1
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Im C, Kim M, Kim JR, Valgepea K, Modin O, Nygård Y, Franzén CJ. Low electric current in a bioelectrochemical system facilitates ethanol production from CO using CO-enriched mixed culture. Front Microbiol 2024; 15:1438758. [PMID: 39268540 PMCID: PMC11390636 DOI: 10.3389/fmicb.2024.1438758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2024] [Accepted: 07/24/2024] [Indexed: 09/15/2024] Open
Abstract
Fossil resources must be replaced by renewable resources in production systems to mitigate green-house gas emissions and combat climate change. Electro-fermentation utilizes a bioelectrochemical system (BES) to valorize industrial and municipal waste. Current electro-fermentation research is mainly focused on microbial electrosynthesis using CO2 for producing commodity chemicals and replacing petroleum-based infrastructures. However, slow production rates and low titers of metabolites during CO2-based microbial electrosynthesis impede its implementation to the real application in the near future. On the other hand, CO is a highly reactive gas and an abundant feedstock discharged from fossil fuel-based industry. Here, we investigated CO and CO2 electro-fermentation, using a CO-enriched culture. Fresh cow fecal waste was enriched under an atmosphere of 50% CO and 20% CO2 in N2 using serial cultivation. The CO-enriched culture was dominated by Clostridium autoethanogenum (≥89%) and showed electro-activity in a BES reactor with CO2 sparging. When 50% CO was included in the 20% CO2 gas with 10 mA applied current, acetate and ethanol were produced up to 12.9 ± 2.7 mM and 2.7 ± 1.1 mM, respectively. The coulombic efficiency was estimated to 148% ± 8% without an electron mediator. At 25 mA, the culture showed faster initial growth and acetate production but no ethanol production, and only at 86% ± 4% coulombic efficiency. The maximum optical density (OD) of 10 mA and 25 mA reactors were 0.29 ± 0.07 and 0.41 ± 0.03, respectively, whereas it was 0.77 ± 0.19 without electric current. These results show that CO electro-fermentation at low current can be an alternative way of valorizing industrial waste gas using a bioelectrochemical system.
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Affiliation(s)
- Chaeho Im
- Division of Industrial Biotechnology, Department of Life Sciences, Chalmers University of Technology, Göteborg, Sweden
| | - Minsoo Kim
- School of Chemical Engineering, Pusan National University, Busan, Republic of Korea
| | - Jung Rae Kim
- School of Chemical Engineering, Pusan National University, Busan, Republic of Korea
| | - Kaspar Valgepea
- Institute of Bioengineering, University of Tartu, Tartu, Estonia
| | - Oskar Modin
- Division of Water Environment Technology, Department of Architecture and Civil Engineering, Chalmers University of Technology, Göteborg, Sweden
| | - Yvonne Nygård
- Division of Industrial Biotechnology, Department of Life Sciences, Chalmers University of Technology, Göteborg, Sweden
- VTT Technical Research Centre of Finland, Espoo, Finland
| | - Carl Johan Franzén
- Division of Industrial Biotechnology, Department of Life Sciences, Chalmers University of Technology, Göteborg, Sweden
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2
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Zhang JZ, Li YZ, Xi ZN, Gao HP, Zhang Q, Liu LC, Li FL, Ma XQ. Engineered acetogenic bacteria as microbial cell factory for diversified biochemicals. Front Bioeng Biotechnol 2024; 12:1395540. [PMID: 39055341 PMCID: PMC11269201 DOI: 10.3389/fbioe.2024.1395540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Accepted: 06/28/2024] [Indexed: 07/27/2024] Open
Abstract
Acetogenic bacteria (acetogens) are a class of microorganisms with conserved Wood-Ljungdahl pathway that can utilize CO and CO2/H2 as carbon source for autotrophic growth and convert these substrates to acetate and ethanol. Acetogens have great potential for the sustainable production of biofuels and bulk biochemicals using C1 gases (CO and CO2) from industrial syngas and waste gases, which play an important role in achieving carbon neutrality. In recent years, with the development and improvement of gene editing methods, the metabolic engineering of acetogens is making rapid progress. With introduction of heterogeneous metabolic pathways, acetogens can improve the production capacity of native products or obtain the ability to synthesize non-native products. This paper reviews the recent application of metabolic engineering in acetogens. In addition, the challenges of metabolic engineering in acetogens are indicated, and strategies to address these challenges are also discussed.
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Affiliation(s)
- Jun-Zhe Zhang
- Qingdao C1 Refinery Engineering Research Center, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yu-Zhen Li
- Qingdao C1 Refinery Engineering Research Center, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Zhi-Ning Xi
- Qingdao C1 Refinery Engineering Research Center, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
| | - Hui-Peng Gao
- Sinopec Dalian (Fushun) Research Institute of Petroleum and Petrochemicals, Dalian, China
| | - Quan Zhang
- Sinopec Dalian (Fushun) Research Institute of Petroleum and Petrochemicals, Dalian, China
| | - Li-Cheng Liu
- Key Laboratory of Marine Chemistry Theory and Technology (Ministry of Education), College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao, China
| | - Fu-Li Li
- Qingdao C1 Refinery Engineering Research Center, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
- Shandong Energy Institute, Qingdao, China
- Qingdao New Energy Shandong Laboratory, Qingdao, China
| | - Xiao-Qing Ma
- Qingdao C1 Refinery Engineering Research Center, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
- Qingdao New Energy Shandong Laboratory, Qingdao, China
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3
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Noori MT, Rossi R, Logan BE, Min B. Hydrogen production in microbial electrolysis cells with biocathodes. Trends Biotechnol 2024; 42:815-828. [PMID: 38360421 DOI: 10.1016/j.tibtech.2023.12.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 12/17/2023] [Accepted: 12/29/2023] [Indexed: 02/17/2024]
Abstract
Electroautotrophic microbes at biocathodes in microbial electrolysis cells (MECs) can catalyze the hydrogen evolution reaction with low energy demand, facilitating long-term stable performance through specific and renewable biocatalysts. However, MECs have not yet reached commercialization due to a lack of understanding of the optimal microbial strains and reactor configurations for achieving high performance. Here, we critically analyze the criteria for the inocula selection, with a focus on the effect of hydrogenase activity and microbe-electrode interactions. We also evaluate the impact of the reactor design and key parameters, such as membrane type, composition, and electrode surface area on internal resistance, mass transport, and pH imbalances within MECs. This analysis paves the way for advancements that could propel biocathode-assisted MECs toward scalable hydrogen gas production.
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Affiliation(s)
- Md Tabish Noori
- Department of Environmental Science and Engineering, Kyung Hee University - Global Campus, Yongin-Si, South Korea
| | - Ruggero Rossi
- Department of Environmental Health and Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Bruce E Logan
- Department of Civil and Environmental Engineering, Penn State University, Pennsylvania, PA 16801, USA
| | - Booki Min
- Department of Environmental Science and Engineering, Kyung Hee University - Global Campus, Yongin-Si, South Korea.
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4
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Martínez-Ruano JA, Suazo A, Véliz F, Otalora F, Conejeros R, González E, Aroca G. Effect of pH on metabolic pathway shift in fermentation and electro-fermentation of xylose by Clostridium autoethanogenum. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 351:119918. [PMID: 38154218 DOI: 10.1016/j.jenvman.2023.119918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 12/06/2023] [Accepted: 12/17/2023] [Indexed: 12/30/2023]
Abstract
Clostridium autoethanogenum can to convert waste gases (CO2, CO, H2) and xylose from hydrolyzed biomass into acetate, lactate, formate, ethanol and 2,3-butanediol, being a candidate for the transformation of waste streams of lignocellulosic biorefineries. Electro-fermentation (EF) modify the pattern of traditional fermentations resulting in improved product yields as has been shown when using Clostridium strains. The aim of this work was to evaluate the influence of pH on microbial growth and product distribution during fermentation and EF of xylose by C. autoethanogenum DSM10061. Fermentation and EF were carried out in a H-type reactor at three controlled pH: 5.0, 5.5 and 5.8, and at a fixed potential of -600 mV (versus Ag/AgCl) in the EF. The experiments showed that maximum biomass concentration increased as the pH increased in fermentation and EF. In accordance with maximum biomass reached, the highest substrate conversion was observed at pH 5.8 for both systems, with 76.80 % in fermentation and 96.18 % in EF. Moreover, the highest concentrations of acetic acid (1.41 ± 0.07 g L-1) and ethanol (1.45 ± 0.15 g L-1) were obtained at the end of cultures in the EF at pH 5.8. The production of lactic and formic acid decreased by the application of the external potential regardless of the pH value, reaching the lowest productivity at pH 5.8. In contrast, the specific productivity of acetic acid and ethanol was lower in both fermentation and EF at the lowest pH. Furthermore, the presence of 0.06 g L-1 of 2,3-butanediol was only detected in EF at pH 5.8. The results revealed that EF modulated microbial metabolism, which can be explained by a possible increased generation of NADP+/NADPH cofactors, which would redirect the metabolic pathway to more reduced products.
