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Rojas D, Marcoleta AE, Gálvez-Silva M, Varas MA, Díaz M, Hernández M, Vargas C, Nourdin-Galindo G, Koch E, Saldivia P, Vielma J, Gan YH, Chen Y, Guiliani N, Chávez FP. Inorganic Polyphosphate Affects Biofilm Assembly, Capsule Formation, and Virulence of Hypervirulent ST23 Klebsiella pneumoniae. ACS Infect Dis 2024; 10:606-623. [PMID: 38205780 DOI: 10.1021/acsinfecdis.3c00509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2024]
Abstract
The emergence of hypervirulent Klebsiella pneumoniae (hvKP) strains poses a significant threat to public health due to high mortality rates and propensity to cause severe community-acquired infections in healthy individuals. The ability to form biofilms and produce a protective capsule contributes to its enhanced virulence and is a significant challenge to effective antibiotic treatment. Polyphosphate kinase 1 (PPK1) is an enzyme responsible for inorganic polyphosphate synthesis and plays a vital role in regulating various physiological processes in bacteria. In this study, we investigated the impact of polyP metabolism on the biofilm and capsule formation and virulence traits in hvKP using Dictyostelium discoideum amoeba as a model host. We found that the PPK1 null mutant was impaired in biofilm and capsule formation and showed attenuated virulence in D. discoideum compared to the wild-type strain. We performed a proteomic analysis to gain further insights into the underlying molecular mechanism. The results revealed that the PPK1 mutant had a differential expression of proteins involved in capsule synthesis (Wzi-Ugd), biofilm formation (MrkC-D-H), synthesis of the colibactin genotoxin precursor (ClbB), as well as proteins associated with the synthesis and modification of lipid A (ArnB-LpxC-PagP). These proteomic findings corroborate the phenotypic observations and indicate that the PPK1 mutation is associated with impaired biofilm and capsule formation and attenuated virulence in hvKP. Overall, our study highlights the importance of polyP synthesis in regulating extracellular biomolecules and virulence in K. pneumoniae and provides insights into potential therapeutic targets for treating K. pneumoniae infections.
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Affiliation(s)
- Diego Rojas
- Laboratorio de Microbiología de Sistemas, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago CP 7800003, Chile
| | - Andrés E Marcoleta
- Grupo de Microbiología Integrativa, Laboratorio de Biología Estructural y Molecular, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago CP 7800003, Chile
| | - Matías Gálvez-Silva
- Laboratorio de Microbiología de Sistemas, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago CP 7800003, Chile
- Grupo de Microbiología Integrativa, Laboratorio de Biología Estructural y Molecular, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago CP 7800003, Chile
| | - Macarena A Varas
- Laboratorio de Microbiología de Sistemas, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago CP 7800003, Chile
- Grupo de Microbiología Integrativa, Laboratorio de Biología Estructural y Molecular, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago CP 7800003, Chile
| | - Mauricio Díaz
- Laboratorio de Comunicación Microbiana, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago CP 7800003, Chile
| | - Mauricio Hernández
- División Biotecnología, Instituto Melisa, San Pedro de la Paz CP 9660000, Chile
| | - Cristian Vargas
- División Biotecnología, Instituto Melisa, San Pedro de la Paz CP 9660000, Chile
| | | | - Elard Koch
- División Biotecnología, Instituto Melisa, San Pedro de la Paz CP 9660000, Chile
| | - Pablo Saldivia
- División Biotecnología, Instituto Melisa, San Pedro de la Paz CP 9660000, Chile
- Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción CP 4070389, Chile
| | - Jorge Vielma
- Laboratorio de Microbiología de Sistemas, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago CP 7800003, Chile
- Grupo de Microbiología Integrativa, Laboratorio de Biología Estructural y Molecular, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago CP 7800003, Chile
| | - Yunn-Hwen Gan
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore CP 119077, Singapore
| | - Yahua Chen
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore CP 119077, Singapore
| | - Nicolás Guiliani
- Laboratorio de Comunicación Microbiana, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago CP 7800003, Chile
| | - Francisco P Chávez
- Laboratorio de Microbiología de Sistemas, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago CP 7800003, Chile
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Ray S, Löffler S, Richter-Dahlfors A. High-Resolution Large-Area Image Analysis Deciphers the Distribution of Salmonella Cells and ECM Components in Biofilms Formed on Charged PEDOT:PSS Surfaces. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024:e2307322. [PMID: 38225703 DOI: 10.1002/advs.202307322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 12/12/2023] [Indexed: 01/17/2024]
