1
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Kratzl F, Urban M, Pandhal J, Shi M, Meng C, Kleigrewe K, Kremling A, Pflüger-Grau K. Pseudomonas putida as saviour for troubled Synechococcus elongatus in a synthetic co-culture - interaction studies based on a multi-OMICs approach. Commun Biol 2024; 7:452. [PMID: 38609451 PMCID: PMC11014904 DOI: 10.1038/s42003-024-06098-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Accepted: 03/22/2024] [Indexed: 04/14/2024] Open
Abstract
In their natural habitats, microbes rarely exist in isolation; instead, they thrive in consortia, where various interactions occur. In this study, a defined synthetic co-culture of the cyanobacterium S. elongatus cscB, which supplies sucrose to the heterotrophic P. putida cscRABY, is investigated to identify potential interactions. Initial experiments reveal a remarkable growth-promoting effect of the heterotrophic partner on the cyanobacterium, resulting in an up to 80% increase in the growth rate and enhanced photosynthetic capacity. Vice versa, the presence of the cyanobacterium has a neutral effect on P. putida cscRABY, highlighting the resilience of pseudomonads against stress and their potential as co-culture partners. Next, a suitable reference process reinforcing the growth-promoting effect is established in a parallel photobioreactor system, which sets the basis for the analysis of the co-culture at the transcriptome, proteome, and metabolome levels. In addition to several moderate changes, including alterations in the metabolism and stress response in both microbes, this comprehensive multi-OMICs approach strongly hints towards the exchange of further molecules beyond the unidirectional feeding with sucrose. Taken together, these findings provide valuable insights into the complex dynamics between both co-culture partners, indicating multi-level interactions, which can be employed for further streamlining of the co-cultivation system.
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Affiliation(s)
- Franziska Kratzl
- Professorship for Systems Biotechnology, TUM School of Engineering and Design, Technical University of Munich, Garching, Germany
| | - Marlene Urban
- Professorship for Systems Biotechnology, TUM School of Engineering and Design, Technical University of Munich, Garching, Germany
| | - Jagroop Pandhal
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, United Kingdom
| | - Mengxun Shi
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, United Kingdom
| | - Chen Meng
- Bavarian Center for Biomolecular Mass Spectrometry (BayBioMS), TUM School of Life Sciences, Technical University of Munich, Freising, Germany
| | - Karin Kleigrewe
- Bavarian Center for Biomolecular Mass Spectrometry (BayBioMS), TUM School of Life Sciences, Technical University of Munich, Freising, Germany
| | - Andreas Kremling
- Professorship for Systems Biotechnology, TUM School of Engineering and Design, Technical University of Munich, Garching, Germany
| | - Katharina Pflüger-Grau
- Professorship for Systems Biotechnology, TUM School of Engineering and Design, Technical University of Munich, Garching, Germany.
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2
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Yun L, Zegarac R, Ducat DC. Impact of irradiance and inorganic carbon availability on heterologous sucrose production in Synechococcus elongatus PCC 7942. FRONTIERS IN PLANT SCIENCE 2024; 15:1378573. [PMID: 38650707 PMCID: PMC11033428 DOI: 10.3389/fpls.2024.1378573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Accepted: 03/27/2024] [Indexed: 04/25/2024]
Abstract
Cyanobacteria have been proposed as a potential alternative carbohydrate feedstock and multiple species have been successfully engineered to secrete fermentable sugars. To date, the most productive cyanobacterial strains are those designed to secrete sucrose, yet there exist considerable differences in reported productivities across different model species and laboratories. In this study, we investigate how cultivation conditions (specifically, irradiance, CO2, and cultivator type) affect the productivity of sucrose-secreting Synechococcus elongatus PCC 7942. We find that S. elongatus produces the highest sucrose yield in irradiances far greater than what is often experimentally utilized, and that high light intensities are tolerated by S. elongatus, especially under higher density cultivation where turbidity may attenuate the effective light experienced in the culture. By increasing light and inorganic carbon availability, S. elongatus cscB/sps produced a total of 3.8 g L-1 of sucrose and the highest productivity within that period being 47.8 mg L-1 h-1. This study provides quantitative description of the impact of culture conditions on cyanobacteria-derived sucrose that may assist to standardize cross-laboratory comparisons and demonstrates a significant capacity to improve productivity via optimizing cultivation conditions.
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Affiliation(s)
- Lisa Yun
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, United States
- Department of Energy-Michigan State University Plant Research Laboratories, Michigan State University, East Lansing, MI, United States
| | - Robert Zegarac
- Department of Energy-Michigan State University Plant Research Laboratories, Michigan State University, East Lansing, MI, United States
| | - Daniel C. Ducat
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, United States
- Department of Energy-Michigan State University Plant Research Laboratories, Michigan State University, East Lansing, MI, United States
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3
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Shi M, Evans CA, McQuillan JL, Noirel J, Pandhal J. LFQRatio: A Normalization Method to Decipher Quantitative Proteome Changes in Microbial Coculture Systems. J Proteome Res 2024; 23:999-1013. [PMID: 38354288 PMCID: PMC10913063 DOI: 10.1021/acs.jproteome.3c00714] [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] [Indexed: 02/16/2024]
Abstract
The value of synthetic microbial communities in biotechnology is gaining traction due to their ability to undertake more complex metabolic tasks than monocultures. However, a thorough understanding of strain interactions, productivity, and stability is often required to optimize growth and scale up cultivation. Quantitative proteomics can provide valuable insights into how microbial strains adapt to changing conditions in biomanufacturing. However, current workflows and methodologies are not suitable for simple artificial coculture systems where strain ratios are dynamic. Here, we established a workflow for coculture proteomics using an exemplar system containing two members, Azotobacter vinelandii and Synechococcus elongatus. Factors affecting the quantitative accuracy of coculture proteomics were investigated, including peptide physicochemical characteristics such as molecular weight, isoelectric point, hydrophobicity, and dynamic range as well as factors relating to protein identification such as varying proteome size and shared peptides between species. Different quantification methods based on spectral counts and intensity were evaluated at the protein and cell level. We propose a new normalization method, named "LFQRatio", to reflect the relative contributions of two distinct cell types emerging from cell ratio changes during cocultivation. LFQRatio can be applied to real coculture proteomics experiments, providing accurate insights into quantitative proteome changes in each strain.
