1
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Li K, Zhang X, Li C, Liang YC, Zhao XQ, Liu CG, Sinskey AJ, Bai FW. Systems metabolic engineering of Corynebacterium glutamicum to assimilate formic acid for biomass accumulation and succinic acid production. BIORESOURCE TECHNOLOGY 2024; 402:130774. [PMID: 38701983 DOI: 10.1016/j.biortech.2024.130774] [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: 01/07/2024] [Revised: 04/28/2024] [Accepted: 04/29/2024] [Indexed: 05/06/2024]
Abstract
Formate as an ideal mediator between the physicochemical and biological realms can be obtained from electrochemical reduction of CO2 and used to produce bio-chemicals. Yet, limitations arise when employing natural formate-utilizing microorganisms due to restricted product range and low biomass yield. This study presents a breakthrough: engineered Corynebacterium glutamicum strains (L2-L4) through modular engineering. L2 incorporates the formate-tetrahydrofolate cycle and reverse glycine cleavage pathway, L3 enhances NAD(P)H regeneration, and L4 reinforces metabolic flux. Metabolic modeling elucidates C1 assimilation, guiding strain optimization for co-fermentation of formate and glucose. Strain L4 achieves an OD600 of 0.5 and produces 0.6 g/L succinic acid. 13C-labeled formate confirms C1 assimilation, and further laboratory evolution yields 1.3 g/L succinic acid. This study showcases a successful model for biologically assimilating formate in C. glutamicum that could be applied in C1-based biotechnological production, ultimately forming a formate-based bioeconomy.
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Affiliation(s)
- Kai Li
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Xue Zhang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Cheng Li
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Disruptive & Sustainable Technologies for Agricultural Precision, Singapore-MIT Alliance for Research and Technology, Singapore 138602, Singapore
| | - Yu-Cheng Liang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Xin-Qing Zhao
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Chen-Guang Liu
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.
| | - Anthony J Sinskey
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Disruptive & Sustainable Technologies for Agricultural Precision, Singapore-MIT Alliance for Research and Technology, Singapore 138602, Singapore
| | - Feng-Wu Bai
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
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2
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Victoria AJ, Astbury MJ, McCormick AJ. Engineering highly productive cyanobacteria towards carbon negative emissions technologies. Curr Opin Biotechnol 2024; 87:103141. [PMID: 38735193 DOI: 10.1016/j.copbio.2024.103141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 04/19/2024] [Accepted: 04/20/2024] [Indexed: 05/14/2024]
Abstract
Cyanobacteria are a diverse and ecologically important group of photosynthetic prokaryotes that contribute significantly to the global carbon cycle through the capture of CO2 as biomass. Cyanobacterial biotechnology could play a key role in a sustainable bioeconomy through negative emissions technologies (NETs), such as carbon sequestration or bioproduction. However, the primary issues of low productivities and high infrastructure costs currently limit the commercialisation of such applications. The isolation of several fast-growing strains and recent advancements in molecular biology tools now offer promising new avenues for improving yields, including metabolic engineering approaches guided by high-throughput screening and metabolic models. Furthermore, emerging research on engineering coculture communities could help to develop more robust culturing systems to support broader NET applications.
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Affiliation(s)
- Angelo J Victoria
- Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, EH9 3BF UK; Centre for Engineering Biology, School of Biological Sciences, University of Edinburgh, EH9 3BF UK
| | - Michael J Astbury
- Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, EH9 3BF UK; Centre for Engineering Biology, School of Biological Sciences, University of Edinburgh, EH9 3BF UK
| | - Alistair J McCormick
- Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, EH9 3BF UK; Centre for Engineering Biology, School of Biological Sciences, University of Edinburgh, EH9 3BF UK.