Abstract
Biofilms, comprised of cells embedded in extracellular matrix (ECM), enable bacterial surface colonization and contribute to pathogenesis and biofouling. Yet, antibacterial surfaces are mainly evaluated for their effect on bacterial cells rather than the ECM. Here, a method is presented to separately quantify amounts and distribution of cells and ECM in Salmonella biofilms grown on electroactive poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS). Within a custom-designed biofilm reactor, biofilm forms on PEDOT:PSS surfaces electrically addressed with a bias potential and simultaneous recording of the resulting current. The amount and distribution of cells and ECM in biofilms are analyzed using a fluorescence-based spectroscopic mapping technique and fluorescence confocal microscopy combined with advanced image processing. The study shows that surface charge leads to upregulated ECM production, leaving the cell counts largely unaffected. An altered texture is also observed, with biofilms forming small foci or more continuous structures. Supported by mutants lacking ECM production, ECM is identified as an important target when developing antibacterial strategies. Also, a central role for biofilm distribution is highlighted that likely influences antimicrobial susceptibility in biofilms. This work provides yet a link between conductive polymer materials and bacterial metabolism and reveals for the first time a specific effect of electrochemical addressing on bacterial ECM formation.
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Affiliation(s)
- Sanhita Ray
- AIMES - Center for the Advancement of Integrated Medical and Engineering Sciences at Karolinska Institutet and KTH Royal Institute of Technology, Stockholm, SE-171 77, Sweden
- Department of Neuroscience, Karolinska Institutet, Stockholm, SE-171 77, Sweden
| | - Susanne Löffler
- AIMES - Center for the Advancement of Integrated Medical and Engineering Sciences at Karolinska Institutet and KTH Royal Institute of Technology, Stockholm, SE-171 77, Sweden
- Department of Neuroscience, Karolinska Institutet, Stockholm, SE-171 77, Sweden
| | - Agneta Richter-Dahlfors
- AIMES - Center for the Advancement of Integrated Medical and Engineering Sciences at Karolinska Institutet and KTH Royal Institute of Technology, Stockholm, SE-171 77, Sweden
- Department of Neuroscience, Karolinska Institutet, Stockholm, SE-171 77, Sweden
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Díaz-Navarro M, Samaniego R, Piqueras JC, Díez R, Hafian R, Manzano I, Muñoz P, Guembe M. Understanding the diagnosis of catheter-related bloodstream infection: real-time monitoring of biofilm growth dynamics using time-lapse optical microscopy. Front Cell Infect Microbiol 2023; 13:1286527. [PMID: 38125909 PMCID: PMC10731284 DOI: 10.3389/fcimb.2023.1286527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 11/13/2023] [Indexed: 12/23/2023] Open
Abstract
Background The differential time to positivity (DTTP) technique is recommended for the conservative diagnosis of catheter-related bloodstream infection (C-RBSI). The technique is based on a 120-minute difference between microbial growth in blood drawn through the catheter and blood drawn through a peripheral vein. However, this cut-off has failed to confirm C-RBSI caused by Candida spp. and Staphylococcus aureus. Objective We hypothesized that the biofilm of both microorganisms disperses faster than that of other microorganisms and that microbial load is rapidly equalized between catheter and peripheral blood. Therefore, our aim was to compare the biofilm dynamics of various microorganisms. Methods Biofilm of ATCC strains of methicillin-resistant Staphylococcus epidermidis, methicillin-susceptible S. aureus, Enterococcus faecalis, Escherichia coli and Candida albicans was grown on silicon disks and analyzed using time-lapse optical microscopy. The time-lapse images of biofilms were processed using ImageJ2 software. Cell dispersal time and biofilm thickness were calculated. Results The mean (standard deviation) dispersal time in C. albicans and S. aureus biofilms was at least nearly 3 hours lower than in biofilm of S. epidermidis, and at least 15 minutes than in E. faecalis and E. coli biofilms. Conclusion Our findings could explain why early dissemination of cells in C. albicans and S. aureus prevents us from confirming or ruling out the catheter as the source of the bloodstream infection using the cut-off of 120 minutes in the DTTP technique. In addition, DTTP may not be sufficiently reliable for E. coli since their dispersion time is less than the cut-off of 120 minutes.
