 38124 Braunschweig Germany
| | - Peter Jomo Walla
- Department of Biophysical Chemistry, Institute for Physical and Theoretical Chemistry; Technische Universität Braunschweig; 38106 Braunschweig, Germany
| | - Uwe Schröder
- Institute of Environmental and Sustainable Chemistry; Technische Universität Braunschweig; 38106 Braunschweig Germany
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55
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Robuschi L, Tomba JP, Busalmen JP. Proving Geobacter biofilm connectivity with confocal Raman microscopy. J Electroanal Chem (Lausanne) 2017. [DOI: 10.1016/j.jelechem.2016.11.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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56
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Gildemyn S, Rozendal RA, Rabaey K. A Gibbs Free Energy-Based Assessment of Microbial Electrocatalysis. Trends Biotechnol 2017; 35:393-406. [DOI: 10.1016/j.tibtech.2017.02.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 02/01/2017] [Accepted: 02/03/2017] [Indexed: 10/19/2022]
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57
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Zhou L, Deng D, Zhang Y, Zhou W, Jiang Y, Liu Y. Isolation of a facultative anaerobic exoelectrogenic strain LZ-1 and probing electron transfer mechanism in situ by linking UV/Vis spectroscopy and electrochemistry. Biosens Bioelectron 2017; 90:264-268. [DOI: 10.1016/j.bios.2016.11.059] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Revised: 11/01/2016] [Accepted: 11/25/2016] [Indexed: 12/12/2022]
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58
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Knoche KL, Aoyama E, Hasan K, Minteer SD. Role of Nitrogenase and Ferredoxin in the Mechanism of Bioelectrocatalytic Nitrogen Fixation by the Cyanobacteria Anabaena variabilis SA-1 Mutant Immobilized on Indium Tin Oxide (ITO) Electrodes. Electrochim Acta 2017. [DOI: 10.1016/j.electacta.2017.02.148] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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59
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60
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Tejedor-Sanz S, Quejigo JR, Berná A, Esteve-Núñez A. The Planktonic Relationship Between Fluid-Like Electrodes and Bacteria: Wiring in Motion. CHEMSUSCHEM 2017; 10:693-700. [PMID: 27860438 DOI: 10.1002/cssc.201601329] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 11/01/2016] [Indexed: 06/06/2023]
Abstract
We have explored a new concept in bacteria-electrode interaction based on the use of fluid-like electrodes and planktonic living cells. We show for the first time that living in a biofilm is not a strict requirement for Geobacter sulfurreducens to exchange electrons with an electrode. The growth of planktonic electroactive G. sulfurreducens could be supported by a fluid-like anode as soluble electron acceptors and with electron transfer rates similar to those reported for electroactive biofilms. This growth was maintained by uncoupling the charge (catabolism) and discharge (extracellular respiration) processes of the cells. Our results reveal a novel method to culture electroactive bacteria in which every single cell in the medium could be instantaneously wired to a fluid-like electrode. Direct extracellular electron transfer is occurring but with a new paradigm behind the bacteria-electrode interaction.
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Affiliation(s)
- Sara Tejedor-Sanz
- Department of Chemical Engineering, Universidad de Alcalá, Alcalá de Henares, Madrid, Spain
- Innovation and Technology Department, FCC Aqualia, S.A., Madrid, Spain
| | - Jose Rodrigo Quejigo
- Department of Chemical Engineering, Universidad de Alcalá, Alcalá de Henares, Madrid, Spain
| | - Antonio Berná
- IMDEA Water, Parque Tecnológico de Alcalá, Alcalá de Henares, Madrid, Spain
| | - Abraham Esteve-Núñez
- Department of Chemical Engineering, Universidad de Alcalá, Alcalá de Henares, Madrid, Spain
- IMDEA Water, Parque Tecnológico de Alcalá, Alcalá de Henares, Madrid, Spain
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61
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Cytochrome OmcZ is essential for the current generation by Geobacter sulfurreducens under low electrode potential. Electrochim Acta 2017. [DOI: 10.1016/j.electacta.2017.01.091] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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62
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Liu T, Wu Y, Li F, Li X, Luo X. Rapid Redox Processes ofc-Type Cytochromes in A Living Cell Suspension ofShewanella oneidensisMR-1. ChemistrySelect 2017. [DOI: 10.1002/slct.201602021] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Tongxu Liu
- Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control; Guangdong Institute of Eco-Environmental and Soil Sciences; Guangzhou 510650 PR China
| | - Yundang Wu
- Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control; Guangdong Institute of Eco-Environmental and Soil Sciences; Guangzhou 510650 PR China
| | - Fangbai Li
- Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control; Guangdong Institute of Eco-Environmental and Soil Sciences; Guangzhou 510650 PR China
| | - Xiaomin Li
- Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control; Guangdong Institute of Eco-Environmental and Soil Sciences; Guangzhou 510650 PR China
| | - Xiaobo Luo
- Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control; Guangdong Institute of Eco-Environmental and Soil Sciences; Guangzhou 510650 PR China
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63
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Garoz-Ruiz J, Heras A, Colina A. Direct Determination of Ascorbic Acid in a Grapefruit: Paving the Way for In Vivo Spectroelectrochemistry. Anal Chem 2017; 89:1815-1822. [DOI: 10.1021/acs.analchem.6b04155] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Jesus Garoz-Ruiz
- Department of Chemistry, Universidad de Burgos, Plaza Misael Bañuelos s/n, E-09001 Burgos, Spain
| | - Aranzazu Heras
- Department of Chemistry, Universidad de Burgos, Plaza Misael Bañuelos s/n, E-09001 Burgos, Spain
| | - Alvaro Colina
- Department of Chemistry, Universidad de Burgos, Plaza Misael Bañuelos s/n, E-09001 Burgos, Spain
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64
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Li DB, Huang YX, Li J, Li LL, Tian LJ, Yu HQ. Electrochemical activities of Geobacter biofilms growing on electrodes with various potentials. Electrochim Acta 2017. [DOI: 10.1016/j.electacta.2016.12.146] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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65
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Engineering of Microbial Electrodes. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2017; 167:135-180. [PMID: 28864879 DOI: 10.1007/10_2017_16] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
This chapter provides an overview of the current state-of-the-art in the engineering of microbial electrodes for application in microbial electrosynthesis. First, important functional aspects and requirements of basic materials for microbial electrodes are introduced, including the meaningful benchmarking of electrode performance, a comparison of electrode materials, and methods to improve microbe-electrode interaction. Suitable current collectors and composite materials that combine different functionalities are also discussed. Subsequently, the chapter focuses on the design of macroscopic electrode structures. Aspects such as mass transfer and electrode topology are touched upon, and a comparison of the performance of microbial electrodes relevant for practical application is provided. The chapter closes with an overall conclusion and outlook, highlighting the future prospects and challenges for the engineering of microbial electrodes toward practical application in the field of microbial electrosynthesis. Graphical Abstract.
