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Zhang J, Li F, Liu D, Liu Q, Song H. Engineering extracellular electron transfer pathways of electroactive microorganisms by synthetic biology for energy and chemicals production. Chem Soc Rev 2024; 53:1375-1446. [PMID: 38117181 DOI: 10.1039/d3cs00537b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
The excessive consumption of fossil fuels causes massive emission of CO2, leading to climate deterioration and environmental pollution. The development of substitutes and sustainable energy sources to replace fossil fuels has become a worldwide priority. Bio-electrochemical systems (BESs), employing redox reactions of electroactive microorganisms (EAMs) on electrodes to achieve a meritorious combination of biocatalysis and electrocatalysis, provide a green and sustainable alternative approach for bioremediation, CO2 fixation, and energy and chemicals production. EAMs, including exoelectrogens and electrotrophs, perform extracellular electron transfer (EET) (i.e., outward and inward EET), respectively, to exchange energy with the environment, whose rate determines the efficiency and performance of BESs. Therefore, we review the synthetic biology strategies developed in the last decade for engineering EAMs to enhance the EET rate in cell-electrode interfaces for facilitating the production of electricity energy and value-added chemicals, which include (1) progress in genetic manipulation and editing tools to achieve the efficient regulation of gene expression, knockout, and knockdown of EAMs; (2) synthetic biological engineering strategies to enhance the outward EET of exoelectrogens to anodes for electricity power production and anodic electro-fermentation (AEF) for chemicals production, including (i) broadening and strengthening substrate utilization, (ii) increasing the intracellular releasable reducing equivalents, (iii) optimizing c-type cytochrome (c-Cyts) expression and maturation, (iv) enhancing conductive nanowire biosynthesis and modification, (v) promoting electron shuttle biosynthesis, secretion, and immobilization, (vi) engineering global regulators to promote EET rate, (vii) facilitating biofilm formation, and (viii) constructing cell-material hybrids; (3) the mechanisms of inward EET, CO2 fixation pathway, and engineering strategies for improving the inward EET of electrotrophic cells for CO2 reduction and chemical production, including (i) programming metabolic pathways of electrotrophs, (ii) rewiring bioelectrical circuits for enhancing inward EET, and (iii) constructing microbial (photo)electrosynthesis by cell-material hybridization; (4) perspectives on future challenges and opportunities for engineering EET to develop highly efficient BESs for sustainable energy and chemical production. We expect that this review will provide a theoretical basis for the future development of BESs in energy harvesting, CO2 fixation, and chemical synthesis.
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Affiliation(s)
- Junqi Zhang
- Frontier Science Center for Synthetic Biology (Ministry of Education), Key Laboratory of Systems Bioengineering, and School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.
| | - Feng Li
- Frontier Science Center for Synthetic Biology (Ministry of Education), Key Laboratory of Systems Bioengineering, and School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.
| | - Dingyuan Liu
- Frontier Science Center for Synthetic Biology (Ministry of Education), Key Laboratory of Systems Bioengineering, and School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.
| | - Qijing Liu
- Frontier Science Center for Synthetic Biology (Ministry of Education), Key Laboratory of Systems Bioengineering, and School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.
| | - Hao Song
- Frontier Science Center for Synthetic Biology (Ministry of Education), Key Laboratory of Systems Bioengineering, and School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.
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Ranaivoarisoa TO, Bai W, Rengasamy K, Steele H, Silberman M, Olabode J, Bose A. Improving bioplastic production by Rhodopseudomonas palustris TIE-1 using synthetic biology and metabolic engineering. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.17.541174. [PMID: 37292853 PMCID: PMC10245724 DOI: 10.1101/2023.05.17.541174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
With the increasing demand for sustainably produced renewable resources, it is important to look towards microorganisms capable of producing bioproducts such as biofuels and bioplastics. Though many systems for bioproduct production are well documented and tested in model organisms, it is essential to look beyond to non-model organisms to expand the field and take advantage of metabolically versatile strains. This investigation centers on Rhodopseudomonas palustris TIE-1, a purple, non-sulfur autotrophic, and anaerobic bacterium capable of producing bioproducts that are comparable to their petroleum-based counterparts. To induce bioplastic overproduction, genes that might have a potential role in the PHB biosynthesis such as the regulator, phaR, and phaZ known for its ability to degrade PHB granules were deleted using markerless deletion. Mutants in pathways that might compete with polyhydroxybutyrate (PHB) production such as glycogen and nitrogen fixation previously created to increase n -butanol production by TIE-1 were also tested. In addition, a phage integration system was developed to insert RuBisCO (RuBisCO form I and II genes) driven by a constitutive promoter P aphII into TIE- 1 genome. Our results show that deletion of the phaR gene of the PHB pathway increases PHB productivity when TIE-1 was grown photoheterotrophically with butyrate and ammonium chloride (NH 4 Cl). Mutants unable to make glycogen or fix dinitrogen gas show an increase in PHB productivity under photoautotrophic growth conditions with hydrogen. In addition, the engineered TIE-1 overexpressing RuBisCO form I and form II produces significantly more polyhydroxybutyrate than the wild type under photoheterotrophy with butyrate and photoautotrophy with hydrogen. Inserting RuBisCO genes into TIE-1 genome is a more effective strategy than deleting competitive pathways to increase PHB production in TIE-1. The phage integration system developed for TIE-1 thus creates numerous opportunities for synthetic biology in TIE-1.
