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Hall AN, Hall BW, Kinney KJ, Olsen GG, Banta AB, Noguera DR, Donohue TJ, Peters JM. Tools for Genetic Engineering and Gene Expression Control in Novosphingobium aromaticivorans and Rhodobacter sphaeroides. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.25.554875. [PMID: 37662258 PMCID: PMC10473679 DOI: 10.1101/2023.08.25.554875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Alphaproteobacteria have a variety of cellular and metabolic features that provide important insights into biological systems and enable biotechnologies. For example, some species are capable of converting plant biomass into valuable biofuels and bioproducts have the potential to form the backbone of the sustainable bioeconomy. Among the Alphaproteobacteria, Novosphingobium aromaticivorans, Rhodobacter sphaeroides, and Zymomonas mobilis, show particular promise as organisms that can be engineered to convert extracted plant lignin or sugars into bioproducts and biofuels. Genetic manipulation of these bacteria is needed to introduce engineered pathways and modulate expression of native genes with the goal of enhancing bioproduct output. Although recent work has expanded the genetic toolkit for Z. mobilis, N. aromaticivorans and R. sphaeroides still need facile, reliable approaches to deliver genetic payloads to the genome and to control gene expression. Here, we expand the platform of genetic tools for N. aromaticivorans and R. sphaeroides to address these issues. We demonstrate that Tn7 transposition is an effective approach for introducing engineered DNA into the chromosome of N. aromaticivorans and R. sphaeroides. We screen a synthetic promoter library to identify inducible promoters with strong, regulated activity in both organisms. Combining Tn7 integration with promoters from our library, we establish CRISPR interference systems for N. aromaticivorans and R. sphaeroides that can target essential genes and modulate engineered pathways. We anticipate that these systems will greatly facilitate both genetic engineering and gene function discovery efforts in these industrially important species and other Alphaproteobacteria.
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Affiliation(s)
- Ashley N. Hall
- DOE Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Benjamin W. Hall
- DOE Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Kyle J. Kinney
- DOE Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Gabby G. Olsen
- DOE Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Amy B. Banta
- DOE Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Daniel R. Noguera
- DOE Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Department of Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Timothy J. Donohue
- DOE Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Jason M. Peters
- DOE Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Center for Genomic Science Innovation, University of Wisconsin-Madison, Madison, Wisconsin, USA
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2
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Klaus O, Hilgers F, Nakielski A, Hasenklever D, Jaeger KE, Axmann IM, Drepper T. Engineering phototrophic bacteria for the production of terpenoids. Curr Opin Biotechnol 2022; 77:102764. [PMID: 35932511 DOI: 10.1016/j.copbio.2022.102764] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 06/24/2022] [Accepted: 06/30/2022] [Indexed: 12/13/2022]
Abstract
With more than 80 000 compounds, terpenoids represent one of the largest classes of secondary metabolites naturally produced by various plants and other organisms. Owing to the tremendous structural diversity, they offer a wide range of properties relevant for biotechnological and pharmaceutical applications. In this context, heterologous terpenoid production in engineered microbial hosts represents an often cost-effective and eco-friendly way to make these valuable compounds industrially available. This review provides an overview of current strategies to employ and engineer oxygenic and anoxygenic phototrophic bacteria as alternative cell factories for sustainable terpenoid production. Besides terpenoid pathway engineering, the effects of different illumination strategies on terpenoid photoproduction are key elements in the latest studies.
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Affiliation(s)
- Oliver Klaus
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Forschungszentrum Jülich GmbH, 52428 Jülich, Germany
| | - Fabienne Hilgers
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Forschungszentrum Jülich GmbH, 52428 Jülich, Germany
| | - Andreas Nakielski
- Institute for Synthetic Microbiology, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Dennis Hasenklever
- Institute for Synthetic Microbiology, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Karl-Erich Jaeger
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Forschungszentrum Jülich GmbH, 52428 Jülich, Germany; Institute of Bio, and Geosciences IBG-1: Biotechnology, Forschungszentrum Jülich GmbH, 52428 Jülich, Germany
| | - Ilka M Axmann
- Institute for Synthetic Microbiology, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany.
| | - Thomas Drepper
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Forschungszentrum Jülich GmbH, 52428 Jülich, Germany.
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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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Yu J, Moon SK, Kim YH, Min J. Isoprene production by Rhodobacter sphaeroides and its antimicrobial activity. Res Microbiol 2022; 173:103938. [DOI: 10.1016/j.resmic.2022.103938] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 03/02/2022] [Accepted: 03/09/2022] [Indexed: 11/25/2022]
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Heterologous Production of Plant Terpenes in the Photosynthetic Bacterium Rhodobacter capsulatus. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2022; 2379:125-154. [PMID: 35188660 DOI: 10.1007/978-1-0716-1791-5_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Terpenes are one of the largest classes of secondary metabolites that occur in all kingdoms of life and offer diverse valuable properties for food and pharma industry including pleasant odor or taste as well as antimicrobial or anticancer activities. A multitude of terpene biosynthesis pathways are known, but their efficient biotechnological exploitation requires an adequate microorganism as host which can ideally provide an optimal supply with biosynthetic isoprene precursors. Rhodobacter capsulatus, a Gram-negative, facultative anaerobic, photosynthetic non-sulfur purple bacterium belonging to the α-proteobacteria represents such a host particularly suitable for terpene production. Here, we describe methods for the expression of terpene biosynthetic enzymes in R. capsulatus and the extraction of products for analysis. At the same time, we summarize the current strategies to adjust the biosynthetic precursor supply via isoprenoid biosynthetic pathways.
