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Juergensen N, Weiler JR, Knoll MT, Gescher J, Edel M. Strategic improvement of Shewanella oneidensis for biocatalysis: Approach to media refinement and scalable application in a microbial electrochemical system. N Biotechnol 2024; 85:31-38. [PMID: 39613153 DOI: 10.1016/j.nbt.2024.11.006] [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: 07/03/2024] [Revised: 11/24/2024] [Accepted: 11/25/2024] [Indexed: 12/01/2024]
Abstract
Microbial electrochemical systems offer a sustainable method for the conversion of chemical energy into electrical energy or hydrogen and the production of valuable compounds, contributing to the development of a bio-based economy. This study aimed to enhance the performance of anodic bioelectrochemical systems by improving the current density of Shewanella oneidensis as a biocatalyst through strain modification and medium refinement. The genetic modification, combining the prophage deletion and overexpression of the speC gene, resulted in a 4.2-fold increase in current density compared to the wild type. Furthermore, medium refinement and incorporating riboflavin, led to an additional 5.7-fold increase in current density. The application of the modified strain and medium in a scalable microbial electrolysis cell resulted in a current density of 1.2 A m-², similar to what was achieved previously with an S. oneidensis and Geobacter sulfurreducens co-culture, substantiating the substantial performance increase for a pure culture of S. oneidensis. Furthermore, S. oneidensis was shown to grow in medium containing up to 500 mM sodium chloride and increasing the salt concentration to 400 mM had a minor influence on growth but significantly lowered the cell voltage of the MEC system.
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Affiliation(s)
- Nikolai Juergensen
- Institute of Technical Microbiology, Hamburg University of Technology, Hamburg 21073, Germany
| | - Janek R Weiler
- Institute of Technical Microbiology, Hamburg University of Technology, Hamburg 21073, Germany
| | - Melanie T Knoll
- Institute of Technical Microbiology, Hamburg University of Technology, Hamburg 21073, Germany
| | - Johannes Gescher
- Institute of Technical Microbiology, Hamburg University of Technology, Hamburg 21073, Germany
| | - Miriam Edel
- Institute of Technical Microbiology, Hamburg University of Technology, Hamburg 21073, Germany.
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2
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Klein EM, Heintz H, Wurst R, Schuldt S, Hähl H, Jacobs K, Gescher J. Comparative analysis of the influence of BpfA and BpfG on biofilm development and current density in Shewanella oneidensis under oxic, fumarate- and anode-respiring conditions. Sci Rep 2024; 14:23174. [PMID: 39369013 PMCID: PMC11455927 DOI: 10.1038/s41598-024-73474-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2024] [Accepted: 09/17/2024] [Indexed: 10/07/2024] Open
Abstract
Biofilm formation by Shewanella oneidensis has been extensively studied under oxic conditions; however, relatively little is known about biofilm formation under anoxic conditions and how biofilm architecture and composition can positively influence current generation in bioelectrochemical systems. In this study, we utilized a recently developed microfluidic biofilm analysis setup with automated 3D imaging to investigate the effects of extracellular electron acceptors and synthetic modifications to the extracellular polymeric matrix on biofilm formation. Our results with the wild type strain demonstrate robust biofilm formation even under anoxic conditions when fumarate is used as the electron acceptor. However, this pattern shifts when a graphite electrode is employed as the electron acceptor, resulting in biofilm formation falling below the detection limit of the optical coherence tomography imaging system. To manipulate biofilm formation, we aimed to express BpfG with a single amino acid substitution in the catalytic center (C116S) and to overexpress bpfA. Our analyses indicate that, under oxic conditions, overarching mechanisms predominantly influence biofilm development, rather than the specific mutations we investigated. Under anoxic conditions, the bpfG mutation led to a quantitative increase in biofilm formation, but both strains exhibited significant qualitative changes in biofilm architecture compared to the controls. When an anode was used as the sole electron acceptor, both the bpfA and bpfG mutations positively impacted mean current density, yielding a 1.8-fold increase for each mutation.
