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Maltz-Matyschsyk M, Melchiorre CK, Knecht DA, Lynes MA. Bacterial metallothionein, PmtA, a novel stress protein found on the bacterial surface of Pseudomonas aeruginosa and involved in management of oxidative stress and phagocytosis. mSphere 2024:e0021024. [PMID: 38712943 DOI: 10.1128/msphere.00210-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Accepted: 04/08/2024] [Indexed: 05/08/2024] Open
Abstract
Metallothioneins (MTs) are small cysteine-rich proteins that play important roles in homeostasis and protection against heavy metal toxicity and oxidative stress. The opportunistic pathogen, Pseudomonas aeruginosa, expresses a bacterial MT known as PmtA. Utilizing genetically modified P. aeruginosa PAO1 strains (a human clinical wound isolate), we show that inducing pmtA increases levels of pyocyanin and biofilm compared to other PAO1 isogenic strains, supporting previous results that pmtA is important for pyocyanin and biofilm production. We also show that overexpression of pmtA in vitro provides protection for cells exposed to oxidants, which is a characteristic of inflammation, indicating a role for PmtA as an antioxidant in inflammation. We found that a pmtA clean deletion mutant is phagocytized faster than other PAO1 isogenic strains in THP-1 human macrophage cells, indicating that PmtA provides protection from the phagocytic attack. Interestingly, we observed that monoclonal anti-PmtA antibody binds to PmtA, which is accessible on the surface of PAO1 strains using both flow cytometry and enzyme-linked immunosorbent assay techniques. Finally, we investigated intracellular persistence of these PAO1 strains within THP-1 macrophages cells and found that the phagocytic endurance of PAO1 strains is affected by pmtA expression. These data show for the first time that a bacterial MT (pmtA) can play a role in the phagocytic process and can be found on the outer surface of PAO1. Our results suggest that PmtA plays a role both in protection from oxidative stress and in the resistance to the host's innate immune response, identifying PmtA as a potential therapeutic target in P. aeruginosa infection. IMPORTANCE The pathogen Pseudomonas aeruginosa is a highly problematic multidrug-resistant (MDR) pathogen with complex virulence networks. MDR P. aeruginosa infections have been associated with increased clinical visits, very poor healthcare outcomes, and these infections are ranked as critical on priority lists of both the Centers for Disease Control and Prevention and the World Health Organization. Known P. aeruginosa virulence factors have been extensively studied and are implicated in counteracting host defenses, causing direct damage to the host tissues, and increased microbial competitiveness. Targeting virulence factors has emerged as a new line of defense in the battle against MDR P. aeruginosa strains. Bacterial metallothionein is a newly recognized virulence factor that enables evasion of the host immune response. The studies described here identify mechanisms in which bacterial metallothionein (PmtA) plays a part in P. aeruginosa pathogenicity and identifies PmtA as a potential therapeutic target.
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Affiliation(s)
| | - Clare K Melchiorre
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut, USA
| | - David A Knecht
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut, USA
| | - Michael A Lynes
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut, USA
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2
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Chen JZ, Kwong Z, Gerardo NM, Vega NM. Ecological drift during colonization drives within-host and between-host heterogeneity in an animal-associated symbiont. PLoS Biol 2024; 22:e3002304. [PMID: 38662791 DOI: 10.1371/journal.pbio.3002304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 05/07/2024] [Accepted: 03/26/2024] [Indexed: 05/08/2024] Open
Abstract
Specialized host-microbe symbioses canonically show greater diversity than expected from simple models, both at the population level and within individual hosts. To understand how this heterogeneity arises, we utilize the squash bug, Anasa tristis, and its bacterial symbionts in the genus Caballeronia. We modulate symbiont bottleneck size and inoculum composition during colonization to demonstrate the significance of ecological drift, the noisy fluctuations in community composition due to demographic stochasticity. Consistent with predictions from the neutral theory of biodiversity, we found that ecological drift alone can account for heterogeneity in symbiont community composition between hosts, even when 2 strains are nearly genetically identical. When acting on competing strains, ecological drift can maintain symbiont genetic diversity among different hosts by stochastically determining the dominant strain within each host. Finally, ecological drift mediates heterogeneity in isogenic symbiont populations even within a single host, along a consistent gradient running the anterior-posterior axis of the symbiotic organ. Our results demonstrate that symbiont population structure across scales does not necessarily require host-mediated selection, as it can emerge as a result of ecological drift acting on both isogenic and unrelated competitors. Our findings illuminate the processes that might affect symbiont transmission, coinfection, and population structure in nature, which can drive the evolution of host-microbe symbioses and microbe-microbe interactions within host-associated microbiomes.
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Affiliation(s)
- Jason Z Chen
- Department of Biology, Emory University, Atlanta, Georgia, United States of America
| | - Zeeyong Kwong
- Laboratory of Bacteriology, National Institutes of Allergy and Infectious Diseases, Hamilton, Montana, United States of America
| | - Nicole M Gerardo
- Department of Biology, Emory University, Atlanta, Georgia, United States of America
| | - Nic M Vega
- Department of Biology, Emory University, Atlanta, Georgia, United States of America
- Department of Physics, Emory University, Atlanta, Georgia, United States of America
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3
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Marinos G, Hamerich IK, Debray R, Obeng N, Petersen C, Taubenheim J, Zimmermann J, Blackburn D, Samuel BS, Dierking K, Franke A, Laudes M, Waschina S, Schulenburg H, Kaleta C. Metabolic model predictions enable targeted microbiome manipulation through precision prebiotics. Microbiol Spectr 2024; 12:e0114423. [PMID: 38230938 PMCID: PMC10846184 DOI: 10.1128/spectrum.01144-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 12/13/2023] [Indexed: 01/18/2024] Open
Abstract
While numerous health-beneficial interactions between host and microbiota have been identified, there is still a lack of targeted approaches for modulating these interactions. Thus, we here identify precision prebiotics that specifically modulate the abundance of a microbiome member species of interest. In the first step, we show that defining precision prebiotics by compounds that are only taken up by the target species but no other species in a community is usually not possible due to overlapping metabolic niches. Subsequently, we use metabolic modeling to identify precision prebiotics for a two-member Caenorhabditis elegans microbiome community comprising the immune-protective target species Pseudomonas lurida MYb11 and the persistent colonizer Ochrobactrum vermis MYb71. We experimentally confirm four of the predicted precision prebiotics, L-serine, L-threonine, D-mannitol, and γ-aminobutyric acid, to specifically increase the abundance of MYb11. L-serine was further assessed in vivo, leading to an increase in MYb11 abundance also in the worm host. Overall, our findings demonstrate that metabolic modeling is an effective tool for the design of precision prebiotics as an important cornerstone for future microbiome-targeted therapies.IMPORTANCEWhile various mechanisms through which the microbiome influences disease processes in the host have been identified, there are still only few approaches that allow for targeted manipulation of microbiome composition as a first step toward microbiome-based therapies. Here, we propose the concept of precision prebiotics that allow to boost the abundance of already resident health-beneficial microbial species in a microbiome. We present a constraint-based modeling pipeline to predict precision prebiotics for a minimal microbial community in the worm Caenorhabditis elegans comprising the host-beneficial Pseudomonas lurida MYb11 and the persistent colonizer Ochrobactrum vermis MYb71 with the aim to boost the growth of MYb11. Experimentally testing four of the predicted precision prebiotics, we confirm that they are specifically able to increase the abundance of MYb11 in vitro and in vivo. These results demonstrate that constraint-based modeling could be an important tool for the development of targeted microbiome-based therapies against human diseases.
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Affiliation(s)
- Georgios Marinos
- Research Group Medical Systems Biology, University Hospital Schleswig-Holstein Campus Kiel, Kiel University, Kiel, Schleswig-Holstein, Germany
| | - Inga K. Hamerich
- Research Group Evolutionary Ecology and Genetics, Zoological Institute, Kiel University, Kiel, Schleswig-Holstein, Germany
| | - Reena Debray
- Department of Integrative Biology, University of California, Berkeley, California, USA
| | - Nancy Obeng
- Research Group Evolutionary Ecology and Genetics, Zoological Institute, Kiel University, Kiel, Schleswig-Holstein, Germany
| | - Carola Petersen
- Research Group Evolutionary Ecology and Genetics, Zoological Institute, Kiel University, Kiel, Schleswig-Holstein, Germany
| | - Jan Taubenheim
- Research Group Medical Systems Biology, University Hospital Schleswig-Holstein Campus Kiel, Kiel University, Kiel, Schleswig-Holstein, Germany
| | - Johannes Zimmermann
- Research Group Medical Systems Biology, University Hospital Schleswig-Holstein Campus Kiel, Kiel University, Kiel, Schleswig-Holstein, Germany
- Max-Planck Institute for Evolutionary Biology, Ploen, Schleswig-Holstein, Germany
| | - Dana Blackburn
- Alkek Center for Metagenomics and Microbiome Research, Baylor College of Medicine, Houston, Texas, USA
| | - Buck S. Samuel
- Alkek Center for Metagenomics and Microbiome Research, Baylor College of Medicine, Houston, Texas, USA
| | - Katja Dierking
- Research Group Evolutionary Ecology and Genetics, Zoological Institute, Kiel University, Kiel, Schleswig-Holstein, Germany
| | - Andre Franke
- Institute of Clinical Molecular Biology, Kiel University, Kiel, Schleswig-Holstein, Germany
| | - Matthias Laudes
- Institute of Diabetes and Clinical Metabolic Research, University Hospital Schleswig-Holstein Campus Kiel, Kiel, Schleswig-Holstein, Germany
| | - Silvio Waschina
- Nutriinformatics, Institute for Human Nutrition and Food Science, Kiel University, Kiel, Schleswig-Holstein, Germany
| | - Hinrich Schulenburg
- Research Group Evolutionary Ecology and Genetics, Zoological Institute, Kiel University, Kiel, Schleswig-Holstein, Germany
- Max-Planck Institute for Evolutionary Biology, Ploen, Schleswig-Holstein, Germany
| | - Christoph Kaleta
- Research Group Medical Systems Biology, University Hospital Schleswig-Holstein Campus Kiel, Kiel University, Kiel, Schleswig-Holstein, Germany
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4
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Gentry-Lear Z, Franco K, Shavlik M, Harms MJ, Baylink A. Navigating contradictions: Salmonella Typhimurium chemotactic responses to conflicting chemoeffector signals show parity with bacterial growth benefits. bioRxiv 2024:2024.01.18.576330. [PMID: 38293242 PMCID: PMC10827161 DOI: 10.1101/2024.01.18.576330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Many bacteria that colonize the guts of animals use chemotaxis to direct swimming motility and select sites for colonization based on sources of effectors derived from the host, diet, and microbial competitors of the local environ. The complex ecosystem of the gastrointestinal tract contains mixtures of chemoattractants and chemorepellents, but it remains poorly understood how swimming bacteria navigate conflicting signals. The enteric pathogen Salmonella Typhimurium possesses Tsr, a chemoreceptor protein that directs both chemoattraction and chemorepulsion responses, which we employed as a model to study chemotaxis in the presence of conflicting effector stimuli. We investigated how S. Typhimurium responds to human fecal matter, an effector source in the enteric lumen that contains high concentrations of indole, a bacteriostatic chemorepellent produced by the native commensals of the microbiota, and also nutrients such as l-serine, a chemoattractant. The indole concentration in human feces is more than 12-fold the concentration required for half-maximal chemorepulsion, however, we find S. Typhimurium, and various clinical isolates of non-typhoidal S. enterica serovars, are strongly attracted to liquid fecal matter. We further investigated the chemotactic responses of S. Typhimurium to titrations of indole and l-serine and revealed that chemorepulsion to indole is overridden in the presence of excess l-serine. We capture the inversion of these two opposing taxis behaviors in a phenomenon we define as "chemohalation" in which the bacteria organize into a halo around the treatment source with an interior zone of avoidance, which represents a compromise between chemoattraction and chemorepulsion. Growth analyses reveal that the chemotactic responses to these opposing effectors align chemoattraction and chemorepulsion with the relative growth of the bacteria in culture. Hence, our study supports the view that evolution has finely tuned chemotaxis to assess environmental habitability by evaluating the tradeoffs in bacterial growth based on the local combination of effectors.