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3
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Domínguez-Lobo MT, Roldán M, Gutiérrez-Diánez AM, Florencio FJ, Muro-Pastor MI. Double blocking of carbon metabolism causes a large increase of Calvin-Benson cycle compounds in cyanobacteria. PLANT PHYSIOLOGY 2024; 195:1491-1505. [PMID: 38377468 PMCID: PMC11142378 DOI: 10.1093/plphys/kiae083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 01/08/2024] [Accepted: 01/19/2024] [Indexed: 02/22/2024]
Abstract
Carbon-flow-regulator A (CfrA) adapts carbon flux to nitrogen conditions in nondiazotrophic cyanobacteria. Under nitrogen deficiency, CfrA leads to the storage of excess carbon, which cannot combine with nitrogen, mainly as glycogen. cfrA overexpression from the arsenite-inducible, nitrogen-independent ParsB promoter allows analysis of the metabolic effects of CfrA accumulation. Considering that the main consequence of cfrA overexpression is glycogen accumulation, we examined carbon distribution in response to cfrA expression in Synechocystis sp. PCC 6803 strains impaired in synthesizing this polymer. We carried out a comparative phenotypic analysis to evaluate cfrA overexpression in the wild-type strain and in a mutant of ADP-glucose pyrophosphorylase (ΔglgC), which is unable to synthesize glycogen. The accumulation of CfrA in the wild-type background caused a photosynthetic readjustment although growth was not affected. However, in a ΔglgC strain, growth decreased depending on CfrA accumulation and photosynthesis was severely affected. An elemental analysis of the H, C, and N content of cells revealed that cfrA expression in the wild-type caused an increase in the C/N ratio, due to decreased nitrogen assimilation. Metabolomic study indicated that these cells store sucrose and glycosylglycerol, in addition to the previously described glycogen accumulation. However, cells deficient in glycogen synthesis accumulated large amounts of Calvin-Benson cycle intermediates as cfrA was expressed. These cells also showed increased levels of some amino acids, mainly alanine, serine, valine, isoleucine, and leucine. The findings suggest that by controlling cfrA expression, in different conditions and strains, we could change the distribution of fixed carbon, with potential biotechnological benefits.
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Affiliation(s)
| | - Miguel Roldán
- Instituto de Bioquímica Vegetal y Fotosíntesis (IBVF), CSIC-Universidad de Sevilla, Sevilla 41092, Spain
- Departamento de Bioquímica Vegetal y Biología Molecular, Facultad de Biología, Universidad de Sevilla, Sevilla 41012, Spain
| | - Alba María Gutiérrez-Diánez
- Instituto de Bioquímica Vegetal y Fotosíntesis (IBVF), CSIC-Universidad de Sevilla, Sevilla 41092, Spain
- Departamento de Bioquímica Vegetal y Biología Molecular, Facultad de Biología, Universidad de Sevilla, Sevilla 41012, Spain
| | - Francisco Javier Florencio
- Instituto de Bioquímica Vegetal y Fotosíntesis (IBVF), CSIC-Universidad de Sevilla, Sevilla 41092, Spain
- Departamento de Bioquímica Vegetal y Biología Molecular, Facultad de Biología, Universidad de Sevilla, Sevilla 41012, Spain
| | - María Isabel Muro-Pastor
- Instituto de Bioquímica Vegetal y Fotosíntesis (IBVF), CSIC-Universidad de Sevilla, Sevilla 41092, Spain
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4
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Yalcin YS, Aydin BN, Sitther V. Impact of Zero-Valent Iron Nanoparticles and Ampicillin on Adenosine Triphosphate and Lactate Metabolism in the Cyanobacterium Fremyella diplosiphon. Microorganisms 2024; 12:612. [PMID: 38543663 PMCID: PMC10975374 DOI: 10.3390/microorganisms12030612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 02/14/2024] [Accepted: 02/22/2024] [Indexed: 04/01/2024] Open
Abstract
In cyanobacteria, the interplay of ATP and lactate dynamics underpins cellular energetics; their pronounced shifts in response to zero-valent iron (nZVI) nanoparticles and ampicillin highlight the nuanced metabolic adaptations to environmental challenges. In this study, we investigated the impact of nZVIs and ampicillin on Fremyella diplosiphon cellular energetics as determined by adenosine triphosphate (ATP) content, intracellular and extracellular lactate levels, and their impact on cell morphology as visualized by transmission electron microscopy. While a significant increase in ATP concentration was observed in 0.8 mg/L ampicillin-treated cells compared to the untreated control, a significant decline was noted in cells treated with 3.2 mg/L nZVIs. ATP levels in the combination regimen of 0.8 mg/L ampicillin and 3.2 mg/L nZVIs were significantly elevated (p < 0.05) compared to the 3.2 mg/L nZVI treatment. Intracellular and extracellular lactate levels were significantly higher in 0.8 mg/L ampicillin, 3.2 mg/L nZVIs, and the combination regimen compared to the untreated control; however, extracellular lactate levels were the highest in cells treated with 3.2 mg/L nZVIs. Visualization of morphological changes indicated increased thylakoid membrane stacks and inter-thylakoidal distances in 3.2 mg/L nZVI-treated cells. Our findings demonstrate a complex interplay of nanoparticle and antibiotic-induced responses, highlighting the differential impact of these stressors on F. diplosiphon metabolism and cellular integrity.