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Affiliation(s)
- Edina Marlen Klein
- Institute of Technical Microbiology, University of Technology Hamburg, 21073, Hamburg, Germany
| | - Hannah Heintz
- Experimental Physics, Center for Biophysics, Saarland University, 66123, Saarbrücken, Germany
| | - René Wurst
- Institute of Technical Microbiology, University of Technology Hamburg, 21073, Hamburg, Germany
| | - Simon Schuldt
- Institute of Technical Microbiology, University of Technology Hamburg, 21073, Hamburg, Germany
| | - Hendrik Hähl
- Experimental Physics, Center for Biophysics, Saarland University, 66123, Saarbrücken, Germany
| | - Karin Jacobs
- Experimental Physics, Center for Biophysics, Saarland University, 66123, Saarbrücken, Germany
- Max Planck School Matter to Life, 69120, Heidelberg, Germany
| | - Johannes Gescher
- Institute of Technical Microbiology, University of Technology Hamburg, 21073, Hamburg, Germany.
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Klein EM, Knoll MT, Gescher J. Microbe-Anode Interactions: Comparing the impact of genetic and material engineering approaches to improve the performance of microbial electrochemical systems (MES). Microb Biotechnol 2023; 16:1179-1202. [PMID: 36808480 PMCID: PMC10221544 DOI: 10.1111/1751-7915.14236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 01/30/2023] [Accepted: 02/02/2023] [Indexed: 02/20/2023] Open
Abstract
Microbial electrochemical systems (MESs) are a highly versatile platform technology with a particular focus on power or energy production. Often, they are used in combination with substrate conversion (e.g., wastewater treatment) and production of value-added compounds via electrode-assisted fermentation. This rapidly evolving field has seen great improvements both technically and biologically, but this interdisciplinarity sometimes hampers overseeing strategies to increase process efficiency. In this review, we first briefly summarize the terminology of the technology and outline the biological background that is essential for understanding and thus improving MES technology. Thereafter, recent research on improvements at the biofilm-electrode interface will be summarized and discussed, distinguishing between biotic and abiotic approaches. The two approaches are then compared, and resulting future directions are discussed. This mini-review therefore provides basic knowledge of MES technology and the underlying microbiology in general and reviews recent improvements at the bacteria-electrode interface.
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Affiliation(s)
- Edina M. Klein
- Institute of Technical MicrobiologyUniversity of Technology HamburgHamburgGermany
| | - Melanie T. Knoll
- Institute of Technical MicrobiologyUniversity of Technology HamburgHamburgGermany
| | - Johannes Gescher
- Institute of Technical MicrobiologyUniversity of Technology HamburgHamburgGermany
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Franco A, Elbahnasy M, Rosenbaum MA. Screening of natural phenazine producers for electroactivity in bioelectrochemical systems. Microb Biotechnol 2023; 16:579-594. [PMID: 36571174 PMCID: PMC9948232 DOI: 10.1111/1751-7915.14199] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 12/05/2022] [Accepted: 12/07/2022] [Indexed: 12/27/2022] Open
Abstract
Mediated extracellular electron transfer (EET) might be a great vehicle to connect microbial bioprocesses with electrochemical control in stirred-tank bioreactors. However, mediated electron transfer to date is not only much less efficient but also much less studied than microbial direct electron transfer to an anode. For example, despite the widespread capacity of pseudomonads to produce phenazine natural products, only Pseudomonas aeruginosa has been studied for its use of phenazines in bioelectrochemical applications. To provide a deeper understanding of the ecological potential for the bioelectrochemical exploitation of phenazines, we here investigated the potential electroactivity of over 100 putative diverse native phenazine producers and the performance within bioelectrochemical systems. Five species from the genera Pseudomonas, Streptomyces, Nocardiopsis, Brevibacterium and Burkholderia were identified as new electroactive bacteria. Electron discharge to the anode and electric current production correlated with the phenazine synthesis of Pseudomonas chlororaphis subsp. aurantiaca. Phenazine-1-carboxylic acid was the dominant molecule with a concentration of 86.1 μg/ml mediating an anodic current of 15.1 μA/cm2 . On the other hand, Nocardiopsis chromatogenes used a wider range of phenazines at low concentrations and likely yet-unknown redox compounds to mediate EET, achieving an anodic current of 9.5 μA/cm2 . Elucidating the energetic and metabolic usage of phenazines in these and other species might contribute to improving electron discharge and respiration. In the long run, this may enhance oxygen-limited bioproduction of value-added compounds based on mediated EET mechanisms.