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Verma M, Singh V, Mishra V. Moving towards the enhancement of extracellular electron transfer in electrogens. World J Microbiol Biotechnol 2023; 39:130. [PMID: 36959310 DOI: 10.1007/s11274-023-03582-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 03/15/2023] [Indexed: 03/25/2023]
Abstract
Electrogens are very common in nature and becoming a contemporary theme for research as they can be exploited for extracellular electron transfer. Extracellular electron transfer is the key mechanism behind bioelectricity generation and bioremediation of pollutants via microbes. Extracellular electron transfer mechanisms for electrogens other than Shewanella and Geobacter are less explored. An efficient extracellular electron transfer system is crucial for the sustainable future of bioelectrochemical systems. At present, the poor extracellular electron transfer efficiency remains a decisive factor in limiting the development of efficient bioelectrochemical systems. In this review article, the EET mechanisms in different electrogens (bacteria and yeast) have been focused. Apart from the well-known electron transfer mechanisms of Shewanella oneidensis and Geobacter metallireducens, a brief introduction of the EET pathway in Rhodopseudomonas palustris TIE-1, Sideroxydans lithotrophicus ES-1, Thermincola potens JR, Lysinibacillus varians GY32, Carboxydothermus ferrireducens, Enterococcus faecalis and Saccharomyces cerevisiae have been included. In addition to this, the article discusses the several approaches to anode modification and genetic engineering that may be used in order to increase the rate of extracellular electron transfer. In the side lines, this review includes the engagement of the electrogens for different applications followed by the future perspective of efficient extracellular electron transfer.
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Affiliation(s)
- Manisha Verma
- School of Biochemical Engineering, IIT (BHU), 221005, Varanasi, India
| | - Vishal Singh
- School of Biochemical Engineering, IIT (BHU), 221005, Varanasi, India
| | - Vishal Mishra
- School of Biochemical Engineering, IIT (BHU), 221005, Varanasi, India.
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Brown B, Wilkins M, Saha R. Rhodopseudomonas palustris: A biotechnology chassis. Biotechnol Adv 2022; 60:108001. [PMID: 35680002 DOI: 10.1016/j.biotechadv.2022.108001] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 05/18/2022] [Accepted: 06/01/2022] [Indexed: 11/26/2022]
Abstract
Rhodopseudomonas palustris is an attractive option for biotechnical applications and industrial engineering due to its metabolic versatility and its ability to catabolize a wide variety of feedstocks and convert them to several high-value products. Given its adaptable metabolism, R. palustris has been studied and applied in an extensive variety of applications such as examining metabolic tradeoffs for environmental perturbations, biodegradation of aromatic compounds, environmental remediation, biofuel production, agricultural biostimulation, and bioelectricity production. This review provides a holistic summary of the commercial applications for R. palustris as a biotechnology chassis and suggests future perspectives for research and engineering.
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Affiliation(s)
- Brandi Brown
- Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln, NE 68583, USA
| | - Mark Wilkins
- Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln, NE 68583, USA; Industrial Agricultural Products Center, University of Nebraska-Lincoln, Lincoln, NE 68583, USA; Department of Food Science and Technology, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - Rajib Saha
- Department of Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588, USA.