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Affiliation(s)
| | | | - Viji Sitther
- Department of Biology, Morgan State University, 1700 E. Cold Spring Lane, Baltimore, MD 21251, USA
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5
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Diankristanti PA, Lin YC, Yi YC, Ng IS. Polyhydroxyalkanoates bioproduction from bench to industry: Thirty years of development towards sustainability. BIORESOURCE TECHNOLOGY 2024; 393:130149. [PMID: 38049017 DOI: 10.1016/j.biortech.2023.130149] [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: 11/09/2023] [Revised: 11/30/2023] [Accepted: 12/01/2023] [Indexed: 12/06/2023]
Abstract
The pursuit of carbon neutrality goals has sparked considerable interest in expanding bioplastics production from microbial cell factories. One prominent class of bioplastics, polyhydroxyalkanoates (PHA), is generated by specific microorganisms, serving as carbon and energy storage materials. To begin with, a native PHA producer, Cupriavidus necator (formerly Ralstonia eutropha) is extensively studied, covering essential topics such as carbon source selection, cultivation techniques, and accumulation enhancement strategies. Recently, various hosts including archaea, bacteria, cyanobacteria, yeast, and plants have been explored, stretching the limit of microbial PHA production. This review provides a comprehensive overview of current advancements in PHA bioproduction, spanning from the native to diversified cell factories. Recovery and purification techniques are discussed, and the current status of industrial applications is assessed as a critical milestone for startups. Ultimately, it concludes by addressing contemporary challenges and future prospects, offering insights into the path towards reduced carbon emissions and sustainable development goals.
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Affiliation(s)
| | - Yu-Chieh Lin
- Department of Chemical Engineering, National Cheng Kung University, Tainan, Taiwan
| | - Ying-Chen Yi
- Department of Chemical Engineering, National Cheng Kung University, Tainan, Taiwan; Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, USA
| | - I-Son Ng
- Department of Chemical Engineering, National Cheng Kung University, Tainan, Taiwan.
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6
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Zedler JAZ, Schirmacher AM, Russo DA, Hodgson L, Gundersen E, Matthes A, Frank S, Verkade P, Jensen PE. Self-Assembly of Nanofilaments in Cyanobacteria for Protein Co-localization. ACS NANO 2023; 17:25279-25290. [PMID: 38065569 PMCID: PMC10754207 DOI: 10.1021/acsnano.3c08600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2023] [Revised: 11/12/2023] [Accepted: 11/15/2023] [Indexed: 12/27/2023]
Abstract
Cyanobacteria offer great potential as alternative biotechnological hosts due to their photoautotrophic capacities. However, in comparison to established heterotrophic hosts, several key aspects, such as product titers, are still lagging behind. Nanobiotechnology is an emerging field with great potential to improve existing hosts, but so far, it has barely been explored in microbial photosynthetic systems. Here, we report the establishment of large proteinaceous nanofilaments in the unicellular model cyanobacterium Synechocystis sp. PCC 6803 and the fast-growing cyanobacterial strain Synechococcus elongatus UTEX 2973. Transmission electron microscopy and electron tomography demonstrated that expression of pduA*, encoding a modified bacterial microcompartment shell protein, led to the generation of bundles of longitudinally aligned nanofilaments in S. elongatus UTEX 2973 and shorter filamentous structures in Synechocystis sp. PCC 6803. Comparative proteomics showed that PduA* was at least 50 times more abundant than the second most abundant protein in the cell and that nanofilament assembly had only a minor impact on cellular metabolism. Finally, as a proof-of-concept for co-localization with the filaments, we targeted a fluorescent reporter protein, mCitrine, to PduA* by fusion with an encapsulation peptide that natively interacts with PduA. The establishment of nanofilaments in cyanobacterial cells is an important step toward cellular organization of heterologous pathways and the establishment of cyanobacteria as next-generation hosts.
