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Jorrin B, Haskett TL, Knights HE, Martyn A, Underwood TJ, Dolliver J, Ledermann R, Poole PS. Stable, fluorescent markers for tracking synthetic communities and assembly dynamics. MICROBIOME 2024; 12:81. [PMID: 38715147 PMCID: PMC11075435 DOI: 10.1186/s40168-024-01792-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 03/09/2024] [Indexed: 05/12/2024]
Abstract
BACKGROUND After two decades of extensive microbiome research, the current forefront of scientific exploration involves moving beyond description and classification to uncovering the intricate mechanisms underlying the coalescence of microbial communities. Deciphering microbiome assembly has been technically challenging due to their vast microbial diversity but establishing a synthetic community (SynCom) serves as a key strategy in unravelling this process. Achieving absolute quantification is crucial for establishing causality in assembly dynamics. However, existing approaches are primarily designed to differentiate a specific group of microorganisms within a particular SynCom. RESULTS To address this issue, we have developed the differential fluorescent marking (DFM) strategy, employing three distinguishable fluorescent proteins in single and double combinations. Building on the mini-Tn7 transposon, DFM capitalises on enhanced stability and broad applicability across diverse Proteobacteria species. The various DFM constructions are built using the pTn7-SCOUT plasmid family, enabling modular assembly, and facilitating the interchangeability of expression and antibiotic cassettes in a single reaction. DFM has no detrimental effects on fitness or community assembly dynamics, and through the application of flow cytometry, we successfully differentiated, quantified, and tracked a diverse six-member SynCom under various complex conditions like root rhizosphere showing a different colonisation assembly dynamic between pea and barley roots. CONCLUSIONS DFM represents a powerful resource that eliminates dependence on sequencing and/or culturing, thereby opening new avenues for studying microbiome assembly. Video Abstract.
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Affiliation(s)
- Beatriz Jorrin
- Molecular Plant Sciences Section, Department of Biology, University of Oxford, Oxford, OX1 3RB, UK.
| | - Timothy L Haskett
- Molecular Plant Sciences Section, Department of Biology, University of Oxford, Oxford, OX1 3RB, UK
| | - Hayley E Knights
- Molecular Plant Sciences Section, Department of Biology, University of Oxford, Oxford, OX1 3RB, UK
| | - Anna Martyn
- Molecular Plant Sciences Section, Department of Biology, University of Oxford, Oxford, OX1 3RB, UK
| | - Thomas J Underwood
- Molecular Plant Sciences Section, Department of Biology, University of Oxford, Oxford, OX1 3RB, UK
| | - Jessica Dolliver
- Molecular Plant Sciences Section, Department of Biology, University of Oxford, Oxford, OX1 3RB, UK
| | - Raphael Ledermann
- Molecular Plant Sciences Section, Department of Biology, University of Oxford, Oxford, OX1 3RB, UK
| | - Philip S Poole
- Molecular Plant Sciences Section, Department of Biology, University of Oxford, Oxford, OX1 3RB, UK
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Ordon J, Thouin J, Nakano RT, Ma KW, Zhang P, Huettel B, Garrido-Oter R, Schulze-Lefert P. Chromosomal barcodes for simultaneous tracking of near-isogenic bacterial strains in plant microbiota. Nat Microbiol 2024; 9:1117-1129. [PMID: 38503974 PMCID: PMC10994850 DOI: 10.1038/s41564-024-01619-8] [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: 04/24/2023] [Accepted: 01/22/2024] [Indexed: 03/21/2024]
Abstract
DNA-amplicon-based microbiota profiling can estimate species diversity and abundance but cannot resolve genetic differences within individuals of the same species. Here we report the development of modular bacterial tags (MoBacTags) encoding DNA barcodes that enable tracking of near-isogenic bacterial commensals in an array of complex microbiome communities. Chromosomally integrated DNA barcodes are then co-amplified with endogenous marker genes of the community by integrating corresponding primer binding sites into the barcode. We use this approach to assess the contributions of individual bacterial genes to Arabidopsis thaliana root microbiota establishment with synthetic communities that include MoBacTag-labelled strains of Pseudomonas capeferrum. Results show reduced root colonization for certain mutant strains with defects in gluconic-acid-mediated host immunosuppression, which would not be detected with traditional amplicon sequencing. Our work illustrates how MoBacTags can be applied to assess scaling of individual bacterial genetic determinants in the plant microbiota.
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Affiliation(s)
- Jana Ordon
- Department of Plant-Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, Germany
- Institute of Plant Molecular Biology, University of Zurich, Zurich, Switzerland
| | - Julien Thouin
- Department of Plant-Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Ryohei Thomas Nakano
- Department of Plant-Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, Germany
- Department of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo, Japan
| | - Ka-Wai Ma
- Department of Plant-Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, Germany
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Pengfan Zhang
- Department of Plant-Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, Germany
- Innovative Genomics Institute (IGI), University of California, Berkeley, CA, USA
| | - Bruno Huettel
- Department of Plant-Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Ruben Garrido-Oter
- Department of Plant-Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, Germany
- Cluster of Excellence on Plant Sciences (CEPLAS), Max Planck Institute for Plant Breeding Research, Cologne, Germany
- Earlham Institute, Norwich, UK
| | - Paul Schulze-Lefert
- Department of Plant-Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, Germany.
- Cluster of Excellence on Plant Sciences (CEPLAS), Max Planck Institute for Plant Breeding Research, Cologne, Germany.
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3
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Addison H, Glatter T, K. A. Hochberg G, Rebelein JG. Two distinct ferredoxins are essential for nitrogen fixation by the iron nitrogenase in Rhodobacter capsulatus. mBio 2024; 15:e0331423. [PMID: 38377621 PMCID: PMC10936413 DOI: 10.1128/mbio.03314-23] [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: 12/07/2023] [Accepted: 01/29/2024] [Indexed: 02/22/2024] Open
Abstract
Nitrogenases are the only enzymes able to fix gaseous nitrogen into bioavailable ammonia and hence are essential for sustaining life. Catalysis by nitrogenases requires both a large amount of ATP and electrons donated by strongly reducing ferredoxins or flavodoxins. Our knowledge about the mechanisms of electron transfer to nitrogenase enzymes is limited: The electron transport to the iron (Fe)-nitrogenase has hardly been investigated. Here, we characterized the electron transfer pathway to the Fe-nitrogenase in Rhodobacter capsulatus via proteome analyses, genetic deletions, complementation studies, and phylogenetics. Proteome analyses revealed an upregulation of four ferredoxins under nitrogen-fixing conditions reliant on the Fe-nitrogenase in a molybdenum nitrogenase knockout strain, compared to non-nitrogen-fixing conditions. Based on these findings, R. capsulatus strains with deletions of ferredoxin (fdx) and flavodoxin (fld, nifF) genes were constructed to investigate their roles in nitrogen fixation by the Fe-nitrogenase. R. capsulatus deletion strains were characterized by monitoring diazotrophic growth and Fe-nitrogenase activity in vivo. Only deletions of fdxC or fdxN resulted in slower growth and reduced Fe-nitrogenase activity, whereas the double deletion of both fdxC and fdxN abolished diazotrophic growth. Differences in the proteomes of ∆fdxC and ∆fdxN strains, in conjunction with differing plasmid complementation behaviors of fdxC and fdxN, indicate that the two Fds likely possess different roles and functions. These findings will guide future engineering of the electron transport systems to nitrogenase enzymes, with the aim of increased electron flux and product formation.IMPORTANCENitrogenases are essential for biological nitrogen fixation, converting atmospheric nitrogen gas to bioavailable ammonia. The production of ammonia by diazotrophic organisms, harboring nitrogenases, is essential for sustaining plant growth. Hence, there is a large scientific interest in understanding the cellular mechanisms for nitrogen fixation via nitrogenases. Nitrogenases rely on highly reduced electrons to power catalysis, although we lack knowledge as to which proteins shuttle the electrons to nitrogenases within cells. Here, we characterized the electron transport to the iron (Fe)-nitrogenase in the model diazotroph Rhodobacter capsulatus, showing that two distinct ferredoxins are very important for nitrogen fixation despite having different redox centers. In addition, our research expands upon the debate on whether ferredoxins have functional redundancy or perform distinct roles within cells. Here, we observe that both essential ferredoxins likely have distinct roles based on differential proteome shifts of deletion strains and different complementation behaviors.
