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Grandy S, Scur M, Dolan K, Nickerson R, Cheng Z. Using model systems to unravel host-Pseudomonas aeruginosa interactions. Environ Microbiol 2023; 25:1765-1784. [PMID: 37290773 DOI: 10.1111/1462-2920.16440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 05/29/2023] [Indexed: 06/10/2023]
Abstract
Using model systems in infection biology has led to the discoveries of many pathogen-encoded virulence factors and critical host immune factors to fight pathogenic infections. Studies of the remarkable Pseudomonas aeruginosa bacterium that infects and causes disease in hosts as divergent as humans and plants afford unique opportunities to shed new light on virulence strategies and host defence mechanisms. One of the rationales for using model systems as a discovery tool to characterise bacterial factors driving human infection outcomes is that many P. aeruginosa virulence factors are required for pathogenesis in diverse different hosts. On the other side, many host signalling components, such as the evolutionarily conserved mitogen-activated protein kinases, are involved in immune signalling in a diverse range of hosts. Some model organisms that have less complex immune systems also allow dissection of the direct impacts of innate immunity on host defence without the interference of adaptive immunity. In this review, we start with discussing the occurrence of P. aeruginosa in the environment and the ability of this bacterium to cause disease in various hosts as a natural opportunistic pathogen. We then summarise the use of some model systems to study host defence and P. aeruginosa virulence.
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Affiliation(s)
- Shannen Grandy
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Michal Scur
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Kathleen Dolan
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Rhea Nickerson
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Zhenyu Cheng
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
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2
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Mun W, Choi SY, Upatissa S, Mitchell RJ. Predatory bacteria as potential biofilm control and eradication agents in the food industry. Food Sci Biotechnol 2023; 32:1729-1743. [PMID: 37780591 PMCID: PMC10533476 DOI: 10.1007/s10068-023-01310-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 04/04/2023] [Accepted: 04/12/2023] [Indexed: 10/03/2023] Open
Abstract
Biofilms are a major concern within the food industry since they have the potential to reduce productivity in situ (within the field), impact food stability and storage, and cause downstream food poisoning. Within this review, predatory bacteria as potential biofilm control and eradication agents are discussed, with a particular emphasis on the intraperiplasmic Bdellovibrio-and-like organism (BALO) grouping. After providing a brief overview of predatory bacteria and their activities, focus is given to how BALOs fulfill four attributes that are essential for biocontrol agents to be successful in the food industry: (1) Broad spectrum activity against pathogens, both plant and human; (2) Activity against biofilms; (3) Safety towards humans and animals; and (4) Compatibility with food. As predatory bacteria possess all of these characteristics, they represent a novel form of biofilm biocontrol that is ripe for use within the food industry.
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Affiliation(s)
- Wonsik Mun
- School of Biological Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919 South Korea
| | - Seong Yeol Choi
- School of Biological Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919 South Korea
| | - Sumudu Upatissa
- School of Biological Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919 South Korea
| | - Robert J. Mitchell
- School of Biological Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919 South Korea
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3
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Characterization of an engineered mucus microenvironment for in vitro modeling of host-microbe interactions. Sci Rep 2022; 12:5515. [PMID: 35365684 PMCID: PMC8975841 DOI: 10.1038/s41598-022-09198-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 03/14/2022] [Indexed: 11/13/2022] Open
Abstract
The human mucus layer plays a vital role in maintaining health by providing a physical barrier to pathogens. This biological hydrogel also provides the microenvironment for commensal bacteria. Common models used to study host–microbe interactions include gnotobiotic animals or mammalian–microbial co-culture platforms. Many of the current in vitro models lack a sufficient mucus layer to host these interactions. In this study, we engineered a mucus-like hydrogel Consisting of a mixed alginate-mucin (ALG-MUC) hydrogel network by using low concentration calcium chloride (CaCl2) as crosslinker. We demonstrated that the incorporation of ALG-MUC hydrogels into an aqueous two-phase system (ATPS) co-culture platform can support the growth of a mammalian monolayer and pathogenic bacteria. The ALG-MUC hydrogels displayed selective diffusivity against macromolecules and stability with ATPS microbial patterning. Additionally, we showed that the presence of mucin within hydrogels contributed to an increase in antimicrobial resistance in ATPS patterned microbial colonies. By using common laboratory chemicals to generate a mammalian–microbial co-culture system containing a representative mucus microenvironment, this model can be readily adopted by typical life science laboratories to study host–microbe interaction and drug discovery.