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Affiliation(s)
| | - Andrés Suazo
- School of Biochemical Engineering, Pontificia Universidad Católica de Valparaíso, Chile
| | - Fabián Véliz
- School of Biochemical Engineering, Pontificia Universidad Católica de Valparaíso, Chile
| | - Fabián Otalora
- School of Biochemical Engineering, Pontificia Universidad Católica de Valparaíso, Chile
| | - Raúl Conejeros
- School of Biochemical Engineering, Pontificia Universidad Católica de Valparaíso, Chile
| | - Ernesto González
- School of Biochemical Engineering, Pontificia Universidad Católica de Valparaíso, Chile; Department of Chemical and Materials Engineering, Faculty of Chemical Sciences, Universidad Complutense de Madrid, Spain
| | - Germán Aroca
- School of Biochemical Engineering, Pontificia Universidad Católica de Valparaíso, Chile.
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Tejedor-Sanz S, Li S, Kundu BB, Ajo-Franklin CM. Extracellular electron uptake from a cathode by the lactic acid bacterium Lactiplantibacillus plantarum. Front Microbiol 2023; 14:1298023. [PMID: 38075918 PMCID: PMC10701730 DOI: 10.3389/fmicb.2023.1298023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 11/03/2023] [Indexed: 01/28/2024] Open
Abstract
A subset of microorganisms that perform respiration can endogenously utilize insoluble electron donors, such as Fe(II) or a cathode, in a process called extracellular electron transfer (EET). However, it is unknown whether similar endogenous EET can be performed by primarily fermentative species like lactic acid bacteria. We report for the first time electron uptake from a cathode by Lactiplantibacillus plantarum, a primarily fermentative bacteria found in the gut of mammals and in fermented foods. L. plantarum consumed electrons from a cathode and coupled this oxidation to the reduction of both an endogenous organic (pyruvate) and an exogenous inorganic electron acceptor (nitrate). This electron uptake from a cathode reroutes glucose fermentation toward lactate degradation and provides cells with a higher viability upon sugar exhaustion. Moreover, the associated genes and cofactors indicate that this activity is mechanistically different from that one employed by lactic acid bacteria to reduce an anode and to perform respiration. Our results expand our knowledge of the diversity of electroactive species and of the metabolic and bioenergetic strategies used by lactic acid bacteria.
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Affiliation(s)
- Sara Tejedor-Sanz
- Department of BioSciences, Rice University, Houston, TX, United States
- Biological Nanostructures Facility, The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - Siliang Li
- Department of BioSciences, Rice University, Houston, TX, United States
| | - Biki Bapi Kundu
- PhD Program in Systems, Synthetic, and Physical Biology, Rice University, Houston, TX, United States
| | - Caroline M. Ajo-Franklin
- Department of BioSciences, Rice University, Houston, TX, United States
- Biological Nanostructures Facility, The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
- Department of Bioengineering, Rice University, Houston, TX, United States
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, TX, United States
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6
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Xie Y, Erşan S, Guan X, Wang J, Sha J, Xu S, Wohlschlegel JA, Park JO, Liu C. Unexpected metabolic rewiring of CO 2 fixation in H 2-mediated materials-biology hybrids. Proc Natl Acad Sci U S A 2023; 120:e2308373120. [PMID: 37816063 PMCID: PMC10589654 DOI: 10.1073/pnas.2308373120] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Accepted: 08/31/2023] [Indexed: 10/12/2023] Open
Abstract
A hybrid approach combining water-splitting electrochemistry and H2-oxidizing, CO2-fixing microorganisms offers a viable solution for producing value-added chemicals from sunlight, water, and air. The classic wisdom without thorough examination to date assumes that the electrochemistry in such a H2-mediated process is innocent of altering microbial behavior. Here, we report unexpected metabolic rewiring induced by water-splitting electrochemistry in H2-oxidizing acetogenic bacterium Sporomusa ovata that challenges such a classic view. We found that the planktonic S. ovata is more efficient in utilizing reducing equivalent for ATP generation in the materials-biology hybrids than cells grown with H2 supply, supported by our metabolomic and proteomic studies. The efficiency of utilizing reducing equivalents and fixing CO2 into acetate has increased from less than 80% of chemoautotrophy to more than 95% under electroautotrophic conditions. These observations unravel previously underappreciated materials' impact on microbial metabolism in seemingly simply H2-mediated charge transfer between biotic and abiotic components. Such a deeper understanding of the materials-biology interface will foster advanced design of hybrid systems for sustainable chemical transformation.
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Affiliation(s)
- Yongchao Xie
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA90095
| | - Sevcan Erşan
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, CA90095
| | - Xun Guan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA90095
| | - Jingyu Wang
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA90095
| | - Jihui Sha
- Department of Biological Chemistry, University of California, Los Angeles, CA90095
| | - Shuangning Xu
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA90095
| | | | - Junyoung O. Park
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, CA90095
- California NanoSystems Institute, University of California, Los Angeles, CA90095
| | - Chong Liu
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA90095
- California NanoSystems Institute, University of California, Los Angeles, CA90095
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7
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Ho CL, Emran MY, Ihara S, Huang W, Wakai S, Li WP, Okamoto A. Osmium-grafted magnetic nanobeads improve microbial current generation via culture-free and quick enrichment of electrogenic bacteria. CHEMICAL ENGINEERING JOURNAL 2023; 466:142936. [DOI: 10.1016/j.cej.2023.142936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
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8
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Thulluru LP, Ghangrekar MM, Chowdhury S. Progress and perspectives on microbial electrosynthesis for valorisation of CO 2 into value-added products. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 332:117323. [PMID: 36716542 DOI: 10.1016/j.jenvman.2023.117323] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 01/06/2023] [Accepted: 01/15/2023] [Indexed: 06/18/2023]
Abstract
Microbial electrosynthesis (MES) is a neoteric technology that facilitates biocatalysed synthesis of organic compounds with the aid of homoacetogenic bacteria, while feeding CO2 as an inorganic carbon source. Operating MES with surplus renewable electricity further enhances the sustainability of this innovative bioelectrochemical system (BES). However, several lacunae exist in the domain knowledge, stunting the widespread application of MES. Despite significant progress in this area over the past decade, the product yield efficiency is not on par with other contemporary technologies. This bottleneck can be overcome by adopting a holistic approach, i.e., applying innovative and integrated solutions to ensure a robust MES operation. Further, the widespread deployment of MES exclusively relies on its ability to mature a sessile biofilm over a biocompatible electrode, while offering minimal charge transfer resistance. Additionally, operating MES preferably at H2-generating reduction potential and valorising industrial off-gas as carbon substrate is crucial to accomplish economic sustainability. In light of the aforementioned, this review collates the latest progress in the design and development of MES-centred systems for valorisation of CO2 into value-added products. Specifically, it highlights the significance of inoculum pre-treatment for promoting biocatalytic activity and biofilm growth on the cathodic surface. In addition, it summarizes the diverse materials that are commonly used as electrodes in MES, with an emphasis on the importance of inexpensive, robust, and biocompatible electrode materials for the practical application of MES technology. Further, the review presents insights into media conditions, operational factors, and reactor configurations that affect the overall performance of MES process. Finally, the product range of MES, downstream processing requirements, and integration of MES with other environmental remediation technologies are also discussed.
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Affiliation(s)
- Lakshmi Pathi Thulluru
- School of Environmental Science and Engineering, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, 721302, India
| | - Makarand M Ghangrekar
- Department of Civil Engineering, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, 721302, India
| | - Shamik Chowdhury
- School of Environmental Science and Engineering, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, 721302, India.