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Affiliation(s)
- Holly Addison
- Microbial Metalloenzymes Research Group, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Timo Glatter
- Core Facility for Mass Spectrometry & Proteomics, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Georg K. A. Hochberg
- Evolutionary Biochemistry Research Group, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
- Center for Synthetic Microbiology (SYNMIKRO), Philipps University Marburg, Marburg, Germany
| | - Johannes G. Rebelein
- Microbial Metalloenzymes Research Group, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
- Center for Synthetic Microbiology (SYNMIKRO), Philipps University Marburg, Marburg, Germany
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4
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Majidian P, Ghorbani HR, Farajpour M. Achieving agricultural sustainability through soybean production in Iran: Potential and challenges. Heliyon 2024; 10:e26389. [PMID: 38404839 PMCID: PMC10884498 DOI: 10.1016/j.heliyon.2024.e26389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 01/17/2024] [Accepted: 02/12/2024] [Indexed: 02/27/2024] Open
Abstract
The utilization of soybean as a key oil crop to enhance sustainable agriculture has garnered significant attention from researchers. Its lower water requirements compared to rice, along with its reduced environmental impact, including greenhouse gas emissions, improved water quality, enhanced biodiversity, and efficient resource utilization, make it an attractive option. Unfortunately, Iran, like many other developing countries, heavily relies on soybean imports (over 90%) to meet the demand for oil and protein in human and livestock food rations. The decline in soybean production, coupled with diminishing cultivation areas, yield rates, and increasing import needs, underscores the urgent need to address the challenges faced in Iran. The decline in soybean production in the country can be attributed to various factors, including environmental stresses (both biotic and abiotic), limited variation in soybean cultivars, inadequate mechanization for cultivation, and economic policies. Hence, this review provides a comprehensive overview of the current status of soybean production in Iran and highlights its potential to enhance sustainable agriculture. Additionally, it examines the challenges and constraints associated with soybean cultivation, such as environmental changes and unbalanced marketing, and explores potential solutions and management strategies to bridge the gap between small-scale and large-scale production. Given the increasing global demand for plant-based protein and the significance of the feed industry, studying the limitations faced by countries with slower soybean production growth can shed light on the issues and present opportunities to capitalize on novel soybean advancements in the future. By addressing these challenges and unlocking the potential of soybean cultivation, Iran can contribute to sustainable agricultural practices and attain a more resilient food system.
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Affiliation(s)
- Parastoo Majidian
- Crop and Horticultural Science Research Department, Mazandaran Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education and Extension Organization (AREEO), Sari, Iran
| | - Hamid Reza Ghorbani
- Crop and Horticultural Science Research Department, Mazandaran Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education and Extension Organization (AREEO), Sari, Iran
| | - Mostafa Farajpour
- Crop and Horticultural Science Research Department, Mazandaran Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education and Extension Organization (AREEO), Sari, Iran
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5
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Elston KM, Phillips LE, Leonard SP, Young E, Holley JAC, Ahsanullah T, McReynolds B, Moran NA, Barrick JE. The Pathfinder plasmid toolkit for genetically engineering newly isolated bacteria enables the study of Drosophila-colonizing Orbaceae. ISME COMMUNICATIONS 2023; 3:49. [PMID: 37225918 PMCID: PMC10209150 DOI: 10.1038/s43705-023-00255-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2023] [Revised: 04/18/2023] [Accepted: 05/11/2023] [Indexed: 05/26/2023]
Abstract
Toolkits of plasmids and genetic parts streamline the process of assembling DNA constructs and engineering microbes. Many of these kits were designed with specific industrial or laboratory microbes in mind. For researchers interested in non-model microbial systems, it is often unclear which tools and techniques will function in newly isolated strains. To address this challenge, we designed the Pathfinder toolkit for quickly determining the compatibility of a bacterium with different plasmid components. Pathfinder plasmids combine three different broad-host-range origins of replication with multiple antibiotic resistance cassettes and reporters, so that sets of parts can be rapidly screened through multiplex conjugation. We first tested these plasmids in Escherichia coli, a strain of Sodalis praecaptivus that colonizes insects, and a Rosenbergiella isolate from leafhoppers. Then, we used the Pathfinder plasmids to engineer previously unstudied bacteria from the family Orbaceae that were isolated from several fly species. Engineered Orbaceae strains were able to colonize Drosophila melanogaster and could be visualized in fly guts. Orbaceae are common and abundant in the guts of wild-caught flies but have not been included in laboratory studies of how the Drosophila microbiome affects fly health. Thus, this work provides foundational genetic tools for studying microbial ecology and host-associated microbes, including bacteria that are a key constituent of the gut microbiome of a model insect species.
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Affiliation(s)
- Katherine M Elston
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Laila E Phillips
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Sean P Leonard
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, 78712, USA
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Eleanor Young
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Jo-Anne C Holley
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX, 78712, USA
- Freshman Research Initiative, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Tasneem Ahsanullah
- Freshman Research Initiative, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Braydin McReynolds
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Nancy A Moran
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Jeffrey E Barrick
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, 78712, USA.
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6
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Haskett TL, Geddes BA, Paramasivan P, Green P, Chitnavis S, Mendes MD, Jorrín B, Knights HE, Bastholm TR, Ramsay JP, Oldroyd GED, Poole PS. Rhizopine biosensors for plant-dependent control of bacterial gene expression. Environ Microbiol 2023; 25:383-396. [PMID: 36428208 PMCID: PMC10107442 DOI: 10.1111/1462-2920.16288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 11/23/2022] [Indexed: 11/27/2022]
Abstract
Engineering signalling between plants and microbes could be exploited to establish host-specificity between plant-growth-promoting bacteria and target crops in the environment. We previously engineered rhizopine-signalling circuitry facilitating exclusive signalling between rhizopine-producing (RhiP) plants and model bacterial strains. Here, we conduct an in-depth analysis of rhizopine-inducible expression in bacteria. We characterize two rhizopine-inducible promoters and explore the bacterial host-range of rhizopine biosensor plasmids. By tuning the expression of rhizopine uptake genes, we also construct a new biosensor plasmid pSIR05 that has minimal impact on host cell growth in vitro and exhibits markedly improved stability of expression in situ on RhiP barley roots compared to the previously described biosensor plasmid pSIR02. We demonstrate that a sub-population of Azorhizobium caulinodans cells carrying pSIR05 can sense rhizopine and activate gene expression when colonizing RhiP barley roots. However, these bacteria were mildly defective for colonization of RhiP barley roots compared to the wild-type parent strain. This work provides advancement towards establishing more robust plant-dependent control of bacterial gene expression and highlights the key challenges remaining to achieve this goal.