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66
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Ing NL, Nusca TD, Hochbaum AI. Geobacter sulfurreducenspili support ohmic electronic conduction in aqueous solution. Phys Chem Chem Phys 2017; 19:21791-21799. [DOI: 10.1039/c7cp03651e] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Solid-state and electrochemical observations of ohmic conductivity in purifiedGeobacter sulfurreducenspili.
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Affiliation(s)
- Nicole L. Ing
- Department of Chemical Engineering and Materials Science
- University of California
- Irvine
- Irvine
- USA
| | - Tyler D. Nusca
- Department of Chemical Engineering and Materials Science
- University of California
- Irvine
- Irvine
- USA
| | - Allon I. Hochbaum
- Department of Chemical Engineering and Materials Science
- University of California
- Irvine
- Irvine
- USA
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67
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Redox- and pH-linked conformational changes in triheme cytochrome PpcA from Geobacter sulfurreducens. Biochem J 2016; 474:231-246. [PMID: 28062839 DOI: 10.1042/bcj20160932] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 11/10/2016] [Accepted: 11/14/2016] [Indexed: 11/17/2022]
Abstract
The periplasmic triheme cytochrome PpcA from Geobacter sulfurreducens is highly abundant; it is the likely reservoir of electrons to the outer surface to assist the reduction of extracellular terminal acceptors; these include insoluble metal oxides in natural habitats and electrode surfaces from which electricity can be harvested. A detailed thermodynamic characterization of PpcA showed that it has an important redox-Bohr effect that might implicate the protein in e-/H+ coupling mechanisms to sustain cellular growth. This functional mechanism requires control of both the redox state and the protonation state. In the present study, isotope-labeled PpcA was produced and the three-dimensional structure of PpcA in the oxidized form was determined by NMR. This is the first solution structure of a G. sulfurreducens cytochrome in the oxidized state. The comparison of oxidized and reduced structures revealed that the heme I axial ligand geometry changed and there were other significant changes in the segments near heme I. The pH-linked conformational rearrangements observed in the vicinity of the redox-Bohr center, both in the oxidized and reduced structures, constitute the structural basis for the differences observed in the pKa values of the redox-Bohr center, providing insights into the e-/H+ coupling molecular mechanisms driven by PpcA in G. sulfurreducens.
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68
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Li T, Wang X, Zhou L, An J, Li J, Li N, Sun H, Zhou Q. Bioelectrochemical Sensor Using Living Biofilm To in Situ Evaluate Flocculant Toxicity. ACS Sens 2016. [DOI: 10.1021/acssensors.6b00571] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Tian Li
- MOE
Key Laboratory of Pollution Processes and Environmental Criteria/Tianjin
Engineering Center of Environmental Diagnosis and Contamination Remediation, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Xin Wang
- MOE
Key Laboratory of Pollution Processes and Environmental Criteria/Tianjin
Engineering Center of Environmental Diagnosis and Contamination Remediation, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Lean Zhou
- MOE
Key Laboratory of Pollution Processes and Environmental Criteria/Tianjin
Engineering Center of Environmental Diagnosis and Contamination Remediation, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Jingkun An
- Tianjin
Key Lab of Indoor Air Environmental Quality Control, School of Environmental
Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Junhui Li
- MOE
Key Laboratory of Pollution Processes and Environmental Criteria/Tianjin
Engineering Center of Environmental Diagnosis and Contamination Remediation, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Nan Li
- Tianjin
Key Lab of Indoor Air Environmental Quality Control, School of Environmental
Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Hongwen Sun
- MOE
Key Laboratory of Pollution Processes and Environmental Criteria/Tianjin
Engineering Center of Environmental Diagnosis and Contamination Remediation, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
| | - Qixing Zhou
- MOE
Key Laboratory of Pollution Processes and Environmental Criteria/Tianjin
Engineering Center of Environmental Diagnosis and Contamination Remediation, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China
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69
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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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70
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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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71
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Yuan Y, Guo T, Qiu X, Tang J, Huang Y, Zhuang L, Zhou S, Li Z, Guan BO, Zhang X, Albert J. Electrochemical Surface Plasmon Resonance Fiber-Optic Sensor: In Situ Detection of Electroactive Biofilms. Anal Chem 2016; 88:7609-16. [DOI: 10.1021/acs.analchem.6b01314] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Yong Yuan
- Guangdong
Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650, China
| | - Tuan Guo
- Guangdong
Key Laboratory of Optical Fiber Sensing and Communications, Institute
of Photonics Technology, Jinan University, Guangzhou 510632, China