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9
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Al-Mamun A, Ahmed W, Jafary T, Nayak JK, Al-Nuaimi A, Sana A. Recent advances in microbial electrosynthesis system: Metabolic investigation and process optimization. Biochem Eng J 2023. [DOI: 10.1016/j.bej.2023.108928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2023]
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10
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Nastro RA, Salvian A, Kuppam C, Pasquale V, Pietrelli A, Rossa CA. Inorganic Carbon Assimilation and Electrosynthesis of Platform Chemicals in Bioelectrochemical Systems (BESs) Inoculated with Clostridium saccharoperbutylacetonicum N1-H4. Microorganisms 2023; 11:735. [PMID: 36985308 PMCID: PMC10051846 DOI: 10.3390/microorganisms11030735] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 03/01/2023] [Accepted: 03/06/2023] [Indexed: 03/14/2023] Open
Abstract
The need for greener processes to satisfy the demand of platform chemicals together with the possibility of reusing CO2 from human activities has recently encouraged research on the set-up, optimization, and development of bioelectrochemical systems (BESs) for the electrosynthesis of organic compounds from inorganic carbon (CO2, HCO3-). In the present study, we tested the ability of Clostridium saccharoperbutylacetonicum N1-4 (DSMZ 14923) to produce acetate and D-3-hydroxybutyrate from inorganic carbon present in a CO2:N2 gas mix. At the same time, we tested the ability of a Shewanella oneidensis MR1 and Pseudomonas aeruginosa PA1430/CO1 consortium to provide reducing power to sustain carbon assimilation at the cathode. We tested the performance of three different systems with the same layouts, inocula, and media, but with the application of 1.5 V external voltage, of a 1000 Ω external load, and without any connection between the electrodes or external devices (open circuit voltage, OCV). We compared both CO2 assimilation rate and production of metabolites (formate, acetate 3-D-hydroxybutyrate) in our BESs with the values obtained in non-electrogenic control cultures and estimated the energy used by our BESs to assimilate 1 mol of CO2. Our results showed that C. saccharoperbutylacetonicum NT-1 achieved the maximum CO2 assimilation (95.5%) when the microbial fuel cells (MFCs) were connected to the 1000 Ω external resistor, with the Shewanella/Pseudomonas consortium as the only source of electrons. Furthermore, we detected a shift in the metabolism of C. saccharoperbutylacetonicum NT-1 because of its prolonged activity in BESs. Our results open new perspectives for the utilization of BESs in carbon capture and electrosynthesis of platform chemicals.
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Affiliation(s)
- Rosa Anna Nastro
- Department of Science and Technology, University of Naples “Parthenope”, 80133 Naples, Italy
| | - Anna Salvian
- Laboratory of Systems Microbiology, Department of Microbial Sciences, University of Surrey, Guildford GU2 7XH, UK
| | - Chandrasekhar Kuppam
- Department of Biotechnology, Vignan’s Foundation for Science, Technology and Research, Vadlamudi, Guntur 522213, Andhra Pradesh, India
| | - Vincenzo Pasquale
- Department of Science and Technology, University of Naples “Parthenope”, 80133 Naples, Italy
| | - Andrea Pietrelli
- Laboratoire Ampere CNRS UMR 5005, Département Génie Electrique et des Procédés Université de Lyon, F-69621 Villeurbanne, France
| | - Claudio Avignone Rossa
- Laboratory of Systems Microbiology, Department of Microbial Sciences, University of Surrey, Guildford GU2 7XH, UK
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Sriram S, Wong JWC, Pradhan N. Recent advances in electro-fermentation technology: A novel approach towards balanced fermentation. BIORESOURCE TECHNOLOGY 2022; 360:127637. [PMID: 35853590 DOI: 10.1016/j.biortech.2022.127637] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2022] [Revised: 07/11/2022] [Accepted: 07/13/2022] [Indexed: 06/15/2023]
Abstract
Biotransformation of organic substrates via acidogenic fermentation (AF) to high-value products such as C1-C6 carboxylic acids and alcohol serves as platform chemicals for various industrial applications. However, the AF technology suffers from low product titers due to thermodynamic constraints. Recent studies suggest that augmenting AF redox potential can regulate the metabolic pathway and provide seamless electron flow by lowering the activation energy barrier, thus positively influencing the substrate utilization rate, product yield, and speciation. Hence, the augmented AF system with an exogenous electricity supply is termed as electro-fermentation (EF), which has enormous potential to strengthen the fermentation technology domain. Therefore, this critical review systematically discusses the current understanding of EF with a special focus on the extracellular electron transfer mechanism of electroactive bacteria and provides perspectives and research gaps to further improve the technology for green chemical synthesis, sustainable waste management, and circular bio-economy.
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Affiliation(s)
- Saranya Sriram
- Department of Biology, Faculty of Science, Hong Kong Baptist University, Hong Kong, SAR
| | - Jonathan W C Wong
- Department of Biology, Faculty of Science, Hong Kong Baptist University, Hong Kong, SAR; Institute of Bioresource and Agriculture, Hong Kong Baptist University, Kowloon Tong, Hong Kong, SAR.
| | - Nirakar Pradhan
- Department of Biology, Faculty of Science, Hong Kong Baptist University, Hong Kong, SAR; Institute of Bioresource and Agriculture, Hong Kong Baptist University, Kowloon Tong, Hong Kong, SAR.
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12
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Baek J, Kim C, Eun Song Y, Kong DS, Mutyala S, Seol EH, Kim JR. Bioelectrochemical metabolic regulation of a heterologously expressed glycerol reductive pathway in E. coli BL21(DE3). Electrochim Acta 2022. [DOI: 10.1016/j.electacta.2022.141260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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13
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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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14
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Lee H, Bae J, Jin S, Kang S, Cho BK. Engineering Acetogenic Bacteria for Efficient One-Carbon Utilization. Front Microbiol 2022; 13:865168. [PMID: 35615514 PMCID: PMC9124964 DOI: 10.3389/fmicb.2022.865168] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Accepted: 04/19/2022] [Indexed: 12/03/2022] Open
Abstract
C1 gases, including carbon dioxide (CO2) and carbon monoxide (CO), are major contributors to climate crisis. Numerous studies have been conducted to fix and recycle C1 gases in order to solve this problem. Among them, the use of microorganisms as biocatalysts to convert C1 gases to value-added chemicals is a promising solution. Acetogenic bacteria (acetogens) have received attention as high-potential biocatalysts owing to their conserved Wood–Ljungdahl (WL) pathway, which fixes not only CO2 but also CO. Although some metabolites have been produced via C1 gas fermentation on an industrial scale, the conversion of C1 gases to produce various biochemicals by engineering acetogens has been limited. The energy limitation of acetogens is one of the challenges to overcome, as their metabolism operates at a thermodynamic limit, and the low solubility of gaseous substrates results in a limited supply of cellular energy. This review provides strategies for developing efficient platform strains for C1 gas conversion, focusing on engineering the WL pathway. Supplying liquid C1 substrates, which can be obtained from CO2, or electricity is introduced as a strategy to overcome the energy limitation. Future prospective approaches on engineering acetogens based on systems and synthetic biology approaches are also discussed.
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Affiliation(s)
- Hyeonsik Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, South Korea
| | - Jiyun Bae
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, South Korea
| | - Sangrak Jin
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, South Korea
| | - Seulgi Kang
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, South Korea
| | - Byung-Kwan Cho
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, South Korea
- KI for the BioCentury, Korea Advanced Institute of Science and Technology, Daejeon, South Korea
- *Correspondence: Byung-Kwan Cho,
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15
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Electron transfer in Gram-positive bacteria: enhancement strategies for bioelectrochemical applications. World J Microbiol Biotechnol 2022; 38:83. [DOI: 10.1007/s11274-022-03255-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 02/21/2022] [Indexed: 12/30/2022]
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16
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Virdis B, Hoelzle R, Marchetti A, Boto ST, Rosenbaum MA, Blasco-Gómez R, Puig S, Freguia S, Villano M. Electro-fermentation: Sustainable bioproductions steered by electricity. Biotechnol Adv 2022; 59:107950. [PMID: 35364226 DOI: 10.1016/j.biotechadv.2022.107950] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 02/22/2022] [Accepted: 03/24/2022] [Indexed: 01/06/2023]
Abstract
The market of biobased products obtainable via fermentation processes is steadily increasing over the past few years, driven by the need to create a decarbonized economy. To date, industrial fermentation (IF) employs either pure or mixed microbial cultures (MMC) whereby the type of the microbial catalysts and the used feedstock affect metabolic pathways and, in turn, the type of product(s) generated. In many cases, especially when dealing with MMC, the economic viability of IF is hindered by factors such as the low attained product titer and selectivity, which ultimately challenge the downstream recovery and purification steps. In this context, electro-fermentation (EF) represents an innovative approach, based on the use of a polarized electrode interface to trigger changes in the rate, yield, titer or product distribution deriving from traditional fermentation processes. In principle, the electrode in EF can act as an electron acceptor (i.e., anodic electro-fermentation, AEF) or donor (i.e., cathodic electro-fermentation, CEF), or simply as a mean to control the oxidation-reduction potential of the fermentation broth. However, the molecular and biochemical basis underlying the EF process are still largely unknown. This review paper provides a comprehensive overview of recent literature studies including both AEF and CEF examples with either pure or mixed microbial cultures. A critical analysis of biochemical, microbiological, and engineering aspects which presently hamper the transition of the EF technology from the laboratory to the market is also presented.