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Affiliation(s)
- Zealon Gentry-Lear
- University of Oregon, Department of Chemistry & Biochemistry, Eugene, OR, 97403
| | - Kailie Franco
- Washington State University, Department of Veterinary Microbiology and Pathology, Pullman, WA 99164
| | - Michael Shavlik
- University of Oregon, Department of Chemistry & Biochemistry, Eugene, OR, 97403
| | - Michael J. Harms
- University of Oregon, Department of Chemistry & Biochemistry, Eugene, OR, 97403
- University of Oregon, Institute of Molecular Biology, Eugene, OR, 97403
| | - Arden Baylink
- Washington State University, Department of Veterinary Microbiology and Pathology, Pullman, WA 99164
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5
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Obeng N, Czerwinski A, Schütz D, Michels J, Leipert J, Bansept F, García García MJ, Schultheiß T, Kemlein M, Fuß J, Tholey A, Traulsen A, Sondermann H, Schulenburg H. Bacterial c-di-GMP has a key role in establishing host-microbe symbiosis. Nat Microbiol 2023; 8:1809-1819. [PMID: 37653009 PMCID: PMC10522488 DOI: 10.1038/s41564-023-01468-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 08/10/2023] [Indexed: 09/02/2023]
Abstract
Most microbes evolve faster than their hosts and should therefore drive evolution of host-microbe interactions. However, relatively little is known about the characteristics that define the adaptive path of microbes to host association. Here we identified microbial traits that mediate adaptation to hosts by experimentally evolving the free-living bacterium Pseudomonas lurida with the nematode Caenorhabditis elegans as its host. After ten passages, we repeatedly observed the evolution of beneficial host-specialist bacteria, with improved persistence in the nematode being associated with increased biofilm formation. Whole-genome sequencing revealed mutations that uniformly upregulate the bacterial second messenger, cyclic diguanylate (c-di-GMP). We subsequently generated mutants with upregulated c-di-GMP in different Pseudomonas strains and species, which consistently increased host association. Comparison of pseudomonad genomes from various environments revealed that c-di-GMP underlies adaptation to a variety of hosts, from plants to humans. This study indicates that c-di-GMP is fundamental for establishing host association.
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Affiliation(s)
- Nancy Obeng
- Department of Evolutionary Ecology and Genetics, University of Kiel, Kiel, Germany
| | - Anna Czerwinski
- Department of Evolutionary Ecology and Genetics, University of Kiel, Kiel, Germany
| | - Daniel Schütz
- Department of Evolutionary Ecology and Genetics, University of Kiel, Kiel, Germany
| | - Jan Michels
- Department of Evolutionary Ecology and Genetics, University of Kiel, Kiel, Germany
| | - Jan Leipert
- Department of Systematic Proteome Research and Bioanalytics, University of Kiel, Kiel, Germany
| | | | - María J García García
- CSSB Centre for Structural Systems Biology, Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
| | - Thekla Schultheiß
- Department of Evolutionary Ecology and Genetics, University of Kiel, Kiel, Germany
- Institute of Toxicology and Pharmacology, University of Kiel, Kiel, Germany
| | - Melinda Kemlein
- Department of Evolutionary Ecology and Genetics, University of Kiel, Kiel, Germany
| | - Janina Fuß
- Institute of Clinical Molecular Biology, University of Kiel, Kiel, Germany
| | - Andreas Tholey
- Department of Systematic Proteome Research and Bioanalytics, University of Kiel, Kiel, Germany
| | - Arne Traulsen
- Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Holger Sondermann
- CSSB Centre for Structural Systems Biology, Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
- Section of Biology, University of Kiel, Kiel, Germany
| | - Hinrich Schulenburg
- Department of Evolutionary Ecology and Genetics, University of Kiel, Kiel, Germany.
- Max Planck Institute for Evolutionary Biology, Plön, Germany.
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6
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Alker AT, Farrell MV, Aspiras AE, Dunbar TL, Fedoriouk A, Jones JE, Mikhail SR, Salcedo GY, Moore BS, Shikuma NJ. A modular plasmid toolkit applied in marine bacteria reveals functional insights during bacteria-stimulated metamorphosis. mBio 2023; 14:e0150223. [PMID: 37530556 PMCID: PMC10470607 DOI: 10.1128/mbio.01502-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Accepted: 06/17/2023] [Indexed: 08/03/2023] Open
Abstract
A conspicuous roadblock to studying marine bacteria for fundamental research and biotechnology is a lack of modular synthetic biology tools for their genetic manipulation. Here, we applied, and generated new parts for, a modular plasmid toolkit to study marine bacteria in the context of symbioses and host-microbe interactions. To demonstrate the utility of this plasmid system, we genetically manipulated the marine bacterium Pseudoalteromonas luteoviolacea, which stimulates the metamorphosis of the model tubeworm, Hydroides elegans. Using these tools, we quantified constitutive and native promoter expression, developed reporter strains that enable the imaging of host-bacteria interactions, and used CRISPR interference (CRISPRi) to knock down a secondary metabolite and a host-associated gene. We demonstrate the broader utility of this modular system for testing the genetic tractability of marine bacteria that are known to be associated with diverse host-microbe symbioses. These efforts resulted in the successful conjugation of 12 marine strains from the Alphaproteobacteria and Gammaproteobacteria classes. Altogether, the present study demonstrates how synthetic biology strategies enable the investigation of marine microbes and marine host-microbe symbioses with potential implications for environmental restoration and biotechnology. IMPORTANCE Marine Proteobacteria are attractive targets for genetic engineering due to their ability to produce a diversity of bioactive metabolites and their involvement in host-microbe symbioses. Modular cloning toolkits have become a standard for engineering model microbes, such as Escherichia coli, because they enable innumerable mix-and-match DNA assembly and engineering options. However, such modular tools have not yet been applied to most marine bacterial species. In this work, we adapt a modular plasmid toolkit for use in a set of 12 marine bacteria from the Gammaproteobacteria and Alphaproteobacteria classes. We demonstrate the utility of this genetic toolkit by engineering a marine Pseudoalteromonas bacterium to study their association with its host animal Hydroides elegans. This work provides a proof of concept that modular genetic tools can be applied to diverse marine bacteria to address basic science questions and for biotechnology innovations.
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Affiliation(s)
- Amanda T. Alker
- Department of Biology, San Diego State University, San Diego, California, USA
| | - Morgan V. Farrell
- Department of Biology, San Diego State University, San Diego, California, USA
| | - Alpher E. Aspiras
- Department of Biology, San Diego State University, San Diego, California, USA
| | - Tiffany L. Dunbar
- Department of Biology, San Diego State University, San Diego, California, USA
| | - Andriy Fedoriouk
- Department of Biology, San Diego State University, San Diego, California, USA
| | - Jeffrey E. Jones
- Department of Biology, San Diego State University, San Diego, California, USA
| | - Sama R. Mikhail
- Department of Biology, San Diego State University, San Diego, California, USA
| | | | - Bradley S. Moore
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, California, USA
| | - Nicholas J. Shikuma
- Department of Biology, San Diego State University, San Diego, California, USA
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7
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Smith TJ, Sundarraman D, Melancon E, Desban L, Parthasarathy R, Guillemin K. A mucin-regulated adhesin determines the spatial organization and inflammatory character of a bacterial symbiont in the vertebrate gut. Cell Host Microbe 2023; 31:1371-1385.e6. [PMID: 37516109 PMCID: PMC10492631 DOI: 10.1016/j.chom.2023.07.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 05/11/2023] [Accepted: 07/06/2023] [Indexed: 07/31/2023]
Abstract
In a healthy gut, microbes are often aggregated with host mucus, yet the molecular basis for this organization and its impact on intestinal health are unclear. Mucus is a viscous physical barrier separating resident microbes from epithelia, but it also provides glycan cues that regulate microbial behaviors. Here, we describe a mucin-sensing pathway in an Aeromonas symbiont of zebrafish, Aer01. In response to the mucin-associated glycan N-acetylglucosamine, a sensor kinase regulates the expression of an aggregation-promoting adhesin we named MbpA. Upon MbpA disruption, Aer01 colonizes to normal levels but is largely planktonic and more pro-inflammatory. Increasing cell surface MbpA rescues these traits. MbpA-like adhesins are common in human-associated bacteria, and the expression of an Akkermansia muciniphila MbpA-like adhesin in MbpA-deficient Aer01 restores lumenal aggregation and reverses its pro-inflammatory character. Our work demonstrates how resident bacteria use mucin glycans to modulate behaviors congruent with host health.
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Affiliation(s)
- T Jarrod Smith
- Institute of Molecular Biology, University of Oregon, Eugene, OR, USA
| | - Deepika Sundarraman
- Department of Physics and Materials Science Institute, University of Oregon, Eugene, OR, USA
| | - Ellie Melancon
- Institute of Neuroscience, University of Oregon, Eugene, OR, USA
| | - Laura Desban
- Institute of Neuroscience, University of Oregon, Eugene, OR, USA
| | - Raghuveer Parthasarathy
- Department of Physics and Materials Science Institute, University of Oregon, Eugene, OR, USA
| | - Karen Guillemin
- Institute of Molecular Biology, University of Oregon, Eugene, OR, USA; Institute of Neuroscience, University of Oregon, Eugene, OR, USA; Humans and the Microbiome Program, Canadian Institute for Advanced Research, Toronto, ON, Canada.
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8
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Villa SM, Chen JZ, Kwong Z, Acosta A, Vega NM, Gerardo NM. Specialized acquisition behaviors maintain reliable environmental transmission in an insect-microbial mutualism. Curr Biol 2023:S0960-9822(23)00724-8. [PMID: 37385254 DOI: 10.1016/j.cub.2023.05.062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 04/07/2023] [Accepted: 05/25/2023] [Indexed: 07/01/2023]
Abstract
Understanding how horizontally transmitted mutualisms are maintained is a major focus of symbiosis research.1,2,3,4 Unlike vertical transmission, hosts that rely on horizontal transmission produce symbiont-free offspring that must find and acquire their beneficial microbes from the environment. This transmission strategy is inherently risky since hosts may not obtain the right symbiont every generation. Despite these potential costs, horizontal transmission underlies stable mutualisms involving a large diversity of both plants and animals.5,6,7,8,9 One largely unexplored way horizontal transmission is maintained is for hosts to evolve sophisticated mechanisms to consistently find and acquire specific symbionts from the environment. Here, we examine this possibility in the squash bug Anasa tristis, an insect pest that requires bacterial symbionts in the genus Caballeronia10 for survival and development.11 We conduct a series of behavioral and transmission experiments that track strain-level transmission in vivo among individuals in real-time. We demonstrate that nymphs can accurately find feces from adult bugs in both the presence and absence of those adults. Once nymphs locate the feces, they deploy feeding behavior that results in nearly perfect symbiont acquisition success. We further demonstrate that nymphs can locate and feed on isolated, cultured symbionts in the absence of feces. Finally, we show this acquisition behavior is highly host specific. Taken together, our data describe not only the evolution of a reliable horizontal transmission strategy, but also a potential mechanism that drives patterns of species-specific microbial communities among closely related, sympatric host species.
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Affiliation(s)
- Scott M Villa
- Department of Biology, Emory University, 1510 Clifton Rd., Atlanta, GA 30322, USA; Department of Biology, Davidson College, 209 Ridge Rd., Davidson, NC 28035, USA.
| | - Jason Z Chen
- Department of Biology, Emory University, 1510 Clifton Rd., Atlanta, GA 30322, USA
| | - Zeeyong Kwong
- Department of Biology, Emory University, 1510 Clifton Rd., Atlanta, GA 30322, USA
| | - Alice Acosta
- Department of Biology, Emory University, 1510 Clifton Rd., Atlanta, GA 30322, USA
| | - Nicole M Vega
- Department of Biology, Emory University, 1510 Clifton Rd., Atlanta, GA 30322, USA
| | - Nicole M Gerardo
- Department of Biology, Emory University, 1510 Clifton Rd., Atlanta, GA 30322, USA
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9
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Abstract
In recent years, evolutionary biologists have developed an increasing interest in the use of barcoding strategies to study eco-evolutionary dynamics of lineages within evolving populations and communities. Although barcoded populations can deliver unprecedented insight into evolutionary change, barcoding microbes presents specific technical challenges. Here, strategies are described for barcoding populations of the model bacterium Pseudomonas fluorescens SBW25, including the design and cloning of barcoded regions, preparation of libraries for amplicon sequencing, and quantification of resulting barcoded lineages. In so doing, we hope to aid the design and implementation of barcoding methodologies in a broad range of model and non-model organisms.
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Affiliation(s)
- Loukas Theodosiou
- Department of Microbial Population Biology, Max Planck Institute for Evolutionary Biology, Plön, Germany.
- Department of Comparative Development and Genetics, Max Planck Institute for Plant Breeding, Cologne, Germany.
| | - Andrew D Farr
- Department of Microbial Population Biology, Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Paul B Rainey
- Department of Microbial Population Biology, Max Planck Institute for Evolutionary Biology, Plön, Germany
- Laboratory of Biophysics and Evolution, CBI, ESPCI Paris, Université PSL, CNRS, Paris, France
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10
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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 Commun 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] [What about the content of this article? (0)] [Affiliation(s)] [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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11
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Marinos G, Hamerich IK, Debray R, Obeng N, Petersen C, Taubenheim J, Zimmermann J, Blackburn D, Samuel BS, Dierking K, Franke A, Laudes M, Waschina S, Schulenburg H, Kaleta C. Metabolic model predictions enable targeted microbiome manipulation through precision prebiotics. bioRxiv 2023:2023.02.17.528811. [PMID: 36824941 PMCID: PMC9949166 DOI: 10.1101/2023.02.17.528811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
The microbiome is increasingly receiving attention as an important modulator of host health and disease. However, while numerous mechanisms through which the microbiome influences its host have been identified, there is still a lack of approaches that allow to specifically modulate the abundance of individual microbes or microbial functions of interest. Moreover, current approaches for microbiome manipulation such as fecal transfers often entail a non-specific transfer of entire microbial communities with potentially unwanted side effects. To overcome this limitation, we here propose the concept of precision prebiotics that specifically modulate the abundance of a microbiome member species of interest. In a first step, we show that defining precision prebiotics by compounds that are only taken up by the target species but no other species in a community is usually not possible due to overlapping metabolic niches. Subsequently, we present a metabolic modeling network framework that allows us to define precision prebiotics for a two-member C. elegans microbiome model community comprising the immune-protective Pseudomonas lurida MYb11 and the persistent colonizer Ochrobactrum vermis MYb71. Thus, we predicted compounds that specifically boost the abundance of the host-beneficial MYb11, four of which were experimentally validated in vitro (L-serine, L-threonine, D-mannitol, and γ-aminobutyric acid). L-serine was further assessed in vivo, leading to an increase in MYb11 abundance also in the worm host. Overall, our findings demonstrate that constraint-based metabolic modeling is an effective tool for the design of precision prebiotics as an important cornerstone for future microbiome-targeted therapies.