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Affiliation(s)
- Marta Díaz-Navarro
- Department of Clinical Microbiology and Infectious Diseases, Hospital General Universitario Gregorio Marañón, Madrid, Spain
- Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain
| | - Rafael Samaniego
- Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain
- Confocal Microscopy Unit, Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain
| | | | - Rafael Díez
- School of Biology, Universidad Complutense de Madrid, Madrid, Spain
| | - Rama Hafian
- School of Biology, Universidad Complutense de Madrid, Madrid, Spain
| | - Irene Manzano
- School of Biology, Universidad Complutense de Madrid, Madrid, Spain
| | - Patricia Muñoz
- Department of Clinical Microbiology and Infectious Diseases, Hospital General Universitario Gregorio Marañón, Madrid, Spain
- Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain
- CIBER Enfermedades Respiratorias-CIBERES (CB06/06/0058), Madrid, Spain
- School of Medicine, Universidad Complutense de Madrid, Madrid, Spain
| | - María Guembe
- Department of Clinical Microbiology and Infectious Diseases, Hospital General Universitario Gregorio Marañón, Madrid, Spain
- Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain
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Ranson TM, Barton ME, McLean RJC. Influence of central metabolism disruption on Escherichia coli biofilm formation. Can J Microbiol 2023; 69:432-438. [PMID: 37728257 DOI: 10.1139/cjm-2023-0096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/21/2023]
Abstract
Biofilms are widely recognized as a prominent mode of microbial growth and strategy of antimicrobial tolerance in many environments. Characteristics that are often overlooked in biofilm investigations include the examination of metabolic pathways as the assumption might be that interference with central pathways such as glycolysis would only reduce growth and thus not be meaningful. Using the Keio collection of Escherichia coli mutants, we investigated the influence of biofilm formation and planktonic growth in full-strength and diluted Luria-Bertani (LB) broths using strains with a disruption of glycolysis (Δpgi), the Entner-Doudoroff pathway (Δedd), or the pentose phosphate pathway (Δgnd). Unexpectedly, in contrast to the E. coli Keio parent strain (BW25113), planktonic growth was enhanced in full strength and diluted LB broths in the metabolic mutants. Using a microtiter biofilm assay, the E. coli parent strain showed the highest crystal violet staining. However, when analyzed by culture assays, there was an increase in biofilm populations in the mutants in comparison to the parent strain. Fluorescence microscopy showed differences in colonization patterns in the strains. Given the availability of mutant collections in many model organisms, similar metabolic studies are warranted for biofilms, given their importance in nature.
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Affiliation(s)
- Taylor M Ranson
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
| | - Marilynn E Barton
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
| | - Robert J C McLean
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
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Richter-Dahlfors A, Kärkkäinen E, Choong FX. Fluorescent optotracers for bacterial and biofilm detection and diagnostics. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2023; 24:2246867. [PMID: 37680974 PMCID: PMC10481766 DOI: 10.1080/14686996.2023.2246867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 07/03/2023] [Accepted: 08/07/2023] [Indexed: 09/09/2023]
Abstract
Effective treatment of bacterial infections requires methods that accurately and quickly identify which antibiotic should be prescribed. This review describes recent research on the development of optotracing methodologies for bacterial and biofilm detection and diagnostics. Optotracers are small, chemically well-defined, anionic fluorescent tracer molecules that detect peptide- and carbohydrate-based biopolymers. This class of organic molecules (luminescent conjugated oligothiophenes) show unique electronic, electrochemical and optical properties originating from the conjugated structure of the compounds. The photophysical properties are further improved as donor-acceptor-donor (D-A-D)-type motifs are incorporated in the conjugated backbone. Optotracers bind their biopolymeric target molecules via electrostatic interactions. Binding alters the optical properties of these tracer molecules, shown as altered absorption and emission spectra, as well as ON-like switch of fluorescence. As the optotracer provides a defined spectral signature for each binding partner, a fingerprint is generated that can be used for identification of the target biopolymer. Alongside their use for in situ experimentation, optotracers have demonstrated excellent use in studies of a number of clinically relevant microbial pathogens. These methods will find widespread use across a variety of communities engaged in reducing the effect of antibiotic resistance. This includes basic researchers studying molecular resistance mechanisms, academia and pharma developing new antimicrobials targeting biofilm infections and tests to diagnose biofilm infections, as well as those developing antibiotic susceptibility tests for biofilm infections (biofilm-AST). By iterating between the microbial world and that of plants, development of the optotracing technology has become a prime example of successful cross-feeding across the boundaries of disciplines. As optotracers offers a capacity to redefine the way we work with polysaccharides in the microbial world as well as with plant biomass, the technology is providing novel outputs desperately needed for global impact of the threat of antimicrobial resistance as well as our strive for a circular bioeconomy.