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Affiliation(s)
| | - Barney A Geddes
- Department of Plant Sciences, University of Oxford, Oxford, UK
- Department of Microbiological Sciences, North Dakota State University, Fargo, North Dakota, USA
| | | | - Patrick Green
- Department of Plant Sciences, University of Oxford, Oxford, UK
| | - Samir Chitnavis
- Department of Plant Sciences, University of Oxford, Oxford, UK
| | - Marta D Mendes
- Department of Plant Sciences, University of Oxford, Oxford, UK
| | - Beatriz Jorrín
- Department of Plant Sciences, University of Oxford, Oxford, UK
| | | | - Tahlia R Bastholm
- Curtin Medical School and Curtin Health Innovation Research Institute, Curtin University, Perth, Western Australia, Australia
| | - Joshua P Ramsay
- Curtin Medical School and Curtin Health Innovation Research Institute, Curtin University, Perth, Western Australia, Australia
| | - Giles E D Oldroyd
- Sainsbury Laboratory, University of Cambridge, Cambridge, UK
- Crop Science Centre, University of Cambridge, Cambridge, UK
| | - Philip S Poole
- Department of Plant Sciences, University of Oxford, Oxford, UK
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7
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Martínez-García E, Fraile S, Algar E, Aparicio T, Velázquez E, Calles B, Tas H, Blázquez B, Martín B, Prieto C, Sánchez-Sampedro L, Nørholm MH, Volke D, Wirth N, Dvořák P, Alejaldre L, Grozinger L, Crowther M, Goñi-Moreno A, Nikel P, Nogales J, de Lorenzo V. SEVA 4.0: an update of the Standard European Vector Architecture database for advanced analysis and programming of bacterial phenotypes. Nucleic Acids Res 2023; 51:D1558-D1567. [PMID: 36420904 PMCID: PMC9825617 DOI: 10.1093/nar/gkac1059] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 10/22/2022] [Accepted: 10/24/2022] [Indexed: 11/27/2022] Open
Abstract
The SEVA platform (https://seva-plasmids.com) was launched one decade ago, both as a database (DB) and as a physical repository of plasmid vectors for genetic analysis and engineering of Gram-negative bacteria with a structure and nomenclature that follows a strict, fixed architecture of functional DNA segments. While the current update keeps the basic features of earlier versions, the platform has been upgraded not only with many more ready-to-use plasmids but also with features that expand the range of target species, harmonize DNA assembly methods and enable new applications. In particular, SEVA 4.0 includes (i) a sub-collection of plasmids for easing the composition of multiple DNA segments with MoClo/Golden Gate technology, (ii) vectors for Gram-positive bacteria and yeast and [iii] off-the-shelf constructs with built-in functionalities. A growing collection of plasmids that capture part of the standard-but not its entirety-has been compiled also into the DB and repository as a separate corpus (SEVAsib) because of its value as a resource for constructing and deploying phenotypes of interest. Maintenance and curation of the DB were accompanied by dedicated diffusion and communication channels that make the SEVA platform a popular resource for genetic analyses, genome editing and bioengineering of a large number of microorganisms.
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Affiliation(s)
- Esteban Martínez-García
- Systems Biology Department, Centro Nacional de Biotecnología (CNB-CSIC), 28049 Cantoblanco-Madrid, Spain
| | - Sofía Fraile
- Systems Biology Department, Centro Nacional de Biotecnología (CNB-CSIC), 28049 Cantoblanco-Madrid, Spain
| | - Elena Algar
- Systems Biology Department, Centro Nacional de Biotecnología (CNB-CSIC), 28049 Cantoblanco-Madrid, Spain
| | - Tomás Aparicio
- Systems Biology Department, Centro Nacional de Biotecnología (CNB-CSIC), 28049 Cantoblanco-Madrid, Spain
| | - Elena Velázquez
- Systems Biology Department, Centro Nacional de Biotecnología (CNB-CSIC), 28049 Cantoblanco-Madrid, Spain
| | - Belén Calles
- Systems Biology Department, Centro Nacional de Biotecnología (CNB-CSIC), 28049 Cantoblanco-Madrid, Spain
| | - Huseyin Tas
- Systems Biology Department, Centro Nacional de Biotecnología (CNB-CSIC), 28049 Cantoblanco-Madrid, Spain
| | - Blas Blázquez
- Systems Biology Department, Centro Nacional de Biotecnología (CNB-CSIC), 28049 Cantoblanco-Madrid, Spain
| | | | | | | | - Morten H H Nørholm
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
| | - Daniel C Volke
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
| | - Nicolas T Wirth
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
| | - Pavel Dvořák
- Department of Experimental Biology, Faculty of Science, Masaryk University, Brno 62500 Czech Republic
| | - Lorea Alejaldre
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (INIA-CSIC), Pozuelo de Alarcón 28223, Spain
| | - Lewis Grozinger
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (INIA-CSIC), Pozuelo de Alarcón 28223, Spain
- School of Computing, Newcastle University, NE4 5TG, UK
| | - Matthew Crowther
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (INIA-CSIC), Pozuelo de Alarcón 28223, Spain
- School of Computing, Newcastle University, NE4 5TG, UK
| | - Angel Goñi-Moreno
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (INIA-CSIC), Pozuelo de Alarcón 28223, Spain
| | - Pablo I Nikel
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
| | - Juan Nogales
- Systems Biology Department, Centro Nacional de Biotecnología (CNB-CSIC), 28049 Cantoblanco-Madrid, Spain
| | - Víctor de Lorenzo
- Systems Biology Department, Centro Nacional de Biotecnología (CNB-CSIC), 28049 Cantoblanco-Madrid, Spain
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Abstract
The continual demand for specialized molecular cloning techniques that suit a broad range of applications has driven the development of many different cloning strategies. One method that has gained significant traction is Golden Gate assembly, which achieves hierarchical assembly of DNA parts by utilizing Type IIS restriction enzymes to produce user-specified sticky ends on cut DNA fragments. This technique has been modularized and standardized, and includes different subfamilies of methods, the most widely adopted of which are the MoClo and Golden Braid standards. Moreover, specialized toolboxes tailored to specific applications or organisms are also available. Still, the quantity and range of assembly methods can constitute a barrier to adoption for new users, and even experienced scientists might find it difficult to discern which tools are best suited toward their goals. In this review, we provide a beginner-friendly guide to Golden Gate assembly, compare the different available standards, and detail the specific features and quirks of commonly used toolboxes. We also provide an update on the state-of-the-art in Golden Gate technology, discussing recent advances and challenges to inform existing users and promote standard practices.
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Affiliation(s)
- Jasmine
E. Bird
- School
of Computing, Faculty of Science Agriculture and Engineering, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom
| | - Jon Marles-Wright
- Biosciences
Institute, Faculty of Medical Sciences, Newcastle University, Newcastle
upon Tyne, NE2 4HH, United
Kingdom,
| | - Andrea Giachino
- Biosciences
Institute, Faculty of Medical Sciences, Newcastle University, Newcastle
upon Tyne, NE2 4HH, United
Kingdom,School
of Science, Engineering & Environment, University of Salford, Salford, M5 4NT, United Kingdom
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Dundas CM, Dinneny JR. Genetic Circuit Design in Rhizobacteria. BIODESIGN RESEARCH 2022; 2022:9858049. [PMID: 37850138 PMCID: PMC10521742 DOI: 10.34133/2022/9858049] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2022] [Accepted: 07/31/2022] [Indexed: 10/19/2023] Open
Abstract
Genetically engineered plants hold enormous promise for tackling global food security and agricultural sustainability challenges. However, construction of plant-based genetic circuitry is constrained by a lack of well-characterized genetic parts and circuit design rules. In contrast, advances in bacterial synthetic biology have yielded a wealth of sensors, actuators, and other tools that can be used to build bacterial circuitry. As root-colonizing bacteria (rhizobacteria) exert substantial influence over plant health and growth, genetic circuit design in these microorganisms can be used to indirectly engineer plants and accelerate the design-build-test-learn cycle. Here, we outline genetic parts and best practices for designing rhizobacterial circuits, with an emphasis on sensors, actuators, and chassis species that can be used to monitor/control rhizosphere and plant processes.
