1
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Ruan C, Ramoneda J, Kan A, Rudge TJ, Wang G, Johnson DR. Phage predation accelerates the spread of plasmid-encoded antibiotic resistance. Nat Commun 2024; 15:5397. [PMID: 38926498 PMCID: PMC11208555 DOI: 10.1038/s41467-024-49840-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Accepted: 06/20/2024] [Indexed: 06/28/2024] Open
Abstract
Phage predation is generally assumed to reduce microbial proliferation while not contributing to the spread of antibiotic resistance. However, this assumption does not consider the effect of phage predation on the spatial organization of different microbial populations. Here, we show that phage predation can increase the spread of plasmid-encoded antibiotic resistance during surface-associated microbial growth by reshaping spatial organization. Using two strains of the bacterium Escherichia coli, we demonstrate that phage predation slows the spatial segregation of the strains during growth. This increases the number of cell-cell contacts and the extent of conjugation-mediated plasmid transfer between them. The underlying mechanism is that phage predation shifts the location of fastest growth from the biomass periphery to the interior where cells are densely packed and aligned closer to parallel with each other. This creates straighter interfaces between the strains that are less likely to merge together during growth, consequently slowing the spatial segregation of the strains and enhancing plasmid transfer between them. Our results have implications for the design and application of phage therapy and reveal a mechanism for how microbial functions that are deleterious to human and environmental health can proliferate in the absence of positive selection.
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Affiliation(s)
- Chujin Ruan
- College of Land Science and Technology, China Agricultural University, Beijing, China
- Department of Environmental Microbiology, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Dübendorf, Switzerland
| | - Josep Ramoneda
- Spanish Research Council (CSIC), Center for Advanced Studies of Blanes (CEAB), Blanes, Spain
- Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, USA
| | - Anton Kan
- Department of Materials, Swiss Federal Institute of Technology (ETH), Zürich, Switzerland
| | - Timothy J Rudge
- Interdisciplinary Computing and Complex Biosystems (ICOS) Research Group, School of Computing, Newcastle University, Newcastle upon Tyne, UK
| | - Gang Wang
- College of Land Science and Technology, China Agricultural University, Beijing, China.
- National Black Soil & Agriculture Research, China Agricultural University, Beijing, China.
| | - David R Johnson
- Department of Environmental Microbiology, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Dübendorf, Switzerland.
- Institute of Ecology and Evolution, University of Bern, Bern, Switzerland.
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2
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Eriksen RS, Larsen F, Svenningsen SL, Sneppen K, Mitarai N. The dynamics of phage predation on a microcolony. Biophys J 2024; 123:147-156. [PMID: 38069473 PMCID: PMC10808037 DOI: 10.1016/j.bpj.2023.12.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Revised: 10/23/2023] [Accepted: 12/04/2023] [Indexed: 12/23/2023] Open
Abstract
Phage predation is an important factor for controlling the bacterial biomass. At face value, dense microbial habitats are expected to be vulnerable to phage epidemics due to the abundance of fresh hosts immediately next to any infected bacteria. Despite this, the bacterial microcolony is a common habitat for bacteria in nature. Here, we experimentally quantify the fate of microcolonies of Escherichia coli exposed to virulent phage T4. It has been proposed that the outer bacterial layers of the colony will shield the inner layers from the phage invasion and thereby constrain the phage to the colony's surface. We develop a dynamical model that incorporates this shielding mechanism and fit the results with experimental measurements to extract important phage-bacteria interaction parameters. The analysis suggests that, while the shielding mechanism delays phage attack, T4 phage are able to diffuse so deep into the dense bacterial environment that colony-level survival of the bacterial community is challenged.
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Affiliation(s)
- Rasmus Skytte Eriksen
- The Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark; Department of Epidemiology Research, Statens Serum Institut, Copenhagen, Denmark
| | - Frej Larsen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark; Department of Food Science, University of Copenhagen, Copenhagen, Denmark
| | | | - Kim Sneppen
- The Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - Namiko Mitarai
- The Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark.
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3
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García Vázquez A, Mitarai N, Jauffred L. Genetic mixing and demixing on expanding spherical frontiers. ISME COMMUNICATIONS 2024; 4:ycae009. [PMID: 38524760 PMCID: PMC10958774 DOI: 10.1093/ismeco/ycae009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 01/17/2024] [Accepted: 01/18/2024] [Indexed: 03/26/2024]
Abstract
Genetic fluctuation during range expansion is a key process driving evolution. When a bacterial population is expanding on a 2D surface, random fluctuations in the growth of the pioneers at the front line cause a strong demixing of genotypes. Even when there is no selective advantage, sectors of low genetic diversity are formed. Experimental studies of range expansions in surface-attached colonies of fluorescently labelled micro-organisms have contributed significantly to our understanding of fundamental evolutionary dynamics. However, experimental studies on genetic fluctuations in 3D range expansions have been sparse, despite their importance for tumour or biofilm development. We encapsulated populations of two fluorescent Escherichia coli strains in inoculation droplets (volumes [Formula: see text] nl). The confined ensemble of cells grew when embedded in a hydrogel-with nutrients-and developed 3D colonies with well-defined, sector-like regions. Using confocal laser scanning microscopy, we imaged the development of 3D colonies and the emergence of sectors. We characterized how cell concentration in the inoculation droplet controls sectors, growth rate, and the transition from branched colonies to quasi-spherical colonies. We further analysed how sectors on the surface change over time. We complement these experimental results with a modified 3D Eden growth model. The model in 3D spherical growth predicts a phase, where sectors are merging, followed by a steady increase (constant rate), and the experimentally analysed sectors were consistent with this prediction. Therefore, our results demonstrate qualitative differences between radial (2D) and spherical (3D) range expansions and their importance in gene fixation processes.
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Affiliation(s)
- Alba García Vázquez
- The Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100 Copenhagen O, Denmark
| | - Namiko Mitarai
- The Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100 Copenhagen O, Denmark
| | - Liselotte Jauffred
- The Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100 Copenhagen O, Denmark
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4
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Mason G, Footer MJ, Rojas ER. Mechanosensation induces persistent bacterial growth during bacteriophage predation. mBio 2023; 14:e0276622. [PMID: 37909775 PMCID: PMC10746221 DOI: 10.1128/mbio.02766-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 09/27/2023] [Indexed: 11/03/2023] Open
Abstract
Although the relationship between bacteria and lytic bacteriophage is fundamentally antagonistic, these microbes not only coexist but thrive side by side in myriad ecological environments. The mechanisms by which coexistence is achieved, however, are not fully understood. By examining Escherichia coli and bacteriophage T7 population dynamics at the single-cell and single-virion level using a novel microfluidics assay, we observed bacteria growing "persistently" when perfused with high-titer bacteriophage. Bacteriophage persistence occurred at a frequency five orders of magnitude higher than is expected from the natural selection of bacteriophage-resistant mutants. Rather, the frequency of persistence was correlated with the degree to which the bacteria were mechanically compressed by the microfluidic perfusion chamber. Using a combination of mutagenesis and fluorescent imaging techniques, we discovered that compression induces persistence by activating the Rcs phosphorelay pathway, which results in the synthesis of extracellular capsule that sterically blocks bacteriophage adsorption. Other forms of mechanical perturbation also promoted Rcs activity and persistence. These findings have important implications for our understanding of microbial ecology in many important environments, including the gut and the soil, where bacteria grow in confinement. IMPORTANCE Bacteria and bacteriophage form one of the most important predator-prey relationships on earth, yet how the long-term stability of this ecological interaction is achieved is unclear. Here, we demonstrate that Escherichia coli can rapidly grow during bacteriophage predation if they are doing so in spatially confined environments. This discovery revises our understanding of bacteria-bacteriophage population dynamics in many real-world environments where bacteria grow in confinement, such as the gut and the soil. Additionally, this result has clear implications for the potential of bacteriophage therapy and the role of mechanosensation during bacterial pathogenesis.
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Affiliation(s)
- Guy Mason
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, New York, USA
| | - Matthew J. Footer
- Department of Biology, Howard Hughes Medical Institute, University of Washington, Seattle, Washington, USA
| | - Enrique R. Rojas
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, New York, USA
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5
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Cordero M, Mitarai N, Jauffred L. Motility mediates satellite formation in confined biofilms. THE ISME JOURNAL 2023; 17:1819-1827. [PMID: 37592064 PMCID: PMC10579341 DOI: 10.1038/s41396-023-01494-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 08/07/2023] [Accepted: 08/08/2023] [Indexed: 08/19/2023]
Abstract
Bacteria have spectacular survival capabilities and can spread in many, vastly different environments. For instance, when pathogenic bacteria infect a host, they expand by proliferation and squeezing through narrow pores and elastic matrices. However, the exact role of surface structures-important for biofilm formation and motility-and matrix density in colony expansion and morphogenesis is still largely unknown. Using confocal laser-scanning microscopy, we show how satellite colonies emerge around Escherichia coli colonies embedded in semi-dense hydrogel in controlled in vitro assays. Using knock-out mutants, we tested how extra-cellular structures, (e.g., exo-polysaccharides, flagella, and fimbria) control this morphology. Moreover, we identify the extra-cellular matrix' density, where this morphology is possible. When paralleled with mathematical modelling, our results suggest that satellite formation allows bacterial communities to spread faster. We anticipate that this strategy is important to speed up expansion in various environments, while retaining the close interactions and protection provided by the community.
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Affiliation(s)
- Mireia Cordero
- The Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100, Copenhagen O, Denmark
| | - Namiko Mitarai
- The Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100, Copenhagen O, Denmark.
| | - Liselotte Jauffred
- The Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100, Copenhagen O, Denmark.
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6
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Balmages I, Liepins J, Zolins S, Bliznuks D, Broks R, Lihacova I, Lihachev A. Tools for classification of growing/non-growing bacterial colonies using laser speckle imaging. Front Microbiol 2023; 14:1279667. [PMID: 37928664 PMCID: PMC10623326 DOI: 10.3389/fmicb.2023.1279667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Accepted: 10/10/2023] [Indexed: 11/07/2023] Open
Abstract
Prior research has indicated the feasibility of assessing growth-associated activity in bacterial colonies through the application of laser speckle imaging techniques. A subpixel correlation method was employed to identify variations in sequential laser speckle images, thereby facilitating the visualization of specific zones indicative of microbial growth within the colony. Such differentiation between active (growing) and inactive (non-growing) bacterial colonies holds considerable implications for medical applications, like bacterial response to certain drugs or antibiotics. The present study substantiates the capability of laser speckle imaging to categorize bacterial colonies as growing or non-growing, a parameter which nonvisible in colonies when observed under white light illumination.