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Affiliation(s)
- Bernardino Virdis
- Australian Centre for Water and Environmental Biotechnology (ACWEB, formerly AWMC), The University of Queensland, Brisbane, QLD 4072, Australia
| | - Robert Hoelzle
- School of Earth and Environmental Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Angela Marchetti
- Department of Chemistry, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy
| | - Santiago T Boto
- Bio Pilot Plant, Leibniz Institute for Natural Product Research and Infection Biology - Hans-Knöll-Institute (HKI), 07745 Jena, Germany; Faculty of Biological Sciences, Friedrich Schiller University (FSU), 07743 Jena, Germany
| | - Miriam A Rosenbaum
- Bio Pilot Plant, Leibniz Institute for Natural Product Research and Infection Biology - Hans-Knöll-Institute (HKI), 07745 Jena, Germany; Faculty of Biological Sciences, Friedrich Schiller University (FSU), 07743 Jena, Germany
| | - Ramiro Blasco-Gómez
- LEQUIA, Institute of the Environment, University of Girona, Maria Aurèlia Capmany 69, 17003 Girona, Spain
| | - Sebastià Puig
- LEQUIA, Institute of the Environment, University of Girona, Maria Aurèlia Capmany 69, 17003 Girona, Spain
| | - Stefano Freguia
- Department of Chemical Engineering, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Marianna Villano
- Department of Chemistry, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy.
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17
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Modeling and Optimal Control of an Electro-Fermentation Process within a Batch Culture. Processes (Basel) 2022. [DOI: 10.3390/pr10030535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Electro-fermentation is a novel process that consists in coupling a microbial fermentative metabolism with an electrochemical system. In such a process, the electrodes act either as the electron sinks or sources modifying the fermentation balance of a microbial fermentative metabolism and provide new options for the control of microbial activity. A theoretical framework for the analysis and control of fermentations using electro-fermentation is currently lacking. In this paper, we propose a simple electro-fermentation model in which a population of fermentative bacteria switch between two metabolic behaviors in response to different electrode potentials. We then mathematically analyze optimal strategies to maximize the production of one of the rising products in a batch fermentation using Pontryagin’s Maximum Principle. The obtained results show that, in some experimental configurations, a dynamic control of the electrode potential is required for the maximization of the desired product. Consequences of the obtained optimal strategy for driving electro-fermentation experiments are discussed through a realistic example. This analysis also highlights that the transition rates between fermentation and electro-fermentation behaviors are currently unknown and would be crucial to quantify in order to apply such a control approach.
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18
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HO CHIALUN, Emran MY, Ihara S, Huang W, Wakai S, Li WP, Okamoto A. Osmium-Grafted Magnetic Nanobeads Increase Microbial Current Generation Via Culture-Free and Quick Enrichment of Electrogenic Bacteria. SSRN ELECTRONIC JOURNAL 2022. [DOI: 10.2139/ssrn.4177599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
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19
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Sato R, Amao Y. Carbonic anhydrase/formate dehydrogenase bienzymatic system for CO 2 capture, utilization and storage. REACT CHEM ENG 2022. [DOI: 10.1039/d1re00405k] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
In order to establish carbon capture, utilization, and storage (CCUS) technology, a system consisting of two different biocatalysts (formate dehydrogenase from Candida boidinii; CbFDH and carbonic anhydrase from bovine erythrocytes; CA) is developed.
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Affiliation(s)
- Ryohei Sato
- Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan
| | - Yutaka Amao
- Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan
- Research Centre for Artificial Photosynthesis (ReCAP), Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan
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20
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Baruch M, Tejedor-Sanz S, Su L, Ajo-Franklin CM. Electronic control of redox reactions inside Escherichia coli using a genetic module. PLoS One 2021; 16:e0258380. [PMID: 34793478 PMCID: PMC8601525 DOI: 10.1371/journal.pone.0258380] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 09/26/2021] [Indexed: 11/22/2022] Open
Abstract
Microorganisms regulate the redox state of different biomolecules to precisely control biological processes. These processes can be modulated by electrochemically coupling intracellular biomolecules to an external electrode, but current approaches afford only limited control and specificity. Here we describe specific electrochemical control of the reduction of intracellular biomolecules in Escherichia coli through introduction of a heterologous electron transfer pathway. E. coli expressing cymAmtrCAB from Shewanella oneidensis MR-1 consumed electrons directly from a cathode when fumarate or nitrate, both intracellular electron acceptors, were present. The fumarate-triggered current consumption occurred only when fumarate reductase was present, indicating all the electrons passed through this enzyme. Moreover, CymAMtrCAB-expressing E. coli used current to stoichiometrically reduce nitrate. Thus, our work introduces a modular genetic tool to reduce a specific intracellular redox molecule with an electrode, opening the possibility of electronically controlling biological processes such as biosynthesis and growth in any microorganism.
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Affiliation(s)
- Moshe Baruch
- The Molecular Foundry, Biological Nanostructures Facility, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Sara Tejedor-Sanz
- The Molecular Foundry, Biological Nanostructures Facility, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
- Department of BioSciences, Rice University, Houston, Texas, United States of America
| | - Lin Su
- The Molecular Foundry, Biological Nanostructures Facility, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
- Department of BioSciences, Rice University, Houston, Texas, United States of America
| | - Caroline M. Ajo-Franklin
- The Molecular Foundry, Biological Nanostructures Facility, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
- Department of BioSciences, Rice University, Houston, Texas, United States of America
- Institute for Biosciences and Bioengineering, Rice University, Houston, Texas, United States of America
- * E-mail:
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21
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Acetogenic bacteria utilize light-driven electrons as an energy source for autotrophic growth. Proc Natl Acad Sci U S A 2021; 118:2020552118. [PMID: 33619098 PMCID: PMC7936347 DOI: 10.1073/pnas.2020552118] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
To develop an efficient artificial photosynthesis system using acetogen-nanoparticle hybrids, the efficiency of the electron–hole pair generation of nanoparticles must be enhanced to demonstrate extracellular electron utilization by the acetogen. Here we verified that Clostridium autoethanogenum, an industrially relevant acetogen, could use electrons generated from size- and structure-controlled chemically synthesized cadmium sulfide nanoparticles displayed on the cell surface under light-exposure conditions. In addition, transcriptomic analysis showed that the electrons generated from nanoparticles were largely transported to the intracellular matrix via the metal ion or flavin-binding proteins. These results illustrate the potential to increase the CO2-fixing efficiency of nanoparticle-based artificial photosynthesis by engineering cellular processes related to electron transfer generated from the cathode. Acetogenic bacteria use cellular redox energy to convert CO2 to acetate using the Wood–Ljungdahl (WL) pathway. Such redox energy can be derived from electrons generated from H2 as well as from inorganic materials, such as photoresponsive semiconductors. We have developed a nanoparticle-microbe hybrid system in which chemically synthesized cadmium sulfide nanoparticles (CdS-NPs) are displayed on the cell surface of the industrial acetogen Clostridium autoethanogenum. The hybrid system converts CO2 into acetate without the need for additional energy sources, such as H2, and uses only light-induced electrons from CdS-NPs. To elucidate the underlying mechanism by which C. autoethanogenum uses electrons generated from external energy sources to reduce CO2, we performed transcriptional analysis. Our results indicate that genes encoding the metal ion or flavin-binding proteins were highly up-regulated under CdS-driven autotrophic conditions along with the activation of genes associated with the WL pathway and energy conservation system. Furthermore, the addition of these cofactors increased the CO2 fixation rate under light-exposure conditions. Our results demonstrate the potential to improve the efficiency of artificial photosynthesis systems based on acetogenic bacteria integrated with photoresponsive nanoparticles.