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Li M, Ning P, Sun Y, Luo J, Yang J. Characteristics and Application of Rhodopseudomonas palustris as a Microbial Cell Factory. Front Bioeng Biotechnol 2022; 10:897003. [PMID: 35646843 PMCID: PMC9133744 DOI: 10.3389/fbioe.2022.897003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 04/27/2022] [Indexed: 01/20/2023] Open
Abstract
Rhodopseudomonas palustris, a purple nonsulfur bacterium, is a bacterium with the properties of extraordinary metabolic versatility, carbon source diversity and metabolite diversity. Due to its biodetoxification and biodegradation properties, R. palustris has been traditionally applied in wastewater treatment and bioremediation. R. palustris is rich in various metabolites, contributing to its application in agriculture, aquaculture and livestock breeding as additives. In recent years, R. palustris has been engineered as a microbial cell factory to produce valuable chemicals, especially photofermentation of hydrogen. The outstanding property of R. palustris as a microbial cell factory is its ability to use a diversity of carbon sources. R. palustris is capable of CO2 fixation, contributing to photoautotrophic conversion of CO2 into valuable chemicals. R. palustris can assimilate short-chain organic acids and crude glycerol from industrial and agricultural wastewater. Lignocellulosic biomass hydrolysates can also be degraded by R. palustris. Utilization of these feedstocks can reduce the industry cost and is beneficial for environment. Applications of R. palustris for biopolymers and their building blocks production, and biofuels production are discussed. Afterward, some novel applications in microbial fuel cells, microbial electrosynthesis and photocatalytic synthesis are summarized. The challenges of the application of R. palustris are analyzed, and possible solutions are suggested.
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Affiliation(s)
- Meijie Li
- Energy-Rich Compound Production by Photosynthetic Carbon Fixation Research Center, Shandong Key Lab of Applied Mycology, Qingdao Agricultural University, Qingdao, China
- College of Life Sciences, Qingdao Agricultural University, Qingdao, China
| | - Peng Ning
- Energy-Rich Compound Production by Photosynthetic Carbon Fixation Research Center, Shandong Key Lab of Applied Mycology, Qingdao Agricultural University, Qingdao, China
- College of Life Sciences, Qingdao Agricultural University, Qingdao, China
| | - Yi Sun
- Haiyang Comprehensive Administrative Law Enforcement Bureau (Agriculture), Haiyang, China
| | - Jie Luo
- Qingdao Garden Forestry Technology School, Qingdao, China
- *Correspondence: Jie Luo, ; Jianming Yang,
| | - Jianming Yang
- Energy-Rich Compound Production by Photosynthetic Carbon Fixation Research Center, Shandong Key Lab of Applied Mycology, Qingdao Agricultural University, Qingdao, China
- College of Life Sciences, Qingdao Agricultural University, Qingdao, China
- *Correspondence: Jie Luo, ; Jianming Yang,
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Conners EM, Rengasamy K, Bose A. "Electroactive biofilms: how microbial electron transfer enables bioelectrochemical applications". J Ind Microbiol Biotechnol 2022; 49:6563884. [PMID: 35381088 PMCID: PMC9338886 DOI: 10.1093/jimb/kuac012] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 03/30/2022] [Indexed: 11/22/2022]
Abstract
Microbial biofilms are ubiquitous. In marine and freshwater ecosystems, microbe–mineral interactions sustain biogeochemical cycles, while biofilms found on plants and animals can range from pathogens to commensals. Moreover, biofouling and biocorrosion represent significant challenges to industry. Bioprocessing is an opportunity to take advantage of biofilms and harness their utility as a chassis for biocommodity production. Electrochemical bioreactors have numerous potential applications, including wastewater treatment and commodity production. The literature examining these applications has demonstrated that the cell–surface interface is vital to facilitating these processes. Therefore, it is necessary to understand the state of knowledge regarding biofilms’ role in bioprocessing. This mini-review discusses bacterial biofilm formation, cell–surface redox interactions, and the role of microbial electron transfer in bioprocesses. It also highlights some current goals and challenges with respect to microbe-mediated bioprocessing and future perspectives.