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Affiliation(s)
- Mengxun Shi
- Department of Chemical and Biological Engineering, The University of Sheffield, Mappin Street, Sheffield S1 3JD, U.K
| | - Caroline A Evans
- Department of Chemical and Biological Engineering, The University of Sheffield, Mappin Street, Sheffield S1 3JD, U.K
| | - Josie L McQuillan
- Department of Chemical and Biological Engineering, The University of Sheffield, Mappin Street, Sheffield S1 3JD, U.K
| | - Josselin Noirel
- GBCM Laboratory (EA7528), Conservatoire National des Arts et Métiers, HESAM Université, 2 rue Conté, Paris 75003, France
| | - Jagroop Pandhal
- Department of Chemical and Biological Engineering, The University of Sheffield, Mappin Street, Sheffield S1 3JD, U.K
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4
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Santos-Merino M, Sakkos JK, Singh AK, Ducat DC. Coordination of carbon partitioning and photosynthesis by a two-component signaling network in Synechococcus elongatus PCC 7942. Metab Eng 2024; 81:38-52. [PMID: 37925065 DOI: 10.1016/j.ymben.2023.11.001] [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: 06/09/2023] [Revised: 10/26/2023] [Accepted: 11/02/2023] [Indexed: 11/06/2023]
Abstract
Photosynthetic organisms need to balance the rate of photosynthesis with the utilization of photosynthetic products by downstream reactions. While such "source/sink" pathways are well-interrogated in plants, analogous regulatory systems are unknown or poorly studied in single-celled algal and cyanobacterial species. Towards the identification of energy/sugar sensors in cyanobacteria, we utilized an engineered strain of Synechococcus elongatus PCC 7942 that allows experimental manipulation of carbon status. We conducted a screening of all two-component systems (TCS) and serine/threonine kinases (STKs) encoded in S. elongatus PCC 7942 by analyzing phenotypes consistent with sucrose-induced relaxation of sink inhibition. We narrowed the candidate sensor proteins by analyzing changes observed after sucrose feeding. We show that a clustered TCS network containing RpaA, CikB, ManS and NblS are involved in the regulation of genes related to photosynthesis, pigment synthesis, and Rubisco concentration in response to sucrose. Altogether, these results highlight a regulatory TCS group that may play under-appreciated functions in carbon partitioning and energy balancing in cyanobacteria.
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Affiliation(s)
- María Santos-Merino
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, United States
| | - Jonathan K Sakkos
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, United States
| | - Amit K Singh
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, United States
| | - Daniel C Ducat
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, United States; Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48824, United States.
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5
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Wang B, Zuniga C, Guarnieri MT, Zengler K, Betenbaugh M, Young JD. Metabolic engineering of Synechococcus elongatus 7942 for enhanced sucrose biosynthesis. Metab Eng 2023; 80:12-24. [PMID: 37678664 DOI: 10.1016/j.ymben.2023.09.002] [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: 05/02/2023] [Revised: 07/28/2023] [Accepted: 09/03/2023] [Indexed: 09/09/2023]
Abstract
The capability of cyanobacteria to produce sucrose from CO2 and light has a remarkable societal and biotechnological impact since sucrose can serve as a carbon and energy source for a variety of heterotrophic organisms and can be converted into value-added products. However, most metabolic engineering efforts have focused on understanding local pathway alterations that drive sucrose biosynthesis and secretion in cyanobacteria rather than analyzing the global flux re-routing that occurs following induction of sucrose production by salt stress. Here, we investigated global metabolic flux alterations in a sucrose-secreting (cscB-overexpressing) strain relative to its wild-type Synechococcus elongatus 7942 parental strain. We used targeted metabolomics, 13C metabolic flux analysis (MFA), and genome-scale modeling (GSM) as complementary approaches to elucidate differences in cellular resource allocation by quantifying metabolic profiles of three cyanobacterial cultures - wild-type S. elongatus 7942 without salt stress (WT), wild-type with salt stress (WT/NaCl), and the cscB-overexpressing strain with salt stress (cscB/NaCl) - all under photoautotrophic conditions. We quantified the substantial rewiring of metabolic fluxes in WT/NaCl and cscB/NaCl cultures relative to WT and identified a metabolic bottleneck limiting carbon fixation and sucrose biosynthesis. This bottleneck was subsequently mitigated through heterologous overexpression of glyceraldehyde-3-phosphate dehydrogenase in an engineered sucrose-secreting strain. Our study also demonstrates that combining 13C-MFA and GSM is a useful strategy to both extend the coverage of MFA beyond central metabolism and to improve the accuracy of flux predictions provided by GSM.
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Affiliation(s)
- Bo Wang
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN, 37235, USA
| | - Cristal Zuniga
- Department of Pediatrics, University of California, San Diego, CA, 92093, USA; Department of Biology, San Diego State University, San Diego, CA, 92182, USA
| | - Michael T Guarnieri
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Karsten Zengler
- Department of Pediatrics, University of California, San Diego, CA, 92093, USA; Department of Bioengineering, University of California, San Diego, CA, 92093, USA; Center for Microbiome Innovation, University of California, San Diego, CA, 92093, USA
| | - Michael Betenbaugh
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Jamey D Young
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN, 37235, USA; Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, 37235, USA.