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Affiliation(s)
- Georgios Marinos
- Research Group Medical Systems Biology, University Hospital Schleswig-Holstein Campus Kiel, Kiel University, Kiel, Schleswig-Holstein, Germany
| | - Inga K Hamerich
- Research Group Evolutionary Ecology and Genetics, Zoological Institute, Kiel University, Kiel, Schleswig-Holstein, Germany
| | - Reena Debray
- Department of Integrative Biology, University of California, Berkeley, California, USA
| | - Nancy Obeng
- Research Group Evolutionary Ecology and Genetics, Zoological Institute, Kiel University, Kiel, Schleswig-Holstein, Germany
| | - Carola Petersen
- Research Group Evolutionary Ecology and Genetics, Zoological Institute, Kiel University, Kiel, Schleswig-Holstein, Germany
| | - Jan Taubenheim
- Research Group Medical Systems Biology, University Hospital Schleswig-Holstein Campus Kiel, Kiel University, Kiel, Schleswig-Holstein, Germany
| | - Johannes Zimmermann
- Research Group Medical Systems Biology, University Hospital Schleswig-Holstein Campus Kiel, Kiel University, Kiel, Schleswig-Holstein, Germany
- Max-Planck Institute for Evolutionary Biology, Ploen, Schleswig-Holstein, Germany
| | - Dana Blackburn
- Alkek Center for Metagenomics and Microbiome Research, Baylor College of Medicine, Houston, Texas, USA
| | - Buck S Samuel
- Alkek Center for Metagenomics and Microbiome Research, Baylor College of Medicine, Houston, Texas, USA
| | - Katja Dierking
- Research Group Evolutionary Ecology and Genetics, Zoological Institute, Kiel University, Kiel, Schleswig-Holstein, Germany
| | - Andre Franke
- Institute of Clinical Molecular Biology, Kiel University, Kiel, Schleswig-Holstein, Germany
| | - Matthias Laudes
- Institute of Diabetes and Clinical Metabolic Research, University Hospital Schleswig-Holstein Campus Kiel, Kiel, Schleswig-Holstein, Germany
| | - Silvio Waschina
- Nutriinformatics, Institute for Human Nutrition and Food Science, Kiel University, Kiel, Schleswig-Holstein, Germany
| | - Hinrich Schulenburg
- Research Group Evolutionary Ecology and Genetics, Zoological Institute, Kiel University, Kiel, Schleswig-Holstein, Germany
- Max-Planck Institute for Evolutionary Biology, Ploen, Schleswig-Holstein, Germany
| | - Christoph Kaleta
- Research Group Medical Systems Biology, University Hospital Schleswig-Holstein Campus Kiel, Kiel University, Kiel, Schleswig-Holstein, Germany
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12
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Alker AT, Aspiras AE, Dunbar TL, Farrell MV, Fedoriouk A, Jones JE, Mikhail SR, Salcedo GY, Moore BS, Shikuma NJ. A modular plasmid toolkit applied in marine Proteobacteria reveals functional insights during bacteria-stimulated metamorphosis. bioRxiv 2023:2023.01.31.526474. [PMID: 36778221 PMCID: PMC9915575 DOI: 10.1101/2023.01.31.526474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A conspicuous roadblock to studying marine bacteria for fundamental research and biotechnology is a lack of modular synthetic biology tools for their genetic manipulation. Here, we applied, and generated new parts for, a modular plasmid toolkit to study marine bacteria in the context of symbioses and host-microbe interactions. To demonstrate the utility of this plasmid system, we genetically manipulated the marine bacterium Pseudoalteromonas luteoviolacea , which stimulates the metamorphosis of the model tubeworm, Hydroides elegans . Using these tools, we quantified constitutive and native promoter expression, developed reporter strains that enable the imaging of host-bacteria interactions, and used CRISPR interference (CRISPRi) to knock down a secondary metabolite and a host-associated gene. We demonstrate the broader utility of this modular system for rapidly creating and iteratively testing genetic tractability by modifying marine bacteria that are known to be associated with diverse host-microbe symbioses. These efforts enabled the successful transformation of twelve marine strains across two Proteobacteria classes, four orders and ten genera. Altogether, the present study demonstrates how synthetic biology strategies enable the investigation of marine microbes and marine host-microbe symbioses with broader implications for environmental restoration and biotechnology.
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13
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Banse AV, VanBeuge S, Smith TJ, Logan SL, Guillemin K. Secreted Aeromonas GlcNAc binding protein GbpA stimulates epithelial cell proliferation in the zebrafish intestine. Gut Microbes 2023; 15:2183686. [PMID: 36859771 PMCID: PMC9988336 DOI: 10.1080/19490976.2023.2183686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 12/19/2022] [Accepted: 02/16/2023] [Indexed: 03/03/2023] Open
Abstract
In response to microbiota colonization, the intestinal epithelia of many animals exhibit increased rates of cell proliferation. We used gnotobiotic larval zebrafish to identify a secreted factor from the mutualist Aeromonas veronii that is sufficient to promote intestinal epithelial cell proliferation. This secreted A. veronii protein is a homologue of the Vibrio cholerae GlcNAc binding protein GbpA, which was identified as a chitin-binding colonization factor in mice. GbpA was subsequently shown to be a lytic polysaccharide monooxygenase (LPMO) that can degrade recalcitrant chitin. Our phenotypic characterization of gbpA deficient A. veronii found no alterations in these cells' biogeography in the zebrafish intestine and only a modest competitive disadvantage in chitin-binding and colonization fitness when competed against the wild-type strain. These results argue against the model of GbpA being a secreted adhesin that binds simultaneously to bacterial cells and GlcNAc, and instead suggests that GbpA is part of a bacterial GlcNAc utilization program. We show that the host proliferative response to GbpA occurs in the absence of bacteria upon exposure of germ-free zebrafish to preparations of native GbpA secreted from either A. veronii or V. cholerae or recombinant A. veronii GbpA. Furthermore, domain 1 of A. veronii GbpA, containing the predicted LPMO activity, is sufficient to stimulate intestinal epithelial proliferation. We propose that intestinal epithelial tissues upregulate their rates of renewal in response to secreted bacterial GbpA proteins as an adaptive strategy for coexisting with bacteria that can degrade glycan constituents of the protective intestinal lining.
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Affiliation(s)
- Allison V. Banse
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - Stephanie VanBeuge
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - T. Jarrod Smith
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | | | - Karen Guillemin
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
- Humans and the Microbiome Program, Canadian Institute for Advanced Research, Toronto, Ontario, Canada
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14
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Xia H, Chen H, Cheng X, Yin M, Yao X, Ma J, Huang M, Chen G, Liu H. Zebrafish: an efficient vertebrate model for understanding role of gut microbiota. Mol Med 2022; 28:161. [PMID: 36564702 PMCID: PMC9789649 DOI: 10.1186/s10020-022-00579-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 11/21/2022] [Indexed: 12/24/2022] Open
Abstract
Gut microbiota plays a critical role in the maintenance of host health. As a low-cost and genetically tractable vertebrate model, zebrafish have been widely used for biological research. Zebrafish and humans share some similarities in intestinal physiology and function, and this allows zebrafish to be a surrogate model for investigating the crosstalk between the gut microbiota and host. Especially, zebrafish have features such as high fecundity, external fertilization, and early optical transparency. These enable the researchers to employ the fish to address questions not easily addressed in other animal models. In this review, we described the intestine structure of zebrafish. Also, we summarized the methods of generating a gnotobiotic zebrafish model, the factors affecting its intestinal flora, and the study progress of gut microbiota functions in zebrafish. Finally, we discussed the limitations and challenges of the zebrafish model for gut microbiota studies. In summary, this review established that zebrafish is an attractive research tool to understand mechanistic insights into host-microbe interaction.
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Affiliation(s)
- Hui Xia
- grid.257143.60000 0004 1772 1285College of Basic Medicine, Hubei University of Chinese Medicine, Huangjiahu West Road 16, Hongshan Disctrict, Wuhan, 430065 China
| | - Huimin Chen
- grid.257143.60000 0004 1772 1285College of Basic Medicine, Hubei University of Chinese Medicine, Huangjiahu West Road 16, Hongshan Disctrict, Wuhan, 430065 China
| | - Xue Cheng
- grid.257143.60000 0004 1772 1285College of Basic Medicine, Hubei University of Chinese Medicine, Huangjiahu West Road 16, Hongshan Disctrict, Wuhan, 430065 China
| | - Mingzhu Yin
- grid.257143.60000 0004 1772 1285College of Basic Medicine, Hubei University of Chinese Medicine, Huangjiahu West Road 16, Hongshan Disctrict, Wuhan, 430065 China
| | - Xiaowei Yao
- grid.257143.60000 0004 1772 1285College of Basic Medicine, Hubei University of Chinese Medicine, Huangjiahu West Road 16, Hongshan Disctrict, Wuhan, 430065 China
| | - Jun Ma
- grid.257143.60000 0004 1772 1285College of Basic Medicine, Hubei University of Chinese Medicine, Huangjiahu West Road 16, Hongshan Disctrict, Wuhan, 430065 China
| | - Mengzhen Huang
- grid.257143.60000 0004 1772 1285College of Basic Medicine, Hubei University of Chinese Medicine, Huangjiahu West Road 16, Hongshan Disctrict, Wuhan, 430065 China
| | - Gang Chen
- grid.477392.cHubei Provincial Hospital of Traditional Chinese Medicine, Wuhan, 430061 China
| | - Hongtao Liu
- grid.257143.60000 0004 1772 1285College of Basic Medicine, Hubei University of Chinese Medicine, Huangjiahu West Road 16, Hongshan Disctrict, Wuhan, 430065 China
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15
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Ulrich L, Giez C, Steiner LX, Hentschel U, Lachnit T. Adaptive lifestyle of bacteria determines phage-bacteria interaction. Front Microbiol 2022; 13:1056388. [PMID: 36560945 PMCID: PMC9763317 DOI: 10.3389/fmicb.2022.1056388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 11/08/2022] [Indexed: 12/12/2022] Open
Abstract
Bacteriophages and their interactions with microbes are not well understood. As a first step toward achieving a better understanding, we isolated and sequenced the Curvibacter phage PCA1 for the purpose of eliminating Curvibacter sp. AEP1.3, the main colonizer of Hydra vulgaris AEP. Our experiments showed that PCA1 phage caused a strong, virulent infection only in sessile Curvibacter sp. AEP1.3 but was unable to infect planktonic and host-associated bacterial cells of the same strain. In an effort to investigate this phenomenon, we compared sessile, planktonic, and host-associated bacteria via RNA sequencing and found that all three states differed significantly in their expression patterns. This finding led us to propose that the adaptive lifestyle of Curvibacter sp. AEP1.3 results in varying degrees of susceptibility to bacteriophage infection. This concept could be relevant for phage research and phage therapy in particular. Finally, we were able to induce phage infection in planktonic cells and pinpoint the infection process to a membrane protein. We further identified potential phage-binding protein candidates based on expression pattern analysis.
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Affiliation(s)
- Laura Ulrich
- Zoological Institute, Christian-Albrechts-Universität, Kiel, Germany
| | - Christoph Giez
- Zoological Institute, Christian-Albrechts-Universität, Kiel, Germany
| | - Leon X. Steiner
- RD3 Marine Ecology, RU Marine Symbioses, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Ute Hentschel
- RD3 Marine Ecology, RU Marine Symbioses, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Tim Lachnit
- Zoological Institute, Christian-Albrechts-Universität, Kiel, Germany,*Correspondence: Tim Lachnit,
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16
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Sundarraman D, Smith TJ, Kast JVZ, Guillemin K, Parthasarathy R. Disaggregation as an interaction mechanism among intestinal bacteria. Biophys J 2022; 121:3458-3473. [PMID: 35982615 PMCID: PMC9515126 DOI: 10.1016/j.bpj.2022.08.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 07/22/2022] [Accepted: 08/11/2022] [Indexed: 12/01/2022] Open
Abstract
The gut microbiome contains hundreds of interacting species that together influence host health and development. The mechanisms by which intestinal microbes can interact, however, remain poorly mapped and are often modeled as spatially unstructured competitions for chemical resources. Recent imaging studies examining the zebrafish gut have shown that patterns of aggregation are central to bacterial population dynamics. In this study, we focus on bacterial species of genera Aeromonas and Enterobacter. Two zebrafish gut-derived isolates, Aeromonas ZOR0001 (AE) and Enterobacter ZOR0014 (EN), when mono-associated with the host, are highly aggregated and located primarily in the intestinal midgut. An Aeromonas isolate derived from the commensal strain, Aeromonas-MB4 (AE-MB4), differs from the parental strain in that it is composed mostly of planktonic cells localized to the anterior gut. When challenged by AE-MB4, clusters of EN rapidly fragment into non-motile, slow-growing, dispersed individual cells with overall abundance two orders of magnitude lower than the mono-association value. In the presence of a certain set of additional gut bacterial species, these effects on EN are dampened. In particular, if AE-MB4 invades an already established multi-species community, EN persists in the form of large aggregates. These observations reveal an unanticipated competition mechanism based on manipulation of bacterial spatial organization, namely dissolution of aggregates, and provide evidence that multi-species communities may facilitate stable intestinal co-existence.