| | - Xuhui Qiu
- Guangdong
Key Laboratory of Optical Fiber Sensing and Communications, Institute
of Photonics Technology, Jinan University, Guangzhou 510632, China
| | - Jiahuan Tang
- Guangdong
Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650, China
| | - Yunyun Huang
- Guangdong
Key Laboratory of Optical Fiber Sensing and Communications, Institute
of Photonics Technology, Jinan University, Guangzhou 510632, China
| | - Li Zhuang
- Guangdong
Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650, China
| | - Shungui Zhou
- Guangdong
Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650, China
| | - Zhaohui Li
- Guangdong
Key Laboratory of Optical Fiber Sensing and Communications, Institute
of Photonics Technology, Jinan University, Guangzhou 510632, China
| | - Bai-Ou Guan
- Guangdong
Key Laboratory of Optical Fiber Sensing and Communications, Institute
of Photonics Technology, Jinan University, Guangzhou 510632, China
| | - Xuming Zhang
- Department
of Applied Physics, Hong Kong Polytechnic University, Hong Kong, People’s Republic of China
| | - Jacques Albert
- Department
of Electronics, Carleton University, Ottawa K1S5B6, Canada
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72
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Liu T, Li X, Li F, Han R, Wu Y, Yuan X, Wang Y. In Situ Spectral Kinetics of Cr(VI) Reduction by c-Type Cytochromes in A Suspension of Living Shewanella putrefaciens 200. Sci Rep 2016; 6:29592. [PMID: 27405048 PMCID: PMC4939527 DOI: 10.1038/srep29592] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 06/22/2016] [Indexed: 11/24/2022] Open
Abstract
Although c-type cytochromes (c-Cyts) mediating metal reduction have been mainly investigated with in vitro purified proteins of dissimilatory metal reducing bacteria, the in vivo behavior of c-Cyts is still unclear given the difficulty in measuring the proteins of intact cells. Here, c-Cyts in living Shewanella putrefaciens 200 (SP200) was successfully quantified using diffuse-transmission UV/Vis spectroscopy due to the strong absorbance of hemes, and the in situ spectral kinetics of Cr(VI) reduction by c-Cyts were examined over time. The reduced product Cr(III) observed on the cell surface may play a role in inhibiting the Cr(VI) reduction and reducing the cell numbers with high concentrations (>200 μM) of Cr(VI) evidenced by the 16S rRNA analysis. A brief kinetic model was established with two predominant reactions, redox transformation of c-Cyts and Cr(VI) reduction by reduced c-Cyts, but the fitting curves were not well-matched with c-Cyts data. The Cr(III)-induced inhibitory effect to the cellular function of redox transformation of c-Cyts was then added to the model, resulting in substantially improved the model fitting. This study provides a case of directly examining the reaction properties of outer-membrane enzyme during microbial metal reduction processes under physiological conditions.
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Affiliation(s)
- Tongxu Liu
- Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou, 510650 P. R. China
| | - Xiaomin Li
- Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou, 510650 P. R. China.,School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW, 2052 Australia
| | - Fangbai Li
- Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou, 510650 P. R. China
| | - Rui Han
- Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou, 510650 P. R. China
| | - Yundang Wu
- Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou, 510650 P. R. China
| | - Xiu Yuan
- School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW, 2052 Australia
| | - Ying Wang
- Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou, 510650 P. R. China
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73
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Han R, Li F, Liu T, Li X, Wu Y, Wang Y, Chen D. Effects of Incubation Conditions on Cr(VI) Reduction by c-type Cytochromes in Intact Shewanella oneidensis MR-1 Cells. Front Microbiol 2016; 7:746. [PMID: 27242759 PMCID: PMC4872037 DOI: 10.3389/fmicb.2016.00746] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 05/03/2016] [Indexed: 11/13/2022] Open
Abstract
It is widely recognized that the outer membrane c-type cytochromes (OM c-Cyts) of metal-reducing bacteria play a key role in microbial metal reduction processes. However, the in situ redox status of OM c-Cyts during microbial metal reduction processes remain poorly understood. In this study, diffuse-transmission UV/Vis spectroscopy is used to investigate the in situ spectral reaction of Cr(VI) reduction by c-Cyts in intact Shewanella oneidensis MR-1 cells under different incubation conditions. The reduced c-Cyts decreased transiently at the beginning and then recovered gradually over time. The Cr(VI) reduction rates decreased with increasing initial Cr(VI) concentrations, and Cr(III) was identified as a reduced product. The presence of Cr(III) substantially inhibited Cr(VI) reduction and the recovery of reduced c-Cyts, indicating that Cr(III) might inhibit cell growth. Cr(VI) reduction rates increased with increasing cell density. The highest Cr(VI) reduction rate and fastest recovery of c-Cyts were obtained at pH 7.0 and 30°C, with sodium lactate serving as an electron donor. The presence of O2 strongly inhibited Cr(VI) reduction, suggesting that O2 might compete with Cr(VI) as an electron acceptor in cells. This study provides a case of directly examining in vivo reaction properties of an outer-membrane enzyme during microbial metal reduction processes under non-invasive physiological conditions.