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Affiliation(s)
- Ilya Balmages
- Faculty of Computer Science and Information Technology, Riga Technical University, Riga, Latvia
- Institute of Atomic Physics and Spectroscopy, University of Latvia, Riga, Latvia
| | - Janis Liepins
- Institute of Microbiology and Biotechnology, University of Latvia, Riga, Latvia
| | | | - Dmitrijs Bliznuks
- Faculty of Computer Science and Information Technology, Riga Technical University, Riga, Latvia
| | - Renars Broks
- Faculty of Computer Science and Information Technology, Riga Technical University, Riga, Latvia
- Department of Biology and Microbiology, Riga Stradins University, Riga, Latvia
| | - Ilze Lihacova
- Institute of Atomic Physics and Spectroscopy, University of Latvia, Riga, Latvia
| | - Alexey Lihachev
- Institute of Atomic Physics and Spectroscopy, University of Latvia, Riga, Latvia
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7
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Attrill EL, Łapińska U, Westra ER, Harding SV, Pagliara S. Slow growing bacteria survive bacteriophage in isolation. ISME COMMUNICATIONS 2023; 3:95. [PMID: 37684358 PMCID: PMC10491631 DOI: 10.1038/s43705-023-00299-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 08/09/2023] [Accepted: 08/14/2023] [Indexed: 09/10/2023]
Abstract
The interactions between bacteria and bacteriophage have important roles in the global ecosystem; in turn changes in environmental parameters affect the interactions between bacteria and phage. However, there is a lack of knowledge on whether clonal bacterial populations harbour different phenotypes that respond to phage in distinct ways and whether the abundance of such phenotypes within bacterial populations is affected by variations in environmental parameters. Here we study the impact of variations in nutrient availability, bacterial growth rate and phage abundance on the interactions between the phage T4 and individual Escherichia coli cells confined in spatial refuges. Surprisingly, we found that fast growing bacteria survive together with all of their clonal kin cells, whereas slow growing bacteria survive in isolation. We also discovered that the number of bacteria that survive in isolation decreases at increasing phage doses possibly due to lysis inhibition in the presence of secondary adsorptions. We further show that these changes in the phenotypic composition of the E. coli population have important consequences on the bacterial and phage population dynamics and should therefore be considered when investigating bacteria-phage interactions in ecological, health or food production settings in structured environments.
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Affiliation(s)
- Erin L Attrill
- Living Systems Institute and Biosciences, University of Exeter, Exeter, UK
| | - Urszula Łapińska
- Living Systems Institute and Biosciences, University of Exeter, Exeter, UK
| | - Edze R Westra
- Environment and Sustainability Institute and Biosciences, University of Exeter, Penryn, UK
| | - Sarah V Harding
- Defence Science and Technology Laboratory, Porton Down, Salisbury, UK
- Department of Respiratory Sciences, University of Leicester, Leicester, UK
| | - Stefano Pagliara
- Living Systems Institute and Biosciences, University of Exeter, Exeter, UK.
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8
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Abedon ST. Schlesinger Nailed It! Assessing a Key Primary Pharmacodynamic Property of Phages for Phage Therapy: Virion Encounter Rates with Motionless Bacterial Targets. DRUGS AND DRUG CANDIDATES 2023; 2:673-688. [PMID: 38770155 PMCID: PMC11104014 DOI: 10.3390/ddc2030034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Bacteriophages (phages) are viruses of bacteria and have been used as antibacterial agents now for over one-hundred years. The primary pharmacodynamics of therapeutic phages can be summed up as follows: phages at a certain concentration can reach bacteria at a certain rate, attach to bacteria that display appropriate receptors on their surfaces, infect, and (ideally) kill those now-adsorbed bacteria. Here, I consider the rate at which phages reach bacteria, during what can be dubbed as an 'extracellular search'. This search is driven by diffusion and can be described by what is known as the phage adsorption rate constant. That constant in turn is thought to be derivable from knowledge of bacterial size, virion diffusion rates, and the likelihood of phage adsorption given this diffusion-driven encounter with a bacterium. Here, I consider only the role of bacterial size in encounter rates. In 1932, Schlesinger hypothesized that bacterial size can be described as a function of cell radius (R , or R 1 ), as based on the non-phage-based theorizing of Smoluchowski (1917). The surface area of a cell-what is actually encountered-varies however instead as a function R 2 . Here, I both provide and review evidence indicating that Schlesinger's assertion seems to have been correct.
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Affiliation(s)
- Stephen T Abedon
- Department of Microbiology, The Ohio State University, Mansfield, OH 44906, USA
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9
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Bumunang EW, Zaheer R, Niu D, Narvaez-Bravo C, Alexander T, McAllister TA, Stanford K. Bacteriophages for the Targeted Control of Foodborne Pathogens. Foods 2023; 12:2734. [PMID: 37509826 PMCID: PMC10379335 DOI: 10.3390/foods12142734] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 07/05/2023] [Accepted: 07/14/2023] [Indexed: 07/30/2023] Open
Abstract
Foodborne illness is exacerbated by novel and emerging pathotypes, persistent contamination, antimicrobial resistance, an ever-changing environment, and the complexity of food production systems. Sporadic and outbreak events of common foodborne pathogens like Shiga toxigenic E. coli (STEC), Salmonella, Campylobacter, and Listeria monocytogenes are increasingly identified. Methods of controlling human infections linked with food products are essential to improve food safety and public health and to avoid economic losses associated with contaminated food product recalls and litigations. Bacteriophages (phages) are an attractive additional weapon in the ongoing search for preventative measures to improve food safety and public health. However, like all other antimicrobial interventions that are being employed in food production systems, phages are not a panacea to all food safety challenges. Therefore, while phage-based biocontrol can be promising in combating foodborne pathogens, their antibacterial spectrum is generally narrower than most antibiotics. The emergence of phage-insensitive single-cell variants and the formulation of effective cocktails are some of the challenges faced by phage-based biocontrol methods. This review examines phage-based applications at critical control points in food production systems with an emphasis on when and where they can be successfully applied at production and processing levels. Shortcomings associated with phage-based control measures are outlined together with strategies that can be applied to improve phage utility for current and future applications in food safety.
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Affiliation(s)
- Emmanuel W Bumunang
- Department of Biological Sciences, University of Lethbridge, Lethbridge, AB T1K 1M4, Canada
| | - Rahat Zaheer
- Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, Lethbridge, AB T1J 4B1, Canada
| | - Dongyan Niu
- Faculty of Veterinary Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Claudia Narvaez-Bravo
- Food and Human Nutritional Sciences, Faculty of Agricultural & Food Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - Trevor Alexander
- Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, Lethbridge, AB T1J 4B1, Canada
| | - Tim A McAllister
- Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, Lethbridge, AB T1J 4B1, Canada
| | - Kim Stanford
- Department of Biological Sciences, University of Lethbridge, Lethbridge, AB T1K 1M4, Canada
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10
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Petrovic Fabijan A, Iredell J, Danis-Wlodarczyk K, Kebriaei R, Abedon ST. Translating phage therapy into the clinic: Recent accomplishments but continuing challenges. PLoS Biol 2023; 21:e3002119. [PMID: 37220114 PMCID: PMC10204993 DOI: 10.1371/journal.pbio.3002119] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023] Open
Abstract
Phage therapy is a medical form of biological control of bacterial infections, one that uses naturally occurring viruses, called bacteriophages or phages, as antibacterial agents. Pioneered over 100 years ago, phage therapy nonetheless is currently experiencing a resurgence in interest, with growing numbers of clinical case studies being published. This renewed enthusiasm is due in large part to phage therapy holding promise for providing safe and effective cures for bacterial infections that traditional antibiotics acting alone have been unable to clear. This Essay introduces basic phage biology, provides an outline of the long history of phage therapy, highlights some advantages of using phages as antibacterial agents, and provides an overview of recent phage therapy clinical successes. Although phage therapy has clear clinical potential, it faces biological, regulatory, and economic challenges to its further implementation and more mainstream acceptance.
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Affiliation(s)
- Aleksandra Petrovic Fabijan
- Centre for Infectious Diseases and Microbiology, Westmead Institute for Medical Research, Westmead, New South Wales, Australia
- Faculty of Health and Medicine, School of Medicine, Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia
| | - Jonathan Iredell
- Centre for Infectious Diseases and Microbiology, Westmead Institute for Medical Research, Westmead, New South Wales, Australia
- Faculty of Health and Medicine, School of Medicine, Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia
- Westmead Hospital, Western Sydney Local Health District, Westmead, New South Wales, Australia
| | - Katarzyna Danis-Wlodarczyk
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, Ohio, United States of America
| | - Razieh Kebriaei
- P3 Research Laboratory, College of Pharmacy, The Ohio State University, Columbus, Ohio, United States of America
| | - Stephen T. Abedon
- Department of Microbiology, The Ohio State University, Mansfield, Ohio, United States of America
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11
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Rasmussen TS, Koefoed AK, Deng L, Muhammed MK, Rousseau GM, Kot W, Sprotte S, Neve H, Franz CMAP, Hansen AK, Vogensen FK, Moineau S, Nielsen DS. CRISPR-Cas provides limited phage immunity to a prevalent gut bacterium in gnotobiotic mice. THE ISME JOURNAL 2023; 17:432-442. [PMID: 36631688 PMCID: PMC9938214 DOI: 10.1038/s41396-023-01358-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 12/22/2022] [Accepted: 01/06/2023] [Indexed: 01/13/2023]
Abstract
Many bacteria and archaea harbor the adaptive CRISPR-Cas system, which stores small nucleotide fragments from previous invasions of nucleic acids via viruses or plasmids. This molecular archive blocks further invaders carrying identical or similar nucleotide sequences. However, few of these systems have been confirmed experimentally to be active in gut bacteria. Here, we demonstrate experimentally that the type I-C CRISPR-Cas system of the prevalent gut bacterium Eggerthella lenta can specifically target and cleave foreign DNA in vitro by using a plasmid transformation assay. We also show that the CRISPR-Cas system acquires new immunities (spacers) from the genome of a virulent E. lenta phage using traditional phage assays in vitro but also in vivo using gnotobiotic (GB) mice. Both high phage titer and an increased number of spacer acquisition events were observed when E. lenta was exposed to a low multiplicity of infection in vitro, and three phage genes were found to contain protospacer hotspots. Fewer new spacer acquisitions were detected in vivo than in vitro. Longitudinal analysis of phage-bacteria interactions showed sustained coexistence in the gut of GB mice, with phage abundance being approximately one log higher than the bacteria. Our findings show that while the type I-C CRISPR-Cas system is active in vitro and in vivo, a highly virulent phage in vitro was still able to co-exist with its bacterial host in vivo. Taken altogether, our results suggest that the CRISPR-Cas defense system of E. lenta provides only partial immunity in the gut.