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Le NTM, Le VV, Shin D, Park SM. Growth-promoting Effect of Alginate Oligosaccharides on Rhodobacter sphaeroides. BIOTECHNOL BIOPROC E 2022. [DOI: 10.1007/s12257-021-0246-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Modulation of Antioxidant Activity Enhances Photoautotrophic Cell Growth of Rhodobacter sphaeroides in Microbial Electrosynthesis. ENERGIES 2022. [DOI: 10.3390/en15030935] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Global warming is currently accelerating due to an increase in greenhouse gas emissions by industrialization. Microbial electrosynthesis (MES) using electroactive autotrophic microorganisms has recently been reported as a method to reduce carbon dioxide, the main culprit of greenhouse gas. However, there are still few cases of application of MES, and the molecular mechanisms are largely unknown. To investigate the growth characteristics in MES, we carried out growth tests according to reducing power sources in Rhodobacter sphaeroides. The growth rate was significantly lower when electrons were directly supplied to cells, compared to when hydrogen was supplied. Through a transcriptome analysis, we found that the expression of reactive oxygen species (ROS)-related genes was meaningfully higher in MES than in normal photoautotrophic conditions. Similarly, endogenous contents of H2O2 were higher and peroxidase activities were lower in MES. The exogenous application of ascorbic acid, a representative biological antioxidant, promotes cell growth by decreasing ROS levels, confirming the inhibitory effects of ROS on MES. Taken together, our observations suggest that reduction of ROS by increasing antioxidant activities is important for enhancing the cell growth and production of CO2-converting substances such as carotenoids in MES in R. sphaeroides
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Schmid F, Novion Ducassou J, Couté Y, Gescher J. Developing Rhodobacter sphaeroides for cathodic biopolymer production. BIORESOURCE TECHNOLOGY 2021; 336:125340. [PMID: 34090098 DOI: 10.1016/j.biortech.2021.125340] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 05/24/2021] [Accepted: 05/25/2021] [Indexed: 06/12/2023]
Abstract
In this work, Rhodobacter sphaeroides was identified as a potential cathodic production strain for photoautotrophic production processes. First, a stable cultivation in a bioelectrochemical system (BES) was established under conditions in which hydrogen produced by a poised cathode served as an electron donor. It was shown that both the introduction of a plasmid vector and exposure to the corresponding antibiotic selection pressure caused a strong improvement in both cathodic biofilm formation and electrochemical properties. A quantitative proteomic analysis identified key players in the molecular adaptation to biofilm growth on the cathodic surface. Furthermore, biofilm formation kinetics were quantified by optical coherence tomography measurements, which showed a strong tendency for biofilm formation together with a robust biofilm architecture. A media switch to N2-limited conditions resulted in increased cathodic poly(3-hydroxybutyrate) (PHB) accumulation, suggesting R. sphaeroides as a potential strain for photoautotrophic PHB production in future industrial applications.
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Affiliation(s)
- Ferdinand Schmid
- Institute for Applied Biosciences, Department of Applied Biology, Karlsruhe Institute of Technology, Karlsruhe Germany
| | - Julia Novion Ducassou
- Univ. Grenoble Alpes, INSERM, CEA, UMR BioSanté U1292, CNRS, CEA, FR2048 38000, Grenoble France
| | - Yohann Couté
- Univ. Grenoble Alpes, INSERM, CEA, UMR BioSanté U1292, CNRS, CEA, FR2048 38000, Grenoble France
| | - Johannes Gescher
- Institute for Applied Biosciences, Department of Applied Biology, Karlsruhe Institute of Technology, Karlsruhe Germany.