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Affiliation(s)
| | - José R. Dinneny
- Department of Biology, Stanford University, Stanford, CA 94305, USA
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10
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Control of nitrogen fixation and ammonia excretion in Azorhizobium caulinodans. PLoS Genet 2022; 18:e1010276. [PMID: 35727841 PMCID: PMC9249168 DOI: 10.1371/journal.pgen.1010276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 07/01/2022] [Accepted: 05/26/2022] [Indexed: 11/19/2022] Open
Abstract
Due to the costly energy demands of nitrogen (N) fixation, diazotrophic bacteria have evolved complex regulatory networks that permit expression of the catalyst nitrogenase only under conditions of N starvation, whereas the same condition stimulates upregulation of high-affinity ammonia (NH3) assimilation by glutamine synthetase (GS), preventing excess release of excess NH3 for plants. Diazotrophic bacteria can be engineered to excrete NH3 by interference with GS, however control is required to minimise growth penalties and prevent unintended provision of NH3 to non-target plants. Here, we tested two strategies to control GS regulation and NH3 excretion in our model cereal symbiont Azorhizobium caulinodans AcLP, a derivative of ORS571. We first attempted to recapitulate previous work where mutation of both PII homologues glnB and glnK stimulated GS shutdown but found that one of these genes was essential for growth. Secondly, we expressed unidirectional adenylyl transferases (uATs) in a ΔglnE mutant of AcLP which permitted strong GS shutdown and excretion of NH3 derived from N2 fixation and completely alleviated negative feedback regulation on nitrogenase expression. We placed a uAT allele under control of the NifA-dependent promoter PnifH, permitting GS shutdown and NH3 excretion specifically under microaerobic conditions, the same cue that initiates N2 fixation, then deleted nifA and transferred a rhizopine nifAL94Q/D95Q-rpoN controller plasmid into this strain, permitting coupled rhizopine-dependent activation of N2 fixation and NH3 excretion. This highly sophisticated and multi-layered control circuitry brings us a step closer to the development of a "synthetic symbioses” where N2 fixation and NH3 excretion could be specifically activated in diazotrophic bacteria colonising transgenic rhizopine producing cereals, targeting delivery of fixed N to the crop while preventing interaction with non-target plants. Inoculation of cereal crops with associative diazotrophic bacteria that convert atmospheric nitrogen (N2) into ammonia (NH3) could be used to sustainably improve delivery of nitrogen to crops. However, due to the costly energy demands of N2 fixation, bacteria restrict excess production of NH3 and release to the plants. Diazotrophs can be engineered for excess NH3 production and release, however genetic control is required to minimise growth penalties and prevent unintended provision of NH3 to non-target weed species. Here, we engineer coupled control of N2 fixation and NH3 release in response to the signalling molecule rhizopine supplemented in vitro. This control circuitry represents a prototype for the future development of a “synthetic symbiosis” where bacterial N2 fixation and NH3 excretion could be specifically activated following colonisation of transgenic rhizopine producing cereals in the field, minimising bacterial energy requirements and preventing provision of NH3 to non-target plants.
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11
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Gardijan L, Miljkovic M, Obradovic M, Borovic B, Vukotic G, Jovanovic G, Kojic M. Redesigned pMAL expression vector for easy and fast purification of active native antimicrobial peptides. J Appl Microbiol 2022; 133:1001-1013. [PMID: 35578999 DOI: 10.1111/jam.15623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 05/05/2022] [Accepted: 05/12/2022] [Indexed: 11/28/2022]
Abstract
AIMS The aim of this study was to construct the improved pMAL expression vector in order to increase the efficacy of small native peptides purification and their clear-cut separation from MBP tag. The modifications we introduced can be applied to many expression vectors. METHODS AND RESULTS To improve the pMAL expression vector we introduced the His6 tag and the enterokinase cleavage site (Ek) downstream from the MBP tag and Xa cleavage site on the original vector. For cloning of a desired peptide DNA, the enterokinase site contains a unique BsaBI restriction site adjacent to the original multi-cloning-site. This redesigned pMAL vector was optimized for the purification of cytoplasmic (pMALc5HisEk) and periplasmic (pMALp5HisEk) peptides. The purification of native and active peptide (P) was obtained following two-step affinity chromatography. In the first step the entire MBP-His6 -Ek-P fusion protein is purified using the Ni-NTA agarose column. This fusion protein was cleaved with active His6 tagged enterokinase. In the second step, the further purification was performed by column containing the mixture of amylose and Ni-NTA agarose resins. This removes both the MBP-His6 and His6 -enterokinase leaving pure native protein in solution. These new vectors and the two-step purification protocol was successfully applied in purification of active native small antimicrobial peptides (AMPs), lactococcin A and human β-defensin. CONCLUSIONS We constructed the improved pMAL expression vectors and established the pipeline and optimal conditions for their use in efficient purification of large amounts of active native small peptides. SIGNIFICANCE AND IMPACT OF THE STUDY Choice of expression vector impacts on the efficiency of expression and purification of desired proteins. The idea of redesigning pMAL vector was driven by need for rapid purification of larger amounts of active native AMPs. This newly improved pMAL vector, the cloning strategy, expression conditions and two-step purification protocol represent a unique simple approach which can be applied in every laboratory.
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Affiliation(s)
- Lazar Gardijan
- Laboratory for Molecular Microbiology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444/a, Belgrade, Serbia
| | - Marija Miljkovic
- Laboratory for Molecular Microbiology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444/a, Belgrade, Serbia
| | - Mina Obradovic
- Laboratory for Molecular Microbiology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444/a, Belgrade, Serbia
| | - Branka Borovic
- Institute of Meat Hygiene and Technology, Kaćanskog 13, Belgrade, Serbia
| | - Goran Vukotic
- Laboratory for Molecular Microbiology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444/a, Belgrade, Serbia.,Faculty of Biology, University of Belgrade, Studentskitrg16, Belgrade, Serbia
| | - Goran Jovanovic
- Laboratory for Molecular Microbiology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444/a, Belgrade, Serbia
| | - Milan Kojic
- Laboratory for Molecular Microbiology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444/a, Belgrade, Serbia
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12
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Abstract
Inoculation of cereals with diazotrophic (N2-fixing) bacteria offers a sustainable alternative to the application of nitrogen fertilizers in agriculture. While natural diazotrophs have evolved multilayered regulatory mechanisms that couple N2 fixation with assimilation of the product NH3 and prevent release to plants, genetic modifications can permit excess production and excretion of NH3. However, a lack of stringent host-specificity for root colonization by the bacteria would allow growth promotion of target and nontarget plants species alike. Here, we exploit synthetic transkingdom signaling to establish plant host-specific control of the N2-fixation catalyst nitrogenase in Azorhizobium caulinodans occupying barley roots. This work demonstrates how partner-specific interactions can be established to avoid potential growth promotion of nontarget plants. Engineering N2-fixing symbioses between cereals and diazotrophic bacteria represents a promising strategy to sustainably deliver biologically fixed nitrogen (N) in agriculture. We previously developed novel transkingdom signaling between plants and bacteria, through plant production of the bacterial signal rhizopine, allowing control of bacterial gene expression in association with the plant. Here, we have developed both a homozygous rhizopine producing (RhiP) barley line and a hybrid rhizopine uptake system that conveys upon our model bacterium Azorhizobium caulinodans ORS571 (Ac) 103-fold improved sensitivity for rhizopine perception. Using this improved genetic circuitry, we established tight rhizopine-dependent transcriptional control of the nitrogenase master regulator nifA and the N metabolism σ-factor rpoN, which drove nitrogenase expression and activity in vitro and in situ by bacteria colonizing RhiP barley roots. Although in situ nitrogenase activity was suboptimally effective relative to the wild-type strain, activation was specific to RhiP barley and was not observed on the roots of wild-type plants. This work represents a key milestone toward the development of a synthetic plant-controlled symbiosis in which the bacteria fix N2 only when in contact with the desired host plant and are prevented from interaction with nontarget plant species.