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22
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Zhang Y, Li J, Meng J, Sun K, Yan H. A neutral red mediated electro-fermentation system of Clostridium beijerinckii for effective co-production of butanol and hydrogen. BIORESOURCE TECHNOLOGY 2021; 332:125097. [PMID: 33845318 DOI: 10.1016/j.biortech.2021.125097] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 03/25/2021] [Accepted: 03/26/2021] [Indexed: 06/12/2023]
Abstract
To enhance the co-production of butanol and hydrogen by the acetone-butanol-ethanol (ABE) fermentation of Clostridium beijerinckii, a novel cathodic electro-fermentation (CEF) system was constructed with neutral red (NR) as electron mediator. With the mediation of NR, production of butanol and hydrogen from glucose in the CEF system achieved 5.49 ± 0.28 g/L and 3.74 ± 0.16 L/L, 569.5% and 325.0% higher than that in the open circuit (OC) system, respectively. The butanol and hydrogen yield of 0.30 ± 0.02 g/g and 206.53 ± 8.20 mL/g was 172.7% and 71.4% higher than that in the OC system, respectively. The effective co-production of butanol and hydrogen in the NR-mediated CEF system was attributed to the cooperation of the introduced polarized electrode and the additional NR. With the control of the polarized electrode, a feasible ORP was available for the effective hydrogen production. And the additional NR had induced more carbon source and electrons to the synthesis of butanol.
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Affiliation(s)
- Yafei Zhang
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, 73 Huanghe Road, Harbin 150090, China
| | - Jianzheng Li
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, 73 Huanghe Road, Harbin 150090, China
| | - Jia Meng
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, 73 Huanghe Road, Harbin 150090, China.
| | - Kai Sun
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, 73 Huanghe Road, Harbin 150090, China
| | - Han Yan
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, 73 Huanghe Road, Harbin 150090, China
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23
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Lee SY, Oh YK, Lee S, Fitriana HN, Moon M, Kim MS, Lee J, Min K, Park GW, Lee JP, Lee JS. Recent developments and key barriers to microbial CO 2 electrobiorefinery. BIORESOURCE TECHNOLOGY 2021; 320:124350. [PMID: 33186841 DOI: 10.1016/j.biortech.2020.124350] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 10/25/2020] [Accepted: 10/27/2020] [Indexed: 06/11/2023]
Abstract
The electrochemical conversion of CO2 can include renewable surplus electricity storage and CO2 utilisation. This review focuses on the microbial CO2 electrobiorefinery based on microbial electrosynthesis (MES) which merges electrochemical and microbial conversion to produce biofuels and higher-value chemicals. In this review, recent developments are discussed about bioelectrochemical conversion of CO2 into biofuels and chemicals in MES via microbial CO2-fixation and electricity utilisation reactions. In addition, this review examines technical approaches to overcome the current limitations of MES including the following: engineering of the biocathode, application of electron mediators, and reactor optimisation, among others. An in-depth discussion of strategies for the CO2 electrobiorefinery is presented, including the integration of the biocathode with inorganic catalysts, screening of novel electroactive microorganisms, and metabolic engineering to improve target productivity from CO2.
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Affiliation(s)
- Soo Youn Lee
- Gwangju Bio/Energy R&D Center, Korea Institute of Energy Research, Gwangju 61003, Republic of Korea
| | - You-Kwan Oh
- School of Chemical & Biomolecular Engineering, Pusan National University, Busan 46241, Republic of Korea
| | - Sangmin Lee
- Gwangju Bio/Energy R&D Center, Korea Institute of Energy Research, Gwangju 61003, Republic of Korea
| | - Hana Nur Fitriana
- Gwangju Bio/Energy R&D Center, Korea Institute of Energy Research, Gwangju 61003, Republic of Korea; Renewable Energy Engineering Department, Korea Institute of Energy Research Campus, University of Science and Technology, Daejeon 34113, South Korea
| | - Myounghoon Moon
- Gwangju Bio/Energy R&D Center, Korea Institute of Energy Research, Gwangju 61003, Republic of Korea
| | - Min-Sik Kim
- Energy Resources Upcycling Research Laboratory, Korea Institute of Energy Research, Daejeon 34129, Republic of Korea
| | - Jiye Lee
- Gwangju Bio/Energy R&D Center, Korea Institute of Energy Research, Gwangju 61003, Republic of Korea
| | - Kyoungseon Min
- Gwangju Bio/Energy R&D Center, Korea Institute of Energy Research, Gwangju 61003, Republic of Korea
| | - Gwon Woo Park
- Gwangju Bio/Energy R&D Center, Korea Institute of Energy Research, Gwangju 61003, Republic of Korea
| | - Joon-Pyo Lee
- Gwangju Bio/Energy R&D Center, Korea Institute of Energy Research, Gwangju 61003, Republic of Korea
| | - Jin-Suk Lee
- Gwangju Bio/Energy R&D Center, Korea Institute of Energy Research, Gwangju 61003, Republic of Korea.
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24
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Paquete CM. Electroactivity across the cell wall of Gram-positive bacteria. Comput Struct Biotechnol J 2020; 18:3796-3802. [PMID: 33335679 PMCID: PMC7720022 DOI: 10.1016/j.csbj.2020.11.021] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 11/11/2020] [Accepted: 11/13/2020] [Indexed: 02/07/2023] Open
Abstract
The growing interest on sustainable biotechnological processes for the production of energy and industrial relevant organic compounds have increased the discovery of electroactive organisms (i.e. organisms that are able to exchange electrons with an electrode) and the characterization of their extracellular electron transfer mechanisms. While most of the knowledge on extracellular electron transfer processes came from studies on Gram-negative bacteria, less is known about the processes performed by Gram-positive bacteria. In contrast to Gram-negative bacteria, Gram-positive bacteria lack an outer-membrane and contain a thick cell wall, which were thought to prevent extracellular electron transfer. However, in the last decade, an increased number of Gram-positive bacteria have been found to perform extracellular electron transfer, and exchange electrons with an electrode. In this mini-review the current knowledge on the extracellular electron transfer processes performed by Gram-positive bacteria is introduced, emphasising their electroactive role in bioelectrochemical systems. Also, the existent information of the molecular processes by which these bacteria exchange electrons with an electrode is highlighted. This understanding is fundamental to advance the implementation of these organisms in sustainable biotechnological processes, either through modification of the systems or through genetic engineering, where the organisms can be optimized to become better catalysts.
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Affiliation(s)
- Catarina M. Paquete
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Portugal
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25
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Lai B, Bernhardt PV, Krömer JO. Cytochrome c Reductase is a Key Enzyme Involved in the Extracellular Electron Transfer Pathway towards Transition Metal Complexes in Pseudomonas Putida. CHEMSUSCHEM 2020; 13:5308-5317. [PMID: 32678505 PMCID: PMC7589348 DOI: 10.1002/cssc.202001645] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 07/16/2020] [Indexed: 05/06/2023]
Abstract
Mediator-based extracellular electron transfer (EET) pathways can balance the redox metabolism of microbes. However, such electro-biosynthesis processes are constrained by the unknown underlying EET mechanisms. In this paper, Pseudomonas putida was studied to systematically investigate its EET pathway to transition metal complexes (i. e., [Fe(CN)6 ]3-/4- and [Co(bpy)3 ]3+/2+ ; bpy=2,2'-bipyridyl) under anaerobic conditions. Comparative proteomics showed the aerobic respiratory components were upregulated in a bioelectrochemical system without oxygen, suggesting their potential contribution to EET. Further tests found inhibiting cytochrome c oxidase activity by NaN3 and NADH dehydrogenase by rotenone did not significantly change the current output. However, the EET pathway was completely blocked, while cytochrome c reductase activity was inhibited by antimycin A. Although it cannot be excluded that cytochrome c and the periplasmic subunit of cytochrome c oxidase donate electrons to the transition metal complexes, these results strongly demonstrate that cytochrome c reductase is a key complex for the EET pathway.
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Affiliation(s)
- Bin Lai
- Systems Biotechnology group, Department of Solar MaterialsHelmholtz Centre for Environmental Research - UFZLeipzig04318Germany
- Advanced Water Management CentreThe University of QueenslandBrisbane4072Australia
| | - Paul V. Bernhardt
- School of Chemical and Molecular BiosciencesThe University of QueenslandBrisbane4072Australia
| | - Jens O. Krömer
- Systems Biotechnology group, Department of Solar MaterialsHelmholtz Centre for Environmental Research - UFZLeipzig04318Germany
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26
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Development of a clostridia-based cell-free system for prototyping genetic parts and metabolic pathways. Metab Eng 2020; 62:95-105. [PMID: 32540392 DOI: 10.1016/j.ymben.2020.06.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 05/15/2020] [Accepted: 06/07/2020] [Indexed: 02/04/2023]
Abstract
Gas fermentation by autotrophic bacteria, such as clostridia, offers a sustainable path to numerous bioproducts from a range of local, highly abundant, waste and low-cost feedstocks, such as industrial flue gases or syngas generated from biomass or municipal waste. Unfortunately, designing and engineering clostridia remains laborious and slow. The ability to prototype individual genetic part function, gene expression patterns, and biosynthetic pathway performance in vitro before implementing designs in cells could help address these bottlenecks by speeding up design. Unfortunately, a high-yielding cell-free gene expression (CFE) system from clostridia has yet to be developed. Here, we report the development and optimization of a high-yielding (236 ± 24 μg/mL) batch CFE platform from the industrially relevant anaerobe, Clostridium autoethanogenum. A key feature of the platform is that both circular and linear DNA templates can be applied directly to the CFE reaction to program protein synthesis. We demonstrate the ability to prototype gene expression, and quantitatively map aerobic cell-free metabolism in lysates from this system. We anticipate that the C. autoethanogenum CFE platform will not only expand the protein synthesis toolkit for synthetic biology, but also serve as a platform in expediting the screening and prototyping of gene regulatory elements in non-model, industrially relevant microbes.