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Affiliation(s)
- Rui Han
- School of Environment and Energy, South China University of TechnologyGuangzhou, China; Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil SciencesGuangzhou, China
| | - Fangbai Li
- Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences Guangzhou, China
| | - Tongxu Liu
- Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences Guangzhou, China
| | - Xiaomin Li
- Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences Guangzhou, China
| | - Yundang Wu
- Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences Guangzhou, China
| | - Ying Wang
- Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences Guangzhou, China
| | - Dandan Chen
- Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences Guangzhou, China
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74
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Santos TC, Silva MA, Morgado L, Dantas JM, Salgueiro CA. Diving into the redox properties of Geobacter sulfurreducens cytochromes: a model for extracellular electron transfer. Dalton Trans 2016; 44:9335-44. [PMID: 25906375 DOI: 10.1039/c5dt00556f] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Geobacter bacteria have a remarkable respiratory versatility that includes the dissimilatory reduction of insoluble metal oxides in natural habitats and electron transfer to electrode surfaces from which electricity can be harvested. In both cases, electrons need to be exported from the cell interior to the exterior via a mechanism designated as extracellular electron transfer (EET). Several c-type cytochromes from G. sulfurreducens (Gs) were identified as key players in this process. Biochemical and biophysical data have been obtained for ten Gs cytochromes, including inner-membrane associated (MacA), periplasmic (PpcA, PpcB, PpcC, PpcD, PpcE and GSU1996) and outer membrane-associated (OmcF, OmcS and OmcZ). The redox properties of these cytochromes have been determined, except for PpcC and GSU1996. In this perspective, the reduction potentials of these two cytochromes were determined by potentiometric redox titrations followed by visible spectroscopy. The data obtained are taken together with those available for other key cytochromes to present a thorough overview of the current knowledge of Gs EET mechanisms and provide a possible rationalization for the existence of several multiheme cytochromes involved in the same respiratory pathways.
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Affiliation(s)
- Telma C Santos
- UCIBIO, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal.
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75
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Virdis B, Millo D, Donose BC, Lu Y, Batstone DJ, Krömer JO. Analysis of electron transfer dynamics in mixed community electroactive microbial biofilms. RSC Adv 2016. [DOI: 10.1039/c5ra15676a] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Electrochemically active microbial biofilms are capable to produce electric current when grown onto electrodes. This work investigates the dynamics of electron transfer inside the biofilm as well as at the biofilm/electrode interface.
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Affiliation(s)
- Bernardino Virdis
- The University of Queensland
- Centre for Microbial Electrochemical Systems (CEMES)
- Brisbane
- Australia
- The University of Queensland
| | - Diego Millo
- Biomolecular Spectroscopy/LaserLaB Amsterdam
- Vrije Universiteit Amsterdam
- NL-1081 HV Amsterdam
- The Netherlands
| | - Bogdan C. Donose
- The University of Queensland
- Centre for Microbial Electrochemical Systems (CEMES)
- Brisbane
- Australia
- The University of Queensland
| | - Yang Lu
- The University of Queensland
- Advanced Water Management Centre (AWMC)
- Brisbane
- Australia
| | - Damien J. Batstone
- The University of Queensland
- Advanced Water Management Centre (AWMC)
- Brisbane
- Australia
| | - Jens O. Krömer
- The University of Queensland
- Centre for Microbial Electrochemical Systems (CEMES)
- Brisbane
- Australia
- The University of Queensland
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76
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Feng C, Liu Y, Li Q, Che Y, Li N, Wang X. Quaternary Ammonium Compound in Anolyte without Functionalization Accelerates the Startup of Bioelectrochemical Systems using Real Wastewater. Electrochim Acta 2016. [DOI: 10.1016/j.electacta.2015.12.069] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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77
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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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78
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Santos TC, de Oliveira AR, Dantas JM, Salgueiro CA, Cordas CM. Thermodynamic and kinetic characterization of PccH, a key protein in microbial electrosynthesis processes in Geobacter sulfurreducens. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:1113-8. [DOI: 10.1016/j.bbabio.2015.06.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 05/29/2015] [Accepted: 06/07/2015] [Indexed: 10/23/2022]
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79
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Yuan Y, Li L, Zhou S. Axial Ligation of Heme in c-Type Cytochromes of LivingShewanella oneidensis: A New Insight into Enhanced Extracellular Electron Transfer. ChemElectroChem 2015. [DOI: 10.1002/celc.201500234] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Yong Yuan
- Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control; Guangdong Institute of Eco-Environmental and Soil Sciences; Guangzhou 510650 China
| | - Laicai Li
- College of Chemistry and Material Science; Sichuan Normal University; Chengdu 610066 China
| | - Shungui Zhou
- Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control; Guangdong Institute of Eco-Environmental and Soil Sciences; Guangzhou 510650 China
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80
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Gong XB, You SJ, Yuan Y, Zhang JN, Sun K, Ren NQ. Three-Dimensional Pseudocapacitive Interface for Enhanced Power Production in a Microbial Fuel Cell. ChemElectroChem 2015. [DOI: 10.1002/celc.201500174] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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81
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Sun D, Cheng S, Wang A, Li F, Logan BE, Cen K. Temporal-spatial changes in viabilities and electrochemical properties of anode biofilms. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:5227-5235. [PMID: 25810405 DOI: 10.1021/acs.est.5b00175] [Citation(s) in RCA: 117] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Sustained current generation by anodic biofilms is a key element for the longevity and success of bioelectrochemical systems. Over time, however, inactive or dead cells can accumulate within the anode biofilm, which can be particularly detrimental to current generation. Mixed and pure culture (Geobacter anodireducens) biofilms were examined here relative to changes in electrochemical properties over time. An analysis of the three-dimensional metabolic structure of the biofilms over time showed that both types of biofilms developed a live outer-layer that covered a dead inner-core. This two-layer structure appeared to be mostly a result of relatively low anodic current densities compared to other studies. During biofilm development, the live layer reached a constant thickness, whereas dead cells continued to accumulate near the electrode surface. This result indicated that only the live outer-layer of biofilm was responsible for current generation and suggested that the dead inner-layer continued to function as an electrically conductive matrix. Analysis of the electrochemical properties and biofilm thickness revealed that the diffusion resistance measured using electrochemical impedance spectroscopy might not be due to acetate or proton diffusion limitations to the live layer, but rather electron-mediator diffusion.