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Affiliation(s)
- Torben Sølbeck Rasmussen
- Section of Microbiology and Fermentation, Department of Food Science, Faculty of Science, University of Copenhagen, 1958, Frederiksberg, Denmark.
| | - Anna Kirstine Koefoed
- Section of Microbiology and Fermentation, Department of Food Science, Faculty of Science, University of Copenhagen, 1958, Frederiksberg, Denmark
| | - Ling Deng
- Section of Microbiology and Fermentation, Department of Food Science, Faculty of Science, University of Copenhagen, 1958, Frederiksberg, Denmark
| | - Musemma K Muhammed
- Section of Microbiology and Fermentation, Department of Food Science, Faculty of Science, University of Copenhagen, 1958, Frederiksberg, Denmark
| | - Geneviève M Rousseau
- Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de 1enie, Université Laval, Québec, QC, G1V 0A6, Canada
- Groupe de recherche en écologie buccale, Faculté de médecine dentaire, Université Laval, Québec, QC, G1V 0A6, Canada
| | - Witold Kot
- Section of Microbial Ecology and Biotechnology, Department of Plant and Environmental Sciences, University of Copenhagen, 1871, Frederiksberg, Denmark
| | - Sabrina Sprotte
- Department of Microbiology and Biotechnology, Max Rubner-Institut, 24103, Kiel, Germany
| | - Horst Neve
- Department of Microbiology and Biotechnology, Max Rubner-Institut, 24103, Kiel, Germany
| | - Charles M A P Franz
- Department of Microbiology and Biotechnology, Max Rubner-Institut, 24103, Kiel, Germany
| | - Axel Kornerup Hansen
- Section of Experimental Animal Models, Department of Veterinary and Animal Sciences, University of Copenhagen, 1871, Frederiksberg, Denmark
| | - Finn Kvist Vogensen
- Section of Microbiology and Fermentation, Department of Food Science, Faculty of Science, University of Copenhagen, 1958, Frederiksberg, Denmark
| | - Sylvain Moineau
- Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de 1enie, Université Laval, Québec, QC, G1V 0A6, Canada
- Groupe de recherche en écologie buccale, Faculté de médecine dentaire, Université Laval, Québec, QC, G1V 0A6, Canada
- Félix d'Hérelle Reference Center for Bacterial Viruses, Faculté de médecine dentaire, Université Laval, Québec, QC, G1V 0A6, Canada
| | - Dennis Sandris Nielsen
- Section of Microbiology and Fermentation, Department of Food Science, Faculty of Science, University of Copenhagen, 1958, Frederiksberg, Denmark.
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12
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Abedon ST. Ecology and Evolutionary Biology of Hindering Phage Therapy: The Phage Tolerance vs. Phage Resistance of Bacterial Biofilms. Antibiotics (Basel) 2023; 12:245. [PMID: 36830158 PMCID: PMC9952518 DOI: 10.3390/antibiotics12020245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 01/17/2023] [Accepted: 01/19/2023] [Indexed: 01/27/2023] Open
Abstract
As with antibiotics, we can differentiate various acquired mechanisms of bacteria-mediated inhibition of the action of bacterial viruses (phages or bacteriophages) into ones of tolerance vs. resistance. These also, respectively, may be distinguished as physiological insensitivities (or protections) vs. resistance mutations, phenotypic resistance vs. genotypic resistance, temporary vs. more permanent mechanisms, and ecologically vs. also near-term evolutionarily motivated functions. These phenomena can result from multiple distinct molecular mechanisms, many of which for bacterial tolerance of phages are associated with bacterial biofilms (as is also the case for the bacterial tolerance of antibiotics). The resulting inhibitions are relevant from an applied perspective because of their potential to thwart phage-based treatments of bacterial infections, i.e., phage therapies, as well as their potential to interfere more generally with approaches to the phage-based biological control of bacterial biofilms. In other words, given the generally low toxicity of properly chosen therapeutic phages, it is a combination of phage tolerance and phage resistance, as displayed by targeted bacteria, that seems to represent the greatest impediments to phage therapy's success. Here I explore general concepts of bacterial tolerance of vs. bacterial resistance to phages, particularly as they may be considered in association with bacterial biofilms.
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Affiliation(s)
- Stephen T Abedon
- Department of Microbiology, The Ohio State University, Mansfield, OH 44906, USA
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13
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Winans JB, Wucher BR, Nadell CD. Multispecies biofilm architecture determines bacterial exposure to phages. PLoS Biol 2022; 20:e3001913. [PMID: 36548227 PMCID: PMC9778933 DOI: 10.1371/journal.pbio.3001913] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Accepted: 11/14/2022] [Indexed: 12/24/2022] Open
Abstract
Numerous ecological interactions among microbes-for example, competition for space and resources, or interaction among phages and their bacterial hosts-are likely to occur simultaneously in multispecies biofilm communities. While biofilms formed by just a single species occur, multispecies biofilms are thought to be more typical of microbial communities in the natural environment. Previous work has shown that multispecies biofilms can increase, decrease, or have no measurable impact on phage exposure of a host bacterium living alongside another species that the phages cannot target. The reasons underlying this variability are not well understood, and how phage-host encounters change within multispecies biofilms remains mostly unexplored at the cellular spatial scale. Here, we study how the cellular scale architecture of model 2-species biofilms impacts cell-cell and cell-phage interactions controlling larger scale population and community dynamics. Our system consists of dual culture biofilms of Escherichia coli and Vibrio cholerae under exposure to T7 phages, which we study using microfluidic culture, high-resolution confocal microscopy imaging, and detailed image analysis. As shown previously, sufficiently mature biofilms of E. coli can protect themselves from phage exposure via their curli matrix. Before this stage of biofilm structural maturity, E. coli is highly susceptible to phages; however, we show that these bacteria can gain lasting protection against phage exposure if they have become embedded in the bottom layers of highly packed groups of V. cholerae in co-culture. This protection, in turn, is dependent on the cell packing architecture controlled by V. cholerae biofilm matrix secretion. In this manner, E. coli cells that are otherwise susceptible to phage-mediated killing can survive phage exposure in the absence of de novo resistance evolution. While co-culture biofilm formation with V. cholerae can confer phage protection to E. coli, it comes at the cost of competing with V. cholerae and a disruption of normal curli-mediated protection for E. coli even in dual species biofilms grown over long time scales. This work highlights the critical importance of studying multispecies biofilm architecture and its influence on the community dynamics of bacteria and phages.
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Affiliation(s)
- James B. Winans
- Department of Biological Sciences, Dartmouth, Hanover, New Hampshire, United States of America
| | - Benjamin R. Wucher
- Department of Biological Sciences, Dartmouth, Hanover, New Hampshire, United States of America
| | - Carey D. Nadell
- Department of Biological Sciences, Dartmouth, Hanover, New Hampshire, United States of America
- * E-mail:
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14
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Igler C. Phenotypic flux: The role of physiology in explaining the conundrum of bacterial persistence amid phage attack. Virus Evol 2022; 8:veac086. [PMID: 36225237 PMCID: PMC9547521 DOI: 10.1093/ve/veac086] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 08/11/2022] [Accepted: 09/09/2022] [Indexed: 11/16/2022] Open
Abstract
Bacteriophages, the viruses of bacteria, have been studied for over a century. They were not only instrumental in laying the foundations of molecular biology, but they are also likely to play crucial roles in shaping our biosphere and may offer a solution to the control of drug-resistant bacterial infections. However, it remains challenging to predict the conditions for bacterial eradication by phage predation, sometimes even under well-defined laboratory conditions, and, most curiously, if the majority of surviving cells are genetically phage-susceptible. Here, I propose that even clonal phage and bacterial populations are generally in a state of continuous 'phenotypic flux', which is caused by transient and nongenetic variation in phage and bacterial physiology. Phenotypic flux can shape phage infection dynamics by reducing the force of infection to an extent that allows for coexistence between phages and susceptible bacteria. Understanding the mechanisms and impact of phenotypic flux may be key to providing a complete picture of phage-bacteria coexistence. I review the empirical evidence for phenotypic variation in phage and bacterial physiology together with the ways they have been modeled and discuss the potential implications of phenotypic flux for ecological and evolutionary dynamics between phages and bacteria, as well as for phage therapy.
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Affiliation(s)
- Claudia Igler
- Department of Environmental Systems Science, ETH Zürich, Institute of Integrative Biology, Universitätstrasse 16, Zurich 8092, Switzerland
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15
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Shkoporov AN, Turkington CJ, Hill C. Mutualistic interplay between bacteriophages and bacteria in the human gut. Nat Rev Microbiol 2022; 20:737-749. [PMID: 35773472 DOI: 10.1038/s41579-022-00755-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/25/2022] [Indexed: 12/12/2022]
Abstract
Bacteriophages (phages) are often described as obligate predators of their bacterial hosts, and phage predation is one of the leading forces controlling the density and distribution of bacterial populations. Every 48 h half of all bacteria on Earth are killed by phages. Efficient killing also forms the basis of phage therapy in humans and animals and the use of phages as food preservatives. In turn, bacteria have a plethora of resistance systems against phage attack, but very few bacterial species, if any, have entirely escaped phage predation. However, in complex communities and environments such as the human gut, this antagonistic model of attack and counter-defence does not fully describe the scope of phage-bacterium interactions. In this Review, we explore some of the more mutualistic aspects of phage-bacterium interactions in the human gut, and we suggest that the relationship between phages and their bacterial hosts in the gut is best characterized not as a fight to the death between enemies but rather as a mutualistic relationship between partners.
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Affiliation(s)
- Andrey N Shkoporov
- APC Microbiome Ireland & School of Microbiology, University College Cork, Cork, Ireland. .,Department of Medicine, University College Cork, Cork, Ireland.
| | | | - Colin Hill
- APC Microbiome Ireland & School of Microbiology, University College Cork, Cork, Ireland.
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16
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Visnapuu A, Van der Gucht M, Wagemans J, Lavigne R. Deconstructing the Phage-Bacterial Biofilm Interaction as a Basis to Establish New Antibiofilm Strategies. Viruses 2022; 14:v14051057. [PMID: 35632801 PMCID: PMC9145820 DOI: 10.3390/v14051057] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 05/11/2022] [Accepted: 05/11/2022] [Indexed: 12/19/2022] Open
Abstract
The bacterial biofilm constitutes a complex environment that endows the bacterial community within with an ability to cope with biotic and abiotic stresses. Considering the interaction with bacterial viruses, these biofilms contain intrinsic defense mechanisms that protect against phage predation; these mechanisms are driven by physical, structural, and metabolic properties or governed by environment-induced mutations and bacterial diversity. In this regard, horizontal gene transfer can also be a driver of biofilm diversity and some (pro)phages can function as temporary allies in biofilm development. Conversely, as bacterial predators, phages have developed counter mechanisms to overcome the biofilm barrier. We highlight how these natural systems have previously inspired new antibiofilm design strategies, e.g., by utilizing exopolysaccharide degrading enzymes and peptidoglycan hydrolases. Next, we propose new potential approaches including phage-encoded DNases to target extracellular DNA, as well as phage-mediated inhibitors of cellular communication; these examples illustrate the relevance and importance of research aiming to elucidate novel antibiofilm mechanisms contained within the vast set of unknown ORFs from phages.