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Affiliation(s)
- Deepika Sundarraman
- Department of Physics and Materials Science Institute, University of Oregon, Eugene, Oregon
| | - T Jarrod Smith
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon
| | - Jade V Z Kast
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon
| | - Karen Guillemin
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon; Humans and the Microbiome Program, CIFAR, Toronto, Ontario
| | - Raghuveer Parthasarathy
- Department of Physics and Materials Science Institute, University of Oregon, Eugene, Oregon; Institute of Molecular Biology, University of Oregon, Eugene, Oregon.
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17
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Russell BJ, Brown SD, Siguenza N, Mai I, Saran AR, Lingaraju A, Maissy ES, Dantas Machado AC, Pinto AFM, Sanchez C, Rossitto LA, Miyamoto Y, Richter RA, Ho SB, Eckmann L, Hasty J, Gonzalez DJ, Saghatelian A, Knight R, Zarrinpar A. Intestinal transgene delivery with native E. coli chassis allows persistent physiological changes. Cell 2022; 185:3263-3277.e15. [PMID: 35931082 PMCID: PMC9464905 DOI: 10.1016/j.cell.2022.06.050] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 04/15/2022] [Accepted: 06/25/2022] [Indexed: 12/26/2022]
Abstract
Live bacterial therapeutics (LBTs) could reverse diseases by engrafting in the gut and providing persistent beneficial functions in the host. However, attempts to functionally manipulate the gut microbiome of conventionally raised (CR) hosts have been unsuccessful because engineered microbial organisms (i.e., chassis) have difficulty in colonizing the hostile luminal environment. In this proof-of-concept study, we use native bacteria as chassis for transgene delivery to impact CR host physiology. Native Escherichia coli bacteria isolated from the stool cultures of CR mice were modified to express functional genes. The reintroduction of these strains induces perpetual engraftment in the intestine. In addition, engineered native E. coli can induce functional changes that affect physiology of and reverse pathology in CR hosts months after administration. Thus, using native bacteria as chassis to “knock in” specific functions allows mechanistic studies of specific microbial activities in the microbiome of CR hosts and enables LBT with curative intent. Native E. coli strains isolated from mouse stool are genetically engineered for long-term engraftment in the conventional mouse gut and enable long-term systemic effects on the host, such as improvements in insulin sensitivity in mouse models of type 2 diabetes.
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Affiliation(s)
- Baylee J Russell
- Division of Gastroenterology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Steven D Brown
- Division of Gastroenterology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Nicole Siguenza
- Division of Gastroenterology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Irene Mai
- Division of Gastroenterology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Anand R Saran
- Division of Gastroenterology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Amulya Lingaraju
- Division of Gastroenterology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Erica S Maissy
- Division of Gastroenterology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Ana C Dantas Machado
- Division of Gastroenterology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Antonio F M Pinto
- Clayton Foundation Laboratories for Peptide Biology, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Concepcion Sanchez
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA; Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Leigh-Ana Rossitto
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA; Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Yukiko Miyamoto
- Division of Gastroenterology, University of California, San Diego, La Jolla, CA 92093, USA
| | - R Alexander Richter
- Division of Gastroenterology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Samuel B Ho
- Division of Gastroenterology, University of California, San Diego, La Jolla, CA 92093, USA; VA Health Sciences San Diego, La Jolla, CA 92161, USA
| | - Lars Eckmann
- Division of Gastroenterology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Jeff Hasty
- BioCircuits Institute, University of California, San Diego, La Jolla, CA 92093, USA; Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA; Center for Microbiome Innovation, University of California, San Diego, La Jolla, CA 92093, USA
| | - David J Gonzalez
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA; Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA 92093, USA; Center for Microbiome Innovation, University of California, San Diego, La Jolla, CA 92093, USA
| | - Alan Saghatelian
- Clayton Foundation Laboratories for Peptide Biology, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Rob Knight
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA; Department of Pediatrics, University of California, San Diego, La Jolla, CA 92093, USA; Center for Microbiome Innovation, University of California, San Diego, La Jolla, CA 92093, USA; Department of Computer Science and Engineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Amir Zarrinpar
- Division of Gastroenterology, University of California, San Diego, La Jolla, CA 92093, USA; VA Health Sciences San Diego, La Jolla, CA 92161, USA; Center for Microbiome Innovation, University of California, San Diego, La Jolla, CA 92093, USA.
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18
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Giarimoglou N, Kouvela A, Patsi I, Zhang J, Stamatopoulou V, Stathopoulos C. Lineage-specific insertions in T-box riboswitches modulate antibiotic binding and action. Nucleic Acids Res 2022; 50:5834-5849. [PMID: 35580054 PMCID: PMC9177973 DOI: 10.1093/nar/gkac359] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 04/21/2022] [Accepted: 05/11/2022] [Indexed: 01/27/2023] Open
Abstract
T-box riboswitches (T-boxes) are essential RNA regulatory elements with a remarkable structural diversity, especially among bacterial pathogens. In staphylococci, all glyS T-boxes synchronize glycine supply during synthesis of nascent polypeptides and cell wall formation and are characterized by a conserved and unique insertion in their antiterminator/terminator domain, termed stem Sa. Interestingly, in Staphylococcus aureus the stem Sa can accommodate binding of specific antibiotics, which in turn induce robust and diverse effects on T-box-mediated transcription. In the present study, domain swap mutagenesis and probing analysis were performed to decipher the role of stem Sa. Deletion of stem Sa significantly reduces both the S. aureus glyS T-box-mediated transcription readthrough levels and the ability to discriminate among tRNAGly isoacceptors, both in vitro and in vivo. Moreover, the deletion inverted the previously reported stimulatory effects of specific antibiotics. Interestingly, stem Sa insertion in the terminator/antiterminator domain of Geobacillus kaustophilus glyS T-box, which lacks this domain, resulted in elevated transcription in the presence of tigecycline and facilitated discrimination among proteinogenic and nonproteinogenic tRNAGly isoacceptors. Overall, stem Sa represents a lineage-specific structural feature required for efficient staphylococcal glyS T-box-mediated transcription and it could serve as a species-selective druggable target through its ability to modulate antibiotic binding.
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Affiliation(s)
- Nikoleta Giarimoglou
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
| | - Adamantia Kouvela
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
| | - Ioanna Patsi
- Department of Biochemistry, School of Medicine, University of Patras, 26504 Patras, Greece
| | - Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA
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19
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Palma V, Gutiérrez MS, Vargas O, Parthasarathy R, Navarrete P. Methods to Evaluate Bacterial Motility and Its Role in Bacterial–Host Interactions. Microorganisms 2022; 10:microorganisms10030563. [PMID: 35336138 PMCID: PMC8953368 DOI: 10.3390/microorganisms10030563] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 02/02/2022] [Accepted: 02/06/2022] [Indexed: 11/16/2022] Open
Abstract
Bacterial motility is a widespread characteristic that can provide several advantages for the cell, allowing it to move towards more favorable conditions and enabling host-associated processes such as colonization. There are different bacterial motility types, and their expression is highly regulated by the environmental conditions. Because of this, methods for studying motility under realistic experimental conditions are required. A wide variety of approaches have been developed to study bacterial motility. Here, we present the most common techniques and recent advances and discuss their strengths as well as their limitations. We classify them as macroscopic or microscopic and highlight the advantages of three-dimensional imaging in microscopic approaches. Lastly, we discuss methods suited for studying motility in bacterial–host interactions, including the use of the zebrafish model.
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Affiliation(s)
- Victoria Palma
- Laboratory of Microbiology and Probiotics, Institute of Nutrition and Food Technology (INTA), University of Chile, El Líbano 5524, Santiago 7830490, Chile; (V.P.); (M.S.G.); (O.V.)
| | - María Soledad Gutiérrez
- Laboratory of Microbiology and Probiotics, Institute of Nutrition and Food Technology (INTA), University of Chile, El Líbano 5524, Santiago 7830490, Chile; (V.P.); (M.S.G.); (O.V.)
- Millennium Science Initiative Program, Milenium Nucleus in the Biology of the Intestinal Microbiota, National Agency for Research and Development (ANID), Moneda 1375, Santiago 8200000, Chile
| | - Orlando Vargas
- Laboratory of Microbiology and Probiotics, Institute of Nutrition and Food Technology (INTA), University of Chile, El Líbano 5524, Santiago 7830490, Chile; (V.P.); (M.S.G.); (O.V.)
| | - Raghuveer Parthasarathy
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA;
- Department of Physics and Materials Science Institute, University of Oregon, Eugene, OR 97403, USA
| | - Paola Navarrete
- Laboratory of Microbiology and Probiotics, Institute of Nutrition and Food Technology (INTA), University of Chile, El Líbano 5524, Santiago 7830490, Chile; (V.P.); (M.S.G.); (O.V.)
- Millennium Science Initiative Program, Milenium Nucleus in the Biology of the Intestinal Microbiota, National Agency for Research and Development (ANID), Moneda 1375, Santiago 8200000, Chile
- Correspondence:
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20
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Kissoyan KAB, Peters L, Giez C, Michels J, Pees B, Hamerich IK, Schulenburg H, Dierking K. Exploring Effects of C. elegans Protective Natural Microbiota on Host Physiology. Front Cell Infect Microbiol 2022; 12:775728. [PMID: 35237530 PMCID: PMC8884406 DOI: 10.3389/fcimb.2022.775728] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 01/14/2022] [Indexed: 11/29/2022] Open
Abstract
The Caenorhabditis elegans natural microbiota was described only recently. Thus, our understanding of its effects on nematode physiology is still in its infancy. We previously showed that the C. elegans natural microbiota isolates Pseudomonas lurida MYb11 and P. fluorescens MYb115 protect the worm against pathogens such as Bacillus thuringiensis (Bt). However, the overall effects of the protective microbiota on worm physiology are incompletely understood. Here, we investigated how MYb11 and MYb115 affect C. elegans lifespan, fertility, and intestinal colonization. We further studied the capacity of MYb11 and MYb115 to protect the worm against purified Bt toxins. We show that while MYb115 and MYb11 affect reproductive timing and increase early reproduction only MYb11 reduces worm lifespan. Moreover, MYb11 aggravates killing upon toxin exposure. We conclude that MYb11 has a pathogenic potential in some contexts. This work thus highlights that certain C. elegans microbiota members can be beneficial and costly to the host in a context-dependent manner, blurring the line between good and bad.
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21
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Matsumoto A, Schlüter T, Melkonian K, Takeda A, Nakagami H, Mine A. A versatile Tn 7 transposon-based bioluminescence tagging tool for quantitative and spatial detection of bacteria in plants. Plant Commun 2022; 3:100227. [PMID: 35059625 PMCID: PMC8760037 DOI: 10.1016/j.xplc.2021.100227] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 06/24/2021] [Accepted: 07/19/2021] [Indexed: 06/14/2023]
Abstract
Investigation of plant-bacteria interactions requires quantification of in planta bacterial titers by means of cumbersome and time-consuming colony-counting assays. Here, we devised a broadly applicable tool for bioluminescence-based quantitative and spatial detection of bacteria in plants. We developed vectors that enable Tn7 transposon-mediated integration of the luxCDABE luciferase operon into a specific genomic location found ubiquitously across bacterial phyla. These vectors allowed for the generation of bioluminescent transformants of various plant pathogenic bacteria from the genera Pseudomonas, Rhizobium (Agrobacterium), and Ralstonia. Direct luminescence measurements of plant tissues inoculated with bioluminescent Pseudomonas syringae pv. tomato DC3000 (Pto-lux) reported bacterial titers as accurately as conventional colony-counting assays in Arabidopsis thaliana, Solanum lycopersicum, Nicotiana benthamiana, and Marchantia polymorpha. We further showed the usefulness of our vectors in converting previously generated Pto derivatives to isogenic bioluminescent strains. Importantly, quantitative bioluminescence assays using these Pto-lux strains accurately reported the effects of plant immunity and bacterial effectors on bacterial growth, with a dynamic range of four orders of magnitude. Moreover, macroscopic bioluminescence imaging illuminated the spatial patterns of Pto-lux growth in/on inoculated plant tissues. In conclusion, our vectors offer untapped opportunities to develop bioluminescence-based assays for a variety of plant-bacteria interactions.
