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Hayashi N, Lai Y, Fuerte-Stone J, Mimee M, Lu TK. Cas9-assisted biological containment of a genetically engineered human commensal bacterium and genetic elements. Nat Commun 2024; 15:2096. [PMID: 38453913 PMCID: PMC10920895 DOI: 10.1038/s41467-024-45893-w] [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: 11/07/2021] [Accepted: 02/07/2024] [Indexed: 03/09/2024] Open
Abstract
Sophisticated gene circuits built by synthetic biology can enable bacteria to sense their environment and respond predictably. Engineered biosensing bacteria outfitted with such circuits can potentially probe the human gut microbiome to prevent, diagnose, or treat disease. To provide robust biocontainment for engineered bacteria, we devised a Cas9-assisted auxotrophic biocontainment system combining thymidine auxotrophy, an Engineered Riboregulator (ER) for controlled gene expression, and a CRISPR Device (CD). The CD prevents the engineered bacteria from acquiring thyA via horizontal gene transfer, which would disrupt the biocontainment system, and inhibits the spread of genetic elements by killing bacteria harboring the gene cassette. This system tunably controlled gene expression in the human gut commensal bacterium Bacteroides thetaiotaomicron, prevented escape from thymidine auxotrophy, and blocked transgene dissemination. These capabilities were validated in vitro and in vivo. This biocontainment system exemplifies a powerful strategy for bringing genetically engineered microorganisms safely into biomedicine.
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Affiliation(s)
- Naoki Hayashi
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- JSR-Keio University Medical and Chemical Innovation Center (JKiC), JSR Corp., 35 Shinanomachi, Shinjuku, Tokyo, 160-8582, Japan
| | - Yong Lai
- Synthetic Biology Group, MIT Synthetic Biology Center, Massachusetts Institute of Technology (MIT), Cambridge, MA, 02139, USA
- Research Laboratory of Electronics, MIT, Cambridge, MA, 02139, USA
- Department of Chemical and Biological Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR
| | - Jay Fuerte-Stone
- Department of Microbiology, The University of Chicago, Chicago, IL, 60637, USA
| | - Mark Mimee
- Department of Microbiology, The University of Chicago, Chicago, IL, 60637, USA.
- Pritzker School of Molecular Engineering, The University of Chicago, Chicago, IL, 60637, USA.
| | - Timothy K Lu
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
- Synthetic Biology Group, MIT Synthetic Biology Center, Massachusetts Institute of Technology (MIT), Cambridge, MA, 02139, USA.
- Research Laboratory of Electronics, MIT, Cambridge, MA, 02139, USA.
- Broad Institute, Cambridge, MA, 02139, USA.
- Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA, 02139, USA.
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Arnold J, Glazier J, Mimee M. Genetic Engineering of Resident Bacteria in the Gut Microbiome. J Bacteriol 2023; 205:e0012723. [PMID: 37382533 PMCID: PMC10367592 DOI: 10.1128/jb.00127-23] [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] [Indexed: 06/30/2023] Open
Abstract
Techniques by which to genetically manipulate members of the microbiota enable both the evaluation of host-microbe interactions and an avenue by which to monitor and modulate human physiology. Genetic engineering applications have traditionally focused on model gut residents, such as Escherichia coli and lactic acid bacteria. However, emerging efforts by which to develop synthetic biology toolsets for "nonmodel" resident gut microbes could provide an improved foundation for microbiome engineering. As genome engineering tools come online, so too have novel applications for engineered gut microbes. Engineered resident gut bacteria facilitate investigations of the roles of microbes and their metabolites on host health and allow for potential live microbial biotherapeutics. Due to the rapid pace of discovery in this burgeoning field, this minireview highlights advancements in the genetic engineering of all resident gut microbes.