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17
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Staes I, Bäcker LE, Simoens K, De Winter K, Marolt G, Cenens W, Wolput S, Vazquez AR, Goos P, Lavigne R, Bernaerts K, Aertsen A. Superinfection exclusion factors drive a history-dependent switch from vertical to horizontal phage transmission. Cell Rep 2022; 39:110804. [PMID: 35545039 DOI: 10.1016/j.celrep.2022.110804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 03/24/2022] [Accepted: 04/19/2022] [Indexed: 11/03/2022] Open
Abstract
Temperate bacterial viruses are commonly thought to favor vertical (lysogenic) transmission over horizontal (lytic) transmission when the virion-to-host-cell ratio is high and available host cells become scarce. In P22-infected Salmonella Typhimurium populations, however, we find that host subpopulations become lytically consumed despite high phage-to-host ratios that would normally favor lysogeny. These subpopulations originate from the proliferation of P22-free siblings that spawn off from P22-carrier cells from which they cytoplasmically inherit P22-borne superinfection exclusion factors (SEFs). In fact, we demonstrate that the gradual dilution of these SEFs in the growing subpopulation of P22-free siblings restricts the number of incoming phages, thereby imposing the perception of a low phage-to-host ratio that favors lytic development. Although their role has so far been neglected, our data indicate that phage-borne SEFs can spur complex infection dynamics and a history-dependent switch from vertical to horizontal transmission in the face of host-cell scarcity.
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Affiliation(s)
- Ines Staes
- Department of Microbial and Molecular Systems, Faculty of Bioscience Engineering, KU Leuven, Kasteelpark Arenberg 23 - bus 2457, 3001 Leuven, Belgium
| | - Leonard E Bäcker
- Department of Microbial and Molecular Systems, Faculty of Bioscience Engineering, KU Leuven, Kasteelpark Arenberg 23 - bus 2457, 3001 Leuven, Belgium
| | - Kenneth Simoens
- Department of Chemical Engineering- (Bio)chemical Reactor Engineering and Safety, Faculty of Engineering, KU Leuven, Leuven, Belgium
| | - Kjerstin De Winter
- Department of Chemical Engineering- (Bio)chemical Reactor Engineering and Safety, Faculty of Engineering, KU Leuven, Leuven, Belgium
| | - Gasper Marolt
- Department of Microbial and Molecular Systems, Faculty of Bioscience Engineering, KU Leuven, Kasteelpark Arenberg 23 - bus 2457, 3001 Leuven, Belgium; Department of Chemical Engineering- (Bio)chemical Reactor Engineering and Safety, Faculty of Engineering, KU Leuven, Leuven, Belgium
| | - William Cenens
- Department of Microbial and Molecular Systems, Faculty of Bioscience Engineering, KU Leuven, Kasteelpark Arenberg 23 - bus 2457, 3001 Leuven, Belgium
| | - Sanne Wolput
- Department of Microbial and Molecular Systems, Faculty of Bioscience Engineering, KU Leuven, Kasteelpark Arenberg 23 - bus 2457, 3001 Leuven, Belgium
| | - Alan R Vazquez
- Department of Biosystems, Faculty of Bioscience Engineering, KU Leuven, Leuven, Belgium
| | - Peter Goos
- Department of Biosystems, Faculty of Bioscience Engineering, KU Leuven, Leuven, Belgium; Department of Engineering Management, University of Antwerp, Antwerp, Belgium
| | - Rob Lavigne
- Department of Biosystems, Faculty of Bioscience Engineering, KU Leuven, Leuven, Belgium
| | - Kristel Bernaerts
- Department of Chemical Engineering- (Bio)chemical Reactor Engineering and Safety, Faculty of Engineering, KU Leuven, Leuven, Belgium
| | - Abram Aertsen
- Department of Microbial and Molecular Systems, Faculty of Bioscience Engineering, KU Leuven, Kasteelpark Arenberg 23 - bus 2457, 3001 Leuven, Belgium.
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18
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Koonjan S, Cardoso Palacios C, Nilsson AS. Population Dynamics of a Two Phages–One Host Infection System Using Escherichia coli Strain ECOR57 and Phages vB_EcoP_SU10 and vB_EcoD_SU57. Pharmaceuticals (Basel) 2022; 15:ph15030268. [PMID: 35337066 PMCID: PMC8953519 DOI: 10.3390/ph15030268] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 02/09/2022] [Accepted: 02/18/2022] [Indexed: 02/01/2023] Open
Abstract
In this study, we looked at the population dynamics of a two phages-one host system using phages vB_EcoP_SU10 (SU10) and vB_EcoD_SU57 (SU57) and the bacteria Escherichia coli, strain ECOR57. Phage-specific growth curves were observed where infections by SU10 resulted in a moderate production of phages and infections by SU57 resulted in a fast and extensive production of phage progeny. Sequentially adding SU10 followed by SU57 did not produce a significant change in growth rates, whereas adding SU57 followed by SU10 resulted in a decrease in SU10 titer The efficiency of the plating assays showed that ECOR57 exhibited a resistance spectrum after infection by both the single and combined phages. Phage-resistant bacteria exhibited four different morphotypes (i.e., normal, slimy, edgy, and pointy). The normal and edgy morphotypes had a high frequency of developing resistance. Bacterial growth and biofilm assays indicated that the edgy and pointy morphotypes reached a stationary phase faster and produced more biofilm compared to the wild type. These findings suggest that the dynamic structure of phage–bacteria communities dictate resistance evolution and development. Understanding when and how resistances arise and phage(s)–hosts interactions could aid in the design of phage therapy treatments.
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Affiliation(s)
- Shazeeda Koonjan
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden;
- Correspondence: (S.K.); (A.S.N.)
| | - Carlos Cardoso Palacios
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden;
- Department of Ecology, Grimsö Wildlife Research Station, Swedish University of Agricultural Sciences, SE-739 93 Riddarhyttan, Sweden
| | - Anders S. Nilsson
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden;
- Correspondence: (S.K.); (A.S.N.)
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19
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Singh A, Padmesh S, Dwivedi M, Kostova I. How Good are Bacteriophages as an Alternative Therapy to Mitigate Biofilms of Nosocomial Infections. Infect Drug Resist 2022; 15:503-532. [PMID: 35210792 PMCID: PMC8860455 DOI: 10.2147/idr.s348700] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 01/27/2022] [Indexed: 12/12/2022] Open
Abstract
Bacteria survive on any surface through the generation of biofilms that provide a protective environment to grow as well as making them drug resistant. Extracellular polymeric matrix is a crucial component in biofilm formation. The presence of biofilms consisting of common opportunistic and nosocomial, drug-resistant pathogens has been reported on medical devices like catheters and prosthetics, leading to many complications. Several approaches are under investigation to combat drug-resistant bacteria. Deployment of bacteriophages is one of the promising approaches to invade biofilm that may expose bacteria to the conditions adverse for their growth. Penetration into these biofilms and their destruction by bacteriophages is brought about due to their small size and ability of their progeny to diffuse through the bacterial cell wall. The other mechanisms employed by phages to infect biofilms may include their relocation through water channels to embedded host cells, replication at local sites followed by infection to the neighboring cells and production of depolymerizing enzymes to decompose viscous biofilm matrix, etc. Various research groups are investigating intricacies involved in phage therapy to mitigate the bacterial infection and biofilm formation. Thus, bacteriophages represent a good control over different biofilms and further understanding of phage-biofilm interaction at molecular level may overcome the clinical challenges in phage therapy. The present review summarizes the comprehensive details on dynamic interaction of phages with bacterial biofilms and the role of phage-derived enzymes - endolysin and depolymerases in extenuating biofilms of clinical and medical concern. The methodology employed was an extensive literature search, using several keywords in important scientific databases, such as Scopus, Web of Science, PubMed, ScienceDirect, etc. The keywords were also used with Boolean operator "And". More than 250 relevant and recent articles were selected and reviewed to discuss the evidence-based data on the application of phage therapy with recent updates, and related potential challenges.
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Affiliation(s)
- Aditi Singh
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Lucknow Campus, Lucknow, 226028, India
| | - Sudhakar Padmesh
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Lucknow Campus, Lucknow, 226028, India
| | - Manish Dwivedi
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Lucknow Campus, Lucknow, 226028, India
| | - Irena Kostova
- Department of Chemistry, Faculty of Pharmacy, Medical University, Sofia, 1000, Bulgaria
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20
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Attrill EL, Claydon R, Łapińska U, Recker M, Meaden S, Brown AT, Westra ER, Harding SV, Pagliara S. Individual bacteria in structured environments rely on phenotypic resistance to phage. PLoS Biol 2021; 19:e3001406. [PMID: 34637438 PMCID: PMC8509860 DOI: 10.1371/journal.pbio.3001406] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 09/02/2021] [Indexed: 12/12/2022] Open
Abstract
Bacteriophages represent an avenue to overcome the current antibiotic resistance crisis, but evolution of genetic resistance to phages remains a concern. In vitro, bacteria evolve genetic resistance, preventing phage adsorption or degrading phage DNA. In natural environments, evolved resistance is lower possibly because the spatial heterogeneity within biofilms, microcolonies, or wall populations favours phenotypic survival to lytic phages. However, it is also possible that the persistence of genetically sensitive bacteria is due to less efficient phage amplification in natural environments, the existence of refuges where bacteria can hide, and a reduced spread of resistant genotypes. Here, we monitor the interactions between individual planktonic bacteria in isolation in ephemeral refuges and bacteriophage by tracking the survival of individual cells. We find that in these transient spatial refuges, phenotypic resistance due to reduced expression of the phage receptor is a key determinant of bacterial survival. This survival strategy is in contrast with the emergence of genetic resistance in the absence of ephemeral refuges in well-mixed environments. Predictions generated via a mathematical modelling framework to track bacterial response to phages reveal that the presence of spatial refuges leads to fundamentally different population dynamics that should be considered in order to predict and manipulate the evolutionary and ecological dynamics of bacteria–phage interactions in naturally structured environments. Bacteriophages represent a promising avenue to overcome the current antibiotic resistance crisis, but evolution of phage resistance remains a concern. This study shows that in the presence of spatial refuges, genetic resistance to phage is less of a problem than commonly assumed, but the persistence of genetically susceptible bacteria suggests that eradicating bacterial pathogens from structured environments may require combined phage-antibiotic therapies.