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Affiliation(s)
- Ayumi Matsumoto
- Research Organization of Science and Technology, Ritsumeikan University, Shiga 525-8577, Japan
| | - Titus Schlüter
- Basic Immune System of Plants, Max Planck Institute for Plant Breeding Research, Cologne 50829, Germany
| | - Katharina Melkonian
- Basic Immune System of Plants, Max Planck Institute for Plant Breeding Research, Cologne 50829, Germany
| | - Atsushi Takeda
- College of Life Sciences, Ritsumeikan University, Shiga 525-8577, Japan
| | - Hirofumi Nakagami
- Basic Immune System of Plants, Max Planck Institute for Plant Breeding Research, Cologne 50829, Germany
| | - Akira Mine
- College of Life Sciences, Ritsumeikan University, Shiga 525-8577, Japan
- JST PRESTO, Kawaguchi-shi, Saitama 332-0012, Japan
- Laboratory of Plant Pathology, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
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22
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Abstract
The spatial organization of gut microbiota influences both microbial abundances and host-microbe interactions, but the underlying rules relating bacterial dynamics to large-scale structure remain unclear. To this end, we studied experimentally and theoretically the formation of three-dimensional bacterial clusters, a key parameter controlling susceptibility to intestinal transport and access to the epithelium. Inspired by models of structure formation in soft materials, we sought to understand how the distribution of gut bacterial cluster sizes emerges from bacterial-scale kinetics. Analyzing imaging-derived data on cluster sizes for eight different bacterial strains in the larval zebrafish gut, we find a common family of size distributions that decay approximately as power laws with exponents close to −2, becoming shallower for large clusters in a strain-dependent manner. We show that this type of distribution arises naturally from a Yule-Simons-type process in which bacteria grow within clusters and can escape from them, coupled to an aggregation process that tends to condense the system toward a single massive cluster, reminiscent of gel formation. Together, these results point to the existence of general, biophysical principles governing the spatial organization of the gut microbiome that may be useful for inferring fast-timescale dynamics that are experimentally inaccessible. The human gut is home to vast numbers of bacteria that grow, compete and cooperate in a dynamic, densely packed space. The spatial arrangement of organisms – for example, if they are clumped together or broadly dispersed – plays a major role in all ecosystems; but how bacteria are organized in the human gut remains mysterious and difficult to investigate. Zebrafish larvae provide a powerful tool for studying microbes in the gut, as they are optically transparent and anatomically similar to other vertebrates, including humans. Furthermore, zebrafish can be easily manipulated so that one species of bacteria can be studied at a time. To investigate whether individual bacterial species are arranged in similar ways, Scholmann and Parthasarathy exposed zebrafish with no gut bacteria to one of eight different strains. Each species was then monitored using three-dimensional microscopy to see how the population shaped itself into clusters (or colonies). Schlomann and Parthasarathy used this data to build a mathematical model that can predict the size of the clusters formed by different gut bacteria. This revealed that the spatial arrangement of each species depended on the same biological processes: bacterial growth, aggregation and fragmentation of clusters, and expulsion from the gut. These new details about how bacteria are organized in zebrafish may help scientists learn more about gut health in humans. Although it is not possible to peer into the human gut and watch how bacteria behave, scientists could use the same analysis method to study the size of bacterial colonies in fecal samples. This may provide further clues about how microbes are spatially arranged in the human gut and the biological processes underlying this formation.
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Affiliation(s)
- Brandon H Schlomann
- Department of Physics, Institute of Molecular Biology, and Materials Science Institute, University of Oregon, Eugene, United States.,Department of Physics and Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Raghuveer Parthasarathy
- Department of Physics, Institute of Molecular Biology, and Materials Science Institute, University of Oregon, Eugene, United States
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23
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Abstract
Animal hosts have initiated myriad symbiotic associations with microorganisms and often have maintained these symbioses for millions of years, spanning drastic changes in ecological conditions and lifestyles. The establishment and persistence of these relationships require genetic innovations on the parts of both symbionts and hosts. The nature of symbiont innovations depends on their genetic population structure, categorized here as open, closed or mixed. These categories reflect modes of inter-host transmission that result in distinct genomic features, or genomic syndromes, in symbionts. Although less studied, hosts also innovate in order to preserve and control symbiotic partnerships. New capabilities to sequence host-associated microbial communities and to experimentally manipulate both hosts and symbionts are providing unprecedented insights into how genetic innovations arise under different symbiont population structures and how these innovations function to support symbiotic relationships.
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Affiliation(s)
- Julie Perreau
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas, USA
| | - Nancy A Moran
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas, USA.
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24
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Robinson CD, Sweeney EG, Ngo J, Ma E, Perkins A, Smith TJ, Fernandez NL, Waters CM, Remington SJ, Bohannan BJM, Guillemin K. Host-emitted amino acid cues regulate bacterial chemokinesis to enhance colonization. Cell Host Microbe 2021; 29:1221-1234.e8. [PMID: 34233153 DOI: 10.1016/j.chom.2021.06.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 04/19/2021] [Accepted: 06/04/2021] [Indexed: 02/08/2023]
Abstract
Animal microbiomes are assembled predominantly from environmental microbes, yet the mechanisms by which individual symbionts regulate their transmission into hosts remain underexplored. By tracking the experimental evolution of Aeromonas veronii in gnotobiotic zebrafish, we identify bacterial traits promoting host colonization. Multiple independently evolved isolates with increased immigration harbored mutations in a gene we named sensor of proline diguanylate cyclase enzyme (SpdE) based on structural, biochemical, and phenotypic evidence that SpdE encodes an amino-acid-sensing diguanylate cyclase. SpdE detects free proline and to a lesser extent valine and isoleucine, resulting in reduced production of intracellular c-di-GMP, a second messenger controlling bacterial motility. Indeed, SpdE binding to amino acids increased bacterial motility and host colonization. Hosts serve as sources of SpdE-detected amino acids, with levels varying based on microbial colonization status. Our work demonstrates that bacteria use chemically regulated motility, or chemokinesis, to sense host-emitted cues that trigger active immigration into hosts.
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Affiliation(s)
| | - Emily G Sweeney
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - Julia Ngo
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - Emily Ma
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - Arden Perkins
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - T Jarrod Smith
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - Nicolas L Fernandez
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA
| | - Christopher M Waters
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA
| | | | | | - Karen Guillemin
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA; Humans and the Microbiome Program, CIFAR, Toronto, ON, Canada.
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25
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Lebov JF, Bohannan BJM. Msh Pilus Mutations Increase the Ability of a Free-Living Bacterium to Colonize a Piscine Host. Genes (Basel) 2021; 12:genes12020127. [PMID: 33498301 PMCID: PMC7909257 DOI: 10.3390/genes12020127] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 01/12/2021] [Accepted: 01/18/2021] [Indexed: 02/07/2023] Open
Abstract
Symbioses between animals and bacteria are ubiquitous. To better understand these relationships, it is essential to unravel how bacteria evolve to colonize hosts. Previously, we serially passaged the free-living bacterium, Shewanella oneidensis, through the digestive tracts of germ-free larval zebrafish (Danio rerio) to uncover the evolutionary changes involved in the initiation of a novel symbiosis with a vertebrate host. After 20 passages, we discovered an adaptive missense mutation in the mshL gene of the msh pilus operon, which improved host colonization, increased swimming motility, and reduced surface adhesion. In the present study, we determined that this mutation was a loss-of-function mutation and found that it improved zebrafish colonization by augmenting S. oneidensis representation in the water column outside larvae through a reduced association with environmental surfaces. Additionally, we found that strains containing the mshL mutation were able to immigrate into host digestive tracts at higher rates per capita. However, mutant and evolved strains exhibited no evidence of a competitive advantage after colonizing hosts. Our results demonstrate that bacterial behaviors outside the host can play a dominant role in facilitating the onset of novel host associations.
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Affiliation(s)
- Jarrett F. Lebov
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Department of Biology, Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403-5289, USA;
- Correspondence:
| | - Brendan J. M. Bohannan
- Department of Biology, Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403-5289, USA;
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26
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Morales Fénero C, Amaral MA, Xavier IK, Padovani BN, Paredes LC, Takiishi T, Lopes-Ferreira M, Lima C, Colombo A, Saraiva Câmara NO. Short chain fatty acids (SCFAs) improves TNBS-induced colitis in zebrafish. Current Research in Immunology 2021; 2:142-154. [PMID: 35492385 PMCID: PMC9040093 DOI: 10.1016/j.crimmu.2021.08.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 08/25/2021] [Accepted: 08/25/2021] [Indexed: 12/20/2022] Open
Affiliation(s)
- Camila Morales Fénero
- Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
- Corresponding author.
| | | | - Izabella Karina Xavier
- Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Barbara Nunes Padovani
- Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Lais Cavalieri Paredes
- Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Tatiana Takiishi
- ULB Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles, Brussels, Belgium
| | - Mônica Lopes-Ferreira
- Center of Toxins, Immune Response and Cellular Signalling (CeTICS), Instituto Butantan, São Paulo, Brazil
| | - Carla Lima
- Center of Toxins, Immune Response and Cellular Signalling (CeTICS), Instituto Butantan, São Paulo, Brazil
| | - Alicia Colombo
- Department of Pathologic Anatomy, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Niels Olsen Saraiva Câmara
- Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
- Department of Medicine, Nephrology Division, Federal University of São Paulo, Brazil
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27
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Aguirre de Cárcer D. Experimental and computational approaches to unravel microbial community assembly. Comput Struct Biotechnol J 2020; 18:4071-4081. [PMID: 33363703 PMCID: PMC7736701 DOI: 10.1016/j.csbj.2020.11.031] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 11/16/2020] [Accepted: 11/19/2020] [Indexed: 12/12/2022] Open
Abstract
Microbial communities have a preponderant role in the life support processes of our common home planet Earth. These extremely diverse communities drive global biogeochemical cycles, and develop intimate relationships with most multicellular organisms, with a significant impact on their fitness. Our understanding of their composition and function has enjoyed a significant thrust during the last decade thanks to the rise of high-throughput sequencing technologies. Intriguingly, the diversity patterns observed in nature point to the possible existence of fundamental community assembly rules. Unfortunately, these rules are still poorly understood, despite the fact that their knowledge could spur a scientific, technological, and economic revolution, impacting, for instance, agricultural, environmental, and health-related practices. In this minireview, I recapitulate the most important wet lab techniques and computational approaches currently employed in the study of microbial community assembly, and briefly discuss various experimental designs. Most of these approaches and considerations are also relevant to the study of microbial microevolution, as it has been shown that it can occur in ecological relevant timescales. Moreover, I provide a succinct review of various recent studies, chosen based on the diversity of ecological concepts addressed, experimental designs, and choice of wet lab and computational techniques. This piece aims to serve as a primer to those new to the field, as well as a source of new ideas to the more experienced researchers.
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28
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Sharma K, Palatinszky M, Nikolov G, Berry D, Shank EA. Transparent soil microcosms for live-cell imaging and non-destructive stable isotope probing of soil microorganisms. eLife 2020; 9:e56275. [PMID: 33140722 PMCID: PMC7609051 DOI: 10.7554/elife.56275] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Accepted: 10/16/2020] [Indexed: 01/02/2023] Open
Abstract
Microscale processes are critically important to soil ecology and biogeochemistry yet are difficult to study due to soil's opacity and complexity. To advance the study of soil processes, we constructed transparent soil microcosms that enable the visualization of microbes via fluorescence microscopy and the non-destructive measurement of microbial activity and carbon uptake in situ via Raman microspectroscopy. We assessed the polymer Nafion and the crystal cryolite as optically transparent soil substrates. We demonstrated that both substrates enable the growth, maintenance, and visualization of microbial cells in three dimensions over time, and are compatible with stable isotope probing using Raman. We applied this system to ascertain that after a dry-down/rewetting cycle, bacteria on and near dead fungal hyphae were more metabolically active than those far from hyphae. These data underscore the impact fungi have facilitating bacterial survival in fluctuating conditions and how these microcosms can yield insights into microscale microbial activities.