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4
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Huang AJ, Clarke AN, Jafari N, Leung BM. Characterization of Patterned Microbial Growth Dynamics in Aqueous Two-Phase Polymer Scaffolds. ACS Biomater Sci Eng 2021; 7:5506-5514. [PMID: 34757724 DOI: 10.1021/acsbiomaterials.1c01130] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Microbial growth confinement using liquid scaffolds based on an aqueous two-phase system (ATPS) is a promising technique to overcome the challenges in microbial-mammalian co-culture in vitro. To better understand the potential use of the ATPS in studying these complex interactions, the goal of this research was to characterize the effects of bacteria loading and biofilm maturation on the stability of a polyethylene glycol (PEG) and dextran (DEX) ATPS. Two ATPS formulations, consisting of 5% PEG/5% DEX and 10% PEG/10% DEX (w/v), were prepared. To test the containment limits of each ATPS formulation, Escherichia coli MG1655 overnight cultures were resuspended in DEX at optical densities (ODs) of 1, 0.3, 0.1, 0.03, and 0.01. Established E. coli colonies initially seeded at lower densities were contained within the DEX phase to a greater extent than E. coli colonies initially seeded at higher densities. Furthermore, the 10% PEG/10% DEX formulation demonstrated longer containment time of E. coli compared to the 5% PEG/5% DEX formulation. E. coli growth dynamics within the ATPS were found to be affected by the initial bacterial density, where colonies of lower initial seeding densities demonstrate more dynamic growth trends compared to colonies of higher initial seeding densities. However, the addition of DEX to the existing ATPS during the growth phase of the bacterial colony does not appear to disrupt the growth inertia of E. coli. We also observed that microbial growth can disrupt ATPS stability below the physical carrying capacity of the DEX droplets. In both E. coli and Streptococcus mutans UA159 colonies, the ATPS interfacial tensions are reduced, as suggested by the loss of fluorescein isothiocyanate (FITC)-DEX confinement and contact angel measurements, while the microbial colony remained well defined. In general, we observed that the stability of the ATPS microbial colony is proportional to polymer concentrations and inversely proportional to seeding density and culture time. These parameters can be combined as part of a toolset to control microbial growth in a heterotypic co-culture platform and should be considered in future work involving mammalian-microbial cell interactions.
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Affiliation(s)
- Andy J Huang
- School of Biomedical Engineering, Faculties of Medicine and Engineering, Dalhousie University, Halifax B3H 4R2, Nova Scotia, Canada.,Department of Applied Oral Sciences, Faculty of Dentistry, Dalhousie University, Halifax B3H 4R2, Nova Scotia, Canada
| | - Andrew N Clarke
- School of Biomedical Engineering, Faculties of Medicine and Engineering, Dalhousie University, Halifax B3H 4R2, Nova Scotia, Canada
| | - Naeimeh Jafari
- School of Biomedical Engineering, Faculties of Medicine and Engineering, Dalhousie University, Halifax B3H 4R2, Nova Scotia, Canada.,Department of Applied Oral Sciences, Faculty of Dentistry, Dalhousie University, Halifax B3H 4R2, Nova Scotia, Canada
| | - Brendan M Leung
- School of Biomedical Engineering, Faculties of Medicine and Engineering, Dalhousie University, Halifax B3H 4R2, Nova Scotia, Canada.,Department of Applied Oral Sciences, Faculty of Dentistry, Dalhousie University, Halifax B3H 4R2, Nova Scotia, Canada.,Department of Pathology, Faculty of Medicine, Dalhousie University, Halifax B3H 4R2, Nova Scotia, Canada
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5
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Ahmed T, Yamanishi C, Kojima T, Takayama S. Aqueous Two-Phase Systems and Microfluidics for Microscale Assays and Analytical Measurements. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2021; 14:231-255. [PMID: 33950741 DOI: 10.1146/annurev-anchem-091520-101759] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Phase separation is a common occurrence in nature. Synthetic and natural polymers, salts, ionic liquids, surfactants, and biomacromolecules phase separate in water, resulting in an aqueous two-phase system (ATPS). This review discusses the properties, handling, and uses of ATPSs. These systems have been used for protein, nucleic acid, virus, and cell purification and have in recent years found new uses for small organics, polysaccharides, extracellular vesicles, and biopharmaceuticals. Analytical biochemistry applications such as quantifying protein-protein binding, probing for conformational changes, or monitoring enzyme activity have been performed with ATPSs. Not only are ATPSs biocompatible, they also retain their properties at the microscale, enabling miniaturization experiments such as droplet microfluidics, bacterial quorum sensing, multiplexed and point-of-care immunoassays, and cell patterning. ATPSs include coacervates and may find wider interest in the context of intracellular phase separation and origin of life. Recent advances in fundamental understanding and in commercial application are also considered.
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Affiliation(s)
- Tasdiq Ahmed
- Walter H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory School of Medicine, Atlanta, Georgia 30332, USA;
| | - Cameron Yamanishi
- Walter H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory School of Medicine, Atlanta, Georgia 30332, USA;
| | - Taisuke Kojima
- Walter H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory School of Medicine, Atlanta, Georgia 30332, USA;
| | - Shuichi Takayama
- Walter H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory School of Medicine, Atlanta, Georgia 30332, USA;
- Parker H. Petit Institute of Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
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6
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Dwidar M, Jang H, Sangwan N, Mun W, Im H, Yoon S, Choi S, Nam D, Mitchell RJ. Diffusible Signaling Factor, a Quorum-Sensing Molecule, Interferes with and Is Toxic Towards Bdellovibrio bacteriovorus 109J. MICROBIAL ECOLOGY 2021; 81:347-356. [PMID: 32892232 DOI: 10.1007/s00248-020-01585-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Accepted: 08/24/2020] [Indexed: 06/11/2023]
Abstract
Bdellovibrio bacteriovorus 109J is a predatory bacterium which lives by predating on other Gram-negative bacteria to obtain the nutrients it needs for replication and survival. Here, we evaluated the effects two classes of bacterial signaling molecules (acyl homoserine lactones (AHLs) and diffusible signaling factor (DSF)) have on B. bacteriovorus 109J behavior and viability. While AHLs had a non-significant impact on predation rates, DSF considerably delayed predation and bdelloplast lysis. Subsequent experiments showed that 50 μM DSF also reduced the motility of attack-phase B. bacteriovorus 109J cells by 50% (38.2 ± 14.9 vs. 17 ± 8.9 μm/s). Transcriptomic analyses found that DSF caused genome-wide changes in B. bacteriovorus 109J gene expression patterns during both the attack and intraperiplasmic phases, including the significant downregulation of the flagellum assembly genes and numerous serine protease genes. While the former accounts for the reduced speeds observed, the latter was confirmed experimentally with 50 μM DSF completely blocking protease secretion from attack-phase cells. Additional experiments found that 30% of the total cellular ATP was released into the supernatant when B. bacteriovorus 109J was exposed to 200 μM DSF, implying that this QS molecule negatively impacts membrane integrity.