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Affiliation(s)
- Eric M Conners
- Department of Biology. One Brookings Drive, Washington University in St. Louis, Missouri, 63105, USA
| | - Karthikeyan Rengasamy
- Department of Biology. One Brookings Drive, Washington University in St. Louis, Missouri, 63105, USA
| | - Arpita Bose
- Department of Biology. One Brookings Drive, Washington University in St. Louis, Missouri, 63105, USA
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Liao X, Pan Q, Tian X, Wu X, Zhao F. Proteomic analysis of the electron uptake pathway of Rhodopseudomonas palustris CGA009 under different cathodic potentials. Process Biochem 2022. [DOI: 10.1016/j.procbio.2022.01.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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8
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Bai W, Ranaivoarisoa TO, Singh R, Rengasamy K, Bose A. n-Butanol production by Rhodopseudomonas palustris TIE-1. Commun Biol 2021; 4:1257. [PMID: 34732832 PMCID: PMC8566592 DOI: 10.1038/s42003-021-02781-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 10/06/2021] [Indexed: 11/09/2022] Open
Abstract
Anthropogenic carbon dioxide (CO2) release in the atmosphere from fossil fuel combustion has inspired scientists to study CO2 to biofuel conversion. Oxygenic phototrophs such as cyanobacteria have been used to produce biofuels using CO2. However, oxygen generation during oxygenic photosynthesis adversely affects biofuel production efficiency. To produce n-butanol (biofuel) from CO2, here we introduce an n-butanol biosynthesis pathway into an anoxygenic (non-oxygen evolving) photoautotroph, Rhodopseudomonas palustris TIE-1 (TIE-1). Using different carbon, nitrogen, and electron sources, we achieve n-butanol production in wild-type TIE-1 and mutants lacking electron-consuming (nitrogen-fixing) or acetyl-CoA-consuming (polyhydroxybutyrate and glycogen synthesis) pathways. The mutant lacking the nitrogen-fixing pathway produce the highest n-butanol. Coupled with novel hybrid bioelectrochemical platforms, this mutant produces n-butanol using CO2, solar panel-generated electricity, and light with high electrical energy conversion efficiency. Overall, this approach showcases TIE-1 as an attractive microbial chassis for carbon-neutral n-butanol bioproduction using sustainable, renewable, and abundant resources.
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Affiliation(s)
- Wei Bai
- grid.4367.60000 0001 2355 7002Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, MO USA
| | - Tahina Onina Ranaivoarisoa
- grid.4367.60000 0001 2355 7002Department of Biology, Washington University in St. Louis, St. Louis, MO USA
| | - Rajesh Singh
- grid.4367.60000 0001 2355 7002Department of Biology, Washington University in St. Louis, St. Louis, MO USA
| | - Karthikeyan Rengasamy
- grid.4367.60000 0001 2355 7002Department of Biology, Washington University in St. Louis, St. Louis, MO USA
| | - Arpita Bose
- grid.4367.60000 0001 2355 7002Department of Biology, Washington University in St. Louis, St. Louis, MO USA
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Photoferrotrophy and phototrophic extracellular electron uptake is common in the marine anoxygenic phototroph Rhodovulum sulfidophilum. THE ISME JOURNAL 2021; 15:3384-3398. [PMID: 34054125 PMCID: PMC8528915 DOI: 10.1038/s41396-021-01015-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 05/07/2021] [Accepted: 05/12/2021] [Indexed: 02/03/2023]
Abstract
Photoferrotrophy allows anoxygenic phototrophs to use reduced iron as an electron donor for primary productivity. Recent work shows that freshwater photoferrotrophs can use electrons from solid-phase conductive substances via phototrophic extracellular electron uptake (pEEU), and the two processes share the underlying electron uptake mechanism. However, the ability of marine phototrophs to perform photoferrotrophy and pEEU, and the contribution of these processes to primary productivity is largely unknown. To fill this knowledge gap, we isolated 15 new strains of the marine anoxygenic phototroph Rhodovulum sulfidophilum on electron donors such as acetate and thiosulfate. We observed that all of the R. sulfidophilum strains isolated can perform photoferrotrophy. We chose strain AB26 as a representative strain to study further, and find that it can also perform pEEU from poised electrodes. We show that during pEEU, AB26 transfers electrons to the photosynthetic electron transport chain. Furthermore, systems biology-guided mutant analysis shows that R. sulfidophilum AB26 uses a previously unknown diheme cytochrome c protein, which we call EeuP, for pEEU but not photoferrotrophy. Homologs of EeuP occur in a range of widely distributed marine microbes. Overall, these results suggest that photoferrotrophy and pEEU contribute to the biogeochemical cycling of iron and carbon in marine ecosystems.
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Assessment of Voltage Influence in Carbon Dioxide Fixation Process by a Photo-Bioelectrochemical System under Photoheterotrophy. Microorganisms 2021; 9:microorganisms9030474. [PMID: 33668742 PMCID: PMC7996144 DOI: 10.3390/microorganisms9030474] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/15/2021] [Accepted: 02/18/2021] [Indexed: 11/16/2022] Open
Abstract
Bioelectrochemical systems are a promising technology capable of reducing CO2 emissions, a renewable carbon source, using electroactive microorganisms for this purpose. Purple Phototrophic Bacteria (PPB) use their versatile metabolism to uptake external electrons from an electrode to fix CO2. In this work, the effect of the voltage (from −0.2 to −0.8 V vs. Ag/AgCl) on the metabolic CO2 fixation of a mixed culture of PPB under photoheterotrophic conditions during the oxidation of a biodegradable carbon source is demonstrated. The minimum voltage to fix CO2 was between −0.2 and −0.4 V. The Calvin–Benson–Bassham (CBB) cycle is the main electron sink at these voltages. However, lower voltages caused the decrease in the current intensity, reaching a minimum at −0.8 V (−4.75 mA). There was also a significant relationship between the soluble carbon uptake in terms of chemical oxygen demand and the electron consumption for the experiments performed at −0.6 and −0.8 V. These results indicate that the CBB cycle is not the only electron sink and some photoheterotrophic metabolic pathways are also being affected under electrochemical conditions. This behavior has not been tested before in photoheterotrophic conditions and paves the way for the future development of photobioelectrochemical systems under heterotrophic conditions.