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Affiliation(s)
- Kriti Sharma
- Department of Biology, University of North CarolinaChapel HillUnited States
| | - Márton Palatinszky
- Department of Microbiology and Ecosystem Science, Centre for Microbiology and Environmental Systems Science, University of ViennaViennaAustria
| | - Georgi Nikolov
- Department of Microbiology and Ecosystem Science, Centre for Microbiology and Environmental Systems Science, University of ViennaViennaAustria
| | - David Berry
- Department of Microbiology and Ecosystem Science, Centre for Microbiology and Environmental Systems Science, University of ViennaViennaAustria
| | - Elizabeth A Shank
- Department of Biology, University of North CarolinaChapel HillUnited States
- Department of Microbiology and Immunology, University of North CarolinaChapel HillUnited States
- Program in Systems Biology, University of Massachusetts Medical SchoolWorcesterUnited States
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29
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Sundarraman D, Hay EA, Martins DM, Shields DS, Pettinari NL, Parthasarathy R. Higher-Order Interactions Dampen Pairwise Competition in the Zebrafish Gut Microbiome. mBio 2020; 11:e01667-20. [PMID: 33051365 PMCID: PMC7554667 DOI: 10.1128/mbio.01667-20] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 09/10/2020] [Indexed: 02/07/2023] Open
Abstract
The microbial communities resident in animal intestines are composed of multiple species that together play important roles in host development, health, and disease. Due to the complexity of these communities and the difficulty of characterizing them in situ, the determinants of microbial composition remain largely unknown. Further, it is unclear for many multispecies consortia whether their species-level makeup can be predicted based on an understanding of pairwise species interactions or whether higher-order interactions are needed to explain emergent compositions. To address this, we examine commensal intestinal microbes in larval zebrafish, initially raised germfree, to allow the introduction of controlled combinations of bacterial species. Using a dissection and plating assay, we demonstrate the construction of communities of one to five bacterial species and show that the outcomes from the two-species competitions fail to predict species abundances in more complex communities. With multiple species present, interbacterial interactions become weaker, suggesting that higher-order interactions in the vertebrate gut stabilize complex communities.IMPORTANCE Understanding the rules governing the composition of the diverse microbial communities that reside in the vertebrate gut environment will enhance our ability to manipulate such communities for therapeutic ends. Synthetic microbial communities, assembled from specific combinations of microbial species in germfree animals, allow investigation of the fundamental question of whether multispecies community composition can be predicted solely based on the combined effects of interactions between pairs of species. If so, such predictability would enable the construction of communities with desired species from the bottom up. If not, the apparent higher-order interactions imply that emergent community-level characteristics are crucial. Our findings using up to five coexisting native bacterial species in larval zebrafish, a model vertebrate, provide experimental evidence for higher-order interactions and, moreover, show that these interactions promote the coexistence of microbial species in the gut.
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Affiliation(s)
- Deepika Sundarraman
- Department of Physics, University of Oregon, Eugene, Oregon, USA
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
- Materials Science Institute, University of Oregon, Eugene, Oregon, USA
| | - Edouard A Hay
- Department of Physics, University of Oregon, Eugene, Oregon, USA
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
- Materials Science Institute, University of Oregon, Eugene, Oregon, USA
| | - Dylan M Martins
- Department of Physics, University of Oregon, Eugene, Oregon, USA
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
- Materials Science Institute, University of Oregon, Eugene, Oregon, USA
| | - Drew S Shields
- Department of Physics, University of Oregon, Eugene, Oregon, USA
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
- Materials Science Institute, University of Oregon, Eugene, Oregon, USA
| | - Noah L Pettinari
- Department of Physics, University of Oregon, Eugene, Oregon, USA
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
- Materials Science Institute, University of Oregon, Eugene, Oregon, USA
| | - Raghuveer Parthasarathy
- Department of Physics, University of Oregon, Eugene, Oregon, USA
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
- Materials Science Institute, University of Oregon, Eugene, Oregon, USA
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30
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Lebov JF, Schlomann BH, Robinson CD, Bohannan BJM. Phenotypic Parallelism during Experimental Adaptation of a Free-Living Bacterium to the Zebrafish Gut. mBio 2020; 11:e01519-20. [PMID: 32817106 DOI: 10.1128/mBio.01519-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Although animals encounter many bacterial species throughout their lives, only a subset colonize vertebrate digestive tracts, and these bacteria can profoundly influence the health and development of their animal hosts. We used experimental evolution to study a free-living bacterium as it adapts to a novel vertebrate host by serially passaging replicate populations of Shewanella oneidensis through the intestines of larval zebrafish (Danio rerio). Our results demonstrate that adaptation to the zebrafish gut is complex, with multiple evolutionary pathways capable of improving colonization, but that motility plays an important role during the onset of host association. Although animals encounter a plethora of bacterial species throughout their lives, only a subset colonize vertebrate digestive tracts, and these bacteria can profoundly influence the health and development of their animal hosts. However, our understanding of how bacteria initiate symbioses with animal hosts remains underexplored, and this process is central to the assembly and function of gut bacterial communities. Therefore, we used experimental evolution to study a free-living bacterium as it adapts to a novel vertebrate host by serially passaging replicate populations of Shewanella oneidensis through the intestines of larval zebrafish (Danio rerio). After approximately 200 bacterial generations, isolates from evolved populations improved their ability to colonize larval zebrafish during competition against their unpassaged ancestor. Genome sequencing revealed unique sets of mutations in the two evolved isolates exhibiting the highest mean competitive fitness. One isolate exhibited increased swimming motility and decreased biofilm formation compared to the ancestor, and we identified a missense mutation in the mannose-sensitive hemagglutinin pilus operon that is sufficient to increase fitness and reproduce these phenotypes. The second isolate exhibited enhanced swimming motility but unchanged biofilm formation, and here the genetic basis for adaptation is less clear. These parallel enhancements in motility and fitness resemble the behavior of a closely related Shewanella strain previously isolated from larval zebrafish and suggest phenotypic convergence with this isolate. Our results demonstrate that adaptation to the zebrafish gut is complex, with multiple evolutionary pathways capable of improving colonization, but that motility plays an important role during the onset of host association.
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31
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Yan Y, Nguyen LH, Franzosa EA, Huttenhower C. Strain-level epidemiology of microbial communities and the human microbiome. Genome Med 2020; 12:71. [PMID: 32791981 PMCID: PMC7427293 DOI: 10.1186/s13073-020-00765-y] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 07/14/2020] [Indexed: 02/07/2023] Open
Abstract
The biological importance and varied metabolic capabilities of specific microbial strains have long been established in the scientific community. Strains have, in the past, been largely defined and characterized based on microbial isolates. However, the emergence of new technologies and techniques has enabled assessments of their ecology and phenotypes within microbial communities and the human microbiome. While it is now more obvious how pathogenic strain variants are detrimental to human health, the consequences of subtle genetic variation in the microbiome have only recently been exposed. Here, we review the operational definitions of strains (e.g., genetic and structural variants) as they can now be identified from microbial communities using different high-throughput, often culture-independent techniques. We summarize the distribution and diversity of strains across the human body and their emerging links to health maintenance, disease risk and progression, and biochemical responses to perturbations, such as diet or drugs. We list methods for identifying, quantifying, and tracking strains, utilizing high-throughput sequencing along with other molecular and “culturomics” technologies. Finally, we discuss implications of population studies in bridging experimental gaps and leading to a better understanding of the health effects of strains in the human microbiome.
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Affiliation(s)
- Yan Yan
- Department of Biostatistics, Harvard T.H. Chan School of Public Health, 677 Huntington Ave, Boston, MA, 02115, USA.,Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Long H Nguyen
- Department of Biostatistics, Harvard T.H. Chan School of Public Health, 677 Huntington Ave, Boston, MA, 02115, USA.,Division of Gastroenterology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.,Clinical and Translational Epidemiology Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Eric A Franzosa
- Department of Biostatistics, Harvard T.H. Chan School of Public Health, 677 Huntington Ave, Boston, MA, 02115, USA.,Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Curtis Huttenhower
- Department of Biostatistics, Harvard T.H. Chan School of Public Health, 677 Huntington Ave, Boston, MA, 02115, USA. .,Broad Institute of MIT and Harvard, Cambridge, MA, USA.
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32
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Abstract
Zebrafish have a 50-year history as a model organism for studying vertebrate developmental biology and more recently have emerged as a powerful model system for studying vertebrate microbiome assembly, dynamics and function. In this Review, we discuss the strengths of the zebrafish model for both observational and manipulative microbiome studies, and we highlight some of the important insights gleaned from zebrafish gut microbiome research.
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Affiliation(s)
- Keaton Stagaman
- Department of Microbiology, Oregon State University, Corvallis, OR, USA
| | - Thomas J Sharpton
- Department of Microbiology, Oregon State University, Corvallis, OR, USA.,Department of Statistics, Oregon State University, Corvallis, OR, USA
| | - Karen Guillemin
- Institute of Molecular Biology, University of Oregon, Eugene, OR, USA. .,Humans and the Microbiome Program, CIFAR, Toronto, Ontario, Canada.
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33
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Wiles TJ, Schlomann BH, Wall ES, Betancourt R, Parthasarathy R, Guillemin K. Swimming motility of a gut bacterial symbiont promotes resistance to intestinal expulsion and enhances inflammation. PLoS Biol 2020; 18:e3000661. [PMID: 32196484 DOI: 10.1371/journal.pbio.3000661] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 04/01/2020] [Accepted: 02/24/2020] [Indexed: 01/07/2023] Open
Abstract
Some of the densest microbial ecosystems in nature thrive within the intestines of humans and other animals. To protect mucosal tissues and maintain immune tolerance, animal hosts actively sequester bacteria within the intestinal lumen. In response, numerous bacterial pathogens and pathobionts have evolved strategies to subvert spatial restrictions, thereby undermining immune homeostasis. However, in many cases, it is unclear how escaping host spatial control benefits gut bacteria and how changes in intestinal biogeography are connected to inflammation. A better understanding of these processes could uncover new targets for treating microbiome-mediated inflammatory diseases. To this end, we investigated the spatial organization and dynamics of bacterial populations within the intestine using larval zebrafish and live imaging. We discovered that a proinflammatory Vibrio symbiont native to zebrafish governs its own spatial organization using swimming motility and chemotaxis. Surprisingly, we found that Vibrio’s motile behavior does not enhance its growth rate but rather promotes its persistence by enabling it to counter intestinal flow. In contrast, Vibrio mutants lacking motility traits surrender to host spatial control, becoming aggregated and entrapped within the lumen. Consequently, nonmotile and nonchemotactic mutants are susceptible to intestinal expulsion and experience large fluctuations in absolute abundance. Further, we found that motile Vibrio cells induce expression of the proinflammatory cytokine tumor necrosis factor alpha (TNFα) in gut-associated macrophages and the liver. Using inducible genetic switches, we demonstrate that swimming motility can be manipulated in situ to modulate the spatial organization, persistence, and inflammatory activity of gut bacterial populations. Together, our findings suggest that host spatial control over resident microbiota plays a broader role in regulating the abundance and persistence of gut bacteria than simply protecting mucosal tissues. Moreover, we show that intestinal flow and bacterial motility are potential targets for therapeutically managing bacterial spatial organization and inflammatory activity within the gut. The use of live imaging and bacteria engineered to carry inducible genetic switches reveals how a gut symbiont uses swimming motility to escape the host's spatial control and persist within the physically dynamic confines of the intestine.
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Schlomann BH, Wiles TJ, Wall ES, Guillemin K, Parthasarathy R. Sublethal antibiotics collapse gut bacterial populations by enhancing aggregation and expulsion. Proc Natl Acad Sci U S A 2019; 116:21392-21400. [PMID: 31591228 PMCID: PMC6815146 DOI: 10.1073/pnas.1907567116] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Antibiotics induce large and highly variable changes in the intestinal microbiome even at sublethal concentrations, through mechanisms that remain elusive. Using gnotobiotic zebrafish, which allow high-resolution examination of microbial dynamics, we found that sublethal doses of the common antibiotic ciprofloxacin cause severe drops in bacterial abundance. Contrary to conventional views of antimicrobial tolerance, disruption was more pronounced for slow-growing, aggregated bacteria than for fast-growing, planktonic species. Live imaging revealed that antibiotic treatment promoted bacterial aggregation and increased susceptibility to intestinal expulsion. Intestinal mechanics therefore amplify the effects of antibiotics on resident bacteria. Microbial dynamics are captured by a biophysical model that connects antibiotic-induced collapses to gelation phase transitions in soft materials, providing a framework for predicting the impact of antibiotics on the intestinal microbiome.
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Affiliation(s)
- Brandon H Schlomann
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403
- Department of Physics, University of Oregon, Eugene, OR 97403
- Materials Science Institute, University of Oregon, Eugene, OR 97403
| | - Travis J Wiles
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403
| | - Elena S Wall
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403
| | - Karen Guillemin
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403
- Humans and the Microbiome Program, CIFAR, Toronto, ON M5G 1Z8, Canada
| | - Raghuveer Parthasarathy
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403;
- Department of Physics, University of Oregon, Eugene, OR 97403
- Materials Science Institute, University of Oregon, Eugene, OR 97403
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Cosetta CM, Wolfe BE. Causes and consequences of biotic interactions within microbiomes. Curr Opin Microbiol 2019; 50:35-41. [PMID: 31627129 DOI: 10.1016/j.mib.2019.09.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2019] [Revised: 08/20/2019] [Accepted: 09/06/2019] [Indexed: 10/25/2022]
Abstract
An integrative pattern-process-mechanism approach is revealing the roles of biotic interactions in microbiome assembly. Patterns of microbiome diversity observed in metagenomic studies can be partly explained by interaction processes (e.g. competition, facilitation) and underlying molecular or genetic mechanisms (e.g. antibiotic production, nutrient cross-feeding). Exciting opportunities remain to fully understand the significance and generalizability of biotic interactions within microbiomes. Many microbial interactions have been studied by chasing easily quantifiable phenotypes including changes in growth or pigmentation, but it is likely that diverse cryptic interactions occur without obvious growth changes or macroscopic phenotypes. A narrow phylogenetic breadth of well-studied microbes limits our understanding of whether there are conserved genetic or molecular mechanisms of microbial interactions. Biotic interactions can impose strong selective pressures that could shape rates and modes of microbial evolution, but few studies have examined the evolutionary consequences of interactions within microbiomes. Continued exploration of the chemical and genetic mechanisms underlying biotic interactions may provide novel tools to manipulate and manage microbiomes.