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27
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Moscoviz R, Quéméner EDL, Trably E, Bernet N, Hamelin J. Novel Outlook in Microbial Ecology: Nonmutualistic Interspecies Electron Transfer. Trends Microbiol 2020; 28:245-253. [PMID: 32155432 DOI: 10.1016/j.tim.2020.01.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 01/16/2020] [Accepted: 01/21/2020] [Indexed: 02/06/2023]
Abstract
Recent advances in microbial electrochemical technologies have revealed the existence of numerous and highly diverse microorganisms able to exchange electrons with electrodes. This diversity could reflect the capacity of microorganisms to release and/or retrieve electrons with each other in natural environments. So far, this interspecies electron transfer has been studied with a special focus on syntrophy and was successfully demonstrated for several couples of species. In this article we argue that electron exchange between microbes exists beyond syntrophy or mutualism and could also promote competitive and even parasitic behaviour. Based on three interesting case studies identified from the literature, we also highlight that such nonmutualistic interactions could be widespread and of particular significance for the survival of pathogens or the shaping of complex microbial communities.
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Affiliation(s)
- Roman Moscoviz
- SUEZ, Centre International de Recherche Sur l'Eau et l'Environnement (CIRSEE), Le Pecq, France.
| | | | - Eric Trably
- INRAE, Université Montpellier, LBE, Narbonne, France
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28
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Norman RO, Millat T, Schatschneider S, Henstra AM, Breitkopf R, Pander B, Annan FJ, Piatek P, Hartman HB, Poolman MG, Fell DA, Winzer K, Minton NP, Hodgman C. Genome‐scale model of
C. autoethanogenum
reveals optimal bioprocess conditions for high‐value chemical production from carbon monoxide. ENGINEERING BIOLOGY 2019. [DOI: 10.1049/enb.2018.5003] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Rupert O.J. Norman
- Synthetic Biology Research CentreUniversity of Nottingham, University ParkNottinghamNG7 2RDUK
- School of BiosciencesUniversity of NottinghamSutton Bonington Campus, Sutton BoningtonLeicestershireLE12 5RDUK
| | - Thomas Millat
- Synthetic Biology Research CentreUniversity of Nottingham, University ParkNottinghamNG7 2RDUK
| | - Sarah Schatschneider
- Synthetic Biology Research CentreUniversity of Nottingham, University ParkNottinghamNG7 2RDUK
- Evonik Nutrition and Care GmbHKantstr. 233798Halle‐KinsbeckGermany
| | - Anne M. Henstra
- Synthetic Biology Research CentreUniversity of Nottingham, University ParkNottinghamNG7 2RDUK
| | - Ronja Breitkopf
- Synthetic Biology Research CentreUniversity of Nottingham, University ParkNottinghamNG7 2RDUK
| | - Bart Pander
- Synthetic Biology Research CentreUniversity of Nottingham, University ParkNottinghamNG7 2RDUK
| | - Florence J. Annan
- Synthetic Biology Research CentreUniversity of Nottingham, University ParkNottinghamNG7 2RDUK
| | - Pawel Piatek
- Synthetic Biology Research CentreUniversity of Nottingham, University ParkNottinghamNG7 2RDUK
| | - Hassan B. Hartman
- Department of Biology and Medical SciencesOxford Brookes UniversityOxfordOX3 0BPUK
- Public Health England61 Colindale AvenueLondonNW9 5EQUK
| | - Mark G. Poolman
- Department of Biology and Medical SciencesOxford Brookes UniversityOxfordOX3 0BPUK
| | - David A. Fell
- Department of Biology and Medical SciencesOxford Brookes UniversityOxfordOX3 0BPUK
| | - Klaus Winzer
- Synthetic Biology Research CentreUniversity of Nottingham, University ParkNottinghamNG7 2RDUK
| | - Nigel P. Minton
- Synthetic Biology Research CentreUniversity of Nottingham, University ParkNottinghamNG7 2RDUK
| | - Charlie Hodgman
- Synthetic Biology Research CentreUniversity of Nottingham, University ParkNottinghamNG7 2RDUK
- School of BiosciencesUniversity of NottinghamSutton Bonington Campus, Sutton BoningtonLeicestershireLE12 5RDUK
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29
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Extracellular electron transfer features of Gram-positive bacteria. Anal Chim Acta 2019; 1076:32-47. [PMID: 31203962 DOI: 10.1016/j.aca.2019.05.007] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 04/23/2019] [Accepted: 05/05/2019] [Indexed: 12/20/2022]
Abstract
Electroactive microorganisms possess the unique ability to transfer electrons to or from solid phase electron conductors, e.g., electrodes or minerals, through various physiological mechanisms. The processes are commonly known as extracellular electron transfer and broadly harnessed in microbial electrochemical systems, such as microbial biosensors, microbial electrosynthesis, or microbial fuel cells. Apart from a few model microorganisms, the nature of the microbe-electrode conductive interaction is poorly understood for most of the electroactive species. The interaction determines the efficiency and a potential scaling up of bioelectrochemical systems. Gram-positive bacteria generally have a thick electron non-conductive cell wall and are believed to exhibit weak extracellular electron shuttling activity. This review highlights reported research accomplishments on electroactive Gram-positive bacteria. The use of electron-conducting polymers as mediators is considered as one promising strategy to enhance the electron transfer efficiency up to application scale. In view of the recent progress in understanding the molecular aspects of the extracellular electron transfer mechanisms of Enterococcus faecalis, the electron transfer properties of this bacterium are especially focused on. Fundamental knowledge on the nature of microbial extracellular electron transfer and its possibilities can provide insight in interspecies electron transfer and biogeochemical cycling of elements in nature. Additionally, a comprehensive understanding of cell-electrode interactions may help in overcoming insufficient electron transfer and restricted operational performance of various bioelectrochemical systems and facilitate their practical applications.
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30
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Tschörtner J, Lai B, Krömer JO. Biophotovoltaics: Green Power Generation From Sunlight and Water. Front Microbiol 2019; 10:866. [PMID: 31114551 PMCID: PMC6503001 DOI: 10.3389/fmicb.2019.00866] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 04/04/2019] [Indexed: 11/29/2022] Open
Abstract
Biophotovoltaics is a relatively new discipline in microbial fuel cell research. The basic idea is the conversion of light energy into electrical energy using photosynthetic microorganisms. The microbes will use their photosynthetic apparatus and the incoming light to split the water molecule. The generated protons and electrons are harvested using a bioelectrochemical system. The key challenge is the extraction of electrons from the microbial electron transport chains into a solid-state anode. On the cathode, a corresponding electrochemical counter reaction will consume the protons and electrons, e.g., through the oxygen reduction to water, or hydrogen formation. In this review, we are aiming to summarize the current state of the art and point out some limitations. We put a specific emphasis on cyanobacteria, as these microbes are considered future workhorses for photobiotechnology and are currently the most widely applied microbes in biophotovoltaics research. Current progress in biophotovoltaics is limited by very low current outputs of the devices while a lack of comparability and standardization of the experimental set-up hinders a systematic optimization of the systems. Nevertheless, the fundamental questions of redox homeostasis in photoautotrophs and the potential to directly harvest light energy from a highly efficient photosystem, rather than through oxidation of inefficiently produced biomass are highly relevant aspects of biophotovoltaics.
