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Tchagang CF, Mah TF, Campbell-Valois FX. Anaerobic fluorescent reporters for live imaging of Pseudomonas aeruginosa. Front Microbiol 2023; 14:1245755. [PMID: 37928662 PMCID: PMC10623331 DOI: 10.3389/fmicb.2023.1245755] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 09/25/2023] [Indexed: 11/07/2023] Open
Abstract
Pseudomonas aeruginosa thrives in the airways of individuals with cystic fibrosis, in part by forming robust biofilms that are resistant to immune clearance or antibiotic treatment. In the cystic fibrosis lung, the thickened mucus layers create an oxygen gradient, often culminating with the formation of anoxic pockets. In this environment, P. aeruginosa can use nitrate instead of oxygen to grow. Current fluorescent reporters for studying P. aeruginosa are limited to the GFP and related analogs. However, these reporters require oxygen for the maturation of their chromophore, making them unsuitable for the study of anaerobically grown P. aeruginosa. To overcome this limitation, we evaluated seven alternative fluorescent proteins, including iLOV, phiLOV2.1, evoglow-Bs2, LucY, UnaG, Fluorescence-Activating and Absorption-Shifting Tag (FAST), and iRFP670, which have been reported to emit light under oxygen-limiting conditions. We generated a series of plasmids encoding these proteins and validated their fluorescence using plate reader assays and confocal microscopy. Six of these proteins successfully labeled P. aeruginosa in anoxia. In particular, phiLOV2.1 and FAST provided superior fluorescence stability and enabled dual-color imaging of both planktonic and biofilm cultures. This study provides a set of fluorescent reporters for monitoring P. aeruginosa under low-oxygen conditions. These reporters will facilitate studies of P. aeruginosa in biofilms or other contexts relevant to its pathogenesis, such as those found in cystic fibrosis airways. Due to the broad host range of our expression vector, the phiLOV2.1 and FAST-based reporters may be applicable to the study of other Gram-negative bacteria that inhabit similar low-oxygen niches.
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Affiliation(s)
- Caetanie F. Tchagang
- Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
- Centre for Infection, Immunity, and Inflammation, University of Ottawa, Ottawa, ON, Canada
- Host-Microbe Interactions Laboratory, Center for Chemical and Synthetic Biology, Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON, Canada
| | - Thien-Fah Mah
- Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
- Centre for Infection, Immunity, and Inflammation, University of Ottawa, Ottawa, ON, Canada
| | - François-Xavier Campbell-Valois
- Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
- Centre for Infection, Immunity, and Inflammation, University of Ottawa, Ottawa, ON, Canada
- Host-Microbe Interactions Laboratory, Center for Chemical and Synthetic Biology, Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON, Canada
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2
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Hocq R, Bottone S, Gautier A, Pflügl S. A fluorescent reporter system for anaerobic thermophiles. Front Bioeng Biotechnol 2023; 11:1226889. [PMID: 37476481 PMCID: PMC10355840 DOI: 10.3389/fbioe.2023.1226889] [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: 05/22/2023] [Accepted: 06/23/2023] [Indexed: 07/22/2023] Open
Abstract
Owing to their inherent capacity to make invisible biological processes visible and quantifiable, fluorescent reporter systems have numerous applications in biotechnology. For classical fluorescent protein systems (i.e., GFP and derivatives), chromophore maturation is O2-dependent, restricting their applications to aerobic organisms. In this work, we pioneered the use of the oxygen-independent system FAST (Fluorescence Activating and absorption Shifting tag) in the thermophilic anaerobe Thermoanaerobacter kivui. We developed a modular cloning system that was used to easily clone a library of FAST expression cassettes in an E. coli-Thermoanaerobacter shuttle plasmid. FAST-mediated fluorescence was then assessed in vivo in T. kivui, and we observed bright green and red fluorescence for cells grown at 55°C. Next, we took advantage of this functional reporter system to characterize a set of homologous and heterologous promoters by quantifying gene expression, expanding the T. kivui genetic toolbox. Low fluorescence at 66°C (Topt for T. kivui) was subsequently investigated at the single-cell level using flow cytometry and attributed to plasmid instability at higher temperatures. Adaptive laboratory evolution circumvented this issue and drastically enhanced fluorescence at 66°C. Whole plasmid sequencing revealed the evolved strain carried functional plasmids truncated at the Gram-positive origin of replication, that could however not be linked to the increased fluorescence displayed by the evolved strain. Collectively, our work demonstrates the applicability of the FAST fluorescent reporter systems to T. kivui, paving the way for further applications in thermophilic anaerobes.