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6
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Bongirwar R, Shukla P. Metabolic sink engineering in cyanobacteria: Perspectives and applications. BIORESOURCE TECHNOLOGY 2023; 379:128974. [PMID: 36990331 DOI: 10.1016/j.biortech.2023.128974] [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: 02/18/2023] [Revised: 03/24/2023] [Accepted: 03/25/2023] [Indexed: 05/03/2023]
Abstract
Recent advances in metabolic engineering have made cyanobacteria emerge as promising and attractive microorganisms for sustainable production, by exploiting their natural capability for producing metabolites. The potential of metabolically engineered cyanobacterium would depend on its source-sink balance in the same way as other phototrophs. In cyanobacteria, the amount of light energy harvested (Source) is incompletely utilized by the cell to fix carbon (sink) resulting in wastage of the absorbed energy causing photoinhibition and cellular damage leading to lowered photosynthetic efficiency. Although regulatory pathways like photo-acclimation and photoprotective processes can be helpful unfortunately they limit the cell's metabolic capacity. This review describes approaches for source-sink balance and engineering heterologous metabolic sinks in cyanobacteria for enhanced photosynthetic efficiency. The advances for engineering additional metabolic pathways in cyanobacteria are also described which will provide a better understanding of the cyanobacterial source-sink balance and approaches for efficient cyanobacterial strains for valuable metabolites.
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Affiliation(s)
- Riya Bongirwar
- Enzyme Technology and Protein Bioinformatics Laboratory, School of Biotechnology, Institute of Science, Banaras Hindu University, Varanasi 221005, Uttar Pradesh, India
| | - Pratyoosh Shukla
- Enzyme Technology and Protein Bioinformatics Laboratory, School of Biotechnology, Institute of Science, Banaras Hindu University, Varanasi 221005, Uttar Pradesh, India.
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7
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Santos-Merino M, Yun L, Ducat DC. Cyanobacteria as cell factories for the photosynthetic production of sucrose. Front Microbiol 2023; 14:1126032. [PMID: 36865782 PMCID: PMC9971976 DOI: 10.3389/fmicb.2023.1126032] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Accepted: 01/24/2023] [Indexed: 02/16/2023] Open
Abstract
Biofuels and other biologically manufactured sustainable goods are growing in popularity and demand. Carbohydrate feedstocks required for industrial fermentation processes have traditionally been supplied by plant biomass, but the large quantities required to produce replacement commodity products may prevent the long-term feasibility of this approach without alternative strategies to produce sugar feedstocks. Cyanobacteria are under consideration as potential candidates for sustainable production of carbohydrate feedstocks, with potentially lower land and water requirements relative to plants. Several cyanobacterial strains have been genetically engineered to export significant quantities of sugars, especially sucrose. Sucrose is not only naturally synthesized and accumulated by cyanobacteria as a compatible solute to tolerate high salt environments, but also an easily fermentable disaccharide used by many heterotrophic bacteria as a carbon source. In this review, we provide a comprehensive summary of the current knowledge of the endogenous cyanobacterial sucrose synthesis and degradation pathways. We also summarize genetic modifications that have been found to increase sucrose production and secretion. Finally, we consider the current state of synthetic microbial consortia that rely on sugar-secreting cyanobacterial strains, which are co-cultivated alongside heterotrophic microbes able to directly convert the sugars into higher-value compounds (e.g., polyhydroxybutyrates, 3-hydroxypropionic acid, or dyes) in a single-pot reaction. We summarize recent advances reported in such cyanobacteria/heterotroph co-cultivation strategies and provide a perspective on future developments that are likely required to realize their bioindustrial potential.
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Affiliation(s)
- María Santos-Merino
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, United States
| | - Lisa Yun
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, United States
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, United States
| | - Daniel C. Ducat
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, United States
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, United States
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8
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Burnap RL. Cyanobacterial Bioenergetics in Relation to Cellular Growth and Productivity. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2023; 183:25-64. [PMID: 36764956 DOI: 10.1007/10_2022_215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
Cyanobacteria, the evolutionary originators of oxygenic photosynthesis, have the capability to convert CO2, water, and minerals into biomass using solar energy. This process is driven by intricate bioenergetic mechanisms that consist of interconnected photosynthetic and respiratory electron transport chains coupled. Over the last few decades, advances in physiochemical analysis, molecular genetics, and structural analysis have enabled us to gain a more comprehensive understanding of cyanobacterial bioenergetics. This includes the molecular understanding of the primary energy conversion mechanisms as well as photoprotective and other dissipative mechanisms that prevent photodamage when the rates of photosynthetic output, primarily in the form of ATP and NADPH, exceed the rates that cellular assimilatory processes consume these photosynthetic outputs. Despite this progress, there is still much to learn about the systems integration and the regulatory circuits that control expression levels for optimal cellular abundance and activity of the photosynthetic complexes and the cellular components that convert their products into biomass. With an improved understanding of these regulatory principles and mechanisms, it should be possible to optimally modify cyanobacteria for enhanced biotechnological purposes.
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Affiliation(s)
- Robert L Burnap
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, USA.
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9
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Lindberg P, Kenkel A, Bühler K. Introduction to Cyanobacteria. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2023; 183:1-24. [PMID: 37009973 DOI: 10.1007/10_2023_217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2023]
Abstract
Cyanobacteria are highly interesting microbes with the capacity for oxygenic photosynthesis. They fulfill an important purpose in nature but are also potent biocatalysts. This chapter gives a brief overview of this diverse phylum and shortly addresses the functions these organisms have in the natural ecosystems. Further, it introduces the main topics covered in this volume, which is dealing with the development and application of cyanobacteria as solar cell factories for the production of chemicals including potential fuels. We discuss cyanobacteria as industrial workhorses, present established chassis strains, and give an overview of the current target products. Genetic engineering strategies aiming at the photosynthetic efficiency as well as approaches to optimize carbon fluxes are summarized. Finally, main cultivation strategies are sketched.
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Affiliation(s)
- Pia Lindberg
- Department of Chemistry-Ångström, Uppsala University, Uppsala, Sweden
| | - Amelie Kenkel
- Helmholtzcenter for Environmental Research, Leipzig, Germany
| | - Katja Bühler
- Helmholtzcenter for Environmental Research, Leipzig, Germany.