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Hage-Hülsmann J, Klaus O, Linke K, Troost K, Gora L, Hilgers F, Wirtz A, Santiago-Schübel B, Loeschcke A, Jaeger KE, Drepper T. Production of C20, C30 and C40 terpenes in the engineered phototrophic bacterium Rhodobacter capsulatus. J Biotechnol 2021; 338:20-30. [PMID: 34237394 DOI: 10.1016/j.jbiotec.2021.07.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 06/28/2021] [Accepted: 07/01/2021] [Indexed: 10/20/2022]
Abstract
Terpenes constitute one of the largest groups of secondary metabolites that are used, for example, as food-additives, fragrances or pharmaceuticals. Due to the formation of an intracytoplasmic membrane system and an efficient intrinsic tetraterpene pathway, the phototrophic α-proteobacterium Rhodobacter capsulatus offers favorable properties for the production of hydrophobic terpenes. However, research efforts have largely focused on sesquiterpene production. Recently, we have developed modular tools allowing to engineer the biosynthesis of terpene precursors. These tools were now applied to boost the biosynthesis of the diterpene casbene, the triterpene squalene and the tetraterpene β-carotene in R. capsulatus SB1003. Selected enzymes of the intrinsic isoprenoid pathway and the heterologous mevalonate (MVA) pathway were co-expressed together with the respective terpene synthases in various combinations. Remarkably, co-expression of genes ispA, idi and dxs enhanced the synthesis of casbene and β-carotene. In contrast, co-expression of precursor biosynthetic genes with the squalene synthase from Arabidopsis thaliana reduced squalene titers. Therefore, we further employed four alternative pro- and eukaryotic squalene synthases. Here, the synthase from Methylococcus capsulatus enabled highest product levels of 90 mg/L squalene upon co-expression with ispA. In summary, we demonstrate the applicability of R. capsulatus for the heterologous production of diverse terpene classes and provide relevant insights for further development of such platforms.
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Affiliation(s)
- Jennifer Hage-Hülsmann
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Forschungszentrum Jülich, Jülich, Germany; Cluster of Excellence on Plant Sciences (CEPLAS), Germany.
| | - Oliver Klaus
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Forschungszentrum Jülich, Jülich, Germany.
| | - Karl Linke
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Forschungszentrum Jülich, Jülich, Germany.
| | - Katrin Troost
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Forschungszentrum Jülich, Jülich, Germany.
| | - Lukas Gora
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Forschungszentrum Jülich, Jülich, Germany.
| | - Fabienne Hilgers
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Forschungszentrum Jülich, Jülich, Germany; Bioeconomy Science Center (BioSC), Forschungszentrum Jülich, Jülich, Germany.
| | - Astrid Wirtz
- Institute of Bio- and Geosciences IBG-1, Forschungszentrum Jülich, Jülich, Germany.
| | - Beatrix Santiago-Schübel
- Central Division of Analytical Chemistry ZEA-3: Analytik/Biospec, Forschungszentrum Jülich, Jülich, Germany.
| | - Anita Loeschcke
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Forschungszentrum Jülich, Jülich, Germany; Cluster of Excellence on Plant Sciences (CEPLAS), Germany; Bioeconomy Science Center (BioSC), Forschungszentrum Jülich, Jülich, Germany.
| | - Karl-Erich Jaeger
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Forschungszentrum Jülich, Jülich, Germany; Institute of Bio- and Geosciences IBG-1, Forschungszentrum Jülich, Jülich, Germany; Cluster of Excellence on Plant Sciences (CEPLAS), Germany; Bioeconomy Science Center (BioSC), Forschungszentrum Jülich, Jülich, Germany.
| | - Thomas Drepper
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Forschungszentrum Jülich, Jülich, Germany; Cluster of Excellence on Plant Sciences (CEPLAS), Germany; Bioeconomy Science Center (BioSC), Forschungszentrum Jülich, Jülich, Germany.
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Hilgers F, Habash SS, Loeschcke A, Ackermann YS, Neumann S, Heck A, Klaus O, Hage-Hülsmann J, Grundler FMW, Jaeger KE, Schleker ASS, Drepper T. Heterologous Production of β-Caryophyllene and Evaluation of Its Activity against Plant Pathogenic Fungi. Microorganisms 2021; 9:microorganisms9010168. [PMID: 33466643 PMCID: PMC7828715 DOI: 10.3390/microorganisms9010168] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 01/08/2021] [Accepted: 01/10/2021] [Indexed: 11/16/2022] Open
Abstract
Terpenoids constitute one of the largest and most diverse groups within the class of secondary metabolites, comprising over 80,000 compounds. They not only exhibit important functions in plant physiology but also have commercial potential in the biotechnological, pharmaceutical, and agricultural sectors due to their promising properties, including various bioactivities against pathogens, inflammations, and cancer. In this work, we therefore aimed to implement the plant sesquiterpenoid pathway leading to β-caryophyllene in the heterologous host Rhodobacter capsulatus and achieved a maximum production of 139 ± 31 mg L-1 culture. As this sesquiterpene offers various beneficial anti-phytopathogenic activities, we evaluated the bioactivity of β-caryophyllene and its oxygenated derivative β-caryophyllene oxide against different phytopathogenic fungi. Here, both compounds significantly inhibited the growth of Sclerotinia sclerotiorum and Fusarium oxysporum by up to 40%, while growth of Alternaria brassicicola was only slightly affected, and Phoma lingam and Rhizoctonia solani were unaffected. At the same time, the compounds showed a promising low inhibitory profile for a variety of plant growth-promoting bacteria at suitable compound concentrations. Our observations thus give a first indication that β-caryophyllene and β-caryophyllene oxide are promising natural agents, which might be applicable for the management of certain plant pathogenic fungi in agricultural crop production.