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Affiliation(s)
- Casey M Cosetta
- Tufts University, Department of Biology, Medford, MA 02155, United States
| | - Benjamin E Wolfe
- Tufts University, Department of Biology, Medford, MA 02155, United States.
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Whitfill T, Oh J. Recoding the metagenome: microbiome engineering in situ. Curr Opin Microbiol 2019; 50:28-34. [PMID: 31622928 DOI: 10.1016/j.mib.2019.09.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 08/19/2019] [Accepted: 09/06/2019] [Indexed: 12/24/2022]
Abstract
Synthetic biology has enabled a new generation of tools for engineering the microbiome, including targeted antibiotics, protein delivery, living biosensors and diagnostics, and metabolic factories. Here, we discuss opportunities and limitations in microbiome engineering, focusing on a new generation of tools for in situ genetic modification of a microbiome that hold particular promise in circumventing these limitations.
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Affiliation(s)
- Travis Whitfill
- Azitra, Inc., 400 Farmington Ave, Farmington, CT 06032, United States
| | - Julia Oh
- The Jackson Laboratory, 10 Discovery Drive, Farmington, CT 06032, United States.
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Martínez-garcía E, de Lorenzo V. Pseudomonas putida in the quest of programmable chemistry. Curr Opin Biotechnol 2019; 59:111-21. [DOI: 10.1016/j.copbio.2019.03.012] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [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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Watts KJ, Vaknin A, Fuqua C, Kazmierczak BI. New Twists and Turns in Bacterial Locomotion and Signal Transduction. J Bacteriol 2019; 201:e00439-19. [PMID: 31358610 DOI: 10.1128/JB.00439-19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Prokaryotic organisms occupy the most diverse set of environments and conditions on our planet. Their ability to sense and respond to a broad range of external cues remain key research areas in modern microbiology, central to behaviors that underlie beneficial and pathogenic interactions of bacteria with multicellular organisms and within complex ecosystems. Advances in our understanding of the one- and two-component signal transduction systems that underlie these sensing pathways have been driven by advances in imaging the behavior of many individual bacterial cells, as well as visualizing individual proteins and protein arrays within living cells. Cryo-electron tomography continues to provide new insights into the structure and function of chemosensory receptors and flagellar motors, while advances in protein labeling and tracking are applied to understand information flow between receptor and motor. Sophisticated microfluidics allow simultaneous analysis of the behavior of thousands of individual cells, increasing our understanding of how variance between individuals is generated, regulated and employed to maximize fitness of a population. In vitro experiments have been complemented by the study of signal transduction and motility in complex in vivo models, allowing investigators to directly address the contribution of motility, chemotaxis and aggregation/adhesion on virulence during infection. Finally, systems biology approaches have demonstrated previously uncharted areas of protein space in which novel two-component signal transduction pathways can be designed and constructed de novo These exciting experimental advances were just some of the many novel findings presented at the 15th Bacterial Locomotion and Signal Transduction conference (BLAST XV) in January 2019.
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Tan F, Limbu SM, Qian Y, Qiao F, Du ZY, Zhang M. The Responses of Germ-Free Zebrafish ( Danio rerio) to Varying Bacterial Concentrations, Colonization Time Points, and Exposure Duration. Front Microbiol 2019; 10:2156. [PMID: 31620110 PMCID: PMC6760068 DOI: 10.3389/fmicb.2019.02156] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 09/02/2019] [Indexed: 01/14/2023] Open
Abstract
Colonizing germ-free (GF) zebrafish with specific bacterial species provides the possibility of understanding the influence on host biological processes including gene expression, development, immunity, and behavioral responses. It also enlightens our understanding on the host-microbe interactions within the physiological context of a living host. However, the responses of GF zebrafish to various colonization conditions such as bacterial concentrations, colonization time points, and exposure duration remain unclear. To address this issue, we explored the responses of GF zebrafish by using two bacterial species at varying concentrations, colonization time points and exposure duration. Therefore, we mono-associated GF zebrafish with Escherichia coli DH5α or Bacillus subtilis WB800N at concentrations ranging from 102 to 107 CFU/ml either at 3 day post fertilization (dpf) or 5 dpf for 24 or 48 h. We evaluated the responses of GF zebrafish by analyzing the survival rate, colonization efficiency, nutrients metabolism, intestinal cell proliferation, innate immunity, stress, and behavior responses by comparing it to conventionally raised zebrafish (CONR) and GF zebrafish. The results indicated that the final bacteria concentrations ranging from 102 to 104 CFU/ml did not cause any mortality when GF mono-associated larvae were exposed to either E. coli DH5α or B. subtilis WB800N at 3 or 5 dpf, while concentrations ranging from 106 to 107 CFU/ml increased the mortality, particularly for 5 dpf owing to the decrease in dissolved oxygen level. The E. coli DH5α mainly induced the expression of genes related to nutrients metabolism, cell proliferation and immunity, while B. subtilis WB800N mainly upregulated the expression of genes related to immunity and stress responses. Moreover, our data revealed that GF zebrafish showed higher levels of physical activity than CONR and the microbial colonization reduced the hyperactivity of GF zebrafish, suggesting colonization of bacteria affected behavior characteristics. This study provides useful information on bacterial colonization of GF zebrafish and the interaction between the host and microbiota.
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Affiliation(s)
- Fang Tan
- Laboratory of Aquaculture Nutrition and Environmental Health, School of Life Sciences, East China Normal University, Shanghai, China
| | - Samwel Mchele Limbu
- Laboratory of Aquaculture Nutrition and Environmental Health, School of Life Sciences, East China Normal University, Shanghai, China.,Department of Aquatic Sciences and Fisheries Technology, University of Dar es Salaam, Dar es Salaam, Tanzania
| | - Ye Qian
- Laboratory of Aquaculture Nutrition and Environmental Health, School of Life Sciences, East China Normal University, Shanghai, China
| | - Fang Qiao
- Laboratory of Aquaculture Nutrition and Environmental Health, School of Life Sciences, East China Normal University, Shanghai, China
| | - Zhen-Yu Du
- Laboratory of Aquaculture Nutrition and Environmental Health, School of Life Sciences, East China Normal University, Shanghai, China
| | - Meiling Zhang
- Laboratory of Aquaculture Nutrition and Environmental Health, School of Life Sciences, East China Normal University, Shanghai, China
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Robinson CD, Bohannan BJ, Britton RA. Scales of persistence: transmission and the microbiome. Curr Opin Microbiol 2019; 50:42-49. [PMID: 31629296 PMCID: PMC6899178 DOI: 10.1016/j.mib.2019.09.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 09/19/2019] [Accepted: 09/23/2019] [Indexed: 01/13/2023]
Abstract
Historically microbiomes have been studied on the scale of the individual host, giving little consideration for the role of extra-host microbial populations in microbiome assembly. However, work in recent years has brought to light the importance of inter-host transmission and its influence on microbiome composition and dynamics. We now appreciate that microbiomes do not exist in isolation, but exchange constituents with the microbial communities of other hosts and the environment. Moving forward, fully understanding the role of transmission in microbiome assembly and dynamics will require a high-resolution view of the colonization and persistence patterns of particular microbial lineages (i.e. strains) across individuals and the environment. Yet, accomplishing this level of resolution will be an immense challenge, requiring improved sampling and bioinformatics approaches as well as employment of tractable experimental models. Insight gained from these investigations will contribute to our understanding of microbiome composition and variation, and lead to improved strategies for modulating microbiomes to improve human health.
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Affiliation(s)
| | | | - Robert A Britton
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA
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Lazarus JE, Warr AR, Kuehl CJ, Giorgio RT, Davis BM, Waldor MK. A New Suite of Allelic-Exchange Vectors for the Scarless Modification of Proteobacterial Genomes. Appl Environ Microbiol 2019; 85:e00990-19. [PMID: 31201277 DOI: 10.1128/AEM.00990-19] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 06/06/2019] [Indexed: 01/05/2023] Open
Abstract
Despite the advent of new techniques for genetic engineering of bacteria, allelic exchange through homologous recombination remains an important tool for genetic analysis. Currently, sacB-based vector systems are often used for allelic exchange, but counterselection escape, which prevents isolation of cells with the desired mutation, occasionally limits their utility. To circumvent this, we engineered a series of "pTOX" allelic-exchange vectors. Each plasmid encodes one of a set of inducible toxins, chosen for their potential utility in a wide range of medically important proteobacteria. A codon-optimized rhaS transcriptional activator with a strong synthetic ribosome-binding site enables tight toxin induction even in organisms lacking an endogenous rhamnose regulon. Expression of the gene encoding blue AmilCP or magenta TsPurple nonfluorescent chromoprotein facilitates monitoring of successful single- and double-crossover events using these vectors. The versatility of these vectors was demonstrated by deleting genes in Serratia marcescens, Escherichia coli O157:H7, Enterobacter cloacae, and Shigella flexneri Finally, pTOX was used to characterize the impact of disruption of all combinations of the 3 paralogous S. marcescens peptidoglycan amidohydrolases on chromosomal ampC β-lactamase activity and the corresponding β-lactam antibiotic resistance. Mutation of multiple amidohydrolases was necessary for high-level ampC derepression and β-lactam resistance. These data suggest why β-lactam resistance may emerge during treatment less frequently in S. marcescens than in other AmpC-producing pathogens, like E. cloacae Collectively, our findings suggest that the pTOX vectors should be broadly useful for genetic engineering of Gram-negative bacteria.IMPORTANCE Targeted modification of bacterial genomes is critical for genetic analysis of microorganisms. Allelic exchange is a technique that relies on homologous recombination to replace native loci with engineered sequences. However, current allelic-exchange vectors often enable only weak selection for successful homologous recombination. We developed a suite of new allelic-exchange vectors, pTOX, which were validated in several medically important proteobacteria. They encode visible nonfluorescent chromoproteins that enable easy identification of colonies bearing integrated vectors and permit stringent selection for the second step of homologous recombination. We demonstrate the utility of these vectors by using them to investigate the effect of inactivation of Serratia marcescens peptidoglycan amidohydrolases on β-lactam antibiotic resistance.
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Abstract
Vast communities of microorganisms inhabit the gastrointestinal tracts of humans and other animals. Understanding their initial development, fluctuations in composition, stability over long times, and responses to transient perturbations - in other words their dynamics - is important both for gaining basic insights into these ecosystems and for rationally manipulating them for therapeutic ends. Gut microbiome dynamics, however, remain poorly understood. We review here studies of gut microbiome dynamics in the presence and absence of external perturbations, noting especially the long timescales associated with overall stability and the short timescales associated with various underlying biological processes. Integrating these disparate timescales, we suggest, is an important goal for future work and is necessary for developing a predictive understanding of microbiome dynamics.
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Affiliation(s)
- Brandon H Schlomann
- Department of Physics, Materials Science Institute, and Institute of Molecular Biology, University of Oregon, Eugene, OR, United States
| | - Raghuveer Parthasarathy
- Department of Physics, Materials Science Institute, and Institute of Molecular Biology, University of Oregon, Eugene, OR, United States.
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Wiles TJ, Guillemin K. The Other Side of the Coin: What Beneficial Microbes Can Teach Us about Pathogenic Potential. J Mol Biol 2019; 431:2946-2956. [PMID: 31078557 DOI: 10.1016/j.jmb.2019.05.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 04/19/2019] [Accepted: 05/01/2019] [Indexed: 02/07/2023]
Abstract
Koch's postulates and molecular Koch's postulates have made an indelible mark on how we study and classify microbes, particularly pathogens. However, rigid adherence to these historic postulates constrains our view of not only microbial pathogenesis but also host-microbe relationships in general. Collectively, the postulates imply that a "microbial pathogen" is a clearly identifiable organism with the exclusive capacity to elicit disease through an arsenal of pathogen-specific "virulence factors." This narrow definition has been repeatedly contradicted. Advances in DNA sequencing technologies and new experimental systems have revealed that the outcomes of host-microbe interactions are highly contextual and dynamic, especially those involving resident microbiota and variable aspects of host biology. Clarifying what differentiates pathogenic from non-pathogenic microbes, including their paradoxical ability to masquerade as one another, is critical to developing targeted diagnostics and treatments for infectious disease. Such endeavors will also inform the design of therapeutic strategies based on microbiome engineering by providing insights into how manipulating entire host-microbe systems may directly or indirectly alter the pathogenic potential of microbial communities. With these goals in mind, we discuss the need to develop experimental models that better capture the contexts that determine the nature of host-microbe relationships. To demonstrate the potential of one such model-the zebrafish and its resident microbiota-we describe recent work that has revealed the thin line between pathogenic and mutualistic relationships, how the intestine physically shapes bacterial populations and inflammation, and the ability of microbial transmission to override the host's innate immune system.