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Affiliation(s)
- Angel Franco
- Bio Pilot Plant, Leibniz Institute for Natural Product Research and Infection Biology - Hans-Knöll-Institute (HKI), Jena, Germany
| | - Mahmoud Elbahnasy
- Bio Pilot Plant, Leibniz Institute for Natural Product Research and Infection Biology - Hans-Knöll-Institute (HKI), Jena, Germany.,Faculty of Biological Sciences, Friedrich Schiller University (FSU), Jena, Germany
| | - Miriam A Rosenbaum
- Bio Pilot Plant, Leibniz Institute for Natural Product Research and Infection Biology - Hans-Knöll-Institute (HKI), Jena, Germany.,Faculty of Biological Sciences, Friedrich Schiller University (FSU), Jena, Germany
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Knoll MT, Fuderer E, Gescher J. Sprayable biofilm – Agarose hydrogels as 3D matrix for enhanced productivity in bioelectrochemical systems. Biofilm 2022; 4:100077. [PMID: 35619831 PMCID: PMC9127277 DOI: 10.1016/j.bioflm.2022.100077] [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: 01/12/2022] [Revised: 04/29/2022] [Accepted: 05/09/2022] [Indexed: 11/11/2022] Open
Abstract
Bio-based energy production utilizing renewable resources can be realized by exoelectrogenic organisms and their application in bioelectrochemical systems (BES). These organisms catalyze the direct conversion of chemical into electrical energy and are already widely used in bioelectronics and biosensing. However, the biofilm-electrode interaction is a factor that limits sufficient space-time-yields for industrial applications. In this study, a hydrogel matrix consisting of agarose fibers was utilized as a scaffold for S. oneidensis cells to improve anodic processes in BES. This synthetic, scalable biofilm reached a higher current density in BES in comparison to naturally formed biofilms. Complemented with carbon nanofibers and riboflavin, the application of this functionalized hydrogel containing S. oneidensis cells led to an overall 9.1-fold increase in current density to 1324 mA m−2 in comparison to 145 mA m−2 for the planktonic control. In addition, the synthetic biofilm can be applied by spraying onto surfaces using a novel spray applicator. The latter allows to apply the biofilm effortless on large surfaces which will facilitate scalability and thus industrial application.