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Affiliation(s)
- Mohammed Dwidar
- Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH, 44195, USA.
- Department of Cardiovascular & Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA.
- Center for Microbiome and Human Health, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA.
| | - Hyochan Jang
- School of Life Sciences, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan, 44919, Republic of Korea
| | - Naseer Sangwan
- Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH, 44195, USA
- Department of Cardiovascular & Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
- Center for Microbiome and Human Health, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Wonsik Mun
- School of Life Sciences, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan, 44919, Republic of Korea
| | - Hansol Im
- School of Life Sciences, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan, 44919, Republic of Korea
| | - Sora Yoon
- School of Life Sciences, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan, 44919, Republic of Korea
| | - Sooin Choi
- School of Life Sciences, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan, 44919, Republic of Korea
| | - Dougu Nam
- School of Life Sciences, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan, 44919, Republic of Korea.
| | - Robert J Mitchell
- School of Life Sciences, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan, 44919, Republic of Korea.
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7
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Tan HY, Toh YC. What can microfluidics do for human microbiome research? BIOMICROFLUIDICS 2020; 14:051303. [PMID: 33062112 PMCID: PMC7538166 DOI: 10.1063/5.0012185] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 09/17/2020] [Indexed: 05/13/2023]
Abstract
Dysregulation of the human microbiome has been linked to various disease states, which has galvanized the efforts to modulate human health through microbiomes. Currently, human microbiome research is going through several phases to identify the constituent components of the microbiome, associate microbiome changes with physiological and pathological states, understand causative relationships, and finally translate this knowledge into therapeutics and diagnostics. The convergence of microfluidic technologies with molecular and cell profiling, microbiology, and tissue engineering can potentially be applied to these different phases of microbiome research to overcome the existing challenges faced by conventional approaches. The goal of this paper is to discuss and highlight the opportunities of applying different microfluidic technologies to specific areas of microbiome research as well as unique challenges that microfluidics must overcome when working with microbiome-relevant biological materials, e.g., micro-organisms, host tissues, and fluids. We will discuss the applicability of integrated microfluidic systems for processing biological samples for genomic sequencing analyses. For functional analysis of the microbiota, we will cover state-of-the-art microfluidic devices for microbiota cultivation and functional measurements. Finally, we highlight the use of organs-on-chips to model various microbiome-host tissue interactions. We envision that microfluidic technologies may hold great promise in advancing the knowledge on the interplay between microbiome and human health, as well as its eventual translation into microbiome-based diagnostics and therapeutics.
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Affiliation(s)
- Hsih-Yin Tan
- Institute for Health Innovation and Technology, National University of Singapore, Singapore 117599
| | - Yi-Chin Toh
- Author to whom correspondence should be addressed:
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8
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Mountcastle SE, Cox SC, Sammons RL, Jabbari S, Shelton RM, Kuehne SA. A review of co-culture models to study the oral microenvironment and disease. J Oral Microbiol 2020; 12:1773122. [PMID: 32922679 PMCID: PMC7448840 DOI: 10.1080/20002297.2020.1773122] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 04/25/2020] [Accepted: 05/19/2020] [Indexed: 12/19/2022] Open
Abstract
Co-cultures allow for the study of cell-cell interactions between different eukaryotic species or with bacteria. Such an approach has enabled researchers to more closely mimic complex tissue structures. This review is focused on co-culture systems modelling the oral cavity, which have been used to evaluate this unique cellular environment and understand disease progression. Over time, these systems have developed significantly from simple 2D eukaryotic cultures and planktonic bacteria to more complex 3D tissue engineered structures and biofilms. Careful selection and design of the co-culture along with critical parameters, such as seeding density and choice of analysis method, have resulted in several advances. This review provides a comparison of existing co-culture systems for the oral environment, with emphasis on progression of 3D models and the opportunity to harness techniques from other fields to improve current methods. While filling a gap in navigating this literature, this review ultimately supports the development of this vital technique in the field of oral biology.