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Affiliation(s)
- Fabienne Hilgers
- Institute of Molecular Enzyme Technology, Heinrich-Heine-University Düsseldorf, Forschungszentrum Jülich, Wilhelm-Johnen-Straße, 52428 Jülich, Germany; (F.H.); (A.L.); (Y.S.A.); (O.K.); (J.H.-H.); (K.-E.J.)
| | - Samer S. Habash
- INRES—Molecular Phytomedicine, University of Bonn, Karlrobert-Kreiten-Str. 13, 53115 Bonn, Germany; (S.S.H.); (S.N.); (F.M.W.G.)
| | - Anita Loeschcke
- Institute of Molecular Enzyme Technology, Heinrich-Heine-University Düsseldorf, Forschungszentrum Jülich, Wilhelm-Johnen-Straße, 52428 Jülich, Germany; (F.H.); (A.L.); (Y.S.A.); (O.K.); (J.H.-H.); (K.-E.J.)
| | - Yannic Sebastian Ackermann
- Institute of Molecular Enzyme Technology, Heinrich-Heine-University Düsseldorf, Forschungszentrum Jülich, Wilhelm-Johnen-Straße, 52428 Jülich, Germany; (F.H.); (A.L.); (Y.S.A.); (O.K.); (J.H.-H.); (K.-E.J.)
| | - Stefan Neumann
- INRES—Molecular Phytomedicine, University of Bonn, Karlrobert-Kreiten-Str. 13, 53115 Bonn, Germany; (S.S.H.); (S.N.); (F.M.W.G.)
| | - Achim Heck
- Institute of Bio- and Geosciences (IBG-1: Biotechnology) Forschungszentrum Jülich, Wilhelm-Johnen-Straße, 52428 Jülich, Germany;
| | - Oliver Klaus
- Institute of Molecular Enzyme Technology, Heinrich-Heine-University Düsseldorf, Forschungszentrum Jülich, Wilhelm-Johnen-Straße, 52428 Jülich, Germany; (F.H.); (A.L.); (Y.S.A.); (O.K.); (J.H.-H.); (K.-E.J.)
| | - Jennifer Hage-Hülsmann
- Institute of Molecular Enzyme Technology, Heinrich-Heine-University Düsseldorf, Forschungszentrum Jülich, Wilhelm-Johnen-Straße, 52428 Jülich, Germany; (F.H.); (A.L.); (Y.S.A.); (O.K.); (J.H.-H.); (K.-E.J.)
| | - Florian M. W. Grundler
- INRES—Molecular Phytomedicine, University of Bonn, Karlrobert-Kreiten-Str. 13, 53115 Bonn, Germany; (S.S.H.); (S.N.); (F.M.W.G.)
| | - Karl-Erich Jaeger
- Institute of Molecular Enzyme Technology, Heinrich-Heine-University Düsseldorf, Forschungszentrum Jülich, Wilhelm-Johnen-Straße, 52428 Jülich, Germany; (F.H.); (A.L.); (Y.S.A.); (O.K.); (J.H.-H.); (K.-E.J.)
- Institute of Bio- and Geosciences (IBG-1: Biotechnology) Forschungszentrum Jülich, Wilhelm-Johnen-Straße, 52428 Jülich, Germany;
| | - A. Sylvia S. Schleker
- INRES—Molecular Phytomedicine, University of Bonn, Karlrobert-Kreiten-Str. 13, 53115 Bonn, Germany; (S.S.H.); (S.N.); (F.M.W.G.)
- Correspondence: (A.S.S.S.); (T.D.)
| | - Thomas Drepper
- Institute of Molecular Enzyme Technology, Heinrich-Heine-University Düsseldorf, Forschungszentrum Jülich, Wilhelm-Johnen-Straße, 52428 Jülich, Germany; (F.H.); (A.L.); (Y.S.A.); (O.K.); (J.H.-H.); (K.-E.J.)
- Correspondence: (A.S.S.S.); (T.D.)
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11
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Orsi E, Beekwilder J, Eggink G, Kengen SWM, Weusthuis RA. The transition of Rhodobacter sphaeroides into a microbial cell factory. Biotechnol Bioeng 2020; 118:531-541. [PMID: 33038009 PMCID: PMC7894463 DOI: 10.1002/bit.27593] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 07/29/2020] [Accepted: 10/09/2020] [Indexed: 12/11/2022]
Abstract
Microbial cell factories are the workhorses of industrial biotechnology and improving their performances can significantly optimize industrial bioprocesses. Microbial strain engineering is often employed for increasing the competitiveness of bio‐based product synthesis over more classical petroleum‐based synthesis. Recently, efforts for strain optimization have been standardized within the iterative concept of “design‐build‐test‐learn” (DBTL). This approach has been successfully employed for the improvement of traditional cell factories like Escherichia coli and Saccharomyces cerevisiae. Within the past decade, several new‐to‐industry microorganisms have been investigated as novel cell factories, including the versatile α‐proteobacterium Rhodobacter sphaeroides. Despite its history as a laboratory strain for fundamental studies, there is a growing interest in this bacterium for its ability to synthesize relevant compounds for the bioeconomy, such as isoprenoids, poly‐β‐hydroxybutyrate, and hydrogen. In this study, we reflect on the reasons for establishing R. sphaeroides as a cell factory from the perspective of the DBTL concept. Moreover, we discuss current and future opportunities for extending the use of this microorganism for the bio‐based economy. We believe that applying the DBTL pipeline for R. sphaeroides will further strengthen its relevance as a microbial cell factory. Moreover, the proposed use of strain engineering via the DBTL approach may be extended to other microorganisms that have not been critically investigated yet for industrial applications.