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Affiliation(s)
- Agneta Richter-Dahlfors
- AIMES – Center for the Advancement of Integrated Medical and Engineering Sciences at Karolinska Institutet and KTH Royal Institute of Technology, Stockholm, Sweden
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
- Department of Fiber and Polymer Technology, School of Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Elina Kärkkäinen
- AIMES – Center for the Advancement of Integrated Medical and Engineering Sciences at Karolinska Institutet and KTH Royal Institute of Technology, Stockholm, Sweden
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Ferdinand X. Choong
- AIMES – Center for the Advancement of Integrated Medical and Engineering Sciences at Karolinska Institutet and KTH Royal Institute of Technology, Stockholm, Sweden
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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6
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Antypas H, Zhang T, Choong FX, Melican K, Richter-Dahlfors A. Dynamic single cell analysis in a proximal-tubule-on-chip reveals heterogeneous epithelial colonization strategies of uropathogenic Escherichia coli under shear stress. FEMS MICROBES 2023; 4:xtad007. [PMID: 37333433 PMCID: PMC10117878 DOI: 10.1093/femsmc/xtad007] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 12/20/2022] [Accepted: 03/01/2023] [Indexed: 03/23/2024] Open
Abstract
The urinary tract is a hydrodynamically challenging microenvironment and uropathogenic Escherichia coli (UPEC) must overcome several physiological challenges in order to adhere and establish a urinary tract infection. Our previous work in vivo revealed a synergy between different UPEC adhesion organelles, which facilitated effective colonization of the renal proximal tubule. To allow high-resolution real-time analysis of this colonization behavior, we established a biomimetic proximal-tubule-on-chip (PToC). The PToC allowed for single-cell resolution analysis of the first stages of bacterial interaction with host epithelial cells, under physiological flow. Time-lapse microscopy and single-cell trajectory analysis in the PToC revealed that while the majority of UPEC moved directly through the system, a minority population initiated heterogeneous adhesion, identified as either rolling or bound. Adhesion was predominantly transient and mediated by P pili at the earliest time-points. These bound bacteria initiated a founder population which rapidly divided, leading to 3D microcolonies. Within the first hours, the microcolonies did not express extracellular curli matrix, but rather were dependent on Type 1 fimbriae as the key element in the microcolony structure. Collectively, our results show the application of Organ-on-chip technology to address bacterial adhesion behaviors, demonstrating a well-orchestrated interplay and redundancy between adhesion organelles that enables UPEC to form microcolonies and persist under physiological shear stress.