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Rengasamy K, Ranaivoarisoa T, Bai W, Bose A. Magnetite nanoparticle anchored graphene cathode enhances microbial electrosynthesis of polyhydroxybutyrate by Rhodopseudomonas palustris TIE-1. NANOTECHNOLOGY 2021; 32:035103. [PMID: 33017807 DOI: 10.1088/1361-6528/abbe58] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Microbial electrosynthesis (MES) is an emerging technology that can convert carbon dioxide (CO2) into value-added organic carbon compounds using electrons supplied from a cathode. However, MES is affected by low product formation due to limited extracellular electron uptake by microbes. Herein, a novel cathode was developed from chemically synthesized magnetite nanoparticles and reduced graphene oxide nanocomposite (rGO-MNPs). This nanocomposite was electrochemically deposited on carbon felt (CF/rGO-MNPs), and the modified material was used as a cathode for MES production. The bioplastic, polyhydroxybutyrate (PHB) produced by Rhodopseudomonas palustris TIE-1 (TIE-1), was measured from reactors with modified and unmodified cathodes. Results demonstrate that the magnetite nanoparticle anchored graphene cathode (CF/rGO-MNPs) exhibited higher PHB production (91.31 ± 0.9 mg l-1). This is ∼4.2 times higher than unmodified carbon felt (CF), and 20 times higher than previously reported using graphite. This modified cathode enhanced electron uptake to -11.7 ± 0.1 μA cm-2, ∼5 times higher than CF cathode (-2.3 ± 0.08 μA cm-2). The faradaic efficiency of the modified cathode was ∼2 times higher than the unmodified cathode. Electrochemical analysis and scanning electron microscopy suggest that rGO-MNPs facilitated electron uptake and improved PHB production by TIE-1. Overall, the nanocomposite (rGO-MNPs) cathode modification enhances MES efficiency.
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Affiliation(s)
- Karthikeyan Rengasamy
- Department of Biology, Washington University in Saint Louis, St. Louis, MO, 63130, United States of America
| | - Tahina Ranaivoarisoa
- Department of Biology, Washington University in Saint Louis, St. Louis, MO, 63130, United States of America
| | - Wei Bai
- Department of Biology, Washington University in Saint Louis, St. Louis, MO, 63130, United States of America
- Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, MO, United States of America
| | - Arpita Bose
- Department of Biology, Washington University in Saint Louis, St. Louis, MO, 63130, United States of America
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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: 26] [Impact Index Per Article: 8.7] [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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Li DB, Edwards MJ, Blake AW, Newton-Payne SE, Piper SEH, Jenner LP, Sokol KP, Reisner E, Van Wonderen JH, Clarke TA, Butt JN. His/Met heme ligation in the PioA outer membrane cytochrome enabling light-driven extracellular electron transfer by Rhodopseudomonas palustris TIE-1. NANOTECHNOLOGY 2020; 31:354002. [PMID: 32403091 DOI: 10.1088/1361-6528/ab92c7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A growing number of bacterial species are known to move electrons across their cell envelopes. Naturally this occurs in support of energy conservation and carbon-fixation. For biotechnology it allows electron exchange between bacteria and electrodes in microbial fuel cells and during microbial electrosynthesis. In this context Rhodopseudomonas palustris TIE-1 is of much interest. These bacteria respond to light by taking electrons from their external environment, including electrodes, to drive CO2-fixation. The PioA cytochrome, that spans the bacterial outer membrane, is essential for this electron transfer and yet little is known about its structure and electron transfer properties. Here we reveal the ten c-type hemes of PioA are redox active across the window +250 to -400 mV versus Standard Hydrogen Electrode and that the hemes with most positive reduction potentials have His/Met and His/H2O ligation. These chemical and redox properties distinguish PioA from the more widely studied family of MtrA outer membrane decaheme cytochromes with ten His/His ligated hemes. We predict a structure for PioA in which the hemes form a chain spanning the longest dimension of the protein, from Heme 1 to Heme 10. Hemes 2, 3 and 7 are identified as those most likely to have His/Met and/or His/H2O ligation. Sequence analysis suggests His/Met ligation of Heme 2 and/or 7 is a defining feature of decaheme PioA homologs from over 30 different bacterial genera. His/Met ligation of Heme 3 appears to be less common and primarily associated with PioA homologs from purple non-sulphur bacteria belonging to the alphaproteobacteria class.