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Affiliation(s)
- Jack Arnold
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois, USA
| | - Joshua Glazier
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois, USA
| | - Mark Mimee
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois, USA
- Department of Microbiology, University of Chicago, Chicago, Illinois, USA
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Genetic tools for the redirection of the central carbon flow towards the production of lactate in the human gut bacterium Phocaeicola (Bacteroides) vulgatus. Appl Microbiol Biotechnol 2022; 106:1211-1225. [PMID: 35080666 PMCID: PMC8816746 DOI: 10.1007/s00253-022-11777-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 01/12/2022] [Accepted: 01/13/2022] [Indexed: 12/26/2022]
Abstract
Species of the genera Bacteroides and Phocaeicola play an important role in the human colon. The organisms contribute to the degradation of complex heteropolysaccharides to small chain fatty acids, which are in part utilized by the human body. Furthermore, these organisms are involved in the synthesis of vitamins and other bioactive compounds. Of special interest is Phocaeicola vulgatus, originally classified as a Bacteroides species, due to its abundance in the human intestinal tract and its ability to degrade many plant-derived heteropolysaccharides. We analyzed different tools for the genetic modification of this microorganism, with respect to homologous gene expression of the ldh gene encoding a D-lactate dehydrogenase (LDH). Therefore, the ldh gene was cloned into the integration vector pMM656 and the shuttle vector pG106 for homologous gene expression in P. vulgatus. We determined the ldh copy number, transcript abundance, and the enzyme activity of the wild type and the mutants. The strain containing the shuttle vector showed an approx. 1500-fold increase in the ldh transcript concentration and an enhanced LDH activity that was about 200-fold higher compared to the parental strain. Overall, the proportion of lactate in the general catabolic carbon flow increased from 2.9% (wild type) to 28.5% in the LDH-overproducing mutant. This approach is a proof of concept, verifying the genetic accessibility of P. vulgatus and could form the basis for targeted genetic optimization. KEY POINTS: • A lactate dehydrogenase was overexpressed in Phocaeicola (Bacteroides) vulgatus. • The ldh transcript abundance and the LDH activity increased sharply in the mutant. • The proportion of lactate in the catabolic carbon flow increased to about 30%.
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Whitaker WR, Shepherd ES, Sonnenburg JL. Tunable Expression Tools Enable Single-Cell Strain Distinction in the Gut Microbiome. Cell 2017; 169:538-546.e12. [PMID: 28431251 DOI: 10.1016/j.cell.2017.03.041] [Citation(s) in RCA: 142] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 01/28/2017] [Accepted: 03/27/2017] [Indexed: 01/07/2023]
Abstract
Applying synthetic biology to engineer gut-resident microbes provides new avenues to investigate microbe-host interactions, perform diagnostics, and deliver therapeutics. Here, we describe a platform for engineering Bacteroides, the most abundant genus in the Western microbiota, which includes a process for high-throughput strain modification. We have identified a novel phage promoter and translational tuning strategy and achieved an unprecedented level of expression that enables imaging of fluorescent-protein-expressing Bacteroides stably colonizing the mouse gut. A detailed characterization of the phage promoter has provided a set of constitutive promoters that span over four logs of strength without detectable fitness burden within the gut over 14 days. These promoters function predictably over a 1,000,000-fold expression range in phylogenetically diverse Bacteroides species. With these promoters, unique fluorescent signatures were encoded to allow differentiation of six species within the gut. Fluorescent protein-based differentiation of isogenic strains revealed that priority of gut colonization determines colonic crypt occupancy.
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Affiliation(s)
- Weston R Whitaker
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA; Novome Biotechnologies, 100 Kimball Way, South San Francisco, San Francisco, CA 94080, USA
| | - Elizabeth Stanley Shepherd
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Justin L Sonnenburg
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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Lim B, Zimmermann M, Barry NA, Goodman AL. Engineered Regulatory Systems Modulate Gene Expression of Human Commensals in the Gut. Cell 2017; 169:547-558.e15. [PMID: 28431252 PMCID: PMC5532740 DOI: 10.1016/j.cell.2017.03.045] [Citation(s) in RCA: 118] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 02/28/2017] [Accepted: 03/27/2017] [Indexed: 12/15/2022]
Abstract
The gut microbiota is implicated in numerous aspects of health and disease, but dissecting these connections is challenging because genetic tools for gut anaerobes are limited. Inducible promoters are particularly valuable tools because these platforms allow real-time analysis of the contribution of microbiome gene products to community assembly, host physiology, and disease. We developed a panel of tunable expression platforms for the prominent genus Bacteroides in which gene expression is controlled by a synthetic inducer. In the absence of inducer, promoter activity is fully repressed; addition of inducer rapidly increases gene expression by four to five orders of magnitude. Because the inducer is absent in mice and their diets, Bacteroides gene expression inside the gut can be modulated by providing the inducer in drinking water. We use this system to measure the dynamic relationship between commensal sialidase activity and liberation of mucosal sialic acid, a receptor and nutrient for pathogens. VIDEO ABSTRACT.