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Affiliation(s)
- Haris Antypas
- AIMES – Center for the Advancement of Integrated Medical and Engineering Sciences, Karolinska Institutet and KTH Royal Institute of Technology, SE-171 77, Stockholm, Sweden
- Department of Neuroscience, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Tianqi Zhang
- AIMES – Center for the Advancement of Integrated Medical and Engineering Sciences, Karolinska Institutet and KTH Royal Institute of Technology, SE-171 77, Stockholm, Sweden
- Department of Neuroscience, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Ferdinand X Choong
- AIMES – Center for the Advancement of Integrated Medical and Engineering Sciences, Karolinska Institutet and KTH Royal Institute of Technology, SE-171 77, Stockholm, Sweden
- Department of Neuroscience, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Keira Melican
- AIMES – Center for the Advancement of Integrated Medical and Engineering Sciences, Karolinska Institutet and KTH Royal Institute of Technology, SE-171 77, Stockholm, Sweden
- Department of Neuroscience, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Agneta Richter-Dahlfors
- AIMES – Center for the Advancement of Integrated Medical and Engineering Sciences, Karolinska Institutet and KTH Royal Institute of Technology, SE-171 77, Stockholm, Sweden
- Department of Neuroscience, Karolinska Institutet, SE-171 77, Stockholm, Sweden
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Eckert JA, Rosenberg M, Rhen M, Choong FX, Richter-Dahlfors A. An optotracer-based antibiotic susceptibility test specifically targeting the biofilm lifestyle of Salmonella. Biofilm 2022; 4:100083. [PMID: 36117547 PMCID: PMC9474290 DOI: 10.1016/j.bioflm.2022.100083] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 08/26/2022] [Accepted: 08/29/2022] [Indexed: 11/25/2022] Open
Abstract
Antimicrobial resistance is a medical threat of global dimensions. Proper antimicrobial susceptibility testing (AST) for drug development, patient diagnosis and treatment is crucial to counteract ineffective drug use and resistance development. Despite the important role of bacterial biofilms in chronic and device-associated infections, the efficacy of antibiotics is determined using planktonic cultures. To address the need for antibiotics targeting bacteria in the biofilm lifestyle, we here present an optotracing-based biofilm-AST using Salmonella as model. Our non-disruptive method enables real-time recording of the extracellular matrix (ECM) components, providing specific detection of the biofilm lifestyle. Biofilm formation prior to antibiotic challenge can thus be confirmed and pre-treatment data collected. By introducing Kirby-Bauer discs, we performed a broad screen of the effects of antibiotics representing multiple classes, and identified compounds with ECM inhibitory as well as promoting effects. These compounds were further tested in agar-based dose-response biofilm-AST assays. By quantifying the ECM based on the amount of curli, and by visualizing the biofilm size and morphology, we achieved new information directly reflecting the treated biofilm. This verified the efficacy of several antibiotics that were effective in eradicating pre-formed biofilms, and it uncovered intriguing possible resistance mechanisms initiated in response to treatments. By providing deeper insights into the resistances and susceptibilities of microbes, expanded use of the biofilm-AST will contribute to more effective treatments of infections and reduced resistance development.
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Affiliation(s)
- Johannes A Eckert
- AIMES - Center for the Advancement of Integrated Medical and Engineering Sciences, Karolinska Institutet and KTH Royal Institute of Technology, Stockholm, Sweden.,Department of Neuroscience, Karolinska Institutet, Solnavägen 9, SE-171 77, Stockholm, Sweden
| | - Ming Rosenberg
- AIMES - Center for the Advancement of Integrated Medical and Engineering Sciences, Karolinska Institutet and KTH Royal Institute of Technology, Stockholm, Sweden.,Department of Neuroscience, Karolinska Institutet, Solnavägen 9, SE-171 77, Stockholm, Sweden
| | - Mikael Rhen
- AIMES - Center for the Advancement of Integrated Medical and Engineering Sciences, Karolinska Institutet and KTH Royal Institute of Technology, Stockholm, Sweden.,Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solnavägen 9, SE-171 77, Stockholm, Sweden
| | - Ferdinand X Choong
- AIMES - Center for the Advancement of Integrated Medical and Engineering Sciences, Karolinska Institutet and KTH Royal Institute of Technology, Stockholm, Sweden.,Department of Neuroscience, Karolinska Institutet, Solnavägen 9, SE-171 77, Stockholm, Sweden