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Affiliation(s)
| | | | - Jens O. Krömer
- Systems Biotechnology, Department of Solar Materials, Helmholtz Centre for Environmental Research, Leipzig, Germany
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Utesch T, Sabra W, Prescher C, Baur J, Arbter P, Zeng A. Enhanced electron transfer of different mediators for strictly opposite shifting of metabolism inClostridium pasteurianumgrown on glycerol in a new electrochemical bioreactor. Biotechnol Bioeng 2019; 116:1627-1643. [DOI: 10.1002/bit.26963] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Revised: 02/08/2019] [Accepted: 02/28/2019] [Indexed: 12/11/2022]
Affiliation(s)
- Tyll Utesch
- Institute of Bioprocess and Biosystems EngineeringHamburg University of Technology Denickestrasse Hamburg Germany
| | - Wael Sabra
- Institute of Bioprocess and Biosystems EngineeringHamburg University of Technology Denickestrasse Hamburg Germany
| | - Christin Prescher
- Institute of Bioprocess and Biosystems EngineeringHamburg University of Technology Denickestrasse Hamburg Germany
| | - Julian Baur
- Institute of Bioprocess and Biosystems EngineeringHamburg University of Technology Denickestrasse Hamburg Germany
| | - Philipp Arbter
- Institute of Bioprocess and Biosystems EngineeringHamburg University of Technology Denickestrasse Hamburg Germany
| | - An‐Ping Zeng
- Institute of Bioprocess and Biosystems EngineeringHamburg University of Technology Denickestrasse Hamburg Germany
- Beijing Advanced Innovation Center for Soft Matter Science and EngineeringBeijing University of Chemical Technology Chaoyang District Beijing China
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32
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Kim MY, Kim C, Ainala SK, Bae H, Jeon BH, Park S, Kim JR. Metabolic shift of Klebsiella pneumoniae L17 by electrode-based electron transfer using glycerol in a microbial fuel cell. Bioelectrochemistry 2019; 125:1-7. [DOI: 10.1016/j.bioelechem.2018.08.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 08/06/2018] [Accepted: 08/06/2018] [Indexed: 10/28/2022]
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Emerson DF, Woolston BM, Liu N, Donnelly M, Currie DH, Stephanopoulos G. Enhancing hydrogen-dependent growth of and carbon dioxide fixation by Clostridium ljungdahlii through nitrate supplementation. Biotechnol Bioeng 2018; 116:294-306. [PMID: 30267586 DOI: 10.1002/bit.26847] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 09/23/2018] [Accepted: 09/28/2018] [Indexed: 12/15/2022]
Abstract
Synthesis gas (syngas) fermentation via the Wood-Ljungdahl pathway is receiving growing attention as a possible platform for the fixation of CO 2 and renewable production of fuels and chemicals. However, the pathway operates near the thermodynamic limit of life, resulting in minimal adenosine triphosphate (ATP) production and long doubling times. This calls into question the feasibility of producing high-energy compounds at industrially relevant levels. In this study, we investigated the possibility of co-utilizing nitrate as an inexpensive additional electron acceptor to enhance ATP production during H 2 -dependent growth of Clostridium ljungdahlii, Moorella thermoacetica, and Acetobacterium woodii. In contrast to other acetogens tested, growth rate and final biomass titer were improved for C. ljungdahlii growing on a mixture of H 2 and CO 2 when supplemented with nitrate. Transcriptomic analysis, 13 CO 2 labeling, and an electron balance were used to understand how electron flux was partitioned between CO 2 and nitrate. We further show that, with nitrate supplementation, the ATP/adenosine diphosphate (ADP) ratio and acetyl-CoA pools were increased by fivefold and threefold, respectively, suggesting that this strategy could be useful for the production of ATP-intensive heterologous products from acetyl-CoA. Finally, we propose a pathway for enhanced ATP production from nitrate and use this as a basis to calculate theoretical yields for a variety of products. This study demonstrates a viable strategy for the decoupling of ATP production from carbon dioxide fixation, which will serve to significantly improve the CO 2 fixation rate and the production metrics of other chemicals from CO 2 and H 2 in this host.
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Affiliation(s)
- David F Emerson
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Benjamin M Woolston
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Nian Liu
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Mackenzie Donnelly
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Devin H Currie
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Gregory Stephanopoulos
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
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Engel M, Holtmann D, Ulber R, Tippkötter N. Increased Biobutanol Production by Mediator‐Less Electro‐Fermentation. Biotechnol J 2018; 14:e1800514. [DOI: 10.1002/biot.201800514] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 10/29/2018] [Indexed: 01/01/2023]
Affiliation(s)
- Mareike Engel
- Bioprocess EngineeringUniversity of Kaiserslautern67663 KaiserslauternGermany
| | - Dirk Holtmann
- Industrial BiotechnologyDECHEMA Research Institute60486 Frankfurt am MainGermany
| | - Roland Ulber
- Bioprocess EngineeringUniversity of Kaiserslautern67663 KaiserslauternGermany
| | - Nils Tippkötter
- Bioprocess EngineeringUniversity of Applied Science AachenHeinrich‐Mußmann‐Straße 152428 JülichGermany
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35
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Rengasamy K, Ranaivoarisoa T, Singh R, Bose A. An insoluble iron complex coated cathode enhances direct electron uptake by Rhodopseudomonas palustris TIE-1. Bioelectrochemistry 2018; 122:164-173. [DOI: 10.1016/j.bioelechem.2018.03.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 03/27/2018] [Accepted: 03/28/2018] [Indexed: 10/17/2022]
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36
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Bengelsdorf FR, Beck MH, Erz C, Hoffmeister S, Karl MM, Riegler P, Wirth S, Poehlein A, Weuster-Botz D, Dürre P. Bacterial Anaerobic Synthesis Gas (Syngas) and CO 2+H 2 Fermentation. ADVANCES IN APPLIED MICROBIOLOGY 2018; 103:143-221. [PMID: 29914657 DOI: 10.1016/bs.aambs.2018.01.002] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Anaerobic bacterial gas fermentation gains broad interest in various scientific, social, and industrial fields. This microbial process is carried out by a specific group of bacterial strains called acetogens. All these strains employ the Wood-Ljungdahl pathway but they belong to different taxonomic groups. Here we provide an overview of the metabolism of acetogens and naturally occurring products. Characteristics of 61 strains were summarized and selected acetogens described in detail. Acetobacterium woodii, Clostridium ljungdahlii, and Moorella thermoacetica serve as model organisms. Results of approaches such as genome-scale modeling, proteomics, and transcriptomics are discussed. Metabolic engineering of acetogens can be used to expand the product portfolio to platform chemicals and to study different aspects of cell physiology. Moreover, the fermentation of gases requires specific reactor configurations and the development of the respective technology, which can be used for an industrial application. Even though the overall process will have a positive effect on climate, since waste and greenhouse gases could be converted into commodity chemicals, some legislative barriers exist, which hamper successful exploitation of this technology.
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Affiliation(s)
- Frank R Bengelsdorf
- Institute of Microbiology and Biotechnology, University of Ulm, Ulm, Germany.
| | - Matthias H Beck
- Institute of Microbiology and Biotechnology, University of Ulm, Ulm, Germany
| | - Catarina Erz
- Institute of Microbiology and Biotechnology, University of Ulm, Ulm, Germany
| | - Sabrina Hoffmeister
- Institute of Microbiology and Biotechnology, University of Ulm, Ulm, Germany
| | - Michael M Karl
- Institute of Microbiology and Biotechnology, University of Ulm, Ulm, Germany
| | - Peter Riegler
- Technical University of Munich, Institute of Biochemical Engineering, Garching, Germany
| | - Steffen Wirth
- Institute of Microbiology and Biotechnology, University of Ulm, Ulm, Germany
| | - Anja Poehlein
- Genomic and Applied Microbiology & Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August University, Göttingen, Germany
| | - Dirk Weuster-Botz
- Technical University of Munich, Institute of Biochemical Engineering, Garching, Germany
| | - Peter Dürre
- Institute of Microbiology and Biotechnology, University of Ulm, Ulm, Germany
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Im CH, Kim C, Song YE, Oh SE, Jeon BH, Kim JR. Electrochemically enhanced microbial CO conversion to volatile fatty acids using neutral red as an electron mediator. CHEMOSPHERE 2018; 191:166-173. [PMID: 29032261 DOI: 10.1016/j.chemosphere.2017.10.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2017] [Revised: 09/30/2017] [Accepted: 10/01/2017] [Indexed: 06/07/2023]
Abstract
Conversion of C1 gas feedstock, including carbon monoxide (CO), into useful platform chemicals has attracted considerable interest in industrial biotechnology. Nevertheless, the low conversion yield and/or growth rate of CO-utilizing microbes make it difficult to develop a C1 gas biorefinery process. The Wood-Ljungdahl pathway which utilize CO is a pathway suffered from insufficient electron supply, in which the conversion can be increased further when an additional electron source like carbohydrate or hydrogen is provided. In this study, electrode-based electron transference using a bioelectrochemical system (BES) was examined to compensate for the insufficient reducing equivalent and increase the production of volatile fatty acids. The BES including neutral red (BES-NR), which facilitated electron transfer between bacteria and electrode, was compared with BES without neutral red and open circuit control. The coulombic efficiency based on the current input to the system and the electrons recovered into VFAs, was significantly higher in BES-NR than the control. These results suggest that the carbon electrode provides a platform to regulate the redox balance for improving the bioconversion of CO, and amending the conventional C1 gas fermentation.