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Affiliation(s)
- Bentley Lim
- Department of Microbial Pathogenesis and Microbial Sciences Institute, Yale University School of Medicine, New Haven, CT 06536-0812, USA
| | - Michael Zimmermann
- Department of Microbial Pathogenesis and Microbial Sciences Institute, Yale University School of Medicine, New Haven, CT 06536-0812, USA
| | - Natasha A Barry
- Department of Microbial Pathogenesis and Microbial Sciences Institute, Yale University School of Medicine, New Haven, CT 06536-0812, USA
| | - Andrew L Goodman
- Department of Microbial Pathogenesis and Microbial Sciences Institute, Yale University School of Medicine, New Haven, CT 06536-0812, USA.
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Horn N, Carvalho AL, Overweg K, Wegmann U, Carding SR, Stentz R. A Novel Tightly Regulated Gene Expression System for the Human Intestinal Symbiont Bacteroides thetaiotaomicron. Front Microbiol 2016; 7:1080. [PMID: 27468280 PMCID: PMC4942465 DOI: 10.3389/fmicb.2016.01080] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 06/27/2016] [Indexed: 11/13/2022] Open
Abstract
There is considerable interest in studying the function of Bacteroides species resident in the human gastrointestinal (GI)-tract and the contribution they make to host health. Reverse genetics and protein expression techniques, such as those developed for well-characterized Escherichia coli cannot be applied to Bacteroides species as they and other members of the Bacteriodetes phylum have unique promoter structures. The availability of useful Bacteroides-specific genetic tools is therefore limited. Here we describe the development of an effective mannan-controlled gene expression system for Bacteroides thetaiotaomicron containing the mannan-inducible promoter-region of an α-1,2-mannosidase gene (BT_3784), a ribosomal binding site designed to modulate expression, a multiple cloning site to facilitate the cloning of genes of interest, and a transcriptional terminator. Using the Lactobacillus pepI as a reporter gene, mannan induction resulted in an increase of reporter activity in a time- and concentration-dependent manner with a wide range of activity. The endogenous BtcepA cephalosporinase gene was used to demonstrate the suitability of this novel expression system, enabling the isolation of a His-tagged version of BtCepA. We have also shown with experiments performed in mice that the system can be induced in vivo in the presence of an exogenous source of mannan. By enabling the controlled expression of endogenous and exogenous genes in B. thetaiotaomicron this novel inducer-dependent expression system will aid in defining the physiological role of individual genes and the functional analyses of their products.
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Affiliation(s)
- Nikki Horn
- Gut Health and Food Safety Programme, Carding's Lab, Institute of Food Research Norwich, UK
| | - Ana L Carvalho
- Gut Health and Food Safety Programme, Carding's Lab, Institute of Food Research Norwich, UK
| | - Karin Overweg
- Gut Health and Food Safety Programme, Carding's Lab, Institute of Food Research Norwich, UK
| | - Udo Wegmann
- Gut Health and Food Safety Programme, Carding's Lab, Institute of Food Research Norwich, UK
| | - Simon R Carding
- Gut Health and Food Safety Programme, Carding's Lab, Institute of Food ResearchNorwich, UK; Department of Medicine, Norwich Medical School, University of East AngliaNorwich, UK
| | - Régis Stentz
- Gut Health and Food Safety Programme, Carding's Lab, Institute of Food Research Norwich, UK
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Mimee M, Tucker AC, Voigt CA, Lu TK. Programming a Human Commensal Bacterium, Bacteroides thetaiotaomicron, to Sense and Respond to Stimuli in the Murine Gut Microbiota. Cell Syst 2015; 1:62-71. [PMID: 26918244 DOI: 10.1016/j.cels.2015.06.001] [Citation(s) in RCA: 211] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Engineering commensal organisms for challenging applications, such as modulating the gut ecosystem, is hampered by the lack of genetic parts. Here, we describe promoters, ribosome-binding sites, and inducible systems for use in the commensal bacterium Bacteroides thetaiotaomicron, a prevalent and stable resident of the human gut. We achieve up to 10,000-fold range in constitutive gene expression and 100-fold regulation of gene expression with inducible promoters and use these parts to record DNA-encoded memory in the genome. We use CRISPR interference (CRISPRi) for regulated knockdown of recombinant and endogenous gene expression to alter the metabolic capacity of B. thetaiotaomicron and its resistance to antimicrobial peptides. Finally, we show that inducible CRISPRi and recombinase systems can function in B. thetaiotaomicron colonizing the mouse gut. These results provide a blueprint for engineering new chassis and a resource to engineer Bacteroides for surveillance of or therapeutic delivery to the gut microbiome.