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Affiliation(s)
- Travis J Wiles
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA.
| | - Karen Guillemin
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA; Humans and the Microbiome Program, CIFAR, Toronto, Ontario, Canada.
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Abstract
Understanding how microbes adapt to their host is an enduring problem in microbiome ecology, and understanding the microbial traits that allow colonization of the host and increase adaptation to the host environment is of particular interest. In this study, Robinson and colleagues use experimental evolution to demonstrate adaptation of a commensal bacterium to its zebrafish host and describe the changes in phenotype that emerge during this evolutionary process. These results provide insight into the evolutionary problem of host adaptation and demonstrate the utility of simple models for understanding host–microbiome dynamics.
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Affiliation(s)
- Nicole M. Vega
- Department of Biology, Emory University, Atlanta, Georgia, United States of America
- * E-mail:
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Mandel MJ, Broderick NA, Martens EC, Guillemin K. Reports from a Healthy Community: The 7th Conference on Beneficial Microbes. Appl Environ Microbiol 2018; 85:AEM.02562-18. [PMID: 30578257 PMCID: PMC6498156 DOI: 10.1128/aem.02562-18] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The last two decades have seen an explosion in research about the beneficial microbial communities associated with plants and animals. Initially this explosion was driven by technological advances that enabled explorations of microbiomes on unprecedented scales. Increasingly, the drive is coming from conceptual advances that are the fruit of research investments into experimental systems to probe the functions of these beneficial microbes and their mechanisms of action. The Conference on Beneficial Microbes has been one of the premiere venues for this research. The 7th Conference on Beneficial Microbes was held July 8-11, 2018, at the University of Wisconsin-Madison Memorial Union. The 308 attendees-representing academia, industry, journals, and funding agencies-participated in an intense 4-day meeting encompassing research frontiers in beneficial microbiology and microbiome science.
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Affiliation(s)
- Mark J Mandel
- University of Wisconsin-Madison, Department of Medical Microbiology & Immunology, Madison, WI 53706
| | - Nichole A Broderick
- University of Connecticut, Department of Molecular and Cell Biology and the Institute for Systems Genomics, Storrs, CT 06268
| | - Eric C Martens
- University of Michigan Medical School, Department of Microbiology & Immunology, Ann Arbor, MI 48109
| | - Karen Guillemin
- University of Oregon, Institute of Molecular Biology, Eugene, OR 97403
- Humans and the Microbiome Program, Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z8, Canada
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Hay EA, Parthasarathy R. Performance of convolutional neural networks for identification of bacteria in 3D microscopy datasets. PLoS Comput Biol 2018; 14:e1006628. [PMID: 30507940 PMCID: PMC6292638 DOI: 10.1371/journal.pcbi.1006628] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 12/13/2018] [Accepted: 11/07/2018] [Indexed: 12/23/2022] Open
Abstract
Three-dimensional microscopy is increasingly prevalent in biology due to the development of techniques such as multiphoton, spinning disk confocal, and light sheet fluorescence microscopies. These methods enable unprecedented studies of life at the microscale, but bring with them larger and more complex datasets. New image processing techniques are therefore called for to analyze the resulting images in an accurate and efficient manner. Convolutional neural networks are becoming the standard for classification of objects within images due to their accuracy and generalizability compared to traditional techniques. Their application to data derived from 3D imaging, however, is relatively new and has mostly been in areas of magnetic resonance imaging and computer tomography. It remains unclear, for images of discrete cells in variable backgrounds as are commonly encountered in fluorescence microscopy, whether convolutional neural networks provide sufficient performance to warrant their adoption, especially given the challenges of human comprehension of their classification criteria and their requirements of large training datasets. We therefore applied a 3D convolutional neural network to distinguish bacteria and non-bacterial objects in 3D light sheet fluorescence microscopy images of larval zebrafish intestines. We find that the neural network is as accurate as human experts, outperforms random forest and support vector machine classifiers, and generalizes well to a different bacterial species through the use of transfer learning. We also discuss network design considerations, and describe the dependence of accuracy on dataset size and data augmentation. We provide source code, labeled data, and descriptions of our analysis pipeline to facilitate adoption of convolutional neural network analysis for three-dimensional microscopy data.
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Affiliation(s)
- Edouard A. Hay
- Department of Physics, Institute of Molecular Biology, Materials Science Institute, University of Oregon, Eugene, Oregon, United States of America
| | - Raghuveer Parthasarathy
- Department of Physics, Institute of Molecular Biology, Materials Science Institute, University of Oregon, Eugene, Oregon, United States of America
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Robinson CD, Klein HS, Murphy KD, Parthasarathy R, Guillemin K, Bohannan BJM. Experimental bacterial adaptation to the zebrafish gut reveals a primary role for immigration. PLoS Biol 2018; 16:e2006893. [PMID: 30532251 PMCID: PMC6301714 DOI: 10.1371/journal.pbio.2006893] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 12/20/2018] [Accepted: 11/21/2018] [Indexed: 02/07/2023] Open
Abstract
All animals live in intimate association with microorganisms that profoundly influence their health and development, yet the traits that allow microorganisms to establish and maintain host associations are not well understood. To date, most investigations aimed at identifying traits required for host association have focused on intrahost niches. Consequently, little is known about the relative contribution of extrahost factors such as environmental growth and survival and immigration into hosts from the external environment, as promoters of host association. To address this, we developed a tractable experimental evolution system that investigates both intra- and extrahost factors contributing to bacterial adaptation to the vertebrate gut. We passaged replicate lines of a zebrafish bacterial isolate, Aeromonas veronii, through populations of germ-free larval zebrafish (Danio rerio), each time using gut-associated Aeromonas populations to inoculate the aquatic environment of the next zebrafish population. We observed rapid increased adaptation to the host in all replicate lines. The initial adaptations present in early-evolved isolates did not increase intrahost fitness but rather enhanced both immigration from the environment and interhost transmission. Only in later-evolved isolates did we find evidence for intrahost-specific adaptations, as demonstrated by comparing their competitive fitness in the host genotype to which they evolved to that in a different genotype. Our results show how selection for bacterial transmission between hosts and their environment can shape bacterial-host association. This work illuminates the nature of selective forces present in host-microbe systems and reveals specific mechanisms of increased host association. Furthermore, our findings demonstrate that the entire host-microbe-environment system must be considered when identifying microbial traits that contribute to host adaptation.
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Affiliation(s)
- Catherine D. Robinson
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, United States of America
| | - Helena S. Klein
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, United States of America
| | - Kyleah D. Murphy
- Department of Physics and Materials Science Institute, University of Oregon, Eugene, Oregon, United States of America
| | - Raghuveer Parthasarathy
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, United States of America
- Department of Physics and Materials Science Institute, University of Oregon, Eugene, Oregon, United States of America
| | - Karen Guillemin
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, United States of America
- Humans and the Microbiome Program, Canadian Institute for Advanced Research, Toronto, Ontario, Canada
| | - Brendan J. M. Bohannan
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon, United States of America
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48
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Rolig AS, Sweeney EG, Kaye LE, DeSantis MD, Perkins A, Banse AV, Hamilton MK, Guillemin K. A bacterial immunomodulatory protein with lipocalin-like domains facilitates host-bacteria mutualism in larval zebrafish. eLife 2018; 7:37172. [PMID: 30398151 PMCID: PMC6219842 DOI: 10.7554/elife.37172] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Accepted: 10/04/2018] [Indexed: 02/06/2023] Open
Abstract
Stable mutualism between a host and its resident bacteria requires a moderated immune response to control bacterial population size without eliciting excessive inflammation that could harm both partners. Little is known about the specific molecular mechanisms utilized by bacterial mutualists to temper their hosts' responses and protect themselves from aggressive immune attack. Using a gnotobiotic larval zebrafish model, we identified an Aeromonas secreted immunomodulatory protein, AimA. AimA is required during colonization to prevent intestinal inflammation that simultaneously compromises both bacterial and host survival. Administration of exogenous AimA prevents excessive intestinal neutrophil accumulation and protects against septic shock in models of both bacterially and chemically induced intestinal inflammation. We determined the molecular structure of AimA, which revealed two related calycin-like domains with structural similarity to the mammalian immune modulatory protein, lipocalin-2. As a secreted bacterial protein required by both partners for optimal fitness, AimA is an exemplar bacterial mutualism factor.
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Affiliation(s)
- Annah S Rolig
- Institute of Molecular Biology, University of Oregon, Eugene, United States
| | | | - Lila E Kaye
- Institute of Molecular Biology, University of Oregon, Eugene, United States
| | - Michael D DeSantis
- Institute of Molecular Biology, University of Oregon, Eugene, United States
| | - Arden Perkins
- Institute of Molecular Biology, University of Oregon, Eugene, United States
| | - Allison V Banse
- Institute of Molecular Biology, University of Oregon, Eugene, United States
| | | | - Karen Guillemin
- Institute of Molecular Biology, University of Oregon, Eugene, United States.,Humans and the Microbiome Program, Canadian Institute for Advanced Research, Toronto, Canada
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Schlomann BH, Wiles TJ, Wall ES, Guillemin K, Parthasarathy R. Bacterial Cohesion Predicts Spatial Distribution in the Larval Zebrafish Intestine. Biophys J 2018; 115:2271-7. [PMID: 30448038 DOI: 10.1016/j.bpj.2018.10.017] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 10/12/2018] [Accepted: 10/22/2018] [Indexed: 02/06/2023] Open
Abstract
Are there general biophysical relationships governing the spatial organization of the gut microbiome? Despite growing realization that spatial structure is important for population stability, interbacterial competition, and host functions, it is unclear in any animal gut whether such structure is subject to predictive, unifying rules or if it results from contextual, species-specific behaviors. To explore this, we used light sheet fluorescence microscopy to conduct a high-resolution comparative study of bacterial distribution patterns throughout the entire intestinal volume of live, larval zebrafish. Fluorescently tagged strains of seven bacterial symbionts, representing six different species native to zebrafish, were each separately monoassociated with animals that had been raised initially germ-free. The strains showed large differences in both cohesion-the degree to which they auto-aggregate-and spatial distribution. We uncovered a striking correlation between each strain's mean position and its cohesion, whether quantified as the fraction of cells existing as planktonic individuals, the average aggregate size, or the total number of aggregates. Moreover, these correlations held within species as well; aggregates of different sizes localized as predicted from the pan-species observations. Together, our findings indicate that bacteria within the zebrafish intestine are subject to generic processes that organize populations by their cohesive properties. The likely drivers of this relationship-peristaltic fluid flow, tubular anatomy, and bacterial growth and aggregation kinetics-are common throughout animals. We therefore suggest that the framework introduced here of biophysical links between bacterial cohesion and spatial organization should be useful for directing explorations in other host-microbe systems, formulating detailed models that can quantitatively map onto experimental data, and developing new tools that manipulate cohesion to engineer microbiome function.
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Wiles TJ, Wall ES, Schlomann BH, Hay EA, Parthasarathy R, Guillemin K. Modernized Tools for Streamlined Genetic Manipulation and Comparative Study of Wild and Diverse Proteobacterial Lineages. mBio 2018; 9:e01877-18. [PMID: 30301859 DOI: 10.1128/mBio.01877-18] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
A great challenge in microbiota research is the immense diversity of symbiotic bacteria with the capacity to impact the lives of plants and animals. Moving beyond correlative DNA sequencing-based studies to define the cellular and molecular mechanisms by which symbiotic bacteria influence the biology of their hosts is stalling because genetic manipulation of new and uncharacterized bacterial isolates remains slow and difficult with current genetic tools. Moreover, developing tools de novo is an arduous and time-consuming task and thus represents a significant barrier to progress. To address this problem, we developed a suite of engineering vectors that streamline conventional genetic techniques by improving postconjugation counterselection, modularity, and allelic exchange. Our modernized tools and step-by-step protocols will empower researchers to investigate the inner workings of both established and newly emerging models of bacterial symbiosis. Correlating the presence of bacteria and the genes they carry with aspects of plant and animal biology is rapidly outpacing the functional characterization of naturally occurring symbioses. A major barrier to mechanistic studies is the lack of tools for the efficient genetic manipulation of wild and diverse bacterial isolates. To address the need for improved molecular tools, we used a collection of proteobacterial isolates native to the zebrafish intestinal microbiota as a testbed to construct a series of modernized vectors that expedite genetic knock-in and knockout procedures across lineages. The innovations that we introduce enhance the flexibility of conventional genetic techniques, making it easier to manipulate many different bacterial isolates with a single set of tools. We developed alternative strategies for domestication-free conjugation, designed plasmids with customizable features, and streamlined allelic exchange using visual markers of homologous recombination. We demonstrate the potential of these tools through a comparative study of bacterial behavior within the zebrafish intestine. Live imaging of fluorescently tagged isolates revealed a spectrum of distinct population structures that differ in their biogeography and dominant growth mode (i.e., planktonic versus aggregated). Most striking, we observed divergent genotype-phenotype relationships: several isolates that are predicted by genomic analysis and in vitro assays to be capable of flagellar motility do not display this trait within living hosts. Together, the tools generated in this work provide a new resource for the functional characterization of wild and diverse bacterial lineages that will help speed the research pipeline from sequencing-based correlations to mechanistic underpinnings.
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