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Affiliation(s)
- Sophie E Mountcastle
- EPSRC Centre for Doctoral Training in Physical Sciences for Health, University of Birmingham, Birmingham, UK
- School of Dentistry, University of Birmingham, Birmingham, UK
| | - Sophie C Cox
- School of Chemical Engineering, University of Birmingham, Birmingham, UK
| | | | - Sara Jabbari
- School of Mathematics, University of Birmingham, Birmingham, UK
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, UK
| | | | - Sarah A Kuehne
- School of Dentistry, University of Birmingham, Birmingham, UK
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, UK
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9
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Im H, Kwon H, Cho G, Kwon J, Choi SY, Mitchell RJ. Viscosity has dichotomous effects on Bdellovibrio bacteriovorus HD100 predation. Environ Microbiol 2019; 21:4675-4684. [PMID: 31498968 DOI: 10.1111/1462-2920.14799] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2019] [Accepted: 09/05/2019] [Indexed: 11/28/2022]
Abstract
Bdellovibrio bacteriovorus HD100 is a highly motile predatory bacterium that consumes other Gram-negative bacteria for its sustenance. Here, we describe the impacts the media viscosity has both on the motility of predator and its attack rates. Experiments performed in polyethylene glycol (PEG) solutions, a linear polymer, found a viscosity of 10 mPa s (5% PEG) negatively impacted predation over a 24-h period. When the viscosity was increased to 27 mPa s (10% PEG), predation was nearly abolished. Tests with three other B. bacteriovorus strains, i.e., 109J and two natural isolates, found identical results. Short-term (2-h) experiments, however, found attack rates were improved in 1% PEG, which had a viscosity of 5.4 mPa s, using bioluminescent prey and their viabilities. In contrast, when experiments were performed in dextran, a branched polymer, no increase in predation was seen even though the viscosity was a comparable 5.1 mPa s. The enhanced attack rates in this solution coincided with a 31% increase in B. bacteriovorus HD100 swimming speeds (62 μm s-1 in 1% PEG vs. 47.5 μm s-1 in HEPES-salt).
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Affiliation(s)
- Hansol Im
- Division of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, South Korea
| | - Heeun Kwon
- Division of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, South Korea
| | - Gayoung Cho
- Division of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, South Korea
| | - Jisoo Kwon
- Division of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, South Korea
| | - Seong Yeol Choi
- Division of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, South Korea
| | - Robert J Mitchell
- Division of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, South Korea
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10
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Cho G, Kwon J, Soh SM, Jang H, Mitchell RJ. Sensitivity of predatory bacteria to different surfactants and their application to check bacterial predation. Appl Microbiol Biotechnol 2019; 103:8169-8178. [PMID: 31407038 DOI: 10.1007/s00253-019-10069-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 07/24/2019] [Accepted: 07/26/2019] [Indexed: 12/27/2022]
Abstract
We evaluated the toxicity of surfactants against different predatory bacteria. Tests with Bdellovibrio bacteriovorus HD100 and SDS, an anionic surfactant, showed the predator was very sensitive; 0.02% SDS completely killed the predatory population (7-log loss; < 10 PFU/ml remaining) both when free-swimming or within the bdelloplast, i.e., intraperiplasmic. Similar results were also observed with B. bacteriovorus 109J and Peredibacter starrii. In contrast, none of the prey (E. coli, Klebsiella pneumoniae, Acinetobacter baumannii, or Pseudomonas sp. DSM 50906) viabilities were negatively affected by SDS. Triton X-100, a nonionic surfactant, was slightly less toxic towards B. bacteriovorus HD100 (viability loss of only 4-log), while two cationic surfactants, i.e., benzalkonium chloride (BZC) and cetyltrimethylammonium bromide (CTAB), were toxic towards both the predator and prey. Based on the above findings, we tested the potential use of SDS as a means to control predation. Addition of 0.02% SDS immediately halted predation based upon the prey bioluminescence, which leveled off and remained steady. This was confirmed using the predator viabilities; no predators were found in any of the samples where SDS was added. Consequently, low concentrations of SDS can be used as a simple means to control B. bacteriovorus HD100 activities.
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Affiliation(s)
- Gayoung Cho
- School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, South Korea
| | - Jisoo Kwon
- School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, South Korea
| | - Sandrine Mabekou Soh
- School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, South Korea
| | - Hyochan Jang
- School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, South Korea
| | - Robert J Mitchell
- School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, South Korea.
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11
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Furst AL, Smith MJ, Francis MB. New Techniques for the Generation and Analysis of Tailored Microbial Systems on Surfaces. Biochemistry 2018; 57:3017-3026. [DOI: 10.1021/acs.biochem.8b00324] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Ariel L. Furst
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720-1460, United States
| | - Matthew J. Smith
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720-1460, United States
| | - Matthew B. Francis
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720-1460, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720-1460, United States
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12
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Teixeira AG, Agarwal R, Ko KR, Grant‐Burt J, Leung BM, Frampton JP. Emerging Biotechnology Applications of Aqueous Two-Phase Systems. Adv Healthc Mater 2018; 7:e1701036. [PMID: 29280350 DOI: 10.1002/adhm.201701036] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 10/30/2017] [Indexed: 02/06/2023]
Abstract
Liquid-liquid phase separation between aqueous solutions containing two incompatible polymers, a polymer and a salt, or a polymer and a surfactant, has been exploited for a wide variety of biotechnology applications throughout the years. While many applications for aqueous two-phase systems fall within the realm of separation science, the ability to partition many different materials within these systems, coupled with recent advances in materials science and liquid handling, has allowed bioengineers to imagine new applications. This progress report provides an overview of the history and key properties of aqueous two-phase systems to lend context to how these materials have progressed to modern applications such as cellular micropatterning and bioprinting, high-throughput 3D tissue assembly, microscale biomolecular assay development, facilitation of cell separation and microcapsule production using microfluidic devices, and synthetic biology. Future directions and present limitations and design considerations of this adaptable and promising toolkit for biomolecule and cellular manipulation are further evaluated.