| | - Agneta Richter-Dahlfors
- AIMES - Center for the Advancement of Integrated Medical and Engineering Sciences, Karolinska Institutet and KTH Royal Institute of Technology, Stockholm, Sweden.,Department of Neuroscience, Karolinska Institutet, Solnavägen 9, SE-171 77, Stockholm, Sweden
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8
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Functional amyloid in a lipid-like environment: a merry dance of many steps. Essays Biochem 2022; 66:1035-1046. [PMID: 36205438 DOI: 10.1042/ebc20220062] [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: 08/08/2022] [Revised: 09/18/2022] [Accepted: 09/21/2022] [Indexed: 11/17/2022]
Abstract
Functional amyloid, which unlike its pathological counterpart serves a biological purpose, is produced in a carefully orchestrated sequence of events. In bacteria, the major amyloid component is transported over the periplasm and through the outer membrane to assemble on the bacterial cell surface. During its life time, the amyloid protein may be exposed to both membrane lipids and extracellular surfactant, making it relevant to study its interactions with these components in vitro. Particularly for charged surfactants, the interaction is quite complex and highly dependent on the surfactant:protein molar ratio. Low ratios typically promote aggregation, likely by binding the proteins to micelles and thus increasing the local concentration of proteins, while higher concentrations see an inhibition of the same process as the protein is diluted out and immobilized on individual micelles. This is particularly pronounced for strongly anionic surfactants like SDS; the naturally occurring biosurfactant rhamnolipid interacts more weakly with the protein, which still not only allows aggregation but also leads to less detrimental effects at higher ratios. Similarly, anionic vesicle-forming lipids largely stimulate aggregation likely because of weaker interactions. Anionic lysolipids, thanks to their micelle-forming properties, resemble SDS in their impact on fibrillation. There are also examples of systems where membrane binding sequesters an otherwise amyloidogenic sequence and prevents fibrillation or-quite the opposite- liberates another part of the protein to engage in self-assembly. Thus, membranes and surfactants have very varied roles to play in the biogenesis and function of bacterial amyloid.
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9
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Kärkkäinen E, Jakobsson SG, Edlund U, Richter-Dahlfors A, Choong FX. Optotracing for live selective fluorescence-based detection of Candida albicans biofilms. Front Cell Infect Microbiol 2022; 12:981454. [PMID: 36118028 PMCID: PMC9478205 DOI: 10.3389/fcimb.2022.981454] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 08/12/2022] [Indexed: 11/13/2022] Open
Abstract
Candida albicans is the most common fungal pathogen in humans, implicated in hospital-acquired infections, secondary infections in human immunodeficiency virus (HIV) patients, and is a significant contributor to the global antimicrobial resistance (AMR) burden. Early detection of this pathogen is needed to guide preventative strategies and the selection and development of therapeutic treatments. Fungal biofilms are a unique heterogeneous mix of cell types, extracellular carbohydrates and amyloid aggregates. Perhaps due to the dominance of carbohydrates in fungi, to date, few specific methods are available for the detection of fungal biofilms. Here we present a new optotracing-based method for the detection and analysis of yeast and biofilms based on C. albicans SC5314 as a model. Using commercial extracts of cell wall carbohydrates, we showed the capability of the optotracer EbbaBiolight 680 for detecting chitin and β-glucans. The sensitivity of this tracer to these carbohydrates in their native environment within fungal cells enabled the visualization of both yeast and hyphal forms of the microbe. Analysis of optotracer fluorescence by confocal laser scanning microscopy revealed extensive staining of fungi cell walls as well as the presence of intracellular amyloid aggregates within a subpopulation of cells within the biofilm. Further analysis of the photophysical properties of bound tracers by spectroscopy and spectral imaging revealed polymorphisms between amyloid aggregates within yeast and hyphal cells and enabled their differentiation. With exceptional spatial and temporal resolution, this assay adds a new technique that facilitates future understanding of fungal biofilms and their formation, and enables direct, unbiased diagnostics of these medically relevant biofilms, as well as the development of antifungal strategies.