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13
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Goosens VJ, Walker KT, Aragon SM, Singh A, Senthivel VR, Dekker L, Caro-Astorga J, Buat MLA, Song W, Lee KY, Ellis T. Komagataeibacter Tool Kit (KTK): A Modular Cloning System for Multigene Constructs and Programmed Protein Secretion from Cellulose Producing Bacteria. ACS Synth Biol 2021; 10:3422-3434. [PMID: 34767345 DOI: 10.1021/acssynbio.1c00358] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Bacteria proficient at producing cellulose are an attractive synthetic biology host for the emerging field of Engineered Living Materials (ELMs). Species from the Komagataeibacter genus produce high yields of pure cellulose materials in a short time with minimal resources, and pioneering work has shown that genetic engineering in these strains is possible and can be used to modify the material and its production. To accelerate synthetic biology progress in these bacteria, we introduce here the Komagataeibacter tool kit (KTK), a standardized modular cloning system based on Golden Gate DNA assembly that allows DNA parts to be combined to build complex multigene constructs expressed in bacteria from plasmids. Working in Komagataeibacter rhaeticus, we describe basic parts for this system, including promoters, fusion tags, and reporter proteins, before showcasing how the assembly system enables more complex designs. Specifically, we use KTK cloning to reformat the Escherichia coli curli amyloid fiber system for functional expression in K. rhaeticus, and go on to modify it as a system for programming protein secretion from the cellulose producing bacteria. With this toolkit, we aim to accelerate modular synthetic biology in these bacteria, and enable more rapid progress in the emerging ELMs community.
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Affiliation(s)
- Vivianne J. Goosens
- Imperial College Centre for Synthetic Biology, Imperial College London, London SW7 2AZ, U.K
- Department of Bioengineering, Imperial College London, London SW7 2AZ, U.K
| | - Kenneth T. Walker
- Imperial College Centre for Synthetic Biology, Imperial College London, London SW7 2AZ, U.K
- Department of Bioengineering, Imperial College London, London SW7 2AZ, U.K
| | - Silvia M. Aragon
- Imperial College Centre for Synthetic Biology, Imperial College London, London SW7 2AZ, U.K
- Department of Life Sciences, Imperial College London, London SW7 2AZ, U.K
| | - Amritpal Singh
- Imperial College Centre for Synthetic Biology, Imperial College London, London SW7 2AZ, U.K
- Department of Bioengineering, Imperial College London, London SW7 2AZ, U.K
| | - Vivek R. Senthivel
- Imperial College Centre for Synthetic Biology, Imperial College London, London SW7 2AZ, U.K
- Department of Bioengineering, Imperial College London, London SW7 2AZ, U.K
| | - Linda Dekker
- Imperial College Centre for Synthetic Biology, Imperial College London, London SW7 2AZ, U.K
- Department of Life Sciences, Imperial College London, London SW7 2AZ, U.K
| | - Joaquin Caro-Astorga
- Imperial College Centre for Synthetic Biology, Imperial College London, London SW7 2AZ, U.K
- Department of Bioengineering, Imperial College London, London SW7 2AZ, U.K
| | | | - Wenzhe Song
- Department of Aeronautics, Imperial College London, London SW7 2AZ, U.K
| | - Koon-Yang Lee
- Department of Aeronautics, Imperial College London, London SW7 2AZ, U.K
| | - Tom Ellis
- Imperial College Centre for Synthetic Biology, Imperial College London, London SW7 2AZ, U.K
- Department of Bioengineering, Imperial College London, London SW7 2AZ, U.K
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14
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Webb IUC, Xu J, Sánchez-Cañizares C, Karunakaran R, Ramachandran VK, Rutten PJ, East AK, Huang WE, Watmough NJ, Poole PS. Regulation and Characterization of Mutants of fixABCX in Rhizobium leguminosarum. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2021; 34:1167-1180. [PMID: 34110256 DOI: 10.1094/mpmi-02-21-0037-r] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Symbiosis between Rhizobium leguminosarum and Pisum sativum requires tight control of redox balance in order to maintain respiration under the microaerobic conditions required for nitrogenase while still producing the eight electrons and sixteen molecules of ATP needed for nitrogen fixation. FixABCX, a cluster of electron transfer flavoproteins essential for nitrogen fixation, is encoded on the Sym plasmid (pRL10), immediately upstream of nifA, which encodes the general transcriptional regulator of nitrogen fixation. There is a symbiotically regulated NifA-dependent promoter upstream of fixA (PnifA1), as well as an additional basal constitutive promoter driving background expression of nifA (PnifA2). These were confirmed by 5'-end mapping of transcription start sites using differential RNA-seq. Complementation of polar fixAB and fixX mutants (Fix- strains) confirmed expression of nifA from PnifA1 in symbiosis. Electron microscopy combined with single-cell Raman microspectroscopy characterization of fixAB mutants revealed previously unknown heterogeneity in bacteroid morphology within a single nodule. Two morphotypes of mutant fixAB bacteroids were observed. One was larger than wild-type bacteroids and contained high levels of polyhydroxy-3-butyrate, a complex energy/reductant storage product. A second bacteroid phenotype was morphologically and compositionally different and resembled wild-type infection thread cells. From these two characteristic fixAB mutant bacteroid morphotypes, inferences can be drawn on the metabolism of wild-type nitrogen-fixing bacteroids.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.
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Affiliation(s)
- Isabel U C Webb
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, U.K
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, U.K
| | - Jiabao Xu
- Department of Engineering, University of Oxford, Parks Road, Oxford OX1 3PJ, U.K
| | | | - Ramakrishnan Karunakaran
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, U.K
| | - Vinoy K Ramachandran
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, U.K
| | - Paul J Rutten
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, U.K
| | - Alison K East
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, U.K
| | - Wei E Huang
- Department of Engineering, University of Oxford, Parks Road, Oxford OX1 3PJ, U.K
| | - Nicholas J Watmough
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, Norfolk NR4 7TJ, U.K
| | - Philip S Poole
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, U.K
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, U.K
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15
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Mendoza-Suárez M, Andersen SU, Poole PS, Sánchez-Cañizares C. Competition, Nodule Occupancy, and Persistence of Inoculant Strains: Key Factors in the Rhizobium-Legume Symbioses. FRONTIERS IN PLANT SCIENCE 2021; 12:690567. [PMID: 34489993 PMCID: PMC8416774 DOI: 10.3389/fpls.2021.690567] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Accepted: 07/19/2021] [Indexed: 05/06/2023]
Abstract
Biological nitrogen fixation by Rhizobium-legume symbioses represents an environmentally friendly and inexpensive alternative to the use of chemical nitrogen fertilizers in legume crops. Rhizobial inoculants, applied frequently as biofertilizers, play an important role in sustainable agriculture. However, inoculants often fail to compete for nodule occupancy against native rhizobia with inferior nitrogen-fixing abilities, resulting in low yields. Strains with excellent performance under controlled conditions are typically selected as inoculants, but the rates of nodule occupancy compared to native strains are rarely investigated. Lack of persistence in the field after agricultural cycles, usually due to the transfer of symbiotic genes from the inoculant strain to naturalized populations, also limits the suitability of commercial inoculants. When rhizobial inoculants are based on native strains with a high nitrogen fixation ability, they often have superior performance in the field due to their genetic adaptations to the local environment. Therefore, knowledge from laboratory studies assessing competition and understanding how diverse strains of rhizobia behave, together with assays done under field conditions, may allow us to exploit the effectiveness of native populations selected as elite strains and to breed specific host cultivar-rhizobial strain combinations. Here, we review current knowledge at the molecular level on competition for nodulation and the advances in molecular tools for assessing competitiveness. We then describe ongoing approaches for inoculant development based on native strains and emphasize future perspectives and applications using a multidisciplinary approach to ensure optimal performance of both symbiotic partners.