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Affiliation(s)
- Dao-Bo Li
- School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom. Present address: Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, China and State Key Laboratory of Applied Microbiology Southern China, Guangzhou, People's Republic of China
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Yee MO, Deutzmann J, Spormann A, Rotaru AE. Cultivating electroactive microbes-from field to bench. NANOTECHNOLOGY 2020; 31:174003. [PMID: 31931483 DOI: 10.1088/1361-6528/ab6ab5] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Electromicrobiology is an emerging field investigating and exploiting the interaction of microorganisms with insoluble electron donors or acceptors. Some of the most recently categorized electroactive microorganisms became of interest to sustainable bioengineering practices. However, laboratories worldwide typically maintain electroactive microorganisms on soluble substrates, which often leads to a decrease or loss of the ability to effectively exchange electrons with solid electrode surfaces. In order to develop future sustainable technologies, we cannot rely solely on existing lab-isolates. Therefore, we must develop isolation strategies for environmental strains with electroactive properties superior to strains in culture collections. In this article, we provide an overview of the studies that isolated or enriched electroactive microorganisms from the environment using an anode as the sole electron acceptor (electricity-generating microorganisms) or a cathode as the sole electron donor (electricity-consuming microorganisms). Next, we recommend a selective strategy for the isolation of electroactive microorganisms. Furthermore, we provide a practical guide for setting up electrochemical reactors and highlight crucial electrochemical techniques to determine electroactivity and the mode of electron transfer in novel organisms.
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Affiliation(s)
- Mon Oo Yee
- Nordcee, Department of Biology, University of Southern Denmark, Odense, DK-5230, Denmark
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Gupta D, Sutherland MC, Rengasamy K, Meacham JM, Kranz RG, Bose A. Photoferrotrophs Produce a PioAB Electron Conduit for Extracellular Electron Uptake. mBio 2019; 10:e02668-19. [PMID: 31690680 PMCID: PMC6831781 DOI: 10.1128/mbio.02668-19] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 10/10/2019] [Indexed: 11/20/2022] Open
Abstract
Photoferrotrophy is a form of anoxygenic photosynthesis whereby bacteria utilize soluble or insoluble forms of ferrous iron as an electron donor to fix carbon dioxide using light energy. They can also use poised electrodes as their electron donor via phototrophic extracellular electron uptake (phototrophic EEU). The electron uptake mechanisms underlying these processes are not well understood. Using Rhodopseudomonas palustris TIE-1 as a model, we show that a single periplasmic decaheme cytochrome c, PioA, and an outer membrane porin, PioB, form a complex allowing extracellular electron uptake across the outer membrane from both soluble iron and poised electrodes. We observe that PioA undergoes postsecretory proteolysis of its N terminus to produce a shorter heme-attached PioA (holo-PioAC, where PioAC represents the C terminus of PioA), which can exist both freely in the periplasm and in a complex with PioB. The extended N-terminal peptide controls heme attachment, and its processing is required to produce wild-type levels of holo-PioAC and holo-PioACB complex. It is also conserved in PioA homologs from other phototrophs. The presence of PioAB in these organisms correlate with their ability to perform photoferrotrophy and phototrophic EEU.IMPORTANCE Some anoxygenic phototrophs use soluble iron, insoluble iron minerals (such as rust), or their proxies (poised electrodes) as electron donors for photosynthesis. However, the underlying electron uptake mechanisms are not well established. Here, we show that these phototrophs use a protein complex made of an outer membrane porin and a periplasmic decaheme cytochrome (electron transfer protein) to harvest electrons from both soluble iron and poised electrodes. This complex has two unique characteristics: (i) it lacks an extracellular cytochrome c, and (ii) the periplasmic decaheme cytochrome c undergoes proteolytic cleavage to produce a functional electron transfer protein. These characteristics are conserved in phototrophs harboring homologous proteins.