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10
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Tóth GS, Siitonen V, Nikkanen L, Sovic L, Kallio P, Kourist R, Kosourov S, Allahverdiyeva Y. Photosynthetically produced sucrose by immobilized Synechocystis sp. PCC 6803 drives biotransformation in E. coli. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2022; 15:146. [PMID: 36575466 PMCID: PMC9795604 DOI: 10.1186/s13068-022-02248-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 12/14/2022] [Indexed: 12/28/2022]
Abstract
BACKGROUND Whole-cell biotransformation is a promising emerging technology for the production of chemicals. When using heterotrophic organisms such as E. coli and yeast as biocatalysts, the dependence on organic carbon source impairs the sustainability and economic viability of the process. As a promising alternative, photosynthetic cyanobacteria with low nutrient requirements and versatile metabolism, could offer a sustainable platform for the heterologous production of organic compounds directly from sunlight and CO2. This strategy has been applied for the photoautotrophic production of sucrose by a genetically engineered cyanobacterium, Synechocystis sp. PCC 6803 strain S02. As the key concept in the current work, this can be further used to generate organic carbon compounds for different heterotrophic applications, including for the whole-cell biotransformation by yeast and bacteria. RESULTS Entrapment of Synechocystis S02 cells in Ca2+-cross-linked alginate hydrogel beads improves the specific sucrose productivity by 86% compared to suspension cultures during 7 days of cultivation under salt stress. The process was further prolonged by periodically changing the medium in the vials for up to 17 days of efficient production, giving the final sucrose yield slightly above 3000 mg l-1. We successfully demonstrated that the medium enriched with photosynthetically produced sucrose by immobilized Synechocystis S02 cells supports the biotransformation of cyclohexanone to ε-caprolactone by the E. coli WΔcscR Inv:Parvi strain engineered to (i) utilize low concentrations of sucrose and (ii) perform biotransformation of cyclohexanone to ε-caprolactone. CONCLUSION We conclude that cell entrapment in Ca2+-alginate beads is an effective method to prolong sucrose production by the engineered cyanobacteria, while allowing efficient separation of the cells from the medium. This advantage opens up novel possibilities to create advanced autotroph-heterotroph coupled cultivation systems for solar-driven production of chemicals via biotransformation, as demonstrated in this work by utilizing the photosynthetically produced sucrose to drive the conversion of cyclohexanone to ε-caprolactone by engineered E. coli.
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Affiliation(s)
- Gábor Szilveszter Tóth
- grid.1374.10000 0001 2097 1371Molecular Plant Biology, Department of Life Technologies, University of Turku, 20014 Turku, Finland
| | - Vilja Siitonen
- grid.1374.10000 0001 2097 1371Molecular Plant Biology, Department of Life Technologies, University of Turku, 20014 Turku, Finland
| | - Lauri Nikkanen
- grid.1374.10000 0001 2097 1371Molecular Plant Biology, Department of Life Technologies, University of Turku, 20014 Turku, Finland
| | - Lucija Sovic
- grid.410413.30000 0001 2294 748XCell and Protein Engineering, Institute of Molecular Biotechnology, Graz University of Technology, 8010 Graz, Austria
| | - Pauli Kallio
- grid.1374.10000 0001 2097 1371Molecular Plant Biology, Department of Life Technologies, University of Turku, 20014 Turku, Finland
| | - Robert Kourist
- grid.410413.30000 0001 2294 748XCell and Protein Engineering, Institute of Molecular Biotechnology, Graz University of Technology, 8010 Graz, Austria
| | - Sergey Kosourov
- grid.1374.10000 0001 2097 1371Molecular Plant Biology, Department of Life Technologies, University of Turku, 20014 Turku, Finland
| | - Yagut Allahverdiyeva
- grid.1374.10000 0001 2097 1371Molecular Plant Biology, Department of Life Technologies, University of Turku, 20014 Turku, Finland
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Kokarakis E, Rillema R, Ducat DC, Sakkos JK. Developing Cyanobacterial Quorum Sensing Toolkits: Toward Interspecies Coordination in Mixed Autotroph/Heterotroph Communities. ACS Synth Biol 2022; 12:265-276. [PMID: 36573789 PMCID: PMC9872165 DOI: 10.1021/acssynbio.2c00527] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
There has been substantial recent interest in the promise of sustainable, light-driven bioproduction using cyanobacteria, including developing efforts for microbial bioproduction using mixed autotroph/heterotroph communities, which could provide useful properties, such as division of metabolic labor. However, building stable mixed-species communities of sufficient productivity remains a challenge, partly due to the lack of strategies for synchronizing and coordinating biological activities across different species. To address this obstacle, we developed an inter-species communication system using quorum sensing (QS) modules derived from well-studied pathways in heterotrophic microbes. In the model cyanobacterium, Synechococcus elongatus PCC 7942 (S. elongatus), we designed, integrated, and characterized genetic circuits that detect acyl-homoserine lactones (AHLs), diffusible signals utilized in many QS pathways. We showed that these receiver modules sense exogenously supplied AHL molecules and activate gene expression in a dose-dependent manner. We characterized these AHL receiver circuits in parallel with Escherichia coli W (E. coli W) to dissect species-specific properties, finding broad agreement, albeit with increased basal expression in S. elongatus. Our engineered "sender" E. coli strains accumulated biologically synthesized AHLs within the supernatant and activated receiver strains similarly to exogenous AHL activation. Our results will bolster the design of sophisticated genetic circuits in cyanobacterial/heterotroph consortia and the engineering of QS-like behaviors across cyanobacterial populations.
