1
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Buck LD, Paladino MM, Nagashima K, Brezel ER, Holtzman JS, Urso SJ, Ryno LM. Temperature-Dependent Influence of FliA Overexpression on PHL628 E. coli Biofilm Growth and Composition. Front Cell Infect Microbiol 2022; 11:775270. [PMID: 34976858 PMCID: PMC8718923 DOI: 10.3389/fcimb.2021.775270] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 11/29/2021] [Indexed: 11/13/2022] Open
Abstract
Biofilm growth and survival pose a problem in both medical and industrial fields. Bacteria in biofilms are more tolerant to antibiotic treatment due to the inability of antibiotics to permeate to the bottom layers of cells in a biofilm and the creation of altered microenvironments of bacteria deep within the biofilm. Despite the abundance of information we have about E. coli biofilm growth and maturation, we are still learning how manipulating different signaling pathways influences the formation and fitness of biofilm. Understanding the impact of signaling pathways on biofilm formation may narrow the search for novel small molecule inhibitors or activators that affect biofilm production and stability. Here, we study the influence of the minor sigma transcription factor FliA (RpoF, sigma-28), which controls late-stage flagellar assembly and chemotaxis, on biofilm production and composition at various temperatures in the E. coli strain PHL628, which abundantly produces the extracellular structural protein curli. We examined FliA's influence on external cellular structures like curli and flagella and the biomolecular composition of the biofilm's extracellular polymeric substance (EPS) using biochemical assays, immunoblotting, and confocal laser scanning microscopy (CLSM). At 37°C, FliA overexpression results in the dramatic growth of biofilm in polystyrene plates and more modest yet significant biofilm growth on silica slides. We observed no significant differences in curli concentration and carbohydrate concentration in the EPS with FliA overexpression. Still, we did see significant changes in the abundance of EPS protein using CLSM at higher growth temperatures. We also noticed increased flagellin concentration, a major structural protein in flagella, occurred with FliA overexpression, specifically in planktonic cultures. These experiments have aided in narrowing our focus to FliA's role in changing the protein composition of the EPS, which we will examine in future endeavors.
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Affiliation(s)
- Luke D Buck
- Department of Chemistry and Biochemistry, Oberlin College, Oberlin, OH, United States
| | - Maddison M Paladino
- Department of Chemistry and Biochemistry, Oberlin College, Oberlin, OH, United States
| | - Kyogo Nagashima
- Department of Chemistry and Biochemistry, Oberlin College, Oberlin, OH, United States
| | - Emma R Brezel
- Department of Chemistry and Biochemistry, Oberlin College, Oberlin, OH, United States
| | - Joshua S Holtzman
- Department of Chemistry and Biochemistry, Oberlin College, Oberlin, OH, United States
| | - Sarel J Urso
- Department of Chemistry and Biochemistry, Oberlin College, Oberlin, OH, United States
| | - Lisa M Ryno
- Department of Chemistry and Biochemistry, Oberlin College, Oberlin, OH, United States
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2
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Co-Treatment with Single and Ternary Mixture Gas of Dimethyl Sulfide, Propanethiol, and Toluene by a Macrokinetic Analysis in a Biotrickling Filter Seeded with Alcaligenes sp. SY1 and Pseudomonas Putida S1. FERMENTATION 2021. [DOI: 10.3390/fermentation7040309] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The biotrickling filter (BTF) treatment is an effective way of dealing with air pollution caused by volatile organic compounds (VOCs). However, this approach is typically used for single VOCs treatment but not for the mixtures of VOC and volatile organic sulfur compounds (VOSCs), even if they are often encountered in industrial applications. Therefore, we investigated the performance of BTF for single and ternary mixture gas of dimethyl sulfide (DMS), propanethiol, and toluene, respectively. Results showed that the co-treatment enhanced the removal efficiency of toluene, but not of dimethyl sulfide or propanethiol. Maximum removal rates (rmax) of DMS, propanethiol and toluene were calculated to be 256.41 g·m−3·h−1, 204.08 g·m−3·h−1 and 90.91 g·m−3·h−1, respectively. For a gas mixture of these three constituents, rmax was measured to be 114.94 g·m−3·h−1, 104.17 g·m−3·h−1 and 99.01 g·m−3·h−1, separately. Illumina MiSeq sequencing analysis further indicated that Proteobacteria and Bacteroidetes were the major bacterial groups in BTF packing materials. A shift of bacterial community structure was observed during the biodegradation process.