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Affiliation(s)
- Julie A. Z. Zedler
- Synthetic
Biology of Photosynthetic Organisms, Matthias Schleiden Institute
for Genetics, Bioinformatics and Molecular Botany, Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Alexandra M. Schirmacher
- Synthetic
Biology of Photosynthetic Organisms, Matthias Schleiden Institute
for Genetics, Bioinformatics and Molecular Botany, Friedrich Schiller University Jena, 07743 Jena, Germany
| | - David A. Russo
- Bioorganic
Analytics, Institute for Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Lorna Hodgson
- School
of Biochemistry, University of Bristol, Bristol, BS8 1TD, United Kingdom
| | - Emil Gundersen
- Department
of Plant and Environmental Sciences, University
of Copenhagen, 1871 Frederiksberg, Denmark
| | - Annemarie Matthes
- Department
of Plant and Environmental Sciences, University
of Copenhagen, 1871 Frederiksberg, Denmark
| | - Stefanie Frank
- Department
of Biochemical Engineering, University College
London, London, WC1E 6BT, United
Kingdom
| | - Paul Verkade
- School
of Biochemistry, University of Bristol, Bristol, BS8 1TD, United Kingdom
| | - Poul Erik Jensen
- Department
of Food Science, University of Copenhagen, 1958 Frederiksberg, Denmark
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7
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Orsi E, Nikel PI, Nielsen LK, Donati S. Synergistic investigation of natural and synthetic C1-trophic microorganisms to foster a circular carbon economy. Nat Commun 2023; 14:6673. [PMID: 37865689 PMCID: PMC10590403 DOI: 10.1038/s41467-023-42166-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 10/02/2023] [Indexed: 10/23/2023] Open
Abstract
A true circular carbon economy must upgrade waste greenhouse gases. C1-based biomanufacturing is an attractive solution, in which one carbon (C1) molecules (e.g. CO2, formate, methanol, etc.) are converted by microbial cell factories into value-added goods (i.e. food, feed, and chemicals). To render C1-based biomanufacturing cost-competitive, we must adapt microbial metabolism to perform chemical conversions at high rates and yields. To this end, the biotechnology community has undertaken two (seemingly opposing) paths: optimizing natural C1-trophic microorganisms versus engineering synthetic C1-assimilation de novo in model microorganisms. Here, we pose how these approaches can instead create synergies for strengthening the competitiveness of C1-based biomanufacturing as a whole.
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Affiliation(s)
- Enrico Orsi
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800, Kgs. Lyngby, Denmark
| | - Pablo Ivan Nikel
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800, Kgs. Lyngby, Denmark
| | - Lars Keld Nielsen
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800, Kgs. Lyngby, Denmark
- Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, 4072, Brisbane, QLD, Australia
| | - Stefano Donati
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800, Kgs. Lyngby, Denmark.
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8
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Liang J, Chen Z, Yin P, Hu H, Cheng W, Shang J, Yang Y, Yuan Z, Pan J, Yin Y, Li W, Chen X, Gao X, Qiu B, Wang B. Efficient Semi-Artificial Photosynthesis of Ethylene by a Self-Assembled InP-Cyanobacterial Biohybrid System. CHEMSUSCHEM 2023; 16:e202300773. [PMID: 37381086 DOI: 10.1002/cssc.202300773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Revised: 06/19/2023] [Accepted: 06/27/2023] [Indexed: 06/30/2023]
Abstract
Biomanufacturing of ethylene is particularly important for modern society. Cyanobacterial cells are able to photosynthesize various valuable chemicals. A promising platform for next-generation biomanufacturing, the semiconductor-cyanobacterial hybrid systems are capable of enhancing the solar-to-chemical conversion efficiency. Herein, the native ethylene-producing capability of a filamentous cyanobacterium Nostoc sphaeroides is confirmed experimentally. The self-assembly characteristic of N. sphaeroides is exploited to facilitate its interaction with InP nanomaterial, and the resulting biohybrid system gave rise to further elevated photosynthetic ethylene production. Based on chlorophyll fluorescence measurement and metabolic analysis, the InP nanomaterial-augmented photosystem I activity and enhanced ethylene production metabolism of biohybrid cells are confirmed, the mechanism underlying the material-cell energy transduction as well as nanomaterial-modulated photosynthetic light and dark reactions are established. This work not only demonstrates the potential application of semiconductor-N. sphaeroides biohybrid system as a good platform for sustainable ethylene production but also provides an important reference for future studies to construct and optimize nano-cell biohybrid systems for efficient solar-driven valuable chemical production.