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Affiliation(s)
- Erin L. Attrill
- Living Systems Institute and Biosciences, University of Exeter, Exeter, United Kingdom
| | - Rory Claydon
- SUPA, School of Physics and Astronomy, The University of Edinburgh, United Kingdom
| | - Urszula Łapińska
- Living Systems Institute and Biosciences, University of Exeter, Exeter, United Kingdom
| | - Mario Recker
- Centre for Ecology and Conservation, University of Exeter, Penryn, United Kingdom
| | - Sean Meaden
- Environment and Sustainability Institute and Biosciences, University of Exeter, Penryn, United Kingdom
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Aidan T. Brown
- SUPA, School of Physics and Astronomy, The University of Edinburgh, United Kingdom
| | - Edze R. Westra
- Environment and Sustainability Institute and Biosciences, University of Exeter, Penryn, United Kingdom
| | - Sarah V. Harding
- Defence Science and Technology Laboratory, Porton Down, Salisbury, United Kingdom
| | - Stefano Pagliara
- Living Systems Institute and Biosciences, University of Exeter, Exeter, United Kingdom
- * E-mail:
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21
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Chevallereau A, Pons BJ, van Houte S, Westra ER. Interactions between bacterial and phage communities in natural environments. Nat Rev Microbiol 2021; 20:49-62. [PMID: 34373631 DOI: 10.1038/s41579-021-00602-y] [Citation(s) in RCA: 156] [Impact Index Per Article: 52.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 06/28/2021] [Indexed: 12/20/2022]
Abstract
We commonly acknowledge that bacterial viruses (phages) shape the composition and evolution of bacterial communities in nature and therefore have important roles in ecosystem functioning. This view stems from studies in the 1990s to the first decade of the twenty-first century that revealed high viral abundance, high viral diversity and virus-induced microbial death in aquatic ecosystems as well as an association between collapses in bacterial density and peaks in phage abundance. The recent surge in metagenomic analyses has provided deeper insight into the abundance, genomic diversity and spatio-temporal dynamics of phages in a wide variety of ecosystems, ranging from deep oceans to soil and the mammalian digestive tract. However, the causes and consequences of variations in phage community compositions remain poorly understood. In this Review, we explore current knowledge of the composition and evolution of phage communities, as well as their roles in controlling the population and evolutionary dynamics of bacterial communities. We discuss the need for greater ecological realism in laboratory studies to capture the complexity of microbial communities that thrive in natural environments.
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Affiliation(s)
- Anne Chevallereau
- Environment and Sustainability Institute, Biosciences, University of Exeter, Penryn, UK. .,Department of Infection, Immunity and Inflammation, Institut Cochin, INSERM U1016, CNRS UMR8104, Université de Paris, Paris, France.
| | - Benoît J Pons
- Environment and Sustainability Institute, Biosciences, University of Exeter, Penryn, UK
| | - Stineke van Houte
- Environment and Sustainability Institute, Biosciences, University of Exeter, Penryn, UK
| | - Edze R Westra
- Environment and Sustainability Institute, Biosciences, University of Exeter, Penryn, UK.
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22
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Abstract
Biofilms are aggregates of bacterial cells surrounded by an extracellular matrix. Much progress has been made in studying biofilm growth on solid substrates; however, little is known about the biophysical mechanisms underlying biofilm development in three-dimensional confined environments in which the biofilm-dwelling cells must push against and even damage the surrounding environment to proliferate. Here, combining single-cell imaging, mutagenesis, and rheological measurement, we reveal the key morphogenesis steps of Vibrio cholerae biofilms embedded in hydrogels as they grow by four orders of magnitude from their initial size. We show that the morphodynamics and cell ordering in embedded biofilms are fundamentally different from those of biofilms on flat surfaces. Treating embedded biofilms as inclusions growing in an elastic medium, we quantitatively show that the stiffness contrast between the biofilm and its environment determines biofilm morphology and internal architecture, selecting between spherical biofilms with no cell ordering and oblate ellipsoidal biofilms with high cell ordering. When embedded in stiff gels, cells self-organize into a bipolar structure that resembles the molecular ordering in nematic liquid crystal droplets. In vitro biomechanical analysis shows that cell ordering arises from stress transmission across the biofilm-environment interface, mediated by specific matrix components. Our imaging technique and theoretical approach are generalizable to other biofilm-forming species and potentially to biofilms embedded in mucus or host tissues as during infection. Our results open an avenue to understand how confined cell communities grow by means of a compromise between their inherent developmental program and the mechanical constraints imposed by the environment.
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23
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Bastolla U. Mathematical Model of SARS-Cov-2 Propagation Versus ACE2 Fits COVID-19 Lethality Across Age and Sex and Predicts That of SARS. Front Mol Biosci 2021; 8:706122. [PMID: 34322518 PMCID: PMC8311794 DOI: 10.3389/fmolb.2021.706122] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 06/30/2021] [Indexed: 12/11/2022] Open
Abstract
The fatality rate of Covid-19 escalates with age and is larger in men than women. I show that these variations correlate strongly with the level of the viral receptor protein ACE2 in rat lungs, which is consistent with the still limited data on human ACE2. Surprisingly, lower receptor levels correlate with higher fatality. I propose two possible explanations of this negative correlation: First, a previous mathematical model predicts that the velocity of viral progression in the organism as a function of the receptor level has a maximum and declines for abundant receptor. Secondly, degradation of ACE2 by the virus may cause the runaway inflammatory response that characterizes severe CoViD-19. I present here a mathematical model that predicts the lethality as a function of ACE2 protein level based on the two above hypothesis. The model fits Covid-19 fatality rate across age and sex in three countries with high accuracy (r 2 > 0.9 ) under the hypothesis that the speed of viral progression in the infected organism is a decreasing function of the ACE2 level. Moreover, rescaling the fitted parameters by the ratio of the binding rates of the spike proteins of SARS-CoV and SARS-CoV-2 allows predicting the fatality rate of SARS-CoV across age and sex, thus linking the molecular and epidemiological levels.
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Affiliation(s)
- Ugo Bastolla
- Centro de Biologia Molecular “Severo Ochoa”, CSIC-UAM Cantoblanco, Madrid, Spain
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24
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Bond MC, Vidakovic L, Singh PK, Drescher K, Nadell CD. Matrix-trapped viruses can prevent invasion of bacterial biofilms by colonizing cells. eLife 2021; 10:65355. [PMID: 34240700 PMCID: PMC8346279 DOI: 10.7554/elife.65355] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 07/08/2021] [Indexed: 12/19/2022] Open
Abstract
Bacteriophages can be trapped in the matrix of bacterial biofilms, such that the cells inside them are protected. It is not known whether these phages are still infectious and whether they pose a threat to newly arriving bacteria. Here, we address these questions using Escherichia coli and its lytic phage T7. Prior work has demonstrated that T7 phages are bound in the outermost curli polymer layers of the E. coli biofilm matrix. We show that these phages do remain viable and can kill colonizing cells that are T7-susceptible. If cells colonize a resident biofilm before phages do, we find that they can still be killed by phage exposure if it occurs soon thereafter. However, if colonizing cells are present on the biofilm long enough before phage exposure, they gain phage protection via envelopment within curli-producing clusters of the resident biofilm cells.
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Affiliation(s)
- Matthew C Bond
- Department of Biological Sciences, Dartmouth College, Hanover, United States
| | - Lucia Vidakovic
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Praveen K Singh
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Knut Drescher
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany.,Department of Physics, Philipps University Marburg, Marburg, Germany.,Biozentrum, University of Basel, Basel, Switzerland
| | - Carey D Nadell
- Department of Biological Sciences, Dartmouth College, Hanover, United States
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25
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Abstract
Bacteriophages and bacterial biofilms are widely present in natural environments, a fact that has accelerated the evolution of phages and their bacterial hosts in these particular niches. Phage-host interactions in biofilm communities are rather complex, where phages are not always merely predators but also can establish symbiotic relationships that induce and strengthen biofilms. In this review we provide an overview of the main features affecting phage-biofilm interactions as well as the currently available methods of studying these interactions. In addition, we address the applications of phages for biofilm control in different contexts.
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Affiliation(s)
- Diana P Pires
- Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal;
| | - Luís D R Melo
- Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal;
| | - Joana Azeredo
- Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal;
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26
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Kauppinen A, Siponen S, Pitkänen T, Holmfeldt K, Pursiainen A, Torvinen E, Miettinen IT. Phage Biocontrol of Pseudomonas aeruginosa in Water. Viruses 2021; 13:928. [PMID: 34067885 PMCID: PMC8156286 DOI: 10.3390/v13050928] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Revised: 05/07/2021] [Accepted: 05/11/2021] [Indexed: 12/30/2022] Open
Abstract
Bacteriophage control of harmful or pathogenic bacteria has aroused growing interest, largely due to the rise of antibiotic resistance. The objective of this study was to test phages as potential agents for the biocontrol of an opportunistic pathogen Pseudomonas aeruginosa in water. Two P. aeruginosa bacteriophages (vB_PaeM_V523 and vB_PaeM_V524) were isolated from wastewater and characterized physically and functionally. Genomic and morphological characterization showed that both were myoviruses within the Pbunavirus genus. Both had a similar latent period (50-55 min) and burst size (124-134 PFU/infected cell), whereas there was variation in the host range. In addition to these environmental phages, a commercial Pseudomonas phage, JG003 (DSM 19870), was also used in the biocontrol experiments. The biocontrol potential of the three phages in water was tested separately and together as a cocktail against two P. aeruginosa strains; PAO1 and the environmental strain 17V1507. With PAO1, all phages initially reduced the numbers of the bacterial host, with phage V523 being the most efficient (>2.4 log10 reduction). For the environmental P. aeruginosa strain (17V1507), only the phage JG003 caused a reduction (1.2 log10) compared to the control. The cocktail of three phages showed a slightly higher decrease in the level of the hosts compared to the use of individual phages. Although no synergistic effect was observed in the host reduction with the use of the phage cocktail, the cocktail-treated hosts did not appear to acquire resistance as rapidly as hosts treated with a single phage. The results of this study provide a significant step in the development of bacteriophage preparations for the control of pathogens and harmful microbes in water environments.
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Affiliation(s)
- Ari Kauppinen
- Expert Microbiology Unit, Department of Health Security, Finnish Institute for Health and Welfare, FI-70701 Kuopio, Finland; (S.S.); (T.P.); (A.P.); (I.T.M.)
| | - Sallamaari Siponen
- Expert Microbiology Unit, Department of Health Security, Finnish Institute for Health and Welfare, FI-70701 Kuopio, Finland; (S.S.); (T.P.); (A.P.); (I.T.M.)
- Department of Environmental and Biological Sciences, University of Eastern Finland, FI-70211 Kuopio, Finland;
| | - Tarja Pitkänen
- Expert Microbiology Unit, Department of Health Security, Finnish Institute for Health and Welfare, FI-70701 Kuopio, Finland; (S.S.); (T.P.); (A.P.); (I.T.M.)
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, FI-00014 Helsinki, Finland
| | - Karin Holmfeldt
- Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Department of Biology and Environmental Sciences, Linnaeus University, SE-39231 Kalmar, Sweden;
| | - Anna Pursiainen
- Expert Microbiology Unit, Department of Health Security, Finnish Institute for Health and Welfare, FI-70701 Kuopio, Finland; (S.S.); (T.P.); (A.P.); (I.T.M.)
| | - Eila Torvinen
- Department of Environmental and Biological Sciences, University of Eastern Finland, FI-70211 Kuopio, Finland;
| | - Ilkka T. Miettinen
- Expert Microbiology Unit, Department of Health Security, Finnish Institute for Health and Welfare, FI-70701 Kuopio, Finland; (S.S.); (T.P.); (A.P.); (I.T.M.)