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Affiliation(s)
- Alyne G. Teixeira
- School of Biomedical Engineering Dalhousie University 5981 University Avenue Halifax NS B3H 4R2 Canada
| | - Rishima Agarwal
- School of Biomedical Engineering Dalhousie University 5981 University Avenue Halifax NS B3H 4R2 Canada
| | - Kristin Robin Ko
- School of Biomedical Engineering Dalhousie University 5981 University Avenue Halifax NS B3H 4R2 Canada
| | - Jessica Grant‐Burt
- School of Biomedical Engineering Dalhousie University 5981 University Avenue Halifax NS B3H 4R2 Canada
| | - Brendan M. Leung
- School of Biomedical Engineering Dalhousie University 5981 University Avenue Halifax NS B3H 4R2 Canada
- Department of Applied Oral Science Dalhousie University 5981 University Avenue Halifax NS B3H 4R2 Canada
| | - John P. Frampton
- School of Biomedical Engineering Dalhousie University 5981 University Avenue Halifax NS B3H 4R2 Canada
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13
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Dwidar M, Yokobayashi Y. Controlling Bdellovibrio bacteriovorus Gene Expression and Predation Using Synthetic Riboswitches. ACS Synth Biol 2017; 6:2035-2041. [PMID: 28812884 DOI: 10.1021/acssynbio.7b00171] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Bdellovibrio bacteriovorus is a predatory bacterium that feeds on Gram-negative bacteria including a wide range of pathogens and thus has potential applications as a biocontrol agent. Owing to its unique life cycle, however, there are limited tools that enable genetic manipulation of B. bacteriovorus. This work describes our first steps toward engineering the predatory bacterium for practical applications by developing basic genetic parts to control gene expression. Specifically, we evaluated four robust promoters that are active during the attack phase of B. bacteriovorus. Subsequently, we tested several synthetic riboswitches that have been reported to function in Escherichia coli, and identified theophylline-activated riboswitches that function in B. bacteriovorus. Finally, we inserted the riboswitch into the bacterial chromosome to regulate expression of the flagellar sigma factor fliA, which was previously predicted to be essential for predation, and observed that the engineered strain shows a faster predation kinetics in the presence of theophylline.
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Affiliation(s)
- Mohammed Dwidar
- Nucleic Acid Chemistry and
Engineering Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904 0495, Japan
| | - Yohei Yokobayashi
- Nucleic Acid Chemistry and
Engineering Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904 0495, Japan
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14
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Dwidar M, Im H, Seo JK, Mitchell RJ. Attack-Phase Bdellovibrio bacteriovorus Responses to Extracellular Nutrients Are Analogous to Those Seen During Late Intraperiplasmic Growth. MICROBIAL ECOLOGY 2017; 74:937-946. [PMID: 28601973 DOI: 10.1007/s00248-017-1003-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2017] [Accepted: 05/29/2017] [Indexed: 06/07/2023]
Abstract
Bdellovibrio bacteriovorus is a predatory bacterium which lives by invading the periplasm of gram-negative bacteria and consuming them from within. This predator was thought to be dependent upon prey for nutrients since it lacks genes encoding for critical enzymes involved in amino acid biosynthesis. This study, however, found that planktonic attack-phase predators are not just dependent upon prey for nutrients, but rather, they respond to nutrients in the surrounding medium and, subsequently, synthesize and secrete proteases in a nutrient-dependent manner. The major secreted proteases were identified through mass spectrometry analyses. Subsequent RT-qPCR analyses found that the nutrient-induced proteases are similar to those expressed within the prey periplasm during the late intraperiplasmic growth phase. Furthermore, RNA sequencing found that incubating the planktonic attack-phase cells in a nutritious environment for a short period of time (4 h) changes its gene expression pattern to a status that is akin to the late intraperiplasmic phase, with more than 94% of the genes previously identified as being late intraperiplasmic-specific also being induced by nutrient broth in this study. This strong correlation between the gene expression patterns hints that the availability of hydrolyzed prey cell components to the predator is likely the stimulus controlling the expression of late intraperiplasmic B. bacteriovorus genes during predation.
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Affiliation(s)
- Mohammed Dwidar
- School of Life Sciences, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan, 689-798, Republic of Korea.
- Nucleic Acid Chemistry and Engineering Unit, Okinawa Institute of Science and Technology (OIST), 1919-1 Tancha, Onna-son, Okinawa, 904-0495, Japan.
| | - Hansol Im
- School of Life Sciences, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan, 689-798, Republic of Korea
| | - Jeong Kon Seo
- UNIST Central Research Facility, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Robert J Mitchell
- School of Life Sciences, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan, 689-798, Republic of Korea.
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15
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Im H, Choi SY, Son S, Mitchell RJ. Combined Application of Bacterial Predation and Violacein to Kill Polymicrobial Pathogenic Communities. Sci Rep 2017; 7:14415. [PMID: 29089523 PMCID: PMC5663959 DOI: 10.1038/s41598-017-14567-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 10/11/2017] [Indexed: 12/02/2022] Open
Abstract
Violacein is a bisindole antibiotic that is effective against Gram-positive bacteria while the bacterial predator, Bdellovibrio bacteriovorus HD100, predates on Gram-negative strains. In this study, we evaluated the use of both together against multidrug resistant pathogens. The two antibacterial agents did not antagonize the activity of the other. For example, treatment of Staphylococcus aureus with violacein reduced its viability by more than 2,000-fold with or without B. bacteriovorus addition. Likewise, predation of Acinetobacter baumannii reduced the viability of this pathogen by more than 13,000-fold, regardless if violacein was present or not. When used individually against mixed bacterial cultures containing both Gram-positive and Gram-negative strains, violacein and B. bacteriovorus HD100 were effective against only their respective strains. The combined application of both violacein and B. bacteriovorus HD100, however, reduced the total pathogen numbers by as much as 84,500-fold. Their combined effectiveness was also demonstrated using a 4-species culture containing S. aureus, A. baumannii, Bacillus cereus and Klebsiella pneumoniae. When used alone, violacein and bacterial predation reduced the total population by only 19% and 68%, respectively. In conjunction with each other, the pathogen viability was reduced by 2,965-fold (99.98%), illustrating the prospective use of these two antimicrobials together against mixed species populations.