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Affiliation(s)
- Emmanuel
J. Kokarakis
- Plant
Research Laboratory, Michigan State University, East Lansing, Michigan48824-1312, United States,Department
of Microbiology & Molecular Genetics, Michigan State University, East Lansing, Michigan48824-1312, United States
| | - Rees Rillema
- Plant
Research Laboratory, Michigan State University, East Lansing, Michigan48824-1312, United States,Department
of Biochemistry and Molecular Biology, Michigan
State University, East Lansing, Michigan48824-1312, United States
| | - Daniel C. Ducat
- Plant
Research Laboratory, Michigan State University, East Lansing, Michigan48824-1312, United States,Department
of Biochemistry and Molecular Biology, Michigan
State University, East Lansing, Michigan48824-1312, United States
| | - Jonathan K. Sakkos
- Plant
Research Laboratory, Michigan State University, East Lansing, Michigan48824-1312, United States,
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12
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Malečková E. Rubisco responds to sucrose give and take in cyanobacteria. PLANT PHYSIOLOGY 2022; 189:444-446. [PMID: 35285507 PMCID: PMC9157106 DOI: 10.1093/plphys/kiac102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 02/23/2022] [Indexed: 06/14/2023]
Affiliation(s)
- Eva Malečková
- Singleron Biotechnologies GmbH, 51105 Cologne, Germany
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13
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Heterologous Lactate Synthesis in Synechocystis sp. Strain PCC 6803 Causes a Growth Condition-Dependent Carbon Sink Effect. Appl Environ Microbiol 2022; 88:e0006322. [PMID: 35369703 PMCID: PMC9040622 DOI: 10.1128/aem.00063-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Cyanobacteria are considered promising hosts for product synthesis directly from CO2 via photosynthetic carbon assimilation. The introduction of heterologous carbon sinks in terms of product synthesis has been reported to induce the so-called “carbon sink effect,” described as the release of unused photosynthetic capacity by the introduction of additional carbon. This effect is thought to arise from a limitation of carbon metabolism that represents a bottleneck in carbon and electron flow, thus enforcing a downregulation of photosynthetic efficiency. It is not known so far how the cellular source/sink balance under different growth conditions influences the extent of the carbon sink effect and in turn product formation from CO2, constituting a heterologous carbon sink. We compared the Synechocystis sp. strain PCC 6803 wild type (WT) with an engineered lactate-producing strain (SAA023) in defined metabolic states. Unexpectedly, high-light conditions combined with carbon limitation enabled additional carbon assimilation for lactate production without affecting biomass formation. Thus, a strong carbon sink effect only was observed under carbon and thus sink limitation, but not under high-sink conditions. We show that the carbon sink effect was accompanied by an increased rate of alternative electron flow (AEF). Thus, AEF plays a crucial role in the equilibration of source/sink imbalances, presumably via ATP/NADPH balancing. This study emphasizes that the evaluation of the biotechnological potential of cyanobacteria profits from cultivation approaches enabling the establishment of defined metabolic states and respective quantitative analytics. Factors stimulating photosynthesis and carbon fixation are discussed. IMPORTANCE Previous studies reported various and differing effects of the heterologous production of carbon-based molecules on photosynthetic and growth efficiency of cyanobacteria. The typically applied cultivation in batch mode, with continuously changing growth conditions, however, precludes a clear differentiation between the impact of cultivation conditions on cell physiology and effects related to the specific nature of the product and its synthesis pathway. In this study, we employed a continuous cultivation system to maintain defined source/sink conditions and thus metabolic states. This allowed a systematic and quantitative analysis of the effect of NADPH-consuming lactate production on photosynthetic and growth efficiency. This approach enables a realistic evaluation of the biotechnological potential of engineered cyanobacterial strains. For example, the quantum requirement for carbon production was found to constitute an excellent indicator of the source/sink balance and thus a key parameter for photobioprocess optimization. Such knowledge is fundamental for rational and efficient strain and process development.
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Yadav I, Rautela A, Kumar S. Approaches in the photosynthetic production of sustainable fuels by cyanobacteria using tools of synthetic biology. World J Microbiol Biotechnol 2021; 37:201. [PMID: 34664124 DOI: 10.1007/s11274-021-03157-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 09/29/2021] [Indexed: 10/20/2022]
Abstract
Cyanobacteria, photosynthetic prokaryotic microorganisms having a simple genetic composition are the prospective photoautotrophic cell factories for the production of a wide range of biofuel molecules. The simple genetic composition of cyanobacteria allows effortless genetic manipulation which leads to increased research endeavors from the synthetic biology approach. Various unicellular model cyanobacterial strains like Synechocystis sp. PCC 6803 and Synechococcus elongatus PCC 7942 have been successfully engineered for biofuels generation. Improved development of synthetic biology tools, genetic modification methods and advancement in transformation techniques to construct a strain that can contain multiple foreign genes in a single operon have vastly expanded the functions that can be used for engineering photosynthetic cyanobacteria for the generation of various biofuel molecules. In this review, recent advancements and approaches in synthetic biology tools used for cyanobacterial genome editing have been discussed. Apart from this, cyanobacterial productions of various fuel molecules like isoprene, limonene, α-farnesene, squalene, alkanes, butanol, and fatty acids, which can be a substitute for petroleum and fossil fuels in the future, have been elaborated.
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Affiliation(s)
- Indrajeet Yadav
- School of Biochemical Engineering, IIT (BHU) Varanasi, Varanasi, Uttar Pradesh, 221005, India
| | - Akhil Rautela
- School of Biochemical Engineering, IIT (BHU) Varanasi, Varanasi, Uttar Pradesh, 221005, India
| | - Sanjay Kumar
- School of Biochemical Engineering, IIT (BHU) Varanasi, Varanasi, Uttar Pradesh, 221005, India.