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27
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Eriksen RS, Mitarai N, Sneppen K. On Phage Adsorption to Bacterial Chains. Biophys J 2020; 119:1896-1904. [PMID: 33069271 PMCID: PMC7677248 DOI: 10.1016/j.bpj.2020.09.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 09/16/2020] [Accepted: 09/21/2020] [Indexed: 11/15/2022] Open
Abstract
Bacteria often arrange themselves in various spatial configurations, which changes how they interact with their surroundings. In this work, we investigate how the structure of the bacterial arrangements influences the adsorption of bacteriophages. We quantify how the adsorption rate scales with the number of bacteria in the arrangement and show that the adsorption rates for microcolonies (increasing with exponent ∼1/3) and bacterial chains (increasing with exponent ∼0.5-0.8) are substantially lower than for well-mixed bacteria (increasing with exponent 1). We further show that, after infection, the spatially clustered arrangements reduce the effective burst size by more than 50% and cause substantial superinfections in a very short time interval after phage lysis.
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Affiliation(s)
| | - Namiko Mitarai
- Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - Kim Sneppen
- Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark.
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28
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Zhang B, Yu P, Wang Z, Alvarez PJJ. Hormetic Promotion of Biofilm Growth by Polyvalent Bacteriophages at Low Concentrations. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:12358-12365. [PMID: 32886494 DOI: 10.1021/acs.est.0c03558] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Interactions between bacteriophages (phages) and biofilms are poorly understood despite their broad ecological and water quality implications. Here, we report that biofilm exposure to lytic polyvalent phages at low concentrations (i.e., 102-104 phages/mL) can counterintuitively promote biofilm growth and densification (corroborated by confocal laser scanning microscopy (CLSM)). Such exposure hormetically upregulated quorum sensing genes (by 4.1- to 24.9-fold), polysaccharide production genes (by 3.7- to 9.3-fold), and curli synthesis genes (by 4.5- to 6.5-fold) in the biofilm-dwelling bacterial hosts (i.e., Escherichia coli and Pseudomonas aeruginosa) relative to unexposed controls. Accordingly, the biofilm matrix increased its polysaccharide and extracellular DNA content relative to unexposed controls (by 41.8 ± 2.3 and 81.4 ± 2.2%, respectively), which decreased biofilm permeability and increased structural integrity. This contributed to enhanced resistance to disinfection with chlorine (bacteria half-lives were 6.08 ± 0.05 vs 3.91 ± 0.03 min for unexposed controls) and to subsequent phage infection (biomass removal was 18.2 ± 1.2 vs 32.3 ± 1.2% for unexposed controls), apparently by mitigating diffusion of these antibacterial agents through the biofilm. Overall, low concentrations of phages reaching a biofilm may result in unintended biofilm stimulation, which might accelerate biofouling, biocorrosion, or other biofilm-related water quality problems.
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Affiliation(s)
- Bo Zhang
- School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Pingfeng Yu
- Department of Civil and Environmental Engineering, Rice University, Houston 77005, United States
| | - Zijian Wang
- School of Civil and Environmental Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Pedro J J Alvarez
- Department of Civil and Environmental Engineering, Rice University, Houston 77005, United States
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29
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Rooney LM, Amos WB, Hoskisson PA, McConnell G. Intra-colony channels in E. coli function as a nutrient uptake system. THE ISME JOURNAL 2020; 14:2461-2473. [PMID: 32555430 PMCID: PMC7490401 DOI: 10.1038/s41396-020-0700-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 05/05/2020] [Accepted: 05/12/2020] [Indexed: 12/13/2022]
Abstract
The ability of microorganisms to grow as aggregated assemblages has been known for many years, however their structure has remained largely unexplored across multiple spatial scales. The development of the Mesolens, an optical system which uniquely allows simultaneous imaging of individual bacteria over a 36 mm2 field of view, has enabled the study of mature Escherichia coli macro-colony biofilm architecture like never before. The Mesolens enabled the discovery of intra-colony channels on the order of 10 μm in diameter, that are integral to E. coli macro-colony biofilms and form as an emergent property of biofilm growth. These channels have a characteristic structure and re-form after total mechanical disaggregation of the colony. We demonstrate that the channels are able to transport particles and play a role in the acquisition of and distribution of nutrients through the biofilm. These channels potentially offer a new route for the delivery of dispersal agents for antimicrobial drugs to biofilms, ultimately lowering their impact on public health and industry.
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Affiliation(s)
- Liam M Rooney
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, 161 Cathedral Street, Glasgow, G4 0RE, UK.
- Institute of Biological Chemistry, Biophysics and Bioengineering, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK.
| | - William B Amos
- Department of Physics, SUPA, University of Strathclyde, 107 Rottenrow East, Glasgow, G4 0NG, UK
| | - Paul A Hoskisson
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, 161 Cathedral Street, Glasgow, G4 0RE, UK
| | - Gail McConnell
- Department of Physics, SUPA, University of Strathclyde, 107 Rottenrow East, Glasgow, G4 0NG, UK
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30
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Guerin E, Hill C. Shining Light on Human Gut Bacteriophages. Front Cell Infect Microbiol 2020; 10:481. [PMID: 33014897 PMCID: PMC7511551 DOI: 10.3389/fcimb.2020.00481] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 08/04/2020] [Indexed: 12/15/2022] Open
Abstract
The human gut is a complex environment that contains a multitude of microorganisms that are collectively termed the microbiome. Multiple factors have a role to play in driving the composition of human gut bacterial communities either toward homeostasis or the instability that is associated with many disease states. One of the most important forces are likely to be bacteriophages, bacteria-infecting viruses that constitute by far the largest portion of the human gut virome. Despite this, bacteriophages (phages) are the one of the least studied residents of the gut. This is largely due to the challenges associated with studying these difficult to culture entities. Modern high throughput sequencing technologies have played an important role in improving our understanding of the human gut phageome but much of the generated sequencing data remains uncharacterised. Overcoming this requires database-independent bioinformatic pipelines and even those phages that are successfully characterized only provide limited insight into their associated biological properties, and thus most viral sequences have been characterized as “viral dark matter.” Fundamental to understanding the role of phages in shaping the human gut microbiome, and in turn perhaps influencing human health, is how they interact with their bacterial hosts. An essential aspect is the isolation of novel phage-bacteria host pairs by direct isolation through various screening methods, which can transform in silico phages into a biological reality. However, this is also beset with multiple challenges including culturing difficulties and the use of traditional methods, such as plaquing, which may bias which phage-host pairs that can be successfully isolated. Phage-bacteria interactions may be influenced by many aspects of complex human gut biology which can be difficult to reproduce under laboratory conditions. Here we discuss some of the main findings associated with the human gut phageome to date including composition, our understanding of phage-host interactions, particularly the observed persistence of virulent phages and their hosts, as well as factors that may influence these highly intricate relationships. We also discuss current methodologies and bottlenecks hindering progression in this field and identify potential steps that may be useful in overcoming these hurdles.
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Affiliation(s)
- Emma Guerin
- APC Microbiome Ireland, University College Cork, Cork, Ireland.,School of Microbiology, University College Cork, Cork, Ireland
| | - Colin Hill
- APC Microbiome Ireland, University College Cork, Cork, Ireland.,School of Microbiology, University College Cork, Cork, Ireland
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31
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Lourenço M, Chaffringeon L, Lamy-Besnier Q, Pédron T, Campagne P, Eberl C, Bérard M, Stecher B, Debarbieux L, De Sordi L. The Spatial Heterogeneity of the Gut Limits Predation and Fosters Coexistence of Bacteria and Bacteriophages. Cell Host Microbe 2020; 28:390-401.e5. [DOI: 10.1016/j.chom.2020.06.002] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 03/30/2020] [Accepted: 06/02/2020] [Indexed: 02/08/2023]
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32
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Jarett JK, Džunková M, Schulz F, Roux S, Paez-Espino D, Eloe-Fadrosh E, Jungbluth SP, Ivanova N, Spear JR, Carr SA, Trivedi CB, Corsetti FA, Johnson HA, Becraft E, Kyrpides N, Stepanauskas R, Woyke T. Insights into the dynamics between viruses and their hosts in a hot spring microbial mat. ISME JOURNAL 2020; 14:2527-2541. [PMID: 32661357 PMCID: PMC7490370 DOI: 10.1038/s41396-020-0705-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 06/03/2020] [Accepted: 06/11/2020] [Indexed: 12/28/2022]
Abstract
Our current knowledge of host-virus interactions in biofilms is limited to computational predictions based on laboratory experiments with a small number of cultured bacteria. However, natural biofilms are diverse and chiefly composed of uncultured bacteria and archaea with no viral infection patterns and lifestyle predictions described to date. Herein, we predict the first DNA sequence-based host-virus interactions in a natural biofilm. Using single-cell genomics and metagenomics applied to a hot spring mat of the Cone Pool in Mono County, California, we provide insights into virus-host range, lifestyle and distribution across different mat layers. Thirty-four out of 130 single cells contained at least one viral contig (26%), which, together with the metagenome-assembled genomes, resulted in detection of 59 viruses linked to 34 host species. Analysis of single-cell amplification kinetics revealed a lack of active viral replication on the single-cell level. These findings were further supported by mapping metagenomic reads from different mat layers to the obtained host-virus pairs, which indicated a low copy number of viral genomes compared to their hosts. Lastly, the metagenomic data revealed high layer specificity of viruses, suggesting limited diffusion to other mat layers. Taken together, these observations indicate that in low mobility environments with high microbial abundance, lysogeny is the predominant viral lifestyle, in line with the previously proposed "Piggyback-the-Winner" theory.
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Affiliation(s)
- Jessica K Jarett
- Department of Energy Joint Genome Institute, Berkeley, CA, USA.,Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.,AnimalBiome, Oakland, CA, USA
| | - Mária Džunková
- Department of Energy Joint Genome Institute, Berkeley, CA, USA. .,Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| | - Frederik Schulz
- Department of Energy Joint Genome Institute, Berkeley, CA, USA.,Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Simon Roux
- Department of Energy Joint Genome Institute, Berkeley, CA, USA.,Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - David Paez-Espino
- Department of Energy Joint Genome Institute, Berkeley, CA, USA.,Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Emiley Eloe-Fadrosh
- Department of Energy Joint Genome Institute, Berkeley, CA, USA.,Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Sean P Jungbluth
- Department of Energy Joint Genome Institute, Berkeley, CA, USA.,Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Natalia Ivanova
- Department of Energy Joint Genome Institute, Berkeley, CA, USA.,Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - John R Spear
- Civil and Environmental Engineering, Colorado School of Mines, Golden, CO, USA
| | | | | | | | - Hope A Johnson
- California State University Fullerton, Fullerton, CA, USA
| | - Eric Becraft
- University of North Alabama, Florence, AL, USA.,Bigelow Laboratory for Ocean Sciences, East Boothbay, ME, USA
| | - Nikos Kyrpides
- Department of Energy Joint Genome Institute, Berkeley, CA, USA.,Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | | | - Tanja Woyke
- Department of Energy Joint Genome Institute, Berkeley, CA, USA. .,Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA, USA. .,University of California, Merced, CA, USA.