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Affiliation(s)
- Dinesh Gupta
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Molly C Sutherland
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | | | - J Mark Meacham
- Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, Missouri, USA
- Institute of Materials Science and Engineering, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Robert G Kranz
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Arpita Bose
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
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16
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Ranaivoarisoa TO, Singh R, Rengasamy K, Guzman MS, Bose A. Towards sustainable bioplastic production using the photoautotrophic bacterium Rhodopseudomonas palustris TIE-1. J Ind Microbiol Biotechnol 2019; 46:1401-1417. [PMID: 30927110 PMCID: PMC6791910 DOI: 10.1007/s10295-019-02165-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 03/23/2019] [Indexed: 12/22/2022]
Abstract
Bacterial synthesis of polyhydroxybutyrates (PHBs) is a potential approach for producing biodegradable plastics. This study assessed the ability of Rhodopseudomonas palustris TIE-1 to produce PHBs under various conditions. We focused on photoautotrophy using a poised electrode (photoelectroautotrophy) or ferrous iron (photoferroautotrophy) as electron donors. Growth conditions were tested with either ammonium chloride or dinitrogen gas as the nitrogen source. Although TIE-1's capacity to produce PHBs varied fairly under different conditions, photoelectroautotrophy and photoferroautotrophy showed the highest PHB electron yield and the highest specific PHB productivity, respectively. Gene expression analysis showed that there was no differential expression in PHB biosynthesis genes. This suggests that the variations in PHB accumulation might be post-transcriptionally regulated. This is the first study to systematically quantify the amount of PHB produced by a microbe via photoelectroautotrophy and photoferroautotrophy. This work could lead to sustainable bioproduction using abundant resources such as light, electricity, iron, and carbon dioxide.
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Affiliation(s)
- Tahina Onina Ranaivoarisoa
- Department of Biology, Washington University in St. Louis, One Brookings Drive, St. Louis, MO, 63130, USA
| | - Rajesh Singh
- Department of Biology, Washington University in St. Louis, One Brookings Drive, St. Louis, MO, 63130, USA
| | - Karthikeyan Rengasamy
- Department of Biology, Washington University in St. Louis, One Brookings Drive, St. Louis, MO, 63130, USA
| | - Michael S Guzman
- Department of Biology, Washington University in St. Louis, One Brookings Drive, St. Louis, MO, 63130, USA
| | - Arpita Bose
- Department of Biology, Washington University in St. Louis, One Brookings Drive, St. Louis, MO, 63130, USA.
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Karthikeyan R, Singh R, Bose A. Microbial electron uptake in microbial electrosynthesis: a mini-review. ACTA ACUST UNITED AC 2019; 46:1419-1426. [DOI: 10.1007/s10295-019-02166-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 03/23/2019] [Indexed: 10/27/2022]
Abstract
Abstract
Microbial electron uptake (EU) is the biological capacity of microbes to accept electrons from electroconductive solid materials. EU has been leveraged for sustainable bioproduction strategies via microbial electrosynthesis (MES). MES often involves the reduction of carbon dioxide to multi-carbon molecules, with electrons derived from electrodes in a bioelectrochemical system. EU can be indirect or direct. Indirect EU-based MES uses electron mediators to transfer electrons to microbes. Although an excellent initial strategy, indirect EU requires higher electrical energy. In contrast, the direct supply of cathodic electrons to microbes (direct EU) is more sustainable and energy efficient. Nonetheless, low product formation due to low electron transfer rates during direct EU remains a major challenge. Compared to indirect EU, direct EU is less well-studied perhaps due to the more recent discovery of this microbial capability. This mini-review focuses on the recent advances and challenges of direct EU in relation to MES.