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Improved photosynthetic capacity and photosystem I oxidation via heterologous metabolism engineering in cyanobacteria. Proc Natl Acad Sci U S A 2021; 118:2021523118. [PMID: 33836593 PMCID: PMC7980454 DOI: 10.1073/pnas.2021523118] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Cyanobacteria have been increasingly explored as a biotechnological platform, although their economic feasibility relies in part on the capacity to maximize their photosynthetic, solar-to-biomass energy conversion efficiency. Here we show that cyanobacterial photosynthetic capacity can be increased by diverting cellular resources toward heterologous, energy-storing metabolic pathways and by reducing electron flow to photoprotective, but energy-dissipating, oxygen reduction reactions. We further show that these heterologous sinks can partially contribute to photosystem I (PSI) oxidation, suggesting an engineering strategy to improve both energy storage capacity and robustness by selective diversion of excess photosynthetic capacity to productive processes. Cyanobacteria must prevent imbalances between absorbed light energy (source) and the metabolic capacity (sink) to utilize it to protect their photosynthetic apparatus against damage. A number of photoprotective mechanisms assist in dissipating excess absorbed energy, including respiratory terminal oxidases and flavodiiron proteins, but inherently reduce photosynthetic efficiency. Recently, it has been hypothesized that some engineered metabolic pathways may improve photosynthetic performance by correcting source/sink imbalances. In the context of this subject, we explored the interconnectivity between endogenous electron valves, and the activation of one or more heterologous metabolic sinks. We coexpressed two heterologous metabolic pathways that have been previously shown to positively impact photosynthetic activity in cyanobacteria, a sucrose production pathway (consuming ATP and reductant) and a reductant-only consuming cytochrome P450. Sucrose export was associated with improved quantum yield of phtotosystem II (PSII) and enhanced electron transport chain flux, especially at lower illumination levels, while cytochrome P450 activity led to photosynthetic enhancements primarily observed under high light. Moreover, coexpression of these two heterologous sinks showed additive impacts on photosynthesis, indicating that neither sink alone was capable of utilizing the full “overcapacity” of the electron transport chain. We find that heterologous sinks may partially compensate for the loss of photosystem I (PSI) oxidizing mechanisms even under rapid illumination changes, although this compensation is incomplete. Our results provide support for the theory that heterologous metabolism can act as a photosynthetic sink and exhibit some overlapping functionality with photoprotective mechanisms, while potentially conserving energy within useful metabolic products that might otherwise be “lost.”
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Xie Y, Chen L, Sun T, Zhang W. Deciphering and engineering high-light tolerant cyanobacteria for efficient photosynthetic cell factories. Chin J Chem Eng 2021. [DOI: 10.1016/j.cjche.2020.11.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Microbial production of limonene and its derivatives: Achievements and perspectives. Biotechnol Adv 2020; 44:107628. [DOI: 10.1016/j.biotechadv.2020.107628] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Revised: 08/24/2020] [Accepted: 08/25/2020] [Indexed: 12/14/2022]
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Lin TY, Wen RC, Shen CR, Tsai SL. Biotransformation of 5-Hydroxymethylfurfural to 2,5-Furandicarboxylic Acid by a Syntrophic Consortium of Engineered Synechococcus elongatus and Pseudomonas putida. Biotechnol J 2020; 15:e1900357. [PMID: 32181597 DOI: 10.1002/biot.201900357] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 02/03/2020] [Indexed: 12/11/2022]
Abstract
2,5-furandicarboxylic acid (FDCA) is one of the top platform chemicals that can be produced from biomass feedstock. To make the cost of industrial FDCA production compatible with plastics made from fossils, the price of substrates and process complexity should be reduced. The aim of this research is to create a CO2 -driven syntrophic consortium for the catalytic conversion of renewable biomass-derived 5-hydroxymethylfurfural (HMF) to FDCA. Sucrose produced from carbon fixation by the engineered Synechococcus elongatus serves as the sole carbon source for the engineered Pseudomonas putida to catalyze the reaction of HMF to FDCA. The yield of FDCA by the consortium reaches around 70% while the conversion of HMF is close to 100%. With further surface engineering to clump the two strains, the FDCA yield is elevated to almost 100% via the specific association between an Src homology 3 (SH3) domain and its ligand. The syntrophic consortium successfully demonstrates its green and cost-effective characteristics for the conversion of CO2 and biomass into platform chemicals.
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Affiliation(s)
- Tzu-Yu Lin
- Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei, 10607, Taiwan
| | - Rex C Wen
- Department of Chemical Engineering, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - Claire R Shen
- Department of Chemical Engineering, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - Shen-Long Tsai
- Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei, 10607, Taiwan
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Chen Q, Arents J, Schuurmans JM, Ganapathy S, de Grip WJ, Cheregi O, Funk C, dos Santos FB, Hellingwerf KJ. Combining retinal-based and chlorophyll-based (oxygenic) photosynthesis: Proteorhodopsin expression increases growth rate and fitness of a ∆PSI strain of Synechocystis sp. PCC6803. Metab Eng 2019; 52:68-76. [DOI: 10.1016/j.ymben.2018.11.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 11/09/2018] [Accepted: 11/10/2018] [Indexed: 11/28/2022]
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Santos-Merino M, Singh AK, Ducat DC. New Applications of Synthetic Biology Tools for Cyanobacterial Metabolic Engineering. Front Bioeng Biotechnol 2019; 7:33. [PMID: 30873404 PMCID: PMC6400836 DOI: 10.3389/fbioe.2019.00033] [Citation(s) in RCA: 109] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 02/05/2019] [Indexed: 01/25/2023] Open
Abstract
Cyanobacteria are promising microorganisms for sustainable biotechnologies, yet unlocking their potential requires radical re-engineering and application of cutting-edge synthetic biology techniques. In recent years, the available devices and strategies for modifying cyanobacteria have been increasing, including advances in the design of genetic promoters, ribosome binding sites, riboswitches, reporter proteins, modular vector systems, and markerless selection systems. Because of these new toolkits, cyanobacteria have been successfully engineered to express heterologous pathways for the production of a wide variety of valuable compounds. Cyanobacterial strains with the potential to be used in real-world applications will require the refinement of genetic circuits used to express the heterologous pathways and development of accurate models that predict how these pathways can be best integrated into the larger cellular metabolic network. Herein, we review advances that have been made to translate synthetic biology tools into cyanobacterial model organisms and summarize experimental and in silico strategies that have been employed to increase their bioproduction potential. Despite the advances in synthetic biology and metabolic engineering during the last years, it is clear that still further improvements are required if cyanobacteria are to be competitive with heterotrophic microorganisms for the bioproduction of added-value compounds.