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Affiliation(s)
| | - Stig U. Andersen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Philip S. Poole
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
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16
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Liu L, Chen Y, Yu S, Chen J, Zhou J. Simultaneous transformation of five vectors in Gluconobacter oxydans. Plasmid 2021; 117:102588. [PMID: 34256060 DOI: 10.1016/j.plasmid.2021.102588] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 07/06/2021] [Accepted: 07/07/2021] [Indexed: 11/19/2022]
Abstract
Gluconobacter oxydans is an obligate Gram-negative bacterium that belongs to the family Acetobacteraceae. It is one of the most frequently used microorganisms in industrial biotechnology to produce chemicals related to incomplete oxidation. However, the fine-tuning of G. oxydans is hampered by the lack of efficient genetic tools to enable sophisticated metabolic manipulations. Thus, a series of shuttle vectors for G. oxydans inspired by a series of wild-type plasmids in different G. oxydans strains were constructed. Fifteen shuttle vectors were employed to express mCherry in G. oxydans WSH-003 using the replication origin of these wild-type plasmids. Among them, the intensity of fluorescent proteins expressed by p15-K-mCherry was about 10 times that of fluorescent proteins expressed by p5-K-mCherry. Quantitative real-time polymerase chain reaction showed that the relative copy number of p15-K-mCherry reached 19 and had high stability. In contrast, some of the plasmids had a relative copy number of less than 10. The co-expression of multiple shuttle vectors revealed five shuttle vectors that could be transformed into G. oxydans WSH-003 and could express five different fluorescent proteins. The shuttle vectors will facilitate genetic operations for Gluconobacter strains to produce useful compounds more efficiently.
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Affiliation(s)
- Li Liu
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; School of Biotechnology and Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Jiangsu Provisional Research Center for Bioactive Product Processing Technology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Yue Chen
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; School of Biotechnology and Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Jiangsu Provisional Research Center for Bioactive Product Processing Technology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Shiqin Yu
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; School of Biotechnology and Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Jiangsu Provisional Research Center for Bioactive Product Processing Technology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Jian Chen
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; School of Biotechnology and Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Jiangsu Provisional Research Center for Bioactive Product Processing Technology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Jingwen Zhou
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; School of Biotechnology and Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Jiangsu Provisional Research Center for Bioactive Product Processing Technology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China.
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17
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Haskett TL, Knights HE, Jorrin B, Mendes MD, Poole PS. A Simple in situ Assay to Assess Plant-Associative Bacterial Nitrogenase Activity. Front Microbiol 2021; 12:690439. [PMID: 34248916 PMCID: PMC8261070 DOI: 10.3389/fmicb.2021.690439] [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: 04/02/2021] [Accepted: 05/25/2021] [Indexed: 11/23/2022] Open
Abstract
Assessment of plant-associative bacterial nitrogen (N) fixation is crucial for selection and development of elite diazotrophic inoculants that could be used to supply cereal crops with nitrogen in a sustainable manner. Although diazotrophic bacteria possess diverse oxygen tolerance mechanisms, most require a sub 21% oxygen environment to achieve optimal stability and function of the N-fixing catalyst nitrogenase. Consequently, assessment of N fixation is routinely carried out on “free-living” bacteria grown in the absence of a host plant and such experiments may not accurately divulge activity in the rhizosphere where the availability and forms of nutrients such as carbon and N, which are key regulators of N fixation, may vary widely. Here, we present a modified in situ acetylene reduction assay (ARA), utilizing the model cereal barley as a host to comparatively assess nitrogenase activity in diazotrophic bacteria. The assay is rapid, highly reproducible, applicable to a broad range of diazotrophs, and can be performed with simple equipment commonly found in most laboratories that investigate plant-microbe interactions. Thus, the assay could serve as a first point of order for high-throughput identification of elite plant-associative diazotrophs.
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Affiliation(s)
- Timothy L Haskett
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
| | - Hayley E Knights
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
| | - Beatriz Jorrin
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
| | - Marta D Mendes
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
| | - Philip S Poole
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
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18
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Wang L, Xiao Y, Wei X, Pan J, Duanmu D. Highly Efficient CRISPR-Mediated Base Editing in Sinorhizobium meliloti. Front Microbiol 2021; 12:686008. [PMID: 34220774 PMCID: PMC8253261 DOI: 10.3389/fmicb.2021.686008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 05/03/2021] [Indexed: 11/13/2022] Open
Abstract
Rhizobia are widespread gram-negative soil bacteria and indispensable symbiotic partners of leguminous plants that facilitate the most highly efficient biological nitrogen fixation in nature. Although genetic studies in Sinorhizobium meliloti have advanced our understanding of symbiotic nitrogen fixation (SNF), the current methods used for genetic manipulations in Sinorhizobium meliloti are time-consuming and labor-intensive. In this study, we report the development of a few precise gene modification tools that utilize the CRISPR/Cas9 system and various deaminases. By fusing the Cas9 nickase to an adenine deaminase, we developed an adenine base editor (ABE) system that facilitated adenine-to-guanine transitions at one-nucleotide resolution without forming double-strand breaks (DSB). We also engineered a cytidine base editor (CBE) and a guanine base editor (GBE) that catalyze cytidine-to-thymine substitutions and cytidine-to-guanine transversions, respectively, by replacing adenine deaminase with cytidine deaminase and other auxiliary enzymes. All of these base editors are amenable to the assembly of multiple synthetic guide RNA (sgRNA) cassettes using Golden Gate Assembly to simultaneously achieve multigene mutations or disruptions. These CRISPR-mediated base editing tools will accelerate the functional genomics study and genome manipulation of rhizobia.
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Affiliation(s)
- Longxiang Wang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China
| | - Yuan Xiao
- College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Xiaowei Wei
- College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Jimin Pan
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China.,College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Deqiang Duanmu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China.,College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
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19
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Minimal gene set from Sinorhizobium ( Ensifer) meliloti pSymA required for efficient symbiosis with Medicago. Proc Natl Acad Sci U S A 2021; 118:2018015118. [PMID: 33384333 DOI: 10.1073/pnas.2018015118] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Reduction of N2 gas to ammonia in legume root nodules is a key component of sustainable agricultural systems. Root nodules are the result of a symbiosis between leguminous plants and bacteria called rhizobia. Both symbiotic partners play active roles in establishing successful symbiosis and nitrogen fixation: while root nodule development is mostly controlled by the plant, the rhizobia induce nodule formation, invade, and perform N2 fixation once inside the plant cells. Many bacterial genes involved in the rhizobia-legume symbiosis are known, and there is much interest in engineering the symbiosis to include major nonlegume crops such as corn, wheat, and rice. We sought to identify and combine a minimal bacterial gene complement necessary and sufficient for symbiosis. We analyzed a model rhizobium, Sinorhizobium (Ensifer) meliloti, using a background strain in which the 1.35-Mb symbiotic megaplasmid pSymA was removed. Three regions representing 162 kb of pSymA were sufficient to recover a complete N2-fixing symbiosis with alfalfa, and a targeted assembly of this gene complement achieved high levels of symbiotic N2 fixation. The resulting gene set contained just 58 of 1,290 pSymA protein-coding genes. To generate a platform for future synthetic manipulation, the minimal symbiotic genes were reorganized into three discrete nod, nif, and fix modules. These constructs will facilitate directed studies toward expanding the symbiosis to other plant partners. They also enable forward-type approaches to identifying genetic components that may not be essential for symbiosis, but which modulate the rhizobium's competitiveness for nodulation and the effectiveness of particular rhizobia-plant symbioses.