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Affiliation(s)
- Rémi Hocq
- Institute of Chemical, Environmental and Bioscience Engineering, Technische Universität Wien, Vienna, Austria
- Christian Doppler Laboratory for Optimized Expression of Carbohydrate-Active Enzymes, Institute of Chemical, Environmental and Bioscience Engineering, Technische Universität Wien, Vienna, Austria
| | - Sara Bottone
- Laboratoire des Biomolécules (LBM), Centre National de la Recherche Scientifique (CNRS), Sorbonne Université, École Normale Supérieure, Université PSL, Paris, France
- Institut Universitaire de France, Paris, France
| | - Arnaud Gautier
- Laboratoire des Biomolécules (LBM), Centre National de la Recherche Scientifique (CNRS), Sorbonne Université, École Normale Supérieure, Université PSL, Paris, France
- Institut Universitaire de France, Paris, France
| | - Stefan Pflügl
- Institute of Chemical, Environmental and Bioscience Engineering, Technische Universität Wien, Vienna, Austria
- Christian Doppler Laboratory for Optimized Expression of Carbohydrate-Active Enzymes, Institute of Chemical, Environmental and Bioscience Engineering, Technische Universität Wien, Vienna, Austria
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McCully AL, Loop Yao M, Brower KK, Fordyce PM, Spormann AM. Double emulsions as a high-throughput enrichment and isolation platform for slower-growing microbes. ISME COMMUNICATIONS 2023; 3:47. [PMID: 37160952 PMCID: PMC10169782 DOI: 10.1038/s43705-023-00241-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 03/27/2023] [Accepted: 04/12/2023] [Indexed: 05/11/2023]
Abstract
Our understanding of in situ microbial physiology is primarily based on physiological characterization of fast-growing and readily-isolatable microbes. Microbial enrichments to obtain novel isolates with slower growth rates or physiologies adapted to low nutrient environments are plagued by intrinsic biases for fastest-growing species when using standard laboratory isolation protocols. New cultivation tools to minimize these biases and enrich for less well-studied taxa are needed. In this study, we developed a high-throughput bacterial enrichment platform based on single cell encapsulation and growth within double emulsions (GrowMiDE). We showed that GrowMiDE can cultivate many different microorganisms and enrich for underrepresented taxa that are never observed in traditional batch enrichments. For example, preventing dominance of the enrichment by fast-growing microbes due to nutrient privatization within the double emulsion droplets allowed cultivation of slower-growing Negativicutes and Methanobacteria from stool samples in rich media enrichment cultures. In competition experiments between growth rate and growth yield specialist strains, GrowMiDE enrichments prevented competition for shared nutrient pools and enriched for slower-growing but more efficient strains. Finally, we demonstrated the compatibility of GrowMiDE with commercial fluorescence-activated cell sorting (FACS) to obtain isolates from GrowMiDE enrichments. Together, GrowMiDE + DE-FACS is a promising new high-throughput enrichment platform that can be easily applied to diverse microbial enrichments or screens.
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Affiliation(s)
- Alexandra L McCully
- Department of Civil and Environmental Engineering, Stanford University, Stanford, CA, USA
| | - McKenna Loop Yao
- Department of Chemical Engineering, Stanford University, Stanford, CA, USA
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA, USA
| | - Kara K Brower
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Polly M Fordyce
- Department of Bioengineering, Stanford University, Stanford, CA, USA
- Department of Genetics, Stanford University, Stanford, CA, USA
- ChEM-H Institute, Stanford University, Stanford, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
| | - Alfred M Spormann
- Department of Civil and Environmental Engineering, Stanford University, Stanford, CA, USA.
- Department of Chemical Engineering, Stanford University, Stanford, CA, USA.
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Richard CSM, Dey H, Øyen F, Maqsood M, Blencke HM. Outer Membrane Integrity-Dependent Fluorescence of the Japanese Eel UnaG Protein in Live Escherichia coli Cells. BIOSENSORS 2023; 13:232. [PMID: 36831998 PMCID: PMC9953992 DOI: 10.3390/bios13020232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 01/28/2023] [Accepted: 02/03/2023] [Indexed: 06/18/2023]
Abstract
Reporter genes are important tools in many biological disciplines. The discovery of novel reporter genes is relatively rare. However, known reporter genes are constantly applied to novel applications. This study reports the performance of the bilirubin-dependent fluorescent protein UnaG from the Japanese eel Anguilla japonicas in live Escherichia coli cells in response to the disruption of outer membrane (OM) integrity at low bilirubin (BR) concentrations. Using the E. coli wild-type strain MC4100, its isogenic OM-deficient mutant strain NR698, and different OM-active compounds, we show that BR uptake and UnaG fluorescence depend on a leaky OM at concentrations of 10 µM BR and below, while fluorescence is mostly OM integrity-independent at concentrations above 50 µM BR. We suggest that these properties of the UnaG-BR couple might be applied as a biosensor as an alternative to the OM integrity assays currently in use.