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Affiliation(s)
- Dan Sun
- †State Key Laboratory of Clean Energy Utilization, Department of Energy Engineering, Zhejiang University, Hangzhou 310027, P.R. China
| | - Shaoan Cheng
- †State Key Laboratory of Clean Energy Utilization, Department of Energy Engineering, Zhejiang University, Hangzhou 310027, P.R. China
| | - Aijie Wang
- ‡Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, China Academy of Sciences, Beijing, China
| | - Fujian Li
- †State Key Laboratory of Clean Energy Utilization, Department of Energy Engineering, Zhejiang University, Hangzhou 310027, P.R. China
| | - Bruce E Logan
- §Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Kefa Cen
- †State Key Laboratory of Clean Energy Utilization, Department of Energy Engineering, Zhejiang University, Hangzhou 310027, P.R. China
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82
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Dantas JM, Campelo LM, Duke NEC, Salgueiro CA, Pokkuluri PR. The structure of PccH from Geobacter sulfurreducens - a novel low reduction potential monoheme cytochrome essential for accepting electrons from an electrode. FEBS J 2015; 282:2215-31. [PMID: 25786707 DOI: 10.1111/febs.13269] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 02/09/2015] [Accepted: 03/13/2015] [Indexed: 11/27/2022]
Abstract
The structure of cytochrome c (GSU3274) designated as PccH from Geobacter sulfurreducens was determined at a resolution of 2.0 Å. PccH is a small (15 kDa) cytochrome containing one c-type heme, found to be essential for the growth of G. sulfurreducens with respect to accepting electrons from graphite electrodes poised at -300 mV versus standard hydrogen electrode. with fumarate as the terminal electron acceptor. The structure of PccH is unique among the monoheme cytochromes described to date. The structural fold of PccH can be described as forming two lobes with the heme sandwiched in a cleft between the two lobes. In addition, PccH has a low reduction potential of -24 mV at pH 7, which is unusual for monoheme cytochromes. Based on difference in structure, together with sequence phylogenetic analysis, we propose that PccH can be regarded as a first characterized example of a new subclass of class I monoheme cytochromes. The low reduction potential of PccH may enable the protein to be redox active at the typically negative potential ranges encountered by G. sulfurreducens. Because PccH is predicted to be located in the periplasm of this bacterium, it could not be involved in the first step of accepting electrons from the electrode but is very likely involved in the downstream electron transport events in the periplasm.
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Affiliation(s)
- Joana M Dantas
- UCIBIO - REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
| | - Luísa M Campelo
- UCIBIO - REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
| | - Norma E C Duke
- Biosciences Division, Argonne National Laboratory, Lemont, IL, USA
| | - Carlos A Salgueiro
- UCIBIO - REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
| | - P Raj Pokkuluri
- Biosciences Division, Argonne National Laboratory, Lemont, IL, USA
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83
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Estevez-Canales M, Kuzume A, Borjas Z, Füeg M, Lovley D, Wandlowski T, Esteve-Núñez A. A severe reduction in the cytochrome C content of Geobacter sulfurreducens eliminates its capacity for extracellular electron transfer. ENVIRONMENTAL MICROBIOLOGY REPORTS 2015; 7:219-226. [PMID: 25348891 DOI: 10.1111/1758-2229.12230] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Accepted: 09/23/2014] [Indexed: 06/04/2023]
Abstract
The ability of Geobacter species to transfer electrons outside the cell enables them to play an important role in a number of biogeochemical and bioenergy processes. Gene deletion studies have implicated periplasmic and outer-surface c-type cytochromes in this extracellular electron transfer. However, even when as many as five c-type cytochrome genes have been deleted, some capacity for extracellular electron transfer remains. In order to evaluate the role of c-type cytochromes in extracellular electron transfer, Geobacter sulfurreducens was grown in a low-iron medium that included the iron chelator (2,2'-bipyridine) to further sequester iron. Haem-staining revealed that the cytochrome content of cells grown in this manner was 15-fold lower than in cells exposed to a standard iron-containing medium. The low cytochrome abundance was confirmed by in situ nanoparticle-enhanced Raman spectroscopy (NERS). The cytochrome-depleted cells reduced fumarate to succinate as well as the cytochrome-replete cells do, but were unable to reduce Fe(III) citrate or to exchange electrons with a graphite electrode. These results demonstrate that c-type cytochromes are essential for extracellular electron transfer by G. sulfurreducens. The strategy for growing cytochrome-depleted G. sulfurreducens will also greatly aid future physiological studies of Geobacter species and other microorganisms capable of extracellular electron transfer.
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Affiliation(s)
- Marta Estevez-Canales
- Department of Chemical Engineering, University of Alcalá, Alcalá de Henares, Madrid, Spain
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84
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Kashima H, Regan JM. Facultative nitrate reduction by electrode-respiring Geobacter metallireducens biofilms as a competitive reaction to electrode reduction in a bioelectrochemical system. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:3195-3202. [PMID: 25622928 DOI: 10.1021/es504882f] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Alternative metabolic options of exoelectrogenic biofilms in bioelectrochemical systems (BESs) are important not only to explain the fundamental ecology and performance of these systems but also to develop reliable integrated nutrient removal strategies in BESs, which potentially involve substrates or intermediates that support/induce those alternative metabolisms. This research focused on dissimilatory nitrate reduction as an alternative metabolism to dissimilatory anode reduction. Using the exoelectrogenic nitrate reducer Geobacter metallireducens, the critical conditions controlling those alternative metabolisms were investigated in two-chamber, potentiostatically controlled BESs at various anode potentials and biofilm thicknesses and challenged over a range of nitrate concentrations. Results showed that anode-reducing biofilms facultatively reduced nitrate at all tested anode potentials (-150 to +900 mV vs Standard Hydrogen Electrode) with a rapid metabolic shift. The critical nitrate concentration that triggered a significant decrease in BES performance was a function of anode biofilm thickness but not anode potential. This indicates that these alternative metabolisms were controlled by the availability of nitrate, which is a function of nitrate concentration in bulk solution and its diffusion into an anode-reducing biofilm. Coulombic recovery decreased as a function of nitrate dose due to electron-acceptor substrate competition, and nitrate-induced suspended biomass growth decreased the effluent quality.