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Affiliation(s)
- Mark Mimee
- Department of Biological Engineering, Synthetic Biology Center, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; MIT Microbiology Program, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Alex C Tucker
- Department of Biological Engineering, Synthetic Biology Center, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Christopher A Voigt
- Department of Biological Engineering, Synthetic Biology Center, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Timothy K Lu
- Department of Biological Engineering, Synthetic Biology Center, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; MIT Microbiology Program, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Elizabethkingia anophelis: molecular manipulation and interactions with mosquito hosts. Appl Environ Microbiol 2015; 81:2233-43. [PMID: 25595771 DOI: 10.1128/aem.03733-14] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Flavobacteria (members of the family Flavobacteriaceae) dominate the bacterial community in the Anopheles mosquito midgut. One such commensal, Elizabethkingia anophelis, is closely associated with Anopheles mosquitoes through transstadial persistence (i.e., from one life stage to the next); these and other properties favor its development for paratransgenic applications in control of malaria parasite transmission. However, the physiological requirements of E. anophelis have not been investigated, nor has its capacity to perpetuate despite digestion pressure in the gut been quantified. To this end, we first developed techniques for genetic manipulation of E. anophelis, including selectable markers, reporter systems (green fluorescent protein [GFP] and NanoLuc), and transposons that function in E. anophelis. A flavobacterial expression system based on the promoter PompA was integrated into the E. anophelis chromosome and showed strong promoter activity to drive GFP and NanoLuc reporter production. Introduced, GFP-tagged E. anophelis associated with mosquitoes at successive developmental stages and propagated in Anopheles gambiae and Anopheles stephensi but not in Aedes triseriatus mosquitoes. Feeding NanoLuc-tagged cells to A. gambiae and A. stephensi in the larval stage led to infection rates of 71% and 82%, respectively. In contrast, a very low infection rate (3%) was detected in Aedes triseriatus mosquitoes under the same conditions. Of the initial E. anophelis cells provided to larvae, 23%, 71%, and 85% were digested in A. stephensi, A. gambiae, and Aedes triseriatus, respectively, demonstrating that E. anophelis adapted to various mosquito midgut environments differently. Bacterial cell growth increased up to 3-fold when arginine was supplemented in the defined medium. Furthermore, the number of NanoLuc-tagged cells in A. stephensi significantly increased when arginine was added to a sugar diet, showing it to be an important amino acid for E. anophelis. Animal erythrocytes promoted E. anophelis growth in vivo and in vitro, indicating that this bacterium could obtain nutrients by participating in erythrocyte lysis in the mosquito midgut.
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The extracytoplasmic function sigma factor EcfO protects Bacteroides fragilis against oxidative stress. J Bacteriol 2012; 195:145-55. [PMID: 23104808 DOI: 10.1128/jb.01491-12] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The anaerobe Bacteroides fragilis is a highly aerotolerant, opportunistic pathogen that is an important component of the human intestinal microbiota. Aerotolerance has been linked to a robust oxidative stress response, which in turn is necessary for maximal virulence in a mouse intra-abdominal abscess model. During oxidative stress, there is a dynamic change in gene expression that encompasses a third of the genome, but there is a paucity of information on factors that control this response. A large number of transcription regulators, including about 14 extracytoplasmic function (ECF) sigma factors, are affected by oxidative stress, and one of these, EcfO, was used as a model of ECF sigma factor activity during stress. Genetic and biochemical experiments showed that EcfO was located in an operon with a structurally unique anti-sigma factor, Reo. Cells deleted for EcfO were impaired during exposure to oxygen or other forms of oxidative stress, whereas reo mutants were more resistant to stress. Protein-protein interaction experiments demonstrated that Reo directly interacts with and regulates the activity of EcfO. Expression microarray and chromatin affinity precipitation assays were used to identify target genes regulated by EcfO, and an EcfO recognition sequence was identified. The results revealed that EcfO controls a regulon of novel lipoproteins whose distribution in nature is restricted to members of the Bacteroidetes phylum.
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