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33
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Simmons EL, Bond MC, Koskella B, Drescher K, Bucci V, Nadell CD. Biofilm Structure Promotes Coexistence of Phage-Resistant and Phage-Susceptible Bacteria. mSystems 2020; 5:e00877-19. [PMID: 32576653 PMCID: PMC7311319 DOI: 10.1128/msystems.00877-19] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 05/29/2020] [Indexed: 01/21/2023] Open
Abstract
Encounters among bacteria and their viral predators (bacteriophages) are among the most common ecological interactions on Earth. These encounters are likely to occur with regularity inside surface-bound communities that microbes most often occupy in natural environments. Such communities, termed biofilms, are spatially constrained: interactions become limited to near neighbors, diffusion of solutes and particulates can be reduced, and there is pronounced heterogeneity in nutrient access and physiological state. It is appreciated from prior theoretical work that phage-bacteria interactions are fundamentally different in spatially structured contexts, as opposed to well-mixed liquid culture. Spatially structured communities are predicted to promote the protection of susceptible host cells from phage exposure, and thus weaken selection for phage resistance. The details and generality of this prediction in realistic biofilm environments, however, are not known. Here, we explore phage-host interactions using experiments and simulations that are tuned to represent the essential elements of biofilm communities. Our simulations show that in biofilms, phage-resistant cells-as their relative abundance increases-can protect clusters of susceptible cells from phage exposure, promoting the coexistence of susceptible and phage-resistant bacteria under a large array of conditions. We characterize the population dynamics underlying this coexistence, and we show that coexistence is recapitulated in an experimental model of biofilm growth measured with confocal microscopy. Our results provide a clear view into the dynamics of phage resistance in biofilms with single-cell resolution of the underlying cell-virion interactions, linking the predictions of canonical theory to realistic models and in vitro experiments of biofilm growth.IMPORTANCE In the natural environment, bacteria most often live in communities bound to one another by secreted adhesives. These communities, or biofilms, play a central role in biogeochemical cycling, microbiome functioning, wastewater treatment, and disease. Wherever there are bacteria, there are also viruses that attack them, called phages. Interactions between bacteria and phages are likely to occur ubiquitously in biofilms. We show here, using simulations and experiments, that biofilms will in most conditions allow phage-susceptible bacteria to be protected from phage exposure, if they are growing alongside other cells that are phage resistant. This result has implications for the fundamental ecology of phage-bacteria interactions, as well as the development of phage-based antimicrobial therapeutics.
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Affiliation(s)
- Emilia L Simmons
- Department of Biological Sciences, Dartmouth, Hanover, New Hampshire, USA
| | - Matthew C Bond
- Department of Biological Sciences, Dartmouth, Hanover, New Hampshire, USA
| | - Britt Koskella
- Department of Integrative Biology, University of California, Berkeley, Berkeley, California, USA
| | - Knut Drescher
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
- Department of Physics, Philipps-Universität Marburg, Marburg, Germany
| | - Vanni Bucci
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Carey D Nadell
- Department of Biological Sciences, Dartmouth, Hanover, New Hampshire, USA
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34
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Hitchhiking, collapse, and contingency in phage infections of migrating bacterial populations. ISME JOURNAL 2020; 14:2007-2018. [PMID: 32358533 DOI: 10.1038/s41396-020-0664-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 04/05/2020] [Accepted: 04/15/2020] [Indexed: 01/17/2023]
Abstract
Natural bacterial populations are subjected to constant predation pressure by bacteriophages. Bacteria use a variety of molecular mechanisms to defend themselves from phage predation. However, since phages are nonmotile, perhaps the simplest defense against phage is for bacteria to move faster than phages. In particular, chemotaxis, the active migration of bacteria up attractant gradients, may help the bacteria escape slowly diffusing phages. Here we study phage infection dynamics in migrating bacterial populations driven by chemotaxis through low viscosity agar plates. We find that expanding phage-bacteria populations supports two moving fronts, an outermost bacterial front driven by nutrient uptake and chemotaxis and an inner phage front at which the bacterial population collapses due to phage predation. We show that with increasing adsorption rate and initial phage population, the speed of the moving phage front increases, eventually overtaking the bacterial front and driving the system across a transition from a regime where bacterial front speed exceeds that of the phage front to one where bacteria must evolve phage resistance to survive. Our data support the claim that this process requires phage to hitchhike with moving bacteria. A deterministic model recapitulates the transition under the assumption that phage virulence declines with host growth rate which we confirm experimentally. Finally, near the transition between regimes we observe macroscopic fluctuations in bacterial densities at the phage front. Our work opens a new, spatio-temporal, line of investigation into the eco-evolutionary struggle between bacteria and phage.
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35
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Tan D, Zhang Y, Qin J, Le S, Gu J, Chen LK, Guo X, Zhu T. A Frameshift Mutation in wcaJ Associated with Phage Resistance in Klebsiella pneumoniae. Microorganisms 2020; 8:microorganisms8030378. [PMID: 32156053 PMCID: PMC7142929 DOI: 10.3390/microorganisms8030378] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 03/03/2020] [Accepted: 03/05/2020] [Indexed: 01/21/2023] Open
Abstract
Phage therapy is a potential and promising avenue for controlling the emergence and spread of multidrug-resistant (MDR) Klebsiella pneumoniae, however, the rapid development of anti-phage resistance has been identified as an obstacle to the development of phage therapy. Little is known about the mechanism employed by MDR K. pneumoniae strains and how they protect themselves from lytic phage predation in vitro and in vivo. In this study, comparative genomic analysis shows undecaprenyl-phosphate glucose-1-phosphate transferase (WcaJ), the initial enzyme catalyzing the biosynthesis of colanic acid, is necessary for the adsorption of phage 117 (Podoviridae) to the host strain Kp36 to complete its lytic life cycle. In-frame deletion of wcaJ alone was sufficient to provide phage 117 resistance in the Kp36 wild-type strain. Complementation assays demonstrated the susceptibility of phage 117, and the mucoid phenotype could be restored in the resistant strain Kp36-117R by expressing the wild-type version of wcaJ. Remarkably, we found that bacterial mobile genetic elements (insA and insB) block phage 117 infections by disrupting the coding region of wcaJ, thus preventing phage adsorption to its phage receptor. Further, we revealed that the wcaJ mutation likely occurred spontaneously rather than adapted by phage 117 predation under unfavorable environments. Taken together, our results address a crucial evolutionary question around the mechanisms of phage-host interactions, increasing our current understandings of anti-phage defense mechanisms in this important MDR pathogen.
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Affiliation(s)
- Demeng Tan
- Shanghai Public Health Clinical Center, Fudan University, Shanghai 201508, China
- Correspondence: (D.T.); (T.Z.)
| | - Yiyuan Zhang
- Shanghai Public Health Clinical Center, Fudan University, Shanghai 201508, China
| | - Jinhong Qin
- Institutes of Medical Sciences, Shanghai Jiao Tong University, Shanghai 200025, China
| | - Shuai Le
- Shanghai Public Health Clinical Center, Fudan University, Shanghai 201508, China
| | - Jingmin Gu
- Shanghai Public Health Clinical Center, Fudan University, Shanghai 201508, China
| | - Li-kuang Chen
- Shanghai Public Health Clinical Center, Fudan University, Shanghai 201508, China
| | - Xiaokui Guo
- Institutes of Medical Sciences, Shanghai Jiao Tong University, Shanghai 200025, China
| | - Tongyu Zhu
- Shanghai Public Health Clinical Center, Fudan University, Shanghai 201508, China
- Correspondence: (D.T.); (T.Z.)
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36
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Henriksen K, Rørbo N, Rybtke ML, Martinet MG, Tolker-Nielsen T, Høiby N, Middelboe M, Ciofu O. P. aeruginosa flow-cell biofilms are enhanced by repeated phage treatments but can be eradicated by phage-ciprofloxacin combination. Pathog Dis 2020; 77:5368070. [PMID: 30821815 DOI: 10.1093/femspd/ftz011] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Accepted: 02/28/2019] [Indexed: 02/06/2023] Open
Abstract
Phage therapy has shown promising results in the treatment of Pseudomonas aeruginosa biofilm infections in animal studies and case reports. The aim of this study was to quantify effects of phage treatments on P. aeruginosa biofilm production and structure. Confocal scanning microscopy was used to follow the interaction between a cocktail of three virulent phages and P. aeruginosa flow-cell biofilms. The role of (i) biofilm age, (ii) repeated phage treatments, (iii) alginate production and (iv) the combination with sub-MIC levels of ciprofloxacin was investigated. Single phage treatment in the early biofilm stages significantly reduced P. aeruginosa PAO1 biovolume (85%-98% reduction). Repeated phage treatments increased the biovolume from 18.25 (untreated biofilm) to 22.24 and 31.07 µm3/µm2 for biofilms treated with phages twice and thrice, respectively. Alginate protected against the phage treatment as the live biovolume remained unaffected by the phage treatment in the mucoid biofilm (20.11 µm3/µm2 in untreated and 21.74 µm3/µm2 in phage-treated biofilm) but decreased in the PAO1 biofilm from 27.35 to 0.89 µm3/µm2. We show that the combination of phages with antibiotics at sub-MIC levels caused a ∼6 log units reduction in the abundance of P. aeruginosa cells in biofilms and that phage treatment increased the size of microcolonies in flow-cell system.
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Affiliation(s)
- Karoline Henriksen
- Department of Immunology and Microbiology, Costerton Biofilm Center, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 N, Copenhagen, Denmark
| | - Nanna Rørbo
- Department of Biology, Marine Biological Section, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, Denmark
| | - Morten Levin Rybtke
- Department of Immunology and Microbiology, Costerton Biofilm Center, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 N, Copenhagen, Denmark
| | - Mark Grevsen Martinet
- Department of Immunology and Microbiology, Costerton Biofilm Center, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 N, Copenhagen, Denmark
| | - Tim Tolker-Nielsen
- Department of Immunology and Microbiology, Costerton Biofilm Center, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 N, Copenhagen, Denmark
| | - Niels Høiby
- Department of Immunology and Microbiology, Costerton Biofilm Center, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 N, Copenhagen, Denmark.,Department of Clinical Microbiology, University Hospital, Rigshospitalet, Henrik Harpestrengs Vej 4A, 2100 , Copenhagen, Denmark
| | - Mathias Middelboe
- Department of Biology, Marine Biological Section, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, Denmark
| | - Oana Ciofu
- Department of Immunology and Microbiology, Costerton Biofilm Center, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 N, Copenhagen, Denmark
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37
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Eriksen RS, Mitarai N, Sneppen K. Sustainability of spatially distributed bacteria-phage systems. Sci Rep 2020; 10:3154. [PMID: 32081858 PMCID: PMC7035299 DOI: 10.1038/s41598-020-59635-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 01/09/2020] [Indexed: 11/09/2022] Open
Abstract
Virulent phages can expose their bacterial hosts to devastating epidemics, in principle leading to complete elimination of their hosts. Although experiments indeed confirm a large reduction of susceptible bacteria, there are no reports of complete extinctions. We here address this phenomenon from the perspective of spatial organization of bacteria and how this can influence the final survival of them. By modelling the transient dynamics of bacteria and phages when they are introduced into an environment with finite resources, we quantify how time delayed lysis, the spatial separation of initial bacterial positions, and the self-protection of bacteria growing in spherical colonies favour bacterial survival. Our results suggest that spatial structures on the millimetre and submillimetre scale play an important role in maintaining microbial diversity.