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Affiliation(s)
- Hiroyuki Kashima
- Department of Civil and Environmental Engineering, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
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85
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A Highly Efficient Mixed-culture Biofilm as Anodic Catalyst and Insights into Its Enhancement through Electrochemistry by Comparison with G. sulfurreducens. Electrochim Acta 2015. [DOI: 10.1016/j.electacta.2014.12.152] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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86
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Deng D, Zhang Y, Liu Y. A Geobacter strain isolated from rice paddy soil with higher bioelectricity generation capability in comparison to Geobacter sulfurreducens PCA. RSC Adv 2015. [DOI: 10.1039/c5ra06211j] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A novel electrochemically active strain D-8 was successfully isolated from rice paddy soil. The strain D-8 can use more carbon sources and show higher current density thanG. sulfurreducensPCA. It might be a promising bioanodic organism in MFCs.
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Affiliation(s)
- Dandan Deng
- College of Life Sciences
- Northwest A&F University
- Yangling
- PR China
| | - Yichi Zhang
- College of Life Sciences
- Northwest A&F University
- Yangling
- PR China
| | - Ying Liu
- College of Life Sciences
- Northwest A&F University
- Yangling
- PR China
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87
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Strycharz-Glaven SM, Roy J, Boyd D, Snider R, Erickson JS, Tender LM. Electron Transport through Early Exponential-Phase Anode-GrownGeobacter sulfurreducensBiofilms. ChemElectroChem 2014. [DOI: 10.1002/celc.201402168] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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88
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Dantas JM, Morgado L, Marques AC, Salgueiro CA. Probing the effect of ionic strength on the functional robustness of the triheme cytochrome PpcA from Geobacter sulfurreducens: a contribution for optimizing biofuel cell's power density. J Phys Chem B 2014; 118:12416-25. [PMID: 25275217 DOI: 10.1021/jp507898x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The increase of conductivity of electrolytes favors the current production in microbial fuel cells (MFCs). Adaptation of cell cultures to higher ionic strength is a promising strategy to increase electricity production. The bacterium Geobacter sulfurreducens is considered a leading candidate for MFCs. Therefore, it is important to evaluate the impact of the ionic strength on the functional properties of key periplasmic proteins that warrants electron transfer to cell exterior. The effect of the ionic strength on the functional properties of triheme cytochrome PpcA, the most abundant periplasmic cytochrome in G. sulfurreducens, was investigated by NMR and potentiometric methods. The redox properties of heme IV are the most affected ones. Chemical shift perturbation measurements on the backbone NMR signals, at increasing ionic strength, also showed that the region close to heme IV is the most affected due to the large number of positively charged residues, which confer a highly positive electrostatic surface around this heme. The shielding of these positive charges at high ionic strength explain the observed decrease in the reduction potential of heme IV and shows that PpcA was designed to maintain its functional mechanistic features even at high ionic strength.
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Affiliation(s)
- Joana M Dantas
- Requimte-CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa , Campus Caparica, 2829-516 Caparica, Portugal
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89
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Wu Y, Liu T, Li X, Li F. Exogenous electron shuttle-mediated extracellular electron transfer of Shewanella putrefaciens 200: electrochemical parameters and thermodynamics. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:9306-9314. [PMID: 25058026 DOI: 10.1021/es5017312] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Despite the importance of exogenous electron shuttles (ESs) in extracellular electron transfer (EET), a lack of understanding of the key properties of ESs is a concern given their different influences on EET processes. Here, the ES-mediated EET capacity of Shewanella putrefaciens 200 (SP200) was evaluated by examining the electricity generated in a microbial fuel cell. The results indicated that all the ESs substantially accelerated the current generation compared to only SP200. The current and polarization parameters were linearly correlated with both the standard redox potential (E(ES)(0)) and the electron accepting capacity (EAC) of the ESs. A thermodynamic analysis of the electron transfer from the electron donor to the electrode suggested that the EET from c-type cytochromes (c-Cyts) to ESs is a crucial step causing the differences in EET capacities among various ESs. Based on the derived equations, both E(ES)(0) and EAC can quantitatively determine potential losses (ΔE) that reflect the potential loss of the ES-mediated EET. In situ spectral kinetic analysis of ES reduction by c-Cyts in a living SP200 suspension was first investigated with the E(ES), E(c-Cyt), and ΔE values being calculated. This study can provide a comprehensive understanding of the role of ESs in EET.
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Affiliation(s)
- Yundang Wu
- Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences , Guangzhou, P. R. China
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90
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Babauta JT, Beasley CA, Beyenal H. Investigation of Electron Transfer by Geobacter sulfurreducens Biofilms by using an Electrochemical Quartz Crystal Microbalance. ChemElectroChem 2014; 1:2007-2016. [PMID: 27525205 PMCID: PMC4964883 DOI: 10.1002/celc.201402127] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2014] [Revised: 06/17/2014] [Indexed: 01/05/2023]
Abstract
Both the short- and long-term electron-transfer processes of electrode-respiring Geobacter sulfurreducens biofilms are demonstrated by using an electrochemical quartz crystal microbalance (QCM). The QCM monitors the frequency shift from the initial resonant frequency (background) in real time, while the current increases, because of biofilm growth. In the short term, the frequency shift is linear with respect to current for the biofilm. In long-term biofilm growth up to the exponential phase, a second linear region of frequency shift with respect to current is observed. In addition to the frequency shift response at constant polarization, the frequency shift response is coupled to cyclic voltammetry experiments. During cyclic voltammetry, a reproducible, negative increase in frequency shift is observed at oxidizing potentials. The results suggest that a QCM can be used in applications in which it is useful to find the most efficient current producer.