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He X, Zhang S, Dang D, Lin T, Ge Y, Chen X, Fan J. Detection of human annexin A1 as the novel N-terminal tag for separation and purification handle. Microb Cell Fact 2023; 22:2. [PMID: 36604649 PMCID: PMC9817314 DOI: 10.1186/s12934-022-02005-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 12/17/2022] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND Several fusion tags for separation handle have been developed, but the fused tag for simply and cheaply separating the target protein is still lacking. RESULTS Separation conditions for the human annexin A1 (hanA1) tagged emerald green fluorescent protein (EmGFP) in Escherichia coli were optimized via precipitation with calcium chloride (CaCl2) and resolubilization with ethylenediamine tetraacetic acid disodium salt (EDTA-Na2). The HanA1-EmGFP absorbing with other three affinity matrix was detected, only it was strongly bound to heparin Sepharose. The separation efficiency of the HanA1-EmGFP was comparable with purification efficiency of the His6-tagged HanA1-EmGFP via metal ion affinity chromatography. Three fluorescent proteins for the EmGFP, mCherry red fluorescent protein and flavin-binding cyan-green fluorescent protein LOV from Chlamydomonas reinhardtii were used for naked-eye detection of the separation and purification processes, and two colored proteins including a red protein for a Vitreoscilla hemoglobin (Vhb), and a brown protein for maize sirohydrochlorin ferrochelatase (mSF) were used for visualizing the separation process. The added EDTA-Na2 disrupted the Fe-S cluster in the mSF, but it showed little impact on heme in Vhb. CONCLUSIONS The selected five colored proteins were efficient for detecting the applicability of the highly selective hanA1 for fusion separation and purification handle. The fused hanA1 tag will be potentially used for simple and cheap affinity separation of the target proteins in industry and diagnosis.
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Affiliation(s)
- Xiaomei He
- grid.460134.40000 0004 1757 393XCollege of Biological and Pharmaceutical Engineering, West Anhui University, Lu’an, 237012 People’s Republic of China ,grid.411389.60000 0004 1760 4804School of Life Science, Anhui, Anhui Agricultural University, 130, Changjiang West Road, Hefei, 230036 People’s Republic of China
| | - Shuncheng Zhang
- grid.411389.60000 0004 1760 4804School of Life Science, Anhui, Anhui Agricultural University, 130, Changjiang West Road, Hefei, 230036 People’s Republic of China
| | - Dongya Dang
- grid.411389.60000 0004 1760 4804School of Life Science, Anhui, Anhui Agricultural University, 130, Changjiang West Road, Hefei, 230036 People’s Republic of China
| | - Tingting Lin
- grid.411389.60000 0004 1760 4804School of Life Science, Anhui, Anhui Agricultural University, 130, Changjiang West Road, Hefei, 230036 People’s Republic of China
| | - Yuanyuan Ge
- grid.411389.60000 0004 1760 4804School of Life Science, Anhui, Anhui Agricultural University, 130, Changjiang West Road, Hefei, 230036 People’s Republic of China
| | - Xiaofeng Chen
- grid.411389.60000 0004 1760 4804School of Life Science, Anhui, Anhui Agricultural University, 130, Changjiang West Road, Hefei, 230036 People’s Republic of China
| | - Jun Fan
- grid.411389.60000 0004 1760 4804School of Life Science, Anhui, Anhui Agricultural University, 130, Changjiang West Road, Hefei, 230036 People’s Republic of China
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Exploring Bacterial Attributes That Underpin Symbiont Life in the Monogastric Gut. Appl Environ Microbiol 2022; 88:e0112822. [PMID: 36036591 PMCID: PMC9499014 DOI: 10.1128/aem.01128-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The large bowel of monogastric animals, such as that of humans, is home to a microbial community (microbiota) composed of a diversity of mostly bacterial species. Interrelationships between the microbiota as an entity and the host are complex and lifelong and are characteristic of a symbiosis. The relationships may be disrupted in association with disease, resulting in dysbiosis. Modifications to the microbiota to correct dysbiosis require knowledge of the fundamental mechanisms by which symbionts inhabit the gut. This review aims to summarize aspects of niche fitness of bacterial species that inhabit the monogastric gut, especially of humans, and to indicate the research path by which progress can be made in exploring bacterial attributes that underpin symbiont life in the gut.