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Affiliation(s)
- Hansol Im
- Division of Biological Sciences, School of Life Sciences Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, South Korea
| | - Seong Yeol Choi
- Division of Biological Sciences, School of Life Sciences Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, South Korea
| | - Sangmo Son
- Division of Biological Sciences, School of Life Sciences Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, South Korea
| | - Robert J Mitchell
- Division of Biological Sciences, School of Life Sciences Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, South Korea.
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16
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Choi SY, Im H, Mitchell RJ. Violacein and bacterial predation: promising alternatives for priority multidrug resistant human pathogens. Future Microbiol 2017; 12:835-838. [DOI: 10.2217/fmb-2017-0090] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Affiliation(s)
- Seong Yeol Choi
- School of Life Sciences, Ulsan National Institute of Science & Technology, 50 UNIST-gil, Ulsan 44919, Republic of Korea
| | - Hansol Im
- School of Life Sciences, Ulsan National Institute of Science & Technology, 50 UNIST-gil, Ulsan 44919, Republic of Korea
| | - Robert J Mitchell
- School of Life Sciences, Ulsan National Institute of Science & Technology, 50 UNIST-gil, Ulsan 44919, Republic of Korea
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17
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Im H, Son S, Mitchell RJ, Ghim CM. Serum albumin and osmolality inhibit Bdellovibrio bacteriovorus predation in human serum. Sci Rep 2017; 7:5896. [PMID: 28725056 PMCID: PMC5517470 DOI: 10.1038/s41598-017-06272-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 06/16/2017] [Indexed: 02/07/2023] Open
Abstract
We evaluated the bactericidal activity of Bdellovibrio bacteriovorus, strain HD100, within blood sera against bacterial strains commonly associated with bacteremic infections, including E. coli, Klebsiella pneumoniae and Salmonella enterica. Tests show that B. bacteriovorus HD100 is not susceptible to serum complement or its bactericidal activity. After a two hour exposure to human sera, the prey populations decreased 15- to 7,300-fold due to the serum complement activity while, in contrast, the B. bacteriovorus HD100 population showed a loss of only 33%. Dot blot analyses showed that this is not due to the absence of antibodies against this predator. Predation in human serum was inhibited, though, by both the osmolality and serum albumin. The activity of B. bacteriovorus HD100 showed a sharp transition between 200 and 250 mOsm/kg, and was progressively reduced as the osmolality increased. Serum albumin also acted to inhibit predation by binding to and coating the predatory cells. This was confirmed via dot blot analyses and confocal microscopy. The results from both the osmolality and serum albumin tests were incorporated into a numerical model describing bacterial predation of pathogens. In conclusion, both of these factors inhibit predation and, as such, they limit its effectiveness against pathogenic prey located within sera.
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Affiliation(s)
- Hansol Im
- School of Life Sciences, Ulsan National Institute of Science & Technology, 50 UNIST-gil Ulju-gun, Ulsan, 44919, Republic of Korea
| | - Sangmo Son
- School of Life Sciences, Ulsan National Institute of Science & Technology, 50 UNIST-gil Ulju-gun, Ulsan, 44919, Republic of Korea
| | - Robert J Mitchell
- School of Life Sciences, Ulsan National Institute of Science & Technology, 50 UNIST-gil Ulju-gun, Ulsan, 44919, Republic of Korea.
| | - Cheol-Min Ghim
- School of Life Sciences, Ulsan National Institute of Science & Technology, 50 UNIST-gil Ulju-gun, Ulsan, 44919, Republic of Korea. .,Department of Physics, Ulsan National Institute of Science & Technology, 50 UNIST-gil Ulju-gun, Ulsan, 44919, Republic of Korea.
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18
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Monnappa AK, Bari W, Choi SY, Mitchell RJ. Investigating the Responses of Human Epithelial Cells to Predatory Bacteria. Sci Rep 2016; 6:33485. [PMID: 27629536 PMCID: PMC5024164 DOI: 10.1038/srep33485] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 08/24/2016] [Indexed: 12/12/2022] Open
Abstract
One beguiling alternative to antibiotics for treating multi-drug resistant infections are Bdellovibrio-and-like-organisms (BALOs), predatory bacteria known to attack human pathogens. Consequently, in this study, the responses from four cell lines (three human and one mouse) were characterized during an exposure to different predatory bacteria, Bdellovibrio bacteriovorus HD100, Bacteriovorus BY1 and Bacteriovorax stolpii EB1. TNF-α levels were induced in Raw 264.7 mouse macrophage cultures with each predator, but paled in comparison to those obtained with E. coli. This was true even though the latter strain was added at an 11.1-fold lower concentration (p < 0.01). Likewise, E. coli led to a significant (54%) loss in the Raw 264.7 murine macrophage viability while the predatory strains had no impact. Tests with various epithelial cells, including NuLi-1 airway, Caco2, HT29 and T84 colorectal cells, gave similar results, with E. coli inducing IL-8 production. The viabilities of the NuLi-1 and Caco-2 cells were slightly reduced (8%) when exposed to the predators, while T84 viability remained steady. In no cases did the predatory bacteria induce actin rearrangement. These results clearly demonstrate the gentle natures of predatory bacteria and their impacts on human cells.