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Affiliation(s)
| | - Namiko Mitarai
- Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark.
| | - Kim Sneppen
- Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark.
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Mitarai N. How pirate phage interferes with helper phage: Comparison of the two distinct strategies. J Theor Biol 2019; 486:110096. [PMID: 31786182 DOI: 10.1016/j.jtbi.2019.110096] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Revised: 11/27/2019] [Accepted: 11/28/2019] [Indexed: 11/26/2022]
Abstract
Pirate phages use the structural proteins encoded by unrelated helper phages to propagate. The best-studied example is the pirate P4 and helper P2 of coliphages, and it has been known that the Staphylococcus aureus pathogenicity islands (SaPIs) that can encode virulence factors act as pirate phages, too. When alone in the host, the pirate phages act as a prophage, but when the helper phage gene is also in the same host cell, the pirate phage has ability to exploit the helper phages structural proteins to produce pirate phage particles and spread, interfering with the helper phage production. The known helper phages in these systems are temperate phages. Interestingly, the interference of the pirate phage to the helper phage occurs in a different manner between the SaPI-helper system and the P4-P2 system. SaPIs cannot lyse a helper lysogen upon infection, while when a helper phage lyse a SaPI lysogen, most of the phage particles produced are the SaPI particles. On the contrary, in the P4-P2 system, a pirate phage P4 can lyse a helper P2 lysogen to produce mostly the P4 particles, while when P2 phage lyses a P4 lysogen, most of the produced phages are the P2 particles. Here, the consequences of these different strategies in the pirate and helper phage spreading among uninfected host is analyzed by using mathematical models. It is found that SaPI's strategy interferes with the helper phage spreading significantly more than the P4's strategy, because SaPI interferes with the helper phage's main reproduction step, while P4 interferes only by forcing the helper lysogens to lyse. However, the interference is found to be weaker in the spatially structured environment than in the well-mixed environment. This is because, in the spatial setting, the system tends to self-organize so that the helper phages take over the front of propagation due to the need of helper phage for the pirate phage spreading.
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Affiliation(s)
- Namiko Mitarai
- The Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, Copenhagen, 2100-DK, Denmark.
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Testa S, Berger S, Piccardi P, Oechslin F, Resch G, Mitri S. Spatial structure affects phage efficacy in infecting dual-strain biofilms of Pseudomonas aeruginosa. Commun Biol 2019; 2:405. [PMID: 31701033 PMCID: PMC6828766 DOI: 10.1038/s42003-019-0633-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 09/26/2019] [Indexed: 12/12/2022] Open
Abstract
Bacterial viruses, or phage, are key members of natural microbial communities. Yet much research on bacterial-phage interactions has been conducted in liquid cultures involving single bacterial strains. Here we explored how bacterial diversity affects the success of lytic phage in structured communities. We infected a sensitive Pseudomonas aeruginosa strain PAO1 with a lytic phage Pseudomonas 352 in the presence versus absence of an insensitive P. aeruginosa strain PA14, in liquid culture versus colonies on agar. We found that both in liquid and in colonies, inter-strain competition reduced resistance evolution in the susceptible strain and decreased phage population size. However, while all sensitive bacteria died in liquid, bacteria in colonies could remain sensitive yet escape phage infection, due mainly to reduced growth in colony centers. In sum, spatial structure can protect bacteria against phage infection, while the presence of competing strains reduces the evolution of resistance to phage.
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Affiliation(s)
- Samuele Testa
- Department of Fundamental Microbiology, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Sarah Berger
- Department of Fundamental Microbiology, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Philippe Piccardi
- Department of Fundamental Microbiology, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Frank Oechslin
- Department of Fundamental Microbiology, University of Lausanne, CH-1015 Lausanne, Switzerland
- Department of Biochemistry, Microbiology and Bioinformatics, Université Laval, Québec City, QC Canada
| | - Grégory Resch
- Department of Fundamental Microbiology, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Sara Mitri
- Department of Fundamental Microbiology, University of Lausanne, CH-1015 Lausanne, Switzerland
- Swiss Institute for Bioinformatics, Lausanne, Switzerland
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40
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Big Impact of the Tiny: Bacteriophage-Bacteria Interactions in Biofilms. Trends Microbiol 2019; 27:739-752. [PMID: 31128928 DOI: 10.1016/j.tim.2019.04.006] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 04/10/2019] [Accepted: 04/19/2019] [Indexed: 01/17/2023]
Abstract
Bacteriophages (phages) have been shaping bacterial ecology and evolution for millions of years, for example, by selecting for defence strategies. Evidence supports that bacterial biofilm formation is one such strategy and that biofilm-mediated protection against phage infection depends on maturation and composition of the extracellular matrix. Interestingly, studies have revealed that phages can induce and strengthen biofilms. Here we review interactions between bacteria and phages in biofilms, discuss the underlying mechanisms, the potential of phage therapy for biofilm control, and emphasize the importance of considering biofilms in future phage research. This is especially relevant as biofilms are associated with increased tolerance towards antibiotics and are implicated in the majority of chronic infections.
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41
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Abstract
Bacteria are under constant attack from bacteriophages (phages), bacterial parasites that are the most abundant biological entity on earth. To resist phage infection, bacteria have evolved an impressive arsenal of anti-phage systems. Recent advances have significantly broadened and deepened our understanding of how bacteria battle phages, spearheaded by new systems like CRISPR-Cas. This review aims to summarize bacterial anti-phage mechanisms, with an emphasis on the most recent developments in the field.
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Affiliation(s)
- Jakob T Rostøl
- Laboratory of Bacteriology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Luciano Marraffini
- Laboratory of Bacteriology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA; Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10065, USA.
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42
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Lourenço M, De Sordi L, Debarbieux L. The Diversity of Bacterial Lifestyles Hampers Bacteriophage Tenacity. Viruses 2018; 10:v10060327. [PMID: 29914064 PMCID: PMC6024678 DOI: 10.3390/v10060327] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 06/08/2018] [Accepted: 06/11/2018] [Indexed: 12/26/2022] Open
Abstract
Phage therapy is based on a simple concept: the use of a virus (bacteriophage) that is capable of killing specific pathogenic bacteria to treat bacterial infections. Since the pioneering work of Félix d’Herelle, bacteriophages (phages) isolated in vitro have been shown to be of therapeutic value. Over decades of study, a large number of rather complex mechanisms that are used by phages to hijack bacterial resources and to produce their progeny have been deciphered. While these mechanisms have been identified and have been studied under optimal conditions in vitro, much less is known about the requirements for successful viral infections in relevant natural conditions. This is particularly true in the context of phage therapy. Here, we highlight the parameters affecting phage replication in both in vitro and in vivo environments, focusing, in particular, on the mammalian digestive tract. We propose avenues for increasing the knowledge-guided implementation of phages as therapeutic tools.
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Affiliation(s)
- Marta Lourenço
- Department of Microbiology, Institut Pasteur, F-75015 Paris, France.
- Collège Doctoral, Sorbonne Université, F-75005 Paris, France.
| | - Luisa De Sordi
- Department of Microbiology, Institut Pasteur, F-75015 Paris, France.
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Bull JJ, Christensen KA, Scott C, Jack BR, Crandall CJ, Krone SM. Phage-Bacterial Dynamics with Spatial Structure: Self Organization around Phage Sinks Can Promote Increased Cell Densities. Antibiotics (Basel) 2018; 7:antibiotics7010008. [PMID: 29382134 PMCID: PMC5872119 DOI: 10.3390/antibiotics7010008] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Revised: 01/21/2018] [Accepted: 01/23/2018] [Indexed: 11/16/2022] Open
Abstract
Bacteria growing on surfaces appear to be profoundly more resistant to control by lytic bacteriophages than do the same cells grown in liquid. Here, we use simulation models to investigate whether spatial structure per se can account for this increased cell density in the presence of phages. A measure is derived for comparing cell densities between growth in spatially structured environments versus well mixed environments (known as mass action). Maintenance of sensitive cells requires some form of phage death; we invoke death mechanisms that are spatially fixed, as if produced by cells. Spatially structured phage death provides cells with a means of protection that can boost cell densities an order of magnitude above that attained under mass action, although the effect is sometimes in the opposite direction. Phage and bacteria self organize into separate refuges, and spatial structure operates so that the phage progeny from a single burst do not have independent fates (as they do with mass action). Phage incur a high loss when invading protected areas that have high cell densities, resulting in greater protection for the cells. By the same metric, mass action dynamics either show no sustained bacterial elevation or oscillate between states of low and high cell densities and an elevated average. The elevated cell densities observed in models with spatial structure do not approach the empirically observed increased density of cells in structured environments with phages (which can be many orders of magnitude), so the empirical phenomenon likely requires additional mechanisms than those analyzed here.
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Affiliation(s)
- James J Bull
- Department of Integrative Biology, University of Texas, Austin, TX 78712, USA.
- The Institute for Cellular and Molecular Biology, University of Texas, Austin, TX 78712, USA.
- Center for Computational Biology and Bioinformatics, University of Texas, Austin, TX 78712, USA.
| | - Kelly A Christensen
- Department of Mathematics, University of Idaho, Moscow, ID 83844, USA.
- Center for Modeling Complex Interactions, University of Idaho, Moscow, ID 83844, USA.
| | - Carly Scott
- Department of Mathematics, University of Idaho, Moscow, ID 83844, USA.
- Department of Biological Sciences, University of Idaho, Moscow, ID 83844, USA.
| | - Benjamin R Jack
- The Institute for Cellular and Molecular Biology, University of Texas, Austin, TX 78712, USA.
| | - Cameron J Crandall
- Department of Biological Sciences, University of Idaho, Moscow, ID 83844, USA.
| | - Stephen M Krone
- Department of Mathematics, University of Idaho, Moscow, ID 83844, USA.
- Center for Modeling Complex Interactions, University of Idaho, Moscow, ID 83844, USA.
- Institute for Bioinformatics and Evolutionary Studies, University of Idaho, Moscow, ID 83844, USA.
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