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Kennedy A, Griffin G, Freemont PS, Polizzi KM, Moore SJ. A curcumin direct protein biosensor for cell‐free prototyping. ENGINEERING BIOLOGY 2022; 6:62-68. [PMID: 36969103 PMCID: PMC9996706 DOI: 10.1049/enb2.12024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 08/10/2022] [Accepted: 08/12/2022] [Indexed: 11/19/2022] Open
Abstract
In synthetic biology, biosensors are routinely coupled with a gene expression system for detecting small molecules and physical signals. We reveal a fluorescent complex, based on the interaction of an Escherichia coli double bond reductase (EcCurA), as a detection unit with its substrate curcumin-we call this a direct protein (DiPro) biosensor. Using a cell-free synthetic biology approach, we use the EcCurA DiPro biosensor to fine tune 10 reaction parameters (cofactor, substrate, and enzyme levels) for cell-free curcumin biosynthesis, assisted through acoustic liquid handling robotics. Overall, we increase EcCurA-curcumin DiPro fluorescence within cell-free reactions by 78-fold. This finding adds to the growing family of protein-ligand complexes that are naturally fluorescent and potentially exploitable for a range of applications, including medical imaging to engineering high-value chemicals.
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Affiliation(s)
- Agata Kennedy
- School of Biosciences University of Kent Canterbury UK
| | - Guy Griffin
- School of Biosciences University of Kent Canterbury UK
| | - Paul S. Freemont
- Centre for Synthetic Biology and Innovation South Kensington Campus London UK
- Department of Medicine South Kensington Campus London UK
- Department of Infectious Disease Section of Structural and Synthetic Biology Imperial College London London UK
- Sir Alexander Fleming Building South Kensington Campus London UK
- UK Dementia Research Institute Care Research and Technology Centre Imperial College London Hammersmith Campus London UK
| | - Karen M. Polizzi
- Centre for Synthetic Biology and Innovation South Kensington Campus London UK
- Department of Life Sciences Imperial College London South Kensington Campus London UK
- Department of Chemical Engineering Imperial College London South Kensington Campus London UK
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Flaiz M, Baur T, Gaibler J, Kröly C, Dürre P. Establishment of Green- and Red-Fluorescent Reporter Proteins Based on the Fluorescence-Activating and Absorption-Shifting Tag for Use in Acetogenic and Solventogenic Anaerobes. ACS Synth Biol 2022; 11:953-967. [PMID: 35081709 DOI: 10.1021/acssynbio.1c00554] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Anaerobic bacteria are promising biocatalysts to produce industrially relevant products from nonfood feedstocks. Several anaerobes are genetically accessible, and various molecular tools for metabolic engineering are available. Still, the use of bright fluorescent reporters, which are commonly used in molecular biological approaches is limited under anaerobic conditions. Therefore, the establishment of different anaerobic fluorescent reporter proteins is of great interest. Here, we present the establishment of the green- and red-fluorescent reporter proteins greenFAST and redFAST for use in different solventogenic and acetogenic bacteria. Green fluorescence of greenFAST was bright in Clostridium saccharoperbutylacetonicum, Clostridium acetobutylicum, Acetobacterium woodii, and Eubacterium limosum, while only C. saccharoperbutylacetonicum showed bright red fluorescence when producing redFAST. We used both reporter proteins in C. saccharoperbutylacetonicum for multicolor approaches. These include the investigation of the co-culture dynamics of metabolically engineered strains. Moreover, we established a tightly regulated inducible two-plasmid system and used greenFAST and redFAST to track the coexistence and interaction of both plasmids under anaerobic conditions in C. saccharoperbutylacetonicum. The establishment of greenFAST and redFAST as fluorescent reporters opens the door for further multicolor approaches to investigate cell dynamics, gene expression, or protein localization under anaerobic conditions.
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Affiliation(s)
- Maximilian Flaiz
- Institute of Microbiology and Biotechnology, University of Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany
| | - Tina Baur
- Institute of Microbiology and Biotechnology, University of Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany
| | - Jana Gaibler
- Institute of Microbiology and Biotechnology, University of Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany
| | - Christian Kröly
- Institute of Microbiology and Biotechnology, University of Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany
| | - Peter Dürre
- Institute of Microbiology and Biotechnology, University of Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany
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