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Affiliation(s)
- Ajay K Monnappa
- Department of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology, 44919, South Korea
| | - Wasimul Bari
- Department of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology, 44919, South Korea
| | - Seong Yeol Choi
- Department of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology, 44919, South Korea
| | - Robert J Mitchell
- Department of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology, 44919, South Korea
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19
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Timm CM, Hansen RR, Doktycz MJ, Retterer ST, Pelletier DA. Microstencils to generate defined, multi-species patterns of bacteria. BIOMICROFLUIDICS 2015; 9:064103. [PMID: 26594264 PMCID: PMC4644145 DOI: 10.1063/1.4935938] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 11/05/2015] [Indexed: 05/21/2023]
Abstract
Microbial communities are complex heterogeneous systems that are influenced by physical and chemical interactions with their environment, host, and community members. Techniques that facilitate the quantitative evaluation of how microscale organization influences the morphogenesis of multispecies communities could provide valuable insights into the dynamic behavior and organization of natural communities, the design of synthetic environments for multispecies culture, and the engineering of artificial consortia. In this work, we demonstrate a method for patterning microbes into simple arrangements that allow the quantitative measurement of growth dynamics as a function of their proximity to one another. The method combines parylene-based liftoff techniques with microfluidic delivery to simultaneously pattern multiple bacterial species with high viability using low-cost, customizable methods. Quantitative measurements of bacterial growth for two competing isolates demonstrate that spatial coordination can play a critical role in multispecies growth and structure.
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Affiliation(s)
- Collin M Timm
- Biosciences Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, USA
| | - Ryan R Hansen
- Department of Chemical Engineering, Kansas State University , Manhattan, Kansas 66506, USA
| | | | | | - Dale A Pelletier
- Biosciences Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, USA
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20
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Singh R, Monnappa AK, Hong S, Mitchell RJ, Jang J. Effects of Carbon Dioxide Aerosols on the Viability of Escherichia coli during Biofilm Dispersal. Sci Rep 2015; 5:13766. [PMID: 26345492 PMCID: PMC4561891 DOI: 10.1038/srep13766] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 08/04/2015] [Indexed: 12/21/2022] Open
Abstract
A periodic jet of carbon dioxide (CO2) aerosols is a very quick and effective mechanical technique to remove biofilms from various substrate surfaces. However, the impact of the aerosols on the viability of bacteria during treatment has never been evaluated. In this study, the effects of high-speed CO2 aerosols, a mixture of solid and gaseous CO2, on bacteria viability was studied. It was found that when CO2 aerosols were used to disperse biofilms of Escherichia coli, they led to a significant loss of viability, with approximately 50% of the dispersed bacteria killed in the process. By comparison, 75.6% of the biofilm-associated bacteria were viable when gently dispersed using Proteinase K and DNase I. Indirect proof that the aerosols are damaging the bacteria was found using a recombinant E. coli expressing the cyan fluorescent protein, as nearly half of the fluorescence was found in the supernatant after CO2 aerosol treatment, while the rest was associated with the bacterial pellet. In comparison, the supernatant fluorescence was only 9% when the enzymes were used to disperse the biofilm. As such, these CO2 aerosols not only remove biofilm-associated bacteria effectively but also significantly impact their viability by disrupting membrane integrity.
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Affiliation(s)
- Renu Singh
- School of Mechanical and Nuclear Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, S. Korea
| | - Ajay K Monnappa
- School of Life Sciences, Department of Biological Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, S. Korea
| | - Seongkyeol Hong
- School of Mechanical and Nuclear Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, S. Korea
| | - Robert J Mitchell
- School of Life Sciences, Department of Biological Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, S. Korea
| | - Jaesung Jang
- School of Mechanical and Nuclear Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, S. Korea
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21
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Dwidar M, Nam D, Mitchell RJ. Indole negatively impacts predation byBdellovibrio bacteriovorusand its release from the bdelloplast. Environ Microbiol 2014; 17:1009-22. [DOI: 10.1111/1462-2920.12463] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 03/21/2014] [Accepted: 03/23/2014] [Indexed: 02/03/2023]
Affiliation(s)
- Mohammed Dwidar
- School of Life Sciences; Ulsan National Institute of Science and Technology; Ulsan 689-798 Korea
| | - Dougu Nam
- School of Life Sciences; Ulsan National Institute of Science and Technology; Ulsan 689-798 Korea
| | - Robert J. Mitchell
- School of Life Sciences; Ulsan National Institute of Science and Technology; Ulsan 689-798 Korea
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22
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Monnappa AK, Dwidar M, Seo JK, Hur JH, Mitchell RJ. Bdellovibrio bacteriovorus inhibits Staphylococcus aureus biofilm formation and invasion into human epithelial cells. Sci Rep 2014; 4:3811. [PMID: 24448451 PMCID: PMC3898049 DOI: 10.1038/srep03811] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 01/02/2014] [Indexed: 12/29/2022] Open
Abstract
Bdellovibrio bacteriovorus HD100 is a predatory bacterium that attacks many Gram-negative human pathogens. A serious drawback of this strain, however, is its ineffectiveness against Gram-positive strains, such as the human pathogen Staphylococcus aureus. Here we demonstrate that the extracellular proteases produced by a host-independent B. bacteriovorus (HIB) effectively degrade/inhibit the formation of S. aureus biofilms and reduce its virulence. A 10% addition of HIB supernatant caused a 75% or greater reduction in S. aureus biofilm formation as well as 75% dispersal of pre-formed biofilms. LC-MS-MS analyses identified various B. bacteriovorus proteases within the supernatant, including the serine proteases Bd2269 and Bd2321. Tests with AEBSF confirmed that serine proteases were active in the supernatant and that they impacted S. aureus biofilm formation. The supernatant also possessed a slight DNAse activity. Furthermore, treatment of planktonic S. aureus with the supernatant diminished its ability to invade MCF-10a epithelial cells by 5-fold but did not affect the MCF-10a viability. In conclusion, this study illustrates the hitherto unknown ability of B. bacteriovorus to disperse Gram-positive pathogenic biofilms and mitigate their virulence.