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Affiliation(s)
- Jerome T Babauta
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering PO Box 646515, Washington State University, Pullman, WA 99164-6515 (USA) E-mail:
| | | | - Haluk Beyenal
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering PO Box 646515, Washington State University, Pullman, WA 99164-6515 (USA) E-mail:
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91
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Abundance of the multiheme c-type cytochrome OmcB increases in outer biofilm layers of electrode-grown Geobacter sulfurreducens. PLoS One 2014; 9:e104336. [PMID: 25090411 PMCID: PMC4121341 DOI: 10.1371/journal.pone.0104336] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 07/14/2014] [Indexed: 11/25/2022] Open
Abstract
When Geobacter sulfurreducens utilizes an electrode as its electron acceptor, cells embed themselves in a conductive biofilm tens of microns thick. While environmental conditions such as pH or redox potential have been shown to change close to the electrode, less is known about the response of G. sulfurreducens to growth in this biofilm environment. To investigate whether respiratory protein abundance varies with distance from the electrode, antibodies against an outer membrane multiheme cytochrome (OmcB) and cytoplasmic acetate kinase (AckA) were used to determine protein localization in slices spanning ∼25 µm-thick G. sulfurreducens biofilms growing on polished electrodes poised at +0.24 V (vs. Standard Hydrogen Electrode). Slices were immunogold labeled post-fixing, imaged via transmission electron microscopy, and digitally reassembled to create continuous images allowing subcellular location and abundance per cell to be quantified across an entire biofilm. OmcB was predominantly localized on cell membranes, and 3.6-fold more OmcB was detected on cells 10–20 µm distant from the electrode surface compared to inner layers (0–10 µm). In contrast, acetate kinase remained constant throughout the biofilm, and was always associated with the cell interior. This method for detecting proteins in intact conductive biofilms supports a model where the utilization of redox proteins changes with depth.
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92
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Zhou X, Lu D, Chao M, Chen W. Experimental and theoretical studies on the thermal decomposition of 1,1,2,2,3,3,4-heptafluorocyclopentane. J Fluor Chem 2014. [DOI: 10.1016/j.jfluchem.2014.04.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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93
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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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94
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Lebedev N, Strycharz-Glaven SM, Tender LM. Spatially resolved confocal resonant Raman microscopic analysis of anode-grown Geobacter sulfurreducens biofilms. Chemphyschem 2014; 15:320-7. [PMID: 24402861 DOI: 10.1002/cphc.201300984] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Indexed: 11/09/2022]
Abstract
When grown on the surface of an anode electrode, Geobacter sulfurreducens forms a multi-cell thick biofilm in which all cells appear to couple the oxidation of acetate with electron transport to the anode, which serves as the terminal metabolic electron acceptor. Just how electrons are transported through such a biofilm from cells to the underlying anode surface over distances that can exceed 20 microns remains unresolved. Current evidence suggests it may occur by electron hopping through a proposed network of redox cofactors composed of immobile outer membrane and/or extracellular multi-heme c-type cytochromes. In the present work, we perform a spatially resolved confocal resonant Raman (CRR) microscopic analysis to investigate anode-grown Geobacter biofilms. The results confirm the presence of an intra-biofilm redox gradient whereby the probability that a heme is in the reduced state increases with increasing distance from the anode surface. Such a gradient is required to drive electron transport toward the anode surface by electron hopping via cytochromes. The results also indicate that at open circuit, when electrons are expected to accumulate in redox cofactors involved in electron transport due to the inability of the anode to accept electrons, nearly all c-type cytochrome hemes detected in the biofilm are oxidized. The same outcome occurs when a comparable potential to that measured at open circuit (-0.30 V vs. SHE) is applied to the anode, whereas nearly all hemes are reduced when an exceedingly negative potential (-0.50 V vs. SHE) is applied to the anode. These results suggest that nearly all c-type cytochrome hemes detected in the biofilm can be electrochemically accessed by the electrode, but most have oxidation potentials too negative to transport electrons originating from acetate metabolism. The results also reveal a lateral heterogeneity (x-y dimensions) in the type of c-type cytochromes within the biofilm that may affect electron transport to the electrode.
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Affiliation(s)
- Nikolai Lebedev
- Center for Bio/Molecular Science and Engineering, US Naval Research Laboratory, Washington, DC 20375 (USA).
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95
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Li X, Liu T, Liu L, Li F. Dependence of the electron transfer capacity on the kinetics of quinone-mediated Fe(iii) reduction by two iron/humic reducing bacteria. RSC Adv 2014. [DOI: 10.1039/c3ra45458d] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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96
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Kuzume A, Zhumaev U, Li J, Fu Y, Füeg M, Estévez M, Borjas Z, Wandlowski T, Esteve-Nuñez A. An in situ surface electrochemistry approach towards whole-cell studies: the structure and reactivity of a Geobacter sulfurreducens submonolayer on electrified metal/electrolyte interfaces. Phys Chem Chem Phys 2014; 16:22229-36. [DOI: 10.1039/c4cp03357d] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Characterisation of direct electron transfer processes between Geobacter sulfurreducens and the Au(111) surface was performed under electrochemical control.