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20
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Glasgow E, Vander Meulen K, Kuch N, Fox BG. Multifunctional cellulases are potent, versatile tools for a renewable bioeconomy. Curr Opin Biotechnol 2021; 67:141-148. [PMID: 33550093 PMCID: PMC8366578 DOI: 10.1016/j.copbio.2020.12.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 12/09/2020] [Accepted: 12/28/2020] [Indexed: 11/21/2022]
Abstract
Enzyme performance is critical to the future bioeconomy based on renewable plant materials. Plant biomass can be efficiently hydrolyzed by multifunctional cellulases (MFCs) into sugars suitable for conversion into fuels and chemicals, and MFCs fall into three functional categories. Recent work revealed MFCs with broad substrate specificity, dual exo-activity/endo-activity on cellulose, and intramolecular synergy, among other novel characteristics. Binding modules and accessory catalytic domains amplify MFC and xylanase activity in a wide variety of ways, and processive endoglucanases achieve autosynergy on cellulose. Multidomain MFCs from Caldicellulosiruptor are heat-tolerant, adaptable to variable cellulose crystallinity, and may provide interchangeable scaffolds for recombinant design. Further studies of MFC properties and their reactivity with plant biomass are recommended for increasing biorefinery yields.
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Affiliation(s)
- Evan Glasgow
- Dept. of Biochemistry, University of Wisconsin - Madison, 433 Babcock Dr., Madison, WI, 53706, United States; Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, 1552 University Ave, Madison, WI, 53726, United States
| | - Kirk Vander Meulen
- Dept. of Biochemistry, University of Wisconsin - Madison, 433 Babcock Dr., Madison, WI, 53706, United States; Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, 1552 University Ave, Madison, WI, 53726, United States
| | - Nate Kuch
- Dept. of Biochemistry, University of Wisconsin - Madison, 433 Babcock Dr., Madison, WI, 53706, United States; Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, 1552 University Ave, Madison, WI, 53726, United States
| | - Brian G Fox
- Dept. of Biochemistry, University of Wisconsin - Madison, 433 Babcock Dr., Madison, WI, 53706, United States; Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, 1552 University Ave, Madison, WI, 53726, United States.
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21
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Young R, Haines M, Storch M, Freemont PS. Combinatorial metabolic pathway assembly approaches and toolkits for modular assembly. Metab Eng 2020; 63:81-101. [PMID: 33301873 DOI: 10.1016/j.ymben.2020.12.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 11/16/2020] [Accepted: 12/03/2020] [Indexed: 12/18/2022]
Abstract
Synthetic Biology is a rapidly growing interdisciplinary field that is primarily built upon foundational advances in molecular biology combined with engineering design principles such as modularity and interoperability. The field considers living systems as programmable at the genetic level and has been defined by the development of new platform technologies and methodological advances. A key concept driving the field is the Design-Build-Test-Learn cycle which provides a systematic framework for building new biological systems. One major application area for synthetic biology is biosynthetic pathway engineering that requires the modular assembly of different genetic regulatory elements and biosynthetic enzymes. In this review we provide an overview of modular DNA assembly and describe and compare the plethora of in vitro and in vivo assembly methods for combinatorial pathway engineering. Considerations for part design and methods for enzyme balancing are also presented, and we briefly discuss alternatives to intracellular pathway assembly including microbial consortia and cell-free systems for biosynthesis. Finally, we describe computational tools and automation for pathway design and assembly and argue that a deeper understanding of the many different variables of genetic design, pathway regulation and cellular metabolism will allow more predictive pathway design and engineering.
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Affiliation(s)
- Rosanna Young
- Department of Infectious Disease, Sir Alexander Fleming Building, South Kensington Campus, Imperial College London, SW7 2AZ, UK
| | - Matthew Haines
- Department of Infectious Disease, Sir Alexander Fleming Building, South Kensington Campus, Imperial College London, SW7 2AZ, UK
| | - Marko Storch
- Department of Infectious Disease, Sir Alexander Fleming Building, South Kensington Campus, Imperial College London, SW7 2AZ, UK; London Biofoundry, Imperial College Translation & Innovation Hub, London, W12 0BZ, UK
| | - Paul S Freemont
- Department of Infectious Disease, Sir Alexander Fleming Building, South Kensington Campus, Imperial College London, SW7 2AZ, UK; London Biofoundry, Imperial College Translation & Innovation Hub, London, W12 0BZ, UK; UK DRI Care Research and Technology Centre, Imperial College London, Hammersmith Campus, Du Cane Road, London, W12 0NN, UK.
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de Lorenzo V, Krasnogor N, Schmidt M. For the sake of the Bioeconomy: define what a Synthetic Biology Chassis is! N Biotechnol 2020; 60:44-51. [PMID: 32889152 DOI: 10.1016/j.nbt.2020.08.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 08/05/2020] [Accepted: 08/08/2020] [Indexed: 12/14/2022]
Abstract
At the onset of the 4th Industrial Revolution, the role of synthetic biology (SynBio) as a fuel for the bioeconomy requires clarification of the terms typically adopted by this growing scientific-technical field. The concept of the chassis as a defined, reusable biological frame where non-native components can be plugged in and out to create new functionalities lies at the boundary between frontline bioengineering and more traditional recombinant DNA technology. As synthetic biology leaves academic laboratories and starts penetrating industrial and environmental realms regulatory agencies demand clear definitions and descriptions of SynBio constituents, processes and products. In this article, the state of the ongoing discussion on what is a chassis is reviewed, a non-equivocal nomenclature for the jargon used is proposed and objective criteria are recommended for distinguishing SynBio agents from traditional GMOs. The use of genomic barcodes as unique identifiers is strongly advocated. Finally the soil bacterium Pseudomonas putida is shown as an example of the roadmap that one environmental isolate may go through to become a bona fide SynBio chassis.
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Affiliation(s)
- Víctor de Lorenzo
- Systems and Synthetic Biology Department, Centro Nacional de Biotecnología (CNB-CSIC) Madrid 28049, Spain.
| | - Natalio Krasnogor
- Interdisciplinary Computing and Complex Biosystems (ICOS) research group, Newcastle University, Newcastle Upon Tyne NE4 5TG UK
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Mendoza-Suárez MA, Geddes BA, Sánchez-Cañizares C, Ramírez-González RH, Kirchhelle C, Jorrin B, Poole PS. Optimizing Rhizobium-legume symbioses by simultaneous measurement of rhizobial competitiveness and N 2 fixation in nodules. Proc Natl Acad Sci U S A 2020; 117:9822-9831. [PMID: 32317381 PMCID: PMC7211974 DOI: 10.1073/pnas.1921225117] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Legumes tend to be nodulated by competitive rhizobia that do not maximize nitrogen (N2) fixation, resulting in suboptimal yields. Rhizobial nodulation competitiveness and effectiveness at N2 fixation are independent traits, making their measurement extremely time-consuming with low experimental throughput. To transform the experimental assessment of rhizobial competitiveness and effectiveness, we have used synthetic biology to develop reporter plasmids that allow simultaneous high-throughput measurement of N2 fixation in individual nodules using green fluorescent protein (GFP) and barcode strain identification (Plasmid ID) through next generation sequencing (NGS). In a proof-of-concept experiment using this technology in an agricultural soil, we simultaneously monitored 84 different Rhizobium leguminosarum strains, identifying a supercompetitive and highly effective rhizobial symbiont for peas. We also observed a remarkable frequency of nodule coinfection by rhizobia, with mixed occupancy identified in ∼20% of nodules, containing up to six different strains. Critically, this process can be adapted to multiple Rhizobium-legume symbioses, soil types, and environmental conditions to permit easy identification of optimal rhizobial inoculants for field testing to maximize agricultural yield.