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Affiliation(s)
- Jun Liang
- CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, P. R. China
| | - Zhen Chen
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, 435002, P. R. China
| | - Panqing Yin
- CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, P. R. China
| | - Haitao Hu
- CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, P. R. China
| | - Wenbo Cheng
- CAS-Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032, P. R. China
| | - Jinlong Shang
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, P. R. China
| | - Yiwen Yang
- College of Pharmacy and Life Sciences, Jiujiang University, Jiujiang, Jiangxi, 332000, P.R. China
| | - Zuwen Yuan
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, 435002, P. R. China
| | - Jinlong Pan
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, 435002, P. R. China
| | - Yongqi Yin
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, 435002, P. R. China
| | - Weizhi Li
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, 435002, P. R. China
| | - Xiongwen Chen
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei, 435002, P. R. China
| | - Xiang Gao
- CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, P. R. China
| | - Baosheng Qiu
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, P. R. China
| | - Bo Wang
- CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, P. R. China
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9
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Tüllinghoff A, Djaya‐Mbissam H, Toepel J, Bühler B. Light-driven redox biocatalysis on gram-scale in Synechocystis sp. PCC 6803 via an in vivo cascade. PLANT BIOTECHNOLOGY JOURNAL 2023; 21:2074-2083. [PMID: 37439151 PMCID: PMC10502755 DOI: 10.1111/pbi.14113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 06/08/2023] [Accepted: 06/18/2023] [Indexed: 07/14/2023]
Abstract
The photosynthetic light reaction in cyanobacteria constitutes a highly attractive tool for productive biocatalysis, as it can provide redox reactions with high-energy reduction equivalents using sunlight and water as sources of energy and electrons, respectively. Here, we describe the first artificial light-driven redox cascade in Synechocystis sp. PCC 6803 to convert cyclohexanone to the polymer building block 6-hydroxyhexanoic acid (6-HA). Co-expression of a Baeyer-Villiger monooxygenase (BVMO) and a lactonase, both from Acidovorax sp. CHX100, enabled this two-step conversion with an activity of up to 63.1 ± 1.0 U/gCDW without accumulating inhibitory ε-caprolactone. Thereby, one of the key limitations of biocatalytic reactions, that is, reactant inhibition or toxicity, was overcome. In 2 L stirred-tank-photobioreactors, the process could be stabilized for 48 h, forming 23.50 ± 0.84 mm (3.11 ± 0.12 g/L) 6-HA. The high specificity enabling a product yield (YP/S ) of 0.96 ± 0.01 mol/mol and the remarkable biocatalyst-related yield of 3.71 ± 0.21 g6-HA /gCDW illustrate the potential of producing this non-toxic product in a synthetic cascade. The fine-tuning of the energy burden on the catalyst was found to be crucial, which indicates a limitation by the metabolic capacity of the cells possibly being compromised by biocatalysis-related reductant withdrawal. Intriguingly, energy balancing revealed that the biotransformation could tap surplus electrons derived from the photosynthetic light reaction and thereby relieve photosynthetic sink limitation. This study shows the feasibility of light-driven biocatalytic cascade operation in cyanobacteria and highlights respective metabolic limitations and engineering targets to unleash the full potential of photosynthesis.
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Affiliation(s)
- Adrian Tüllinghoff
- Helmholtz‐Centre for Environmental Research – UFZ, PermoserstrLeipzigGermany
| | | | - Jörg Toepel
- Helmholtz‐Centre for Environmental Research – UFZ, PermoserstrLeipzigGermany
| | - Bruno Bühler
- Helmholtz‐Centre for Environmental Research – UFZ, PermoserstrLeipzigGermany
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