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Affiliation(s)
- Chae Ho Im
- School of Chemical and Biomolecular Engineering, Pusan National University, Busan 46241, Republic of Korea
| | - Changman Kim
- School of Chemical and Biomolecular Engineering, Pusan National University, Busan 46241, Republic of Korea
| | - Young Eun Song
- School of Chemical and Biomolecular Engineering, Pusan National University, Busan 46241, Republic of Korea
| | - Sang-Eun Oh
- Department of Biological Environment, Kangwon National University, 192-1, Hyoja 2-dong, Chuncheon, Kangwon-do 200-701, Republic of Korea
| | - Byong-Hun Jeon
- Department of Natural Resources and Environmental Engineering, Hanyang University, Seoul 133- 791, Republic of Korea.
| | - Jung Rae Kim
- School of Chemical and Biomolecular Engineering, Pusan National University, Busan 46241, Republic of Korea.
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Balancing cellular redox metabolism in microbial electrosynthesis and electro fermentation - A chance for metabolic engineering. Metab Eng 2017; 45:109-120. [PMID: 29229581 DOI: 10.1016/j.ymben.2017.12.003] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 09/15/2017] [Accepted: 12/06/2017] [Indexed: 01/05/2023]
Abstract
More and more microbes are discovered that are capable of extracellular electron transfer, a process in which they use external electrodes as electron donors or acceptors for metabolic reactions. This feature can be used to overcome cellular redox limitations and thus optimizing microbial production. The technologies, termed microbial electrosynthesis and electro-fermentation, have the potential to open novel bio-electro production platforms from sustainable energy and carbon sources. However, the performance of reported systems is currently limited by low electron transport rates between microbes and electrodes and our limited ability for targeted engineering of these systems due to remaining knowledge gaps about the underlying fundamental processes. Metabolic engineering offers many opportunities to optimize these processes, for instance by genetic engineering of pathways for electron transfer on the one hand and target product synthesis on the other hand. With this review, we summarize the status quo of knowledge and engineering attempts around chemical production in bio-electrochemical systems from a microbe perspective. Challenges associated with the introduction or enhancement of extracellular electron transfer capabilities into production hosts versus the engineering of target compound synthesis pathways in natural exoelectrogens are discussed. Recent advances of the research community in both directions are examined critically. Further, systems biology approaches, for instance using metabolic modelling, are examined for their potential to provide insight into fundamental processes and to identify targets for metabolic engineering.
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Predicting and experimental evaluating bio-electrochemical synthesis — A case study with Clostridium kluyveri. Bioelectrochemistry 2017; 118:114-122. [DOI: 10.1016/j.bioelechem.2017.07.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 07/24/2017] [Accepted: 07/24/2017] [Indexed: 11/20/2022]
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40
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Revealing extracellular electron transfer mediated parasitism: energetic considerations. Sci Rep 2017; 7:7766. [PMID: 28798305 PMCID: PMC5552874 DOI: 10.1038/s41598-017-07593-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 06/29/2017] [Indexed: 12/21/2022] Open
Abstract
Extracellular electron transfer (EET) is a mechanism that allows energetic coupling between two microorganisms or between a microorganism and an electrode surface. EET is either supported by direct physical contacts or mediated by electron shuttles. So far, studies dealing with interspecies EET (so-called IET) have mainly focused on possible syntrophic interactions between microorganisms favoured by this mechanism. In this article, the case of fermentative bacteria receiving extracellular electrons while fermenting a substrate is considered. A thermodynamical analysis based on metabolic energy balances was applied to re-investigate experimental data from the literature. Results suggest that the observations of a decrease of cell biomass yields of fermentative electron-accepting species, as mostly reported, can be unravelled by EET energetics and correspond to parasitism in case of IET. As an illustration, the growth yield decrease of Propionibacterium freudenreichii (−14%) observed in electro-fermentation experiments was fully explained by EET energetics when electrons were used by this species at a potential of −0.12 ± 0.01 V vs SHE. Analysis of other cases showed that, in addition to EET energetics in Clostridium pasteurianum, biological regulations can also be involved in such biomass yield decrease (−33% to −38%). Interestingly, the diminution of bacterial biomass production is always concomitant with an increased production of reduced compounds making IET-mediated parasitism and electro-fermentation attractive ways to optimize carbon fluxes in fermentation processes.
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Villano M, Paiano P, Palma E, Miccheli A, Majone M. Electrochemically Driven Fermentation of Organic Substrates with Undefined Mixed Microbial Cultures. CHEMSUSCHEM 2017; 10:3091-3097. [PMID: 28471044 DOI: 10.1002/cssc.201700360] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2017] [Indexed: 06/07/2023]
Abstract
Growing scientific interest in mixed microbial culture-based anaerobic biotechnologies for the production of value-added chemicals and fuels from organic waste residues requires a parallel focus on the development and implementation of strategies to control the distribution of products. This study examined the feasibility of an electrofermentation approach, based on the introduction of a polarized (-700 mV vs. the standard hydrogen electrode) graphite electrode in the fermentation medium, to steer the product distribution during the conversion of organic substrates (glucose, ethanol, and acetate supplied as single compounds or in mixtures) by undefined mixed microbial cultures. In batch experiments, the polarized electrode triggered a nearly 20-fold increase (relative to open circuit controls) in the yield of isobutyrate production (0.43±0.01 vs. 0.02±0.02 mol mol-1 glucose) during the anaerobic fermentation of the ternary mixture of substrates, without adversely affecting the rate of substrate bioconversion. The observed change in the fermentative metabolism was most likely triggered by the (potentiostatic) regulation of the oxidation-reduction potential of the reaction medium rather than by the electrode serving as an electron donor.
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Affiliation(s)
- Marianna Villano
- Department of Chemistry, Sapienza University of Rome, P. le Aldo Moro 5, 00185, Rome, Italy
| | - Paola Paiano
- Department of Chemistry, Sapienza University of Rome, P. le Aldo Moro 5, 00185, Rome, Italy
| | - Enza Palma
- Department of Chemistry, Sapienza University of Rome, P. le Aldo Moro 5, 00185, Rome, Italy
| | - Alfredo Miccheli
- Department of Chemistry, Sapienza University of Rome, P. le Aldo Moro 5, 00185, Rome, Italy
| | - Mauro Majone
- Department of Chemistry, Sapienza University of Rome, P. le Aldo Moro 5, 00185, Rome, Italy
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Moscoviz R, Trably E, Bernet N. Electro-fermentation triggering population selection in mixed-culture glycerol fermentation. Microb Biotechnol 2017; 11:74-83. [PMID: 28695687 PMCID: PMC5743810 DOI: 10.1111/1751-7915.12747] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 04/04/2017] [Accepted: 05/22/2017] [Indexed: 02/06/2023] Open
Abstract
Electro‐fermentation is a new technique that could be used to influence the global metabolism in mixed‐culture fermentation. In this study, a mixed‐culture cathodic electro‐fermentation of glycerol was investigated. Both microbial community structure and metabolic patterns were altered when compared to standard fermentation. This microbial population shift was more significant when the working electrodes were pre‐colonized by Geobacter sulfurreducens, before electro‐fermentation. The electro‐fermenting microbial community was more efficient for producing 1,3‐propanediol with an improved yield of 10% when compared with fermentation controls. Such improvement did not require high energy and total electron input represented < 1% of the total electron equivalents provided only by glycerol. A linear model was developed to estimate the individual metabolic pattern of each operational taxonomic unit. Application of this model compared to the experimental results suggests that the changes in global metabolism were supported by bacterial population selection rather than individual metabolism shift. This study shows for the first time that both fermentation pattern and bacterial community composition can be influenced by electro‐fermentation conditions.
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Affiliation(s)
- Roman Moscoviz
- LBE, INRA, 102 Avenue des étangs, 11100, Narbonne, France
| | - Eric Trably
- LBE, INRA, 102 Avenue des étangs, 11100, Narbonne, France
| | - Nicolas Bernet
- LBE, INRA, 102 Avenue des étangs, 11100, Narbonne, France
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