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Affiliation(s)
- Enrico Orsi
- Bioprocess Engineering, Wageningen University, Wageningen, The Netherlands.,Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | | | - Gerrit Eggink
- Bioprocess Engineering, Wageningen University, Wageningen, The Netherlands.,Wageningen Food and Biobased Research, Wageningen, The Netherlands
| | - Servé W M Kengen
- Laboratory of Microbiology, Wageningen University, Wageningen, The Netherlands
| | - Ruud A Weusthuis
- Bioprocess Engineering, Wageningen University, Wageningen, The Netherlands
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12
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Orsi E, Beekwilder J, van Gelder D, van Houwelingen A, Eggink G, Kengen SW, Weusthuis RA. Functional replacement of isoprenoid pathways in Rhodobacter sphaeroides. Microb Biotechnol 2020; 13:1082-1093. [PMID: 32207882 PMCID: PMC7264872 DOI: 10.1111/1751-7915.13562] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 01/30/2020] [Accepted: 03/02/2020] [Indexed: 01/09/2023] Open
Abstract
Advances in synthetic biology and metabolic engineering have proven the potential of introducing metabolic by-passes within cell factories. These pathways can provide a more efficient alternative to endogenous counterparts due to their insensitivity to host's regulatory mechanisms. In this work, we replaced the endogenous essential 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway for isoprenoid biosynthesis in the industrially relevant bacterium Rhodobacter sphaeroides by an orthogonal metabolic route. The native 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway was successfully replaced by a heterologous mevalonate (MVA) pathway from a related bacterium. The functional replacement was confirmed by analysis of the reporter molecule amorpha-4,11-diene after cultivation with [4-13 C]glucose. The engineered R. sphaeroides strain relying exclusively on the MVA pathway was completely functional in conditions for sesquiterpene production and, upon increased expression of the MVA enzymes, it reached even higher sesquiterpene yields than the control strain coexpressing both MEP and MVA modules. This work represents an example where substitution of an essential biochemical pathway by an alternative, heterologous pathway leads to enhanced biosynthetic performance.
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Affiliation(s)
- Enrico Orsi
- Bioprocess EngineeringWageningen University6708PBWageningenThe Netherlands
| | | | - Dewi van Gelder
- Bioprocess EngineeringWageningen University6708PBWageningenThe Netherlands
| | | | - Gerrit Eggink
- Bioprocess EngineeringWageningen University6708PBWageningenThe Netherlands
- Wageningen Food and Biobased Research6708WGWageningenThe Netherlands
| | - Servé W.M. Kengen
- Laboratory of MicrobiologyWageningen University6708WEWageningenThe Netherlands
| | - Ruud A. Weusthuis
- Bioprocess EngineeringWageningen University6708PBWageningenThe Netherlands
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13
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Orsi E, Mougiakos I, Post W, Beekwilder J, Dompè M, Eggink G, van der Oost J, Kengen SWM, Weusthuis RA. Growth-uncoupled isoprenoid synthesis in Rhodobacter sphaeroides. BIOTECHNOLOGY FOR BIOFUELS 2020; 13:123. [PMID: 32684976 PMCID: PMC7359475 DOI: 10.1186/s13068-020-01765-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 07/07/2020] [Indexed: 05/16/2023]
Abstract
BACKGROUND Microbial cell factories are usually engineered and employed for cultivations that combine product synthesis with growth. Such a strategy inevitably invests part of the substrate pool towards the generation of biomass and cellular maintenance. Hence, engineering strains for the formation of a specific product under non-growth conditions would allow to reach higher product yields. In this respect, isoprenoid biosynthesis represents an extensively studied example of growth-coupled synthesis with rather unexplored potential for growth-independent production. Rhodobacter sphaeroides is a model bacterium for isoprenoid biosynthesis, either via the native 2-methyl-d-erythritol 4-phosphate (MEP) pathway or the heterologous mevalonate (MVA) pathway, and for poly-β-hydroxybutyrate (PHB) biosynthesis. RESULTS This study investigates the use of this bacterium for growth-independent production of isoprenoids, with amorpha-4,11-diene as reporter molecule. For this purpose, we employed the recently developed Cas9-based genome editing tool for R. sphaeroides to rapidly construct single and double deletion mutant strains of the MEP and PHB pathways, and we subsequently transformed the strains with the amorphadiene producing plasmid. Furthermore, we employed 13C-metabolic flux ratio analysis to monitor the changes in the isoprenoid metabolic fluxes under different cultivation conditions. We demonstrated that active flux via both isoprenoid pathways while inactivating PHB synthesis maximizes growth-coupled isoprenoid synthesis. On the other hand, the strain that showed the highest growth-independent isoprenoid yield and productivity, combined the plasmid-based heterologous expression of the orthogonal MVA pathway with the inactivation of the native MEP and PHB production pathways. CONCLUSIONS Apart from proposing a microbial cell factory for growth-independent isoprenoid synthesis, this work provides novel insights about the interaction of MEP and MVA pathways under different growth conditions.