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Affiliation(s)
- Akiyoshi Kuzume
- Department of Chemistry and Biochemistry
- University of Bern
- 3012 Bern, Switzerland
| | - Ulmas Zhumaev
- Department of Chemistry and Biochemistry
- University of Bern
- 3012 Bern, Switzerland
| | - Jianfeng Li
- Department of Chemistry and Biochemistry
- University of Bern
- 3012 Bern, Switzerland
| | - Yongchun Fu
- Department of Chemistry and Biochemistry
- University of Bern
- 3012 Bern, Switzerland
| | - Michael Füeg
- Department of Chemistry and Biochemistry
- University of Bern
- 3012 Bern, Switzerland
| | - Marta Estévez
- Department of Chemical Engineering
- University of Alcalá
- 28871 Alcalá de Heranes, Spain
| | - Zulema Borjas
- Department of Chemical Engineering
- University of Alcalá
- 28871 Alcalá de Heranes, Spain
- IMDEA WATER
- Parque Tecnológico de Alcalá
| | - Thomas Wandlowski
- Department of Chemistry and Biochemistry
- University of Bern
- 3012 Bern, Switzerland
| | - Abraham Esteve-Nuñez
- Department of Chemical Engineering
- University of Alcalá
- 28871 Alcalá de Heranes, Spain
- IMDEA WATER
- Parque Tecnológico de Alcalá
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97
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Li DB, Cheng YY, Li LL, Li WW, Huang YX, Pei DN, Tong ZH, Mu Y, Yu HQ. Light-driven microbial dissimilatory electron transfer to hematite. Phys Chem Chem Phys 2014; 16:23003-11. [DOI: 10.1039/c4cp04065a] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Excitation of hematite with visible light promotes electron transfer from the dissimilatory metal-reducing speciesGeobacter sulfurreducensto the hematite surface.
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Affiliation(s)
- Dao-Bo Li
- Department of Chemistry
- University of Science & Technology of China
- Hefei, China
| | - Yuan-Yuan Cheng
- Department of Chemistry
- University of Science & Technology of China
- Hefei, China
| | - Ling-Li Li
- Department of Chemistry
- University of Science & Technology of China
- Hefei, China
| | - Wen-Wei Li
- Department of Chemistry
- University of Science & Technology of China
- Hefei, China
| | - Yu-Xi Huang
- Department of Chemistry
- University of Science & Technology of China
- Hefei, China
| | - Dan-Ni Pei
- Department of Chemistry
- University of Science & Technology of China
- Hefei, China
| | - Zhong-Hua Tong
- Department of Chemistry
- University of Science & Technology of China
- Hefei, China
| | - Yang Mu
- Department of Chemistry
- University of Science & Technology of China
- Hefei, China
| | - Han-Qing Yu
- Department of Chemistry
- University of Science & Technology of China
- Hefei, China
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98
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Rimboud M, Pocaznoi D, Erable B, Bergel A. Electroanalysis of microbial anodes for bioelectrochemical systems: basics, progress and perspectives. Phys Chem Chem Phys 2014; 16:16349-66. [DOI: 10.1039/c4cp01698j] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Over about the last ten years, microbial anodes have been the subject of a huge number of fundamental studies dealing with an increasing variety of possible application domains.
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Affiliation(s)
- M. Rimboud
- Laboratoire de Génie Chimique
- CNRS - Université de Toulouse
- 31432 Toulouse, France
| | - D. Pocaznoi
- Laboratoire de Génie Chimique
- CNRS - Université de Toulouse
- 31432 Toulouse, France
| | - B. Erable
- Laboratoire de Génie Chimique
- CNRS - Université de Toulouse
- 31432 Toulouse, France
| | - A. Bergel
- Laboratoire de Génie Chimique
- CNRS - Université de Toulouse
- 31432 Toulouse, France
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99
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Jana PS, Katuri K, Kavanagh P, Kumar A, Leech D. Charge transport in films of Geobacter sulfurreducens on graphite electrodes as a function of film thickness. Phys Chem Chem Phys 2014; 16:9039-46. [DOI: 10.1039/c4cp01023j] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Charge transport throughGeobacter sulfurreducensbiofilms increases with film thickness, as more porous films improves ion transport upon electrolysis.
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Affiliation(s)
- Partha Sarathi Jana
- School of Chemistry & Ryan Institute
- National University of Ireland Galway
- Galway, Ireland
| | - Krishna Katuri
- School of Chemistry & Ryan Institute
- National University of Ireland Galway
- Galway, Ireland
- Water Desalination and Reuse Research Center
- King Abdullah University of Science and Technology
| | - Paul Kavanagh
- School of Chemistry & Ryan Institute
- National University of Ireland Galway
- Galway, Ireland
| | - Amit Kumar
- School of Chemistry & Ryan Institute
- National University of Ireland Galway
- Galway, Ireland
| | - Dónal Leech
- School of Chemistry & Ryan Institute
- National University of Ireland Galway
- Galway, Ireland
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100
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Peng X, Yu H, Ai L, Li N, Wang X. Time behavior and capacitance analysis of nano-Fe3O4 added microbial fuel cells. BIORESOURCE TECHNOLOGY 2013; 144:689-692. [PMID: 23899577 DOI: 10.1016/j.biortech.2013.07.037] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Revised: 07/07/2013] [Accepted: 07/09/2013] [Indexed: 06/02/2023]
Abstract
The addition of nano Fe3O4 is beneficial to boost the transient charge storage of the anode accompanying with the enhancement of power performance in microbial fuel cells (MFCs) in our previous study. Here we found that both the anodic open circuit potential and the current increased when comparing the AcFeM (Fe3O4 added activated carbon anode) with the AcM (activated carbon anode), indicating that the Fe3O4 dynamically accelerated the anodic electron transfer although it thermodynamically limited the anode potential. The net storage capacity initially increased followed by a decrease with the maximum capacitance of 574.6 C m(-2) (AcFeM) and 459 C m(-2) (AcM) under 20 min of open circuit interval. The Fe3O4/Fe(II) possibly stored charges temporarily as a solid-state electron shuttle.
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Affiliation(s)
- Xinhong Peng
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Nankai District, Tianjin, China
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