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Affiliation(s)
- Ajay K. Monnappa
- School of Life Sciences, Ulsan National Institute of Science and Technology
- These authors contributed equally to this work
| | - Mohammed Dwidar
- School of Life Sciences, Ulsan National Institute of Science and Technology
- These authors contributed equally to this work
| | - Jeong Kon Seo
- UNIST Central Research Facility, Ulsan National Institute of Science and Technology
| | - Jin-Hoe Hur
- UNIST Central Research Facility, Ulsan National Institute of Science and Technology
| | - Robert J. Mitchell
- School of Life Sciences, Ulsan National Institute of Science and Technology
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23
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Im H, Kim D, Ghim CM, Mitchell RJ. Shedding light on microbial predator-prey population dynamics using a quantitative bioluminescence assay. MICROBIAL ECOLOGY 2014; 67:167-176. [PMID: 24272279 DOI: 10.1007/s00248-013-0323-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 10/29/2013] [Indexed: 06/02/2023]
Abstract
This study assessed the dynamics of predation by Bdellovibrio bacteriovorus HD 100. Predation tests with two different bioluminescent strains of Escherichia coli, one expressing a heat-labile bacterial luciferase and the other a heat-stable form, showed near identical losses from both, indicating that protein expression and stability are not responsible for the "shutting-off" of the prey bioluminescence (BL). Furthermore, it was found that the loss in the prey BL was not proportional with the predator-to-prey ratio (PPR), with significantly greater losses seen as this value was increased. This suggests that other factors also play a role in lowering the prey BL. The loss in BL, however, was very consistent within nine independent experiments to the point that we were able to reliably estimate the predator numbers within only 1 h when present at a PPR of 6 or higher, Using a fluorescent prey, we found that premature lysis of the prey occurs at a significant level and was more prominent as the PPR ratio increased. Based upon the supernatant fluorescent signal, even a relatively low PPR of 10-20 led to approximately 5% of the prey population being prematurely lysed within 1 h, while a PPR of 90 led to nearly 15% lysis. Consequently, we developed a modified Lotka-Volterra predator-prey model that accounted for this lysis and is able to reliably estimate the prey and bdelloplast populations for a wide range of PPRs.
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Affiliation(s)
- Hansol Im
- School of Life Sciences, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan, 689-798, South Korea
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24
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Kim EH, Dwidar M, Kwon YN, Mitchell RJ. Pretreatment with alum or powdered activated carbon reduces bacterial predation-associated irreversible fouling of membranes. BIOFOULING 2014; 30:1225-1233. [PMID: 25410737 DOI: 10.1080/08927014.2014.970538] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
This study evaluated the co-application of bacterial predation by Bdellovibrio bacteriovorus and either alum coagulation or powdered activated carbon adsorption to reduce fouling caused by Escherichia coli rich feed solutions in dead-end microfiltration tests. The flux increased when the samples were predated upon or treated with 100 ppm alum or PAC, but co-treatment with alum and predation gave the best flux results. The total membrane resistance caused by the predated sample was reduced six-fold when treated with 100 ppm PAC, from 11.8 to 1.98 × 10(11) m(-1), while irreversible fouling (Rp) was 2.7-fold lower. Treatment with 100 ppm alum reduced the total resistance 14.9-fold (11.8 to 0.79 × 10(11) m(-1)) while the Rp decreased 4.25-fold. SEM imaging confirmed this, with less obvious fouling of the membrane after the combined process. This study illustrates that the combination of bacterial predation and the subsequent removal of debris using coagulation or adsorption mitigates membrane biofouling and improves membrane performance.
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Affiliation(s)
- Eun-Ho Kim
- a School of Urban and Environmental Engineering , Ulsan National Institute of Science and Technology , Ulsan , South Korea
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25
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Dwidar M, Takayama S, Mitchell RJ. Aqueous two-phase system technology for patterning bacterial communities and biofilms. Methods Mol Biol 2014; 1147:23-32. [PMID: 24664823 DOI: 10.1007/978-1-4939-0467-9_2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We describe a novel method which makes use of polymer-based aqueous two-phase systems to pattern bacterial communities inside Petri dishes. This method allows us to culture submillimeter-sized bacterial communities in spatially distinct spots while maintaining a degree of chemical connectedness to each other through the aqueous phase. Given sufficient time, these bacterial cultures develop biofilms, each corresponding to the footprint of the droplet spot. This method can be used to study the interactions between bacterial communities and biofilms spotted adjacent to each other. Furthermore, it can be extended to study the interactions between different bacterial communities and an underlying epithelial cell layer.
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Affiliation(s)
- Mohammed Dwidar
- School of Nano-Bioscience and Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
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