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Affiliation(s)
- María Santos-Merino
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, United States
| | - Amit K. Singh
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, United States
| | - Daniel C. Ducat
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, United States
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, United States
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Grund M, Jakob T, Wilhelm C, Bühler B, Schmid A. Electron balancing under different sink conditions reveals positive effects on photon efficiency and metabolic activity of Synechocystis sp. PCC 6803. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:43. [PMID: 30858880 PMCID: PMC6391784 DOI: 10.1186/s13068-019-1378-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 02/14/2019] [Indexed: 05/19/2023]
Abstract
BACKGROUND Cyanobacteria are ideal model organisms to exploit photosynthetically derived electrons or fixed carbon for the biotechnological synthesis of high value compounds and energy carriers. Much effort is spent on the rational design of heterologous pathways to produce value-added chemicals. Much less focus is drawn on the basic physiological responses and potentials of phototrophs to deal with natural or artificial electron and carbon sinks. However, an understanding of how electron sinks influence or regulate cellular physiology is essential for the efficient application of phototrophic organisms in an industrial setting, i.e., to achieve high productivities and product yields. RESULTS The physiological responses of the cyanobacterium Synechocystis sp. PCC 6803 to electron sink variation were investigated in a systematic and quantitative manner. A variation in electron demand was achieved by providing two N sources with different degrees of reduction. By additionally varying light and CO2 availabilities, steady state conditions with strongly differing source-sink ratios were established. Balancing absorbed photons and electrons used for different metabolic processes revealed physiological responses to sink/source ratio variation. Surprisingly, an additional electron sink under light and thus energy limitation was found not to hamper growth, but was compensated by improved photosynthetic efficiency and activity. In the absence of carbon and light limitation, an increase in electron demand even stimulated carbon assimilation and growth. CONCLUSION The metabolism of Synechocystis sp. PCC 6803 is highly flexible regarding the compensation of additional electron demands. Under light limitation, photosynthesis obviously does not necessarily run at its maximal capacity, possibly for the sake of robustness. Increased electron demands can even boost photosynthetic activity and growth.
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Affiliation(s)
- Marcel Grund
- Department of Solar Materials, Helmholtz Center for Environmental Research GmbH–UFZ, Permoserstraße 15, 04318 Leipzig, Germany
| | - Torsten Jakob
- Plant Physiology Group, Institute for Biology, University of Leipzig, Johannisallee 21-23, 04103 Leipzig, Germany
| | - Christian Wilhelm
- Plant Physiology Group, Institute for Biology, University of Leipzig, Johannisallee 21-23, 04103 Leipzig, Germany
| | - Bruno Bühler
- Department of Solar Materials, Helmholtz Center for Environmental Research GmbH–UFZ, Permoserstraße 15, 04318 Leipzig, Germany
| | - Andreas Schmid
- Department of Solar Materials, Helmholtz Center for Environmental Research GmbH–UFZ, Permoserstraße 15, 04318 Leipzig, Germany
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Metabolic engineering tools in model cyanobacteria. Metab Eng 2018; 50:47-56. [DOI: 10.1016/j.ymben.2018.03.014] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 03/15/2018] [Accepted: 03/15/2018] [Indexed: 12/27/2022]
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Berepiki A, Gittins JR, Moore CM, Bibby TS. Rational engineering of photosynthetic electron flux enhances light-powered cytochrome P450 activity. Synth Biol (Oxf) 2018; 3:ysy009. [PMID: 32995517 PMCID: PMC7445785 DOI: 10.1093/synbio/ysy009] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 05/04/2018] [Accepted: 05/25/2018] [Indexed: 11/21/2022] Open
Abstract
In this study, we exploited a modified photosynthetic electron transfer chain (PET) in the model cyanobacterium Synechococcus PCC 7002, where electrons derived from water-splitting are used to power reactions catalyzed by a heterologous cytochrome P450 (CYP1A1). A simple in vivo fluorescent assay for CYP1A1 activity was employed to determine the impact of rationally engineering of photosynthetic electron flow. This showed that knocking out a subunit of the type I NADH dehydrogenase complex (NDH-1), suggested to be involved in cyclic photosynthetic electron flow (ΔndhD2), can double the activity of CYP1A1, with a concomitant increase in the flux of electrons from photosynthesis. This also resulted in an increase in cellular adenosine triphosphate (ATP) and the ATP/nicotinamide adenine dinucleotide phosphate (NADPH) ratio, suggesting that expression of a heterologous electron sink in photosynthetic organisms can be used to modify the bioenergetic landscape of the cell. We therefore demonstrate that CYP1A1 is limited by electron supply and that photosynthesis can be re-engineered to increase heterologous P450 activity for the production of high-value bioproducts. The increase in cellular ATP achieved could be harnessed to support metabolically demanding heterologous processes. Furthermore, this experimental system could provide valuable insights into the mechanisms of photosynthesis.