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Affiliation(s)
- Enrico Orsi
- Bioprocess Engineering, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
- Present Address: Systems and Synthetic Metabolism Group, Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Ioannis Mougiakos
- Laboratory of Microbiology, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
- Present Address: Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz-Centre for Infection Research (HZI), 97080 Würzburg, Germany
| | - Wilbert Post
- Bioprocess Engineering, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
- Laboratory of Microbiology, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | | | - Marco Dompè
- Physical Chemistry and Soft Matter, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Gerrit Eggink
- Bioprocess Engineering, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
- Wageningen Food & Biobased Research, 6708WG Wageningen, The Netherlands
| | - John van der Oost
- Laboratory of Microbiology, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Servé W. M. Kengen
- Laboratory of Microbiology, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Ruud A. Weusthuis
- Bioprocess Engineering, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
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14
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Metabolic flux ratio analysis by parallel 13C labeling of isoprenoid biosynthesis in Rhodobacter sphaeroides. Metab Eng 2019; 57:228-238. [PMID: 31843486 DOI: 10.1016/j.ymben.2019.12.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 12/02/2019] [Accepted: 12/12/2019] [Indexed: 11/21/2022]
Abstract
Metabolic engineering for increased isoprenoid production often benefits from the simultaneous expression of the two naturally available isoprenoid metabolic routes, namely the 2-methyl-D-erythritol 4-phosphate (MEP) pathway and the mevalonate (MVA) pathway. Quantification of the contribution of these pathways to the overall isoprenoid production can help to obtain a better understanding of the metabolism within a microbial cell factory. Such type of investigation can benefit from 13C metabolic flux ratio studies. Here, we designed a method based on parallel labeling experiments (PLEs), using [1-13C]- and [4-13C]glucose as tracers to quantify the metabolic flux ratios in the glycolytic and isoprenoid pathways. By just analyzing a reporter isoprenoid molecule and employing only four equations, we could describe the metabolism involved from substrate catabolism to product formation. These equations infer 13C atom incorporation into the universal isoprenoid building blocks, isopentenyl-pyrophosphate (IPP) and dimethylallyl-pyrophosphate (DMAPP). Therefore, this renders the method applicable to the study of any of isoprenoid of interest. As proof of principle, we applied it to study amorpha-4,11-diene biosynthesis in the bacterium Rhodobacter sphaeroides. We confirmed that in this species the Entner-Doudoroff pathway is the major pathway for glucose catabolism, while the Embden-Meyerhof-Parnas pathway contributes to a lesser extent. Additionally, we demonstrated that co-expression of the MEP and MVA pathways caused a mutual enhancement of their metabolic flux capacity. Surprisingly, we also observed that the isoprenoid flux ratio remains constant under exponential growth conditions, independently from the expression level of the MVA pathway. Apart from proposing and applying a tool for studying isoprenoid biosynthesis within a microbial cell factory, our work reveals important insights from the co-expression of MEP and MVA pathways, including the existence of a yet unclear interaction between them.
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15
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Mougiakos I, Orsi E, Ghiffary MR, Post W, de Maria A, Adiego-Perez B, Kengen SWM, Weusthuis RA, van der Oost J. Efficient Cas9-based genome editing of Rhodobacter sphaeroides for metabolic engineering. Microb Cell Fact 2019; 18:204. [PMID: 31767004 PMCID: PMC6876111 DOI: 10.1186/s12934-019-1255-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 11/13/2019] [Indexed: 12/18/2022] Open
Abstract
Background Rhodobacter sphaeroides is a metabolically versatile bacterium that serves as a model for analysis of photosynthesis, hydrogen production and terpene biosynthesis. The elimination of by-products formation, such as poly-β-hydroxybutyrate (PHB), has been an important metabolic engineering target for R. sphaeroides. However, the lack of efficient markerless genome editing tools for R. sphaeroides is a bottleneck for fundamental studies and biotechnological exploitation. The Cas9 RNA-guided DNA-endonuclease from the type II CRISPR-Cas system of Streptococcus pyogenes (SpCas9) has been extensively employed for the development of genome engineering tools for prokaryotes and eukaryotes, but not for R. sphaeroides. Results Here we describe the development of a highly efficient SpCas9-based genomic DNA targeting system for R. sphaeroides, which we combine with plasmid-borne homologous recombination (HR) templates developing a Cas9-based markerless and time-effective genome editing tool. We further employ the tool for knocking-out the uracil phosphoribosyltransferase (upp) gene from the genome of R. sphaeroides, as well as knocking it back in while altering its start codon. These proof-of-principle processes resulted in editing efficiencies of up to 100% for the knock-out yet less than 15% for the knock-in. We subsequently employed the developed genome editing tool for the consecutive deletion of the two predicted acetoacetyl-CoA reductase genes phaB and phbB in the genome of R. sphaeroides. The culturing of the constructed knock-out strains under PHB producing conditions showed that PHB biosynthesis is supported only by PhaB, while the growth of the R. sphaeroides ΔphbB strains under the same conditions is only slightly affected. Conclusions In this study, we combine the SpCas9 targeting activity with the native homologous recombination (HR) mechanism of R. sphaeroides for the development of a genome editing tool. We further employ the developed tool for the elucidation of the PHB production pathway of R. sphaeroides. We anticipate that the presented work will accelerate molecular research with R. sphaeroides.