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Gemünde A, Lai B, Pause L, Krömer J, Holtmann D. Redox mediators in microbial electrochemical systems. ChemElectroChem 2022. [DOI: 10.1002/celc.202200216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- André Gemünde
- Technische Hochschule Mittelhessen Institute of Bioprocess Engineering and Pharmaceutical Technology Wiesenstraße 14 35390 Gießen GERMANY
| | - Bin Lai
- Helmholtz Centre for Environmental Research UFZ Department of Environmental Microbiology: Helmholtz-Zentrum fur Umweltforschung UFZ Abteilung Umweltmikrobiologie Systems Biotechnology 04318 Leipzig GERMANY
| | - Laura Pause
- Helmholtz Centre for Environmental Research UFZ Environmental Engineering and Biotechnology Research Unit: Helmholtz-Zentrum fur Umweltforschung UFZ Themenbereich Umwelt- und Biotechnologie Systems Biotechnology 04318 Leipzig GERMANY
| | - Jens Krömer
- Helmholtz Centre for Environmental Research UFZ Environmental Engineering and Biotechnology Research Unit: Helmholtz-Zentrum fur Umweltforschung UFZ Themenbereich Umwelt- und Biotechnologie Systems Biotechnology 04318 Leipzig GERMANY
| | - Dirk Holtmann
- Technische Hochschule Mittelhessen IBPT Wiesenstrasse 14 35390 Giessen GERMANY
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Erben J, Pinder ZA, Lüdtke MS, Kerzenmacher S. Local Acidification Limits the Current Production and Biofilm Formation of Shewanella oneidensis MR-1 With Electrospun Anodes. Front Microbiol 2021; 12:660474. [PMID: 34194407 PMCID: PMC8236948 DOI: 10.3389/fmicb.2021.660474] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 05/03/2021] [Indexed: 11/30/2022] Open
Abstract
The anodic current production of Shewanella oneidensis MR-1 is typically lower compared to other electroactive bacteria. The main reason for the low current densities is the poor biofilm growth on most anode materials. We demonstrate that the high current production of Shewanella oneidensis MR-1 with electrospun anodes exhibits a similar threshold current density as dense Geobacter spp biofilms. The threshold current density is a result of local acidification in the biofilm. Increasing buffer concentration from 10 to 40 mM results in a 1.8-fold increase of the current density [(590 ± 25) μA cm−2] while biofilm growth stimulation by riboflavin has little effect on the current production. The current production of a reference material below the threshold did not respond to the increased buffer concentration but could be enhanced by supplemented riboflavin that stimulated the biofilm growth. Our results suggest that the current production with S. oneidensis is limited (1) by the biofilm growth on the anode that can be enhanced by the choice of the electrode material, and (2) by the proton transport through the biofilm and the associated local acidification.
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Affiliation(s)
- Johannes Erben
- Center for Environmental Research and Sustainable Technology (UFT), University of Bremen, Bremen, Germany
| | | | - Malte S Lüdtke
- Center for Environmental Research and Sustainable Technology (UFT), University of Bremen, Bremen, Germany
| | - Sven Kerzenmacher
- Center for Environmental Research and Sustainable Technology (UFT), University of Bremen, Bremen, Germany
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Edel M, Sturm G, Sturm-Richter K, Wagner M, Ducassou JN, Couté Y, Horn H, Gescher J. Extracellular riboflavin induces anaerobic biofilm formation in Shewanella oneidensis. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:130. [PMID: 34082787 PMCID: PMC8176591 DOI: 10.1186/s13068-021-01981-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 05/26/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND Some microorganisms can respire with extracellular electron acceptors using an extended electron transport chain to the cell surface. This process can be applied in bioelectrochemical systems in which the organisms produce an electrical current by respiring with an anode as electron acceptor. These organisms apply flavin molecules as cofactors to facilitate one-electron transfer catalyzed by the terminal reductases and in some cases as endogenous electron shuttles. RESULTS In the model organism Shewanella oneidensis, riboflavin production and excretion trigger a specific biofilm formation response that is initiated at a specific threshold concentration, similar to canonical quorum-sensing molecules. Riboflavin-mediated messaging is based on the overexpression of the gene encoding the putrescine decarboxylase speC which leads to posttranscriptional overproduction of proteins involved in biofilm formation. Using a model of growth-dependent riboflavin production under batch and biofilm growth conditions, the number of cells necessary to produce the threshold concentration per time was deduced. Furthermore, our results indicate that specific retention of riboflavin in the biofilm matrix leads to localized concentrations, which by far exceed the necessary threshold value. CONCLUSION This study describes a new quorum-sensing mechanism in S. oneidensis. Biofilm formation of S. oneidensis is induced by low concentrations of riboflavin resulting in an upregulation of the ornithine-decarboxylase speC. The results can be applied for the development of strains catalyzing increased current densities in bioelectrochemical systems.