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Affiliation(s)
- Elina Kärkkäinen
- AIMES-Center for the Advancement of Integrated Medical and Engineering Sciences Karolinska Institutet and KTH Royal Institute of Technology, Stockholm, Sweden
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Saga G. Jakobsson
- AIMES-Center for the Advancement of Integrated Medical and Engineering Sciences Karolinska Institutet and KTH Royal Institute of Technology, Stockholm, Sweden
- Fibre and Polymer Technology, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Ulrica Edlund
- AIMES-Center for the Advancement of Integrated Medical and Engineering Sciences Karolinska Institutet and KTH Royal Institute of Technology, Stockholm, Sweden
- Fibre and Polymer Technology, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Agneta Richter-Dahlfors
- AIMES-Center for the Advancement of Integrated Medical and Engineering Sciences Karolinska Institutet and KTH Royal Institute of Technology, Stockholm, Sweden
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Ferdinand X. Choong
- AIMES-Center for the Advancement of Integrated Medical and Engineering Sciences Karolinska Institutet and KTH Royal Institute of Technology, Stockholm, Sweden
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
- *Correspondence: Ferdinand X. Choong,
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Tran VN, Khan F, Han W, Luluil M, Truong VG, Yun HG, Choi S, Kim YM, Shin JH, Kang HW. Real-time monitoring of mono- and dual-species biofilm formation and eradication using microfluidic platform. Sci Rep 2022; 12:9678. [PMID: 35690659 PMCID: PMC9188611 DOI: 10.1038/s41598-022-13699-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 05/26/2022] [Indexed: 11/17/2022] Open
Abstract
In a human host, bacterial Staphylococcus aureus and fungal Candida albicans pathogens form a mixed biofilm that causes severe mortality and morbidity. However, research on the formation and eradication of mixed biofilms under dynamic conditions is lacking. Thus, this study employed a microfluidic technique to analyze the real-time formation of mono- and dual-species (S. aureus and C. albicans) biofilms and noninvasive optical treatment of the established mature biofilm using 405-nm laser light. A herringbone mixer thoroughly mixed both bacterial and fungal cells in the growth media before being injected into the observation channels on the microfluidic chip. At a flow rate of 1.0 µL/min of growth media for 24 h, the bacterial biofilm coverage was up to 15% higher than that of the fungal biofilm (50% for bacteria vs. 35% for fungus). On the other hand, the dual-species biofilm yielded the highest coverage of ~ 96.5% because of the collective interaction between S. aureus and C. albicans. The number of cell proliferation events in S. aureus was higher than that of C. albicans for 12 h, which indicates that the S. aureus biofilm was developed faster than C. albicans. The novel in situ test platform showed a significant bactericidal effect (80%) of the 405-nm laser light at 1080 J/cm2 towards the established S. aureus biofilm, whereas the same treatment removed approximately 69% of the mixed cells in the dual-species biofilm. This study revealed that the developed microfluidic platform could be utilized to monitor the formation of dual-species biofilms in real-time and laser-induced antimicrobial effects on dual-species biofilms.
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Affiliation(s)
- Van Nam Tran
- Industry 4.0 Convergence Bionics Engineering and Marine-Integrated Biomedical Technology Center, Pukyong National University, Busan, 48513, South Korea
| | - Fazlurrahman Khan
- Research Center for Marine Integrated Bionics Technology, Pukyong National University, Busan, 48513, South Korea
| | - Won Han
- Department of Biomedical Engineering, Pukyong National University, Busan, 48513, South Korea
| | - Maknuna Luluil
- Industry 4.0 Convergence Bionics Engineering and Marine-Integrated Biomedical Technology Center, Pukyong National University, Busan, 48513, South Korea
| | - Van Gia Truong
- Industry 4.0 Convergence Bionics Engineering and Marine-Integrated Biomedical Technology Center, Pukyong National University, Busan, 48513, South Korea
| | - Hyo Geun Yun
- Department of Electronic Engineering, Hanyang University, Seoul, 04763, South Korea
| | - Sungyoung Choi
- Department of Electronic Engineering, Hanyang University, Seoul, 04763, South Korea.,Department of Biomedical Engineering, Hanyang University, Seoul, 04763, South Korea
| | - Young-Mog Kim
- Research Center for Marine Integrated Bionics Technology, Pukyong National University, Busan, 48513, South Korea.,Department of Food Science and Technology, Pukyong National University, Busan, 48513, South Korea
| | - Joong Ho Shin
- Industry 4.0 Convergence Bionics Engineering and Marine-Integrated Biomedical Technology Center, Pukyong National University, Busan, 48513, South Korea. .,Department of Biomedical Engineering, Pukyong National University, Busan, 48513, South Korea.
| | - Hyun Wook Kang
- Industry 4.0 Convergence Bionics Engineering and Marine-Integrated Biomedical Technology Center, Pukyong National University, Busan, 48513, South Korea. .,Research Center for Marine Integrated Bionics Technology, Pukyong National University, Busan, 48513, South Korea. .,Department of Biomedical Engineering, Pukyong National University, Busan, 48513, South Korea.
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