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Affiliation(s)
- Adokiye Berepiki
- Ocean and Earth Science, University of Southampton, Waterfront Campus, National Oceanography Centre, Southampton SO14 3ZH, UK.,Manchester Institute of Biotechnology, University of Manchester, Princess St, Manchester M1 7DN, UK
| | - John R Gittins
- Ocean and Earth Science, University of Southampton, Waterfront Campus, National Oceanography Centre, Southampton SO14 3ZH, UK
| | - C Mark Moore
- Ocean and Earth Science, University of Southampton, Waterfront Campus, National Oceanography Centre, Southampton SO14 3ZH, UK
| | - Thomas S Bibby
- Ocean and Earth Science, University of Southampton, Waterfront Campus, National Oceanography Centre, Southampton SO14 3ZH, UK
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Liang F, Englund E, Lindberg P, Lindblad P. Engineered cyanobacteria with enhanced growth show increased ethanol production and higher biofuel to biomass ratio. Metab Eng 2018; 46:51-59. [DOI: 10.1016/j.ymben.2018.02.006] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 12/14/2017] [Accepted: 02/18/2018] [Indexed: 01/02/2023]
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Weiss TL, Young EJ, Ducat DC. A synthetic, light-driven consortium of cyanobacteria and heterotrophic bacteria enables stable polyhydroxybutyrate production. Metab Eng 2017; 44:236-245. [DOI: 10.1016/j.ymben.2017.10.009] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 09/28/2017] [Accepted: 10/16/2017] [Indexed: 10/18/2022]
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Korosh TC, Markley AL, Clark RL, McGinley LL, McMahon KD, Pfleger BF. Engineering photosynthetic production of L-lysine. Metab Eng 2017; 44:273-283. [PMID: 29111438 PMCID: PMC5776718 DOI: 10.1016/j.ymben.2017.10.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 09/01/2017] [Accepted: 10/26/2017] [Indexed: 10/28/2022]
Abstract
L-lysine and other amino acids are commonly produced through fermentation using strains of heterotrophic bacteria such as Corynebacterium glutamicum. Given the large amount of sugar this process consumes, direct photosynthetic production is intriguing alternative. In this study, we report the development of a cyanobacterium, Synechococcus sp. strain PCC 7002, capable of producing L-lysine with CO2 as the sole carbon-source. We found that heterologous expression of a lysine transporter was required to excrete lysine and avoid intracellular accumulation that correlated with poor fitness. Simultaneous expression of a feedback inhibition resistant aspartate kinase and lysine transporter were sufficient for high productivities, but this was also met with a decreased chlorophyll content and reduced growth rates. Increasing the reductant supply by using NH4+, a more reduced nitrogen source relative to NO3-, resulted in a two-fold increase in productivity directing 18% of fixed carbon to lysine. Given this advantage, we demonstrated lysine production from media formulated with a municipal wastewater treatment sidestream as a nutrient source for increased economic and environmental sustainability. Based on our results, we project that Synechococcus sp. strain PCC 7002 could produce lysine at areal productivities approaching that of sugar cane to lysine via fermentation using non-agricultural lands and low-cost feedstocks.
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Affiliation(s)
- Travis C Korosh
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706, United States; Environmental Chemistry and Technology Program, University of Wisconsin-Madison, Madison, WI 53706, United States
| | - Andrew L Markley
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706, United States
| | - Ryan L Clark
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706, United States
| | - Laura L McGinley
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706, United States
| | - Katherine D McMahon
- Environmental Chemistry and Technology Program, University of Wisconsin-Madison, Madison, WI 53706, United States; Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, WI 53706, United States; Department of Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, WI 53706, United States; Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, United States
| | - Brian F Pfleger
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706, United States; Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, WI 53706, United States.
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Kohzuma K, Chiba M, Nagano S, Anai T, Ueda MU, Oguchi R, Shirai K, Hanada K, Hikosaka K, Fujii N. Mutant selection in the self-incompatible plant radish ( Raphanus sativus L. var. sativus) using two-step TILLING. BREEDING SCIENCE 2017; 67:268-276. [PMID: 28744180 PMCID: PMC5515317 DOI: 10.1270/jsbbs.16200] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 03/15/2017] [Indexed: 05/08/2023]
Abstract
Radish (Raphanus sativus L. var. sativus), a widely cultivated root vegetable crop, possesses a large sink organ (the root), implying that photosynthetic activity in radish can be enhanced by altering both the source and sink capacity of the plant. However, since radish is a self-incompatible plant, improved mutation-breeding strategies are needed for this crop. TILLING (Targeting Induced Local Lesions IN Genomes) is a powerful method used for reverse genetics. In this study, we developed a new TILLING strategy involving a two-step mutant selection process for mutagenized radish plants: the first selection is performed to identify a BC1M1 line, that is, progenies of M1 plants crossed with wild-type, and the second step is performed to identify BC1M1 individuals with mutations. We focused on Rubisco as a target, since Rubisco is the most abundant plant protein and a key photosynthetic enzyme. We found that the radish genome contains six RBCS genes and one pseudogene encoding small Rubisco subunits. We screened 955 EMS-induced BC1M1 lines using our newly developed TILLING strategy and obtained six mutant lines for the six RsRBCS genes, encoding proteins with four different types of amino acid substitutions. Finally, we selected a homozygous mutant and subjected it to physiological measurements.
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Affiliation(s)
- Kaori Kohzuma
- Graduate School of Life Sciences, Tohoku University,
Sendai, Miyagi 980-8578,
Japan
- CREST, Japan Science and Technology Agency,
Tokyo 102-0076,
Japan
| | - Motoko Chiba
- Graduate School of Life Sciences, Tohoku University,
Sendai, Miyagi 980-8578,
Japan
- CREST, Japan Science and Technology Agency,
Tokyo 102-0076,
Japan
| | - Soichiro Nagano
- Graduate School of Life Sciences, Tohoku University,
Sendai, Miyagi 980-8578,
Japan
- CREST, Japan Science and Technology Agency,
Tokyo 102-0076,
Japan
| | - Toyoaki Anai
- Faculty of Agriculture, Saga University,
Saga, Saga 840-8502,
Japan
| | - Miki U. Ueda
- Graduate School of Life Sciences, Tohoku University,
Sendai, Miyagi 980-8578,
Japan
| | - Riichi Oguchi
- Graduate School of Life Sciences, Tohoku University,
Sendai, Miyagi 980-8578,
Japan
| | - Kazumasa Shirai
- Frontier Research Academy for Young Researchers, Kyusyu Institute of Technology,
Iizuka, Fukuoka 820-8502,
Japan
- CREST, Japan Science and Technology Agency,
Tokyo 102-0076,
Japan
| | - Kousuke Hanada
- Frontier Research Academy for Young Researchers, Kyusyu Institute of Technology,
Iizuka, Fukuoka 820-8502,
Japan
- CREST, Japan Science and Technology Agency,
Tokyo 102-0076,
Japan
| | - Kouki Hikosaka
- Graduate School of Life Sciences, Tohoku University,
Sendai, Miyagi 980-8578,
Japan
- CREST, Japan Science and Technology Agency,
Tokyo 102-0076,
Japan
| | - Nobuharu Fujii
- Graduate School of Life Sciences, Tohoku University,
Sendai, Miyagi 980-8578,
Japan
- CREST, Japan Science and Technology Agency,
Tokyo 102-0076,
Japan
- Corresponding author (e-mail: )
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