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Affiliation(s)
- Miriam Edel
- Institute for Applied Biosciences, Department of Applied Biology, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Gunnar Sturm
- Institute for Biological Interfaces, Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, Germany
| | - Katrin Sturm-Richter
- Institute for Applied Biosciences, Department of Applied Biology, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Michael Wagner
- Institute for Biological Interfaces, Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, Germany
| | | | - Yohann Couté
- University Grenoble Alpes, CEA, INSERM, IRIG, BGE, Grenoble, France
| | - Harald Horn
- Engler-Bunte-Institute, Water Chemistry and Water Technology, Karlsruhe Institute of Technology, Karlsruhe, Germany
- DVGW Research Laboratories for Water Chemistry and Water Technology, Karlsruhe, Germany
| | - Johannes Gescher
- Institute for Applied Biosciences, Department of Applied Biology, Karlsruhe Institute of Technology, Karlsruhe, Germany.
- Institute for Biological Interfaces, Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, Germany.
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Erben J, Wang X, Kerzenmacher S. High Current Production of
Shewanella Oneidensis
with Electrospun Carbon Nanofiber Anodes is Directly Linked to Biofilm Formation**. ChemElectroChem 2021. [DOI: 10.1002/celc.202100192] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Johannes Erben
- Center for Environmental Research and Sustainable Technology (UFT) University of Bremen 28359 Bremen Germany
| | - Xinyu Wang
- Laboratory for MEMS Applications IMTEK – Department of Microsystems Engineering University of Freiburg Georges-Koehler-Allee 103 79110 Freiburg Germany
| | - Sven Kerzenmacher
- Center for Environmental Research and Sustainable Technology (UFT) University of Bremen 28359 Bremen Germany
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Vassilev I, Averesch NJH, Ledezma P, Kokko M. Anodic electro-fermentation: Empowering anaerobic production processes via anodic respiration. Biotechnol Adv 2021; 48:107728. [PMID: 33705913 DOI: 10.1016/j.biotechadv.2021.107728] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 01/31/2021] [Accepted: 03/03/2021] [Indexed: 11/24/2022]
Abstract
In nature as well as in industrial microbiology, all microorganisms need to achieve redox balance. Their redox state and energy conservation highly depend on the availability of a terminal electron acceptor, for example oxygen in aerobic production processes. Under anaerobic conditions in the absence of an electron acceptor, redox balance is achieved via the production of reduced carbon-compounds (fermentation). An alternative strategy to artificially stabilize microbial redox and energy state is the use of anodic electro-fermentation (AEF). This emerging biotechnology empowers respiration under anaerobic conditions using the anode of a bioelectrochemical system as an undepletable terminal electron acceptor. Electrochemical control of redox metabolism and energy conservation via AEF can steer the carbon metabolism towards a product of interest and avoid the need for continuous and cost-inefficient supply of oxygen as well as the production of mixed reduced by-products, as is the case in aerobic production and fermentation processes, respectively. The great challenge for AEF is to establish efficient extracellular electron transfer (EET) from the microbe to the anode and link it to central carbon metabolism to enhance the synthesis of a target product. This article reviews the advantages and challenges of AEF, EET mechanisms, microbial energy gain, and discusses the rational choice of substrate-product couple as well as the choice of microbial catalyst. Besides, it discusses the potential of the industrial model-organism Bacillus subtilis as a promising candidate for AEF, which has not been yet considered for such an application. This prospective review contributes to a better understanding of how industrial microbiology can benefit from AEF and analyses key-factors required to successfully implement AEF processes. Overall, this work aims to advance the young research field especially by critically revisiting the fundamental aspects of AEF.
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Affiliation(s)
- Igor Vassilev
- Faculty of Engineering and Natural Sciences, Tampere University, Tampere, Finland.
| | - Nils J H Averesch
- Department of Civil and Environmental Engineering, Stanford University, Stanford, CA, United States.
| | - Pablo Ledezma
- Advanced Water Management Centre, The University of Queensland, Brisbane, QLD, Australia.
| | - Marika Kokko
- Faculty of Engineering and Natural Sciences, Tampere University, Tampere, Finland.
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