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Affiliation(s)
- Ioannis Mougiakos
- Laboratory of Microbiology, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, The Netherlands
| | - Enrico Orsi
- Bioprocess Engineering, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands
| | - Mohammad Rifqi Ghiffary
- Laboratory of Microbiology, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, The Netherlands.,Bioprocess Engineering, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands.,Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, Daejeon, South Korea
| | - Wilbert Post
- Bioprocess Engineering, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands
| | - Alberto de Maria
- Laboratory of Microbiology, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, The Netherlands.,Bioprocess Engineering, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands.,Systems and Synthetic Metabolism Group, Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476, Potsdam, Germany
| | - Belén Adiego-Perez
- Bioprocess Engineering, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands
| | - Servé W M Kengen
- Laboratory of Microbiology, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, The Netherlands
| | - Ruud A Weusthuis
- Bioprocess Engineering, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands.
| | - John van der Oost
- Laboratory of Microbiology, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, The Netherlands.
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16
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Troost K, Loeschcke A, Hilgers F, Özgür AY, Weber TM, Santiago-Schübel B, Svensson V, Hage-Hülsmann J, Habash SS, Grundler FMW, Schleker ASS, Jaeger KE, Drepper T. Engineered Rhodobacter capsulatus as a Phototrophic Platform Organism for the Synthesis of Plant Sesquiterpenoids. Front Microbiol 2019; 10:1998. [PMID: 31555236 PMCID: PMC6742980 DOI: 10.3389/fmicb.2019.01998] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 08/15/2019] [Indexed: 12/11/2022] Open
Abstract
Sesquiterpenoids are a large class of natural compounds offering manifold properties valuable for food, cosmetics, agriculture, and pharma industry. Production in microorganisms is a sustainable approach to provide sesquiterpenoids for research and industrial use independent of their natural sources. This requires the functional transfer of the respective biocatalytic pathways in an adequate host microorganism offering a sufficient supply of precursors that is ideally adjusted to the individual demand of the recombinant biosynthesis route. The phototrophic purple bacterium Rhodobacter capsulatus offers unique physiological properties that are favorable for biosynthesis of hydrophobic terpenes. Under phototrophic conditions, it develops a large intracytoplasmic membrane suitable for hosting membrane-bound enzymes and metabolites of respective biosynthetic pathways. In addition, Rhodobacter harbors an intrinsic carotenoid biosynthesis that can be engineered toward the production of foreign terpenes. Here, we evaluate R. capsulatus as host for the production of plant sesquiterpenoids under phototrophic conditions using patchoulol and valencene as a proof of concept. The heterologous expression of patchoulol synthase PcPS from Pogostemon cablin as well as the valencene synthases CsVS from Citrus sinensis and CnVS from Callitropsis nootkatensis led to the production of the respective sesquiterpenoids in R. capsulatus. To analyze, if gradually adjustable formation of the key precursor farnesylpyrophosphate (FPP) is beneficial for sesquiterpene synthesis under phototrophic conditions, the intrinsic 1-deoxy-D-xylulose 5-phosphate (DXP) pathway genes as well as the heterologous mevalonate pathway genes were modularly expressed in various combinations. To this end, different plasmids and chromosomally integrated expression tools were developed harboring the strong and tightly controlled Pnif promoter for heterologous gene expression. Notably, comparative studies identified a distinct combination of precursor biosynthetic genes as best-performing setup for each of the tested sesquiterpene synthases. In summary, we could demonstrate that R. capsulatus is a promising alternative platform organism that is suited for sustainable sesquiterpenoid formation under phototrophic cultivation conditions. A modular engineering of R. capsulatus strains via tailored co-expression of FPP biosynthetic genes further allowed adaptation of sesquiterpene precursor formation to its catalytic conversion by different plant terpene synthases.