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Affiliation(s)
| | - Barney A Geddes
- Department of Plant Sciences, University of Oxford, OX1 3RB Oxford, United Kingdom
| | | | | | - Charlotte Kirchhelle
- Department of Plant Sciences, University of Oxford, OX1 3RB Oxford, United Kingdom
| | - Beatriz Jorrin
- Department of Plant Sciences, University of Oxford, OX1 3RB Oxford, United Kingdom
| | - Philip S Poole
- Department of Plant Sciences, University of Oxford, OX1 3RB Oxford, United Kingdom;
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24
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Martínez-García E, Goñi-Moreno A, Bartley B, McLaughlin J, Sánchez-Sampedro L, Pascual del Pozo H, Prieto Hernández C, Marletta AS, De Lucrezia D, Sánchez-Fernández G, Fraile S, de Lorenzo V. SEVA 3.0: an update of the Standard European Vector Architecture for enabling portability of genetic constructs among diverse bacterial hosts. Nucleic Acids Res 2020; 48:D1164-D1170. [PMID: 31740968 PMCID: PMC7018797 DOI: 10.1093/nar/gkz1024] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2019] [Revised: 10/17/2019] [Accepted: 10/18/2019] [Indexed: 11/29/2022] Open
Abstract
The Standard European Vector Architecture 3.0 database (SEVA-DB 3.0, http://seva.cnb.csic.es) is the update of the platform launched in 2013 both as a web-based resource and as a material repository of formatted genetic tools (mostly plasmids) for analysis, construction and deployment of complex bacterial phenotypes. The period between the first version of SEVA-DB and the present time has witnessed several technical, computational and conceptual advances in genetic/genomic engineering of prokaryotes that have enabled upgrading of the utilities of the updated database. Novelties include not only a more user-friendly web interface and many more plasmid vectors, but also new links of the plasmids to advanced bioinformatic tools. These provide an intuitive visualization of the constructs at stake and a range of virtual manipulations of DNA segments that were not possible before. Finally, the list of canonical SEVA plasmids is available in machine-readable SBOL (Synthetic Biology Open Language) format. This ensures interoperability with other platforms and affords simulations of their behaviour under different in vivo conditions. We argue that the SEVA-DB will remain a useful resource for extending Synthetic Biology approaches towards non-standard bacterial species as well as genetically programming new prokaryotic chassis for a suite of fundamental and biotechnological endeavours.
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Affiliation(s)
- Esteban Martínez-García
- Systems Biology Program, Centro Nacional de Biotecnología CSIC, Campus de la Universidad Autónoma de Madrid, 28049 Spain
| | | | | | | | | | | | | | | | | | | | - Sofía Fraile
- Systems Biology Program, Centro Nacional de Biotecnología CSIC, Campus de la Universidad Autónoma de Madrid, 28049 Spain
| | - Víctor de Lorenzo
- Systems Biology Program, Centro Nacional de Biotecnología CSIC, Campus de la Universidad Autónoma de Madrid, 28049 Spain
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Sharma M, Tyagi JL, Poluri KM. Quantifying bacterial cell lysis using GFP based fluorimetric assay. Int J Biol Macromol 2019; 138:881-889. [PMID: 31356938 DOI: 10.1016/j.ijbiomac.2019.07.172] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 07/24/2019] [Accepted: 07/25/2019] [Indexed: 11/24/2022]
Abstract
Quantitative measurement of cell lysis against a given microbial strain is essential to calculate the antimicrobial potency of protein/peptide/nanomaterial based formulations. Fluorescence spectroscopy based measurements offer precise quantification of a process via selected flurophore emission profile. In this context, we elucidate a reliable and robust green fluorescent protein (GFP) based fluorescence spectroscopy protocol to evaluate the antimicrobial activity of proteins. The technique is based on the fact that the intensity of the GFP emission released from cells correlates with cell lysis and henceforth the antimicrobial potential of the chosen agent. The technique was demonstrated with two different families of bacteriophage endolysins (T7 and T4 endolysins) using GFP expressing E. coli cells. The GFP based method allowed the absolute quantification of T4 and T7 endolysins cell lysis characteristics at different pH, salt concentrations, and metal ions. The results obtained from GFP based fluorimetric assay were substantiated with turbidimetric assay and fluorescence microscopy. This fluorimetric method in conjugation with different GFP expressing microbial strains and antimicrobial agents can be efficiently applied as a quantification technique to precisely measure cell lysis.
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Affiliation(s)
- Meenakshi Sharma
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, Uttarakhand, India
| | - Jaya Lakshmi Tyagi
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, Uttarakhand, India
| | - Krishna Mohan Poluri
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, Uttarakhand, India; Centre for Nanotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, Uttarakhand, India.
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26
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Pseudomonas putida in the quest of programmable chemistry. Curr Opin Biotechnol 2019; 59:111-121. [DOI: 10.1016/j.copbio.2019.03.012] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 02/15/2019] [Accepted: 03/12/2019] [Indexed: 11/19/2022]
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27
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Geddes BA, Paramasivan P, Joffrin A, Thompson AL, Christensen K, Jorrin B, Brett P, Conway SJ, Oldroyd GED, Poole PS. Engineering transkingdom signalling in plants to control gene expression in rhizosphere bacteria. Nat Commun 2019; 10:3430. [PMID: 31366919 PMCID: PMC6668481 DOI: 10.1038/s41467-019-10882-x] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Accepted: 06/07/2019] [Indexed: 01/10/2023] Open
Abstract
The root microbiota is critical for agricultural yield, with growth-promoting bacteria able to solubilise phosphate, produce plant growth hormones, antagonise pathogens and fix N2. Plants control the microorganisms in their immediate environment and this is at least in part through direct selection, the immune system, and interactions with other microorganisms. Considering the importance of the root microbiota for crop yields it is attractive to artificially regulate this environment to optimise agricultural productivity. Towards this aim we express a synthetic pathway for the production of the rhizopine scyllo-inosamine in plants. We demonstrate the production of this bacterial derived signal in both Medicago truncatula and barley and show its perception by rhizosphere bacteria, containing bioluminescent and fluorescent biosensors. This study lays the groundwork for synthetic signalling networks between plants and bacteria, allowing the targeted regulation of bacterial gene expression in the rhizosphere for delivery of useful functions to plants. The root microbiota is critical for promoting crop yield. Here, the authors create a synthetic pathway for the production of the rhizopine scyllo-inosamine in Medicago truncatula and barley, and show its perception by rhizosphere bacteria for targeted regulation of bacterial gene expression.
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Affiliation(s)
- Barney A Geddes
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, UK
| | - Ponraj Paramasivan
- Sainsbury Laboratory, University of Cambridge, Bateman Street, Cambridge, CB2 1LR, UK
| | - Amelie Joffrin
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford, OX1 3TA, UK
| | - Amber L Thompson
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford, OX1 3TA, UK
| | - Kirsten Christensen
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford, OX1 3TA, UK
| | - Beatriz Jorrin
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, UK
| | - Paul Brett
- Department of Metabolic Biology, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Stuart J Conway
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford, OX1 3TA, UK
| | - Giles E D Oldroyd
- Sainsbury Laboratory, University of Cambridge, Bateman Street, Cambridge, CB2 1LR, UK
| | - Philip S Poole
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, UK.
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