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Affiliation(s)
- Rengasamy Karthikeyan
- grid.4367.6 0000 0001 2355 7002 Department of Biology Washington University in Saint Louis One Brookings Drive 63130 St. Louis MO USA
| | - Rajesh Singh
- grid.4367.6 0000 0001 2355 7002 Department of Biology Washington University in Saint Louis One Brookings Drive 63130 St. Louis MO USA
| | - Arpita Bose
- grid.4367.6 0000 0001 2355 7002 Department of Biology Washington University in Saint Louis One Brookings Drive 63130 St. Louis MO USA
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Soundararajan M, Ledbetter R, Kusuma P, Zhen S, Ludden P, Bugbee B, Ensign SA, Seefeldt LC. Phototrophic N 2 and CO 2 Fixation Using a Rhodopseudomonas palustris-H 2 Mediated Electrochemical System With Infrared Photons. Front Microbiol 2019; 10:1817. [PMID: 31474945 PMCID: PMC6705187 DOI: 10.3389/fmicb.2019.01817] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 07/23/2019] [Indexed: 11/13/2022] Open
Abstract
A promising approach for the synthesis of high value reduced compounds is to couple bacteria to the cathode of an electrochemical cell, with delivery of electrons from the electrode driving reductive biosynthesis in the bacteria. Such systems have been used to reduce CO2 to acetate and other C-based compounds. Here, we report an electrosynthetic system that couples a diazotrophic, photoautotrophic bacterium, Rhodopseudomonas palustris TIE-1, to the cathode of an electrochemical cell through the mediator H2 that allows reductive capture of both CO2 and N2 with all of the energy coming from the electrode and infrared (IR) photons. R. palustris TIE-1 was shown to utilize a narrow band of IR radiation centered around 850 nm to support growth under both photoheterotrophic, non-diazotrophic and photoautotrophic, diazotrophic conditions with growth rates similar to those achieved using broad spectrum incandescent light. The bacteria were also successfully cultured in the cathodic compartment of an electrochemical cell with the sole source of electrons coming from electrochemically generated H2, supporting reduction of both CO2 and N2 using 850 nm photons as an energy source. Growth rates were similar to non-electrochemical conditions, revealing that the electrochemical system can fully support bacterial growth. Faradaic efficiencies for N2 and CO2 reduction were 8.5 and 47%, respectively. These results demonstrate that a microbial-electrode hybrid system can be used to achieve reduction and capture of both CO2 and N2 using low energy IR radiation and electrons provided by an electrode.
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Affiliation(s)
- Mathangi Soundararajan
- Department of Chemistry and Biochemistry, Utah State University, Logan, UT, United States
| | - Rhesa Ledbetter
- Department of Biological Sciences, Idaho State University, Pocatello, ID, United States
| | - Paul Kusuma
- Department of Plant, Soils and Climate, Utah State University, Logan, UT, United States
| | - Shuyang Zhen
- Department of Plant, Soils and Climate, Utah State University, Logan, UT, United States
| | - Paul Ludden
- Department of Biology, Southern Methodist University, Dallas, TX, United States
| | - Bruce Bugbee
- Department of Plant, Soils and Climate, Utah State University, Logan, UT, United States
| | - Scott A Ensign
- Department of Chemistry and Biochemistry, Utah State University, Logan, UT, United States
| | - Lance C Seefeldt
- Department of Chemistry and Biochemistry, Utah State University, Logan, UT, United States
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19
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Guzman MS, Rengasamy K, Binkley MM, Jones C, Ranaivoarisoa TO, Singh R, Fike DA, Meacham JM, Bose A. Phototrophic extracellular electron uptake is linked to carbon dioxide fixation in the bacterium Rhodopseudomonas palustris. Nat Commun 2019; 10:1355. [PMID: 30902976 PMCID: PMC6430793 DOI: 10.1038/s41467-019-09377-6] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 03/07/2019] [Indexed: 01/06/2023] Open
Abstract
Extracellular electron uptake (EEU) is the ability of microbes to take up electrons from solid-phase conductive substances such as metal oxides. EEU is performed by prevalent phototrophic bacterial genera, but the electron transfer pathways and the physiological electron sinks are poorly understood. Here we show that electrons enter the photosynthetic electron transport chain during EEU in the phototrophic bacterium Rhodopseudomonas palustris TIE-1. Cathodic electron flow is also correlated with a highly reducing intracellular redox environment. We show that reducing equivalents are used for carbon dioxide (CO2) fixation, which is the primary electron sink. Deletion of the genes encoding ruBisCO (the CO2-fixing enzyme of the Calvin-Benson-Bassham cycle) leads to a 90% reduction in EEU. This work shows that phototrophs can directly use solid-phase conductive substances for electron transfer, energy transduction, and CO2 fixation. Extracellular electron uptake (EEU) is the ability of microbes to take up electrons from solid-phase conductive substances such as metal oxides. Here, Guzman et al. show that electrons enter the photosynthetic electron transport chain and are used for CO2 fixation during EEU in a phototrophic bacterium.
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Affiliation(s)
- Michael S Guzman
- Department of Biology, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Karthikeyan Rengasamy
- Department of Biology, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Michael M Binkley
- Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Clive Jones
- Department of Earth and Planetary Sciences, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | | | - Rajesh Singh
- Department of Biology, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - David A Fike
- Department of Earth and Planetary Sciences, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - J Mark Meacham
- Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, MO, 63130, USA.,Institute of Materials Science Engineering, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Arpita Bose
- Department of Biology, Washington University in St. Louis, St. Louis, MO, 63130, USA.
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