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Affiliation(s)
- Katrin Troost
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany, Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Anita Loeschcke
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany, Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Fabienne Hilgers
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany, Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Armagan Yakup Özgür
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany, Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Tim Moritz Weber
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany, Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Beatrix Santiago-Schübel
- Central Institute for Engineering, Electronics and Analytics ZEA-3, Analytics, Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Vera Svensson
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany, Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Jennifer Hage-Hülsmann
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany, Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Samer S Habash
- INRES-Molecular Phytomedicine, Rhenish Friedrich-Wilhelm University of Bonn, Bonn, Germany
| | - Florian M W Grundler
- INRES-Molecular Phytomedicine, Rhenish Friedrich-Wilhelm University of Bonn, Bonn, Germany
| | - A Sylvia S Schleker
- INRES-Molecular Phytomedicine, Rhenish Friedrich-Wilhelm University of Bonn, Bonn, Germany
| | - Karl-Erich Jaeger
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany, Forschungszentrum Jülich GmbH, Jülich, Germany.,Institute of Bio- and Geosciences IBG-1, Biotechnology, Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Thomas Drepper
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany, Forschungszentrum Jülich GmbH, Jülich, Germany
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17
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Hage-Hülsmann J, Metzger S, Wewer V, Buechel F, Troost K, Thies S, Loeschcke A, Jaeger KE, Drepper T. Biosynthesis of cycloartenol by expression of plant and bacterial oxidosqualene cyclases in engineered Rhodobacter capsulatus. J Biotechnol 2019; 306S:100014. [PMID: 34112372 DOI: 10.1016/j.btecx.2020.100014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 01/14/2020] [Accepted: 01/29/2020] [Indexed: 02/07/2023]
Abstract
Cyclic triterpenes are a large group of secondary metabolites produced by plants, fungi and bacteria. They have diverse biological functions, and offer potential health benefits for humans. Although various terpenes from the mono-, sesqui- and diterpene classes are easy to produce in engineered bacteria, heterologous synthesis of cyclic triterpenes is more challenging. We have recently shown that the triterpene cycloartenol can be produced in Rhodobacter capsulatus SB1003 but initial titers were low with 0.34mgL-1. To assess, if this phototrophic α-proteobacterium can be engineered for enhanced triterpene production, we followed two alternative strategies by comparing the performance of the R. capsulatus SB1003 wildtype strain with two recombinant strains carrying either a mevalonate pathway implemented from Paracoccus zeaxanthinifaciens or a deletion in the intrinsic carotenoid biosynthesis gene crtE. These strains are thus engineered for an enhanced isoprenoid biosynthesis or a suppressed precursor conversion by the competing carotenoid pathway. Moreover, three different cycloartenol synthase (CAS) genes from Arabidopsis thaliana or the myxobacterial strains Stigmatella aurantiaca Sga15 and DW4/3-1 were tested for heterologous cycloartenol synthesis. We found that the heterologous expression of mevalonate pathway enzymes had little impact on cycloartenol levels irrespective of the chosen CAS. In contrast, the use of the newly constructed carotenoid-deficient crtE deletion strain showed threefold increased cycloartenol product titers. We conclude that R. capsulatus is a promising alternative host for the functional expression of triterpene biosynthetic enzymes from plants and microbes. Apparently, product titers can also be improved by suppression of competing precursor consumption.
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Affiliation(s)
- Jennifer Hage-Hülsmann
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Forschungszentrum Jülich, Jülich, D-52425, Germany; Cluster of Excellence on Plant Sciences (CEPLAS) Düsseldorf, D-40225, Germany.
| | - Sabine Metzger
- Cluster of Excellence on Plant Sciences (CEPLAS) Düsseldorf, D-40225, Germany; MS Platform, Department of Biology, University of Cologne, Cologne, D-50674, Germany.
| | - Vera Wewer
- Cluster of Excellence on Plant Sciences (CEPLAS) Düsseldorf, D-40225, Germany; MS Platform, Department of Biology, University of Cologne, Cologne, D-50674, Germany.
| | - Felix Buechel
- Cluster of Excellence on Plant Sciences (CEPLAS) Düsseldorf, D-40225, Germany; MS Platform, Department of Biology, University of Cologne, Cologne, D-50674, Germany.
| | - Katrin Troost
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Forschungszentrum Jülich, Jülich, D-52425, Germany; Bioeconomy Science Center (BioSC), Forschungszentrum Jülich, Jülich, D-52425, Germany.
| | - Stephan Thies
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Forschungszentrum Jülich, Jülich, D-52425, Germany; Bioeconomy Science Center (BioSC), Forschungszentrum Jülich, Jülich, D-52425, Germany.
| | - Anita Loeschcke
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Forschungszentrum Jülich, Jülich, D-52425, Germany; Cluster of Excellence on Plant Sciences (CEPLAS) Düsseldorf, D-40225, Germany; Bioeconomy Science Center (BioSC), Forschungszentrum Jülich, Jülich, D-52425, Germany.
| | - Karl-Erich Jaeger
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Forschungszentrum Jülich, Jülich, D-52425, Germany; Cluster of Excellence on Plant Sciences (CEPLAS) Düsseldorf, D-40225, Germany; Bioeconomy Science Center (BioSC), Forschungszentrum Jülich, Jülich, D-52425, Germany; Institute of Bio- and Geosciences IBG-1, Forschungszentrum Jülich, Jülich, D-52425, Germany. k.-
| | - Thomas Drepper
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Forschungszentrum Jülich, Jülich, D-52425, Germany; Cluster of Excellence on Plant Sciences (CEPLAS) Düsseldorf, D-40225, Germany.
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