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3
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Lerche CJ, Schwartz F, Theut M, Fosbøl EL, Iversen K, Bundgaard H, Høiby N, Moser C. Anti-biofilm Approach in Infective Endocarditis Exposes New Treatment Strategies for Improved Outcome. Front Cell Dev Biol 2021; 9:643335. [PMID: 34222225 PMCID: PMC8249808 DOI: 10.3389/fcell.2021.643335] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 05/04/2021] [Indexed: 12/13/2022] Open
Abstract
Infective endocarditis (IE) is a life-threatening infective disease with increasing incidence worldwide. From early on, in the antibiotic era, it was recognized that high-dose and long-term antibiotic therapy was correlated to improved outcome. In addition, for several of the common microbial IE etiologies, the use of combination antibiotic therapy further improves outcome. IE vegetations on affected heart valves from patients and experimental animal models resemble biofilm infections. Besides the recalcitrant nature of IE, the microorganisms often present in an aggregated form, and gradients of bacterial activity in the vegetations can be observed. Even after appropriate antibiotic therapy, such microbial formations can often be identified in surgically removed, infected heart valves. Therefore, persistent or recurrent cases of IE, after apparent initial infection control, can be related to biofilm formation in the heart valve vegetations. On this background, the present review will describe potentially novel non-antibiotic, antimicrobial approaches in IE, with special focus on anti-thrombotic strategies and hyperbaric oxygen therapy targeting the biofilm formation of the infected heart valves caused by Staphylococcus aureus. The format is translational from preclinical models to actual clinical treatment strategies.
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Affiliation(s)
- Christian Johann Lerche
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Franziska Schwartz
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Marie Theut
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Emil Loldrup Fosbøl
- Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Kasper Iversen
- Department of Cardiology, Herlev and Gentofte Hospital, University of Copenhagen, Herlev, Denmark.,Department of Emergency Medicine, Herlev and Gentofte Hospital, University of Copenhagen, Herlev, Denmark
| | - Henning Bundgaard
- Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Niels Høiby
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.,Costerton Biofilm Center, Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - Claus Moser
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
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4
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Lachowicz JI, Szczepski K, Scano A, Casu C, Fais S, Orrù G, Pisano B, Piras M, Jaremko M. The Best Peptidomimetic Strategies to Undercover Antibacterial Peptides. Int J Mol Sci 2020; 21:E7349. [PMID: 33027928 PMCID: PMC7583890 DOI: 10.3390/ijms21197349] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 09/23/2020] [Accepted: 09/25/2020] [Indexed: 02/05/2023] Open
Abstract
Health-care systems that develop rapidly and efficiently may increase the lifespan of humans. Nevertheless, the older population is more fragile, and is at an increased risk of disease development. A concurrently growing number of surgeries and transplantations have caused antibiotics to be used much more frequently, and for much longer periods of time, which in turn increases microbial resistance. In 1945, Fleming warned against the abuse of antibiotics in his Nobel lecture: "The time may come when penicillin can be bought by anyone in the shops. Then there is the danger that the ignorant man may easily underdose himself and by exposing his microbes to non-lethal quantities of the drug make them resistant". After 70 years, we are witnessing the fulfilment of Fleming's prophecy, as more than 700,000 people die each year due to drug-resistant diseases. Naturally occurring antimicrobial peptides protect all living matter against bacteria, and now different peptidomimetic strategies to engineer innovative antibiotics are being developed to defend humans against bacterial infections.
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Affiliation(s)
- Joanna Izabela Lachowicz
- Department of Medical Sciences and Public Health, University of Cagliari, Cittadella Universitaria, 09042 Monserrato, Italy; (B.P.); (M.P.)
| | - Kacper Szczepski
- Division of Biological and Environmental Sciences and Engineering (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia;
| | - Alessandra Scano
- Department of Surgical Science, OBL Oral Biotechnology Laboratory, University of Cagliari, 09124 Cagliari, Italy; (A.S.); (C.C.); (S.F.); (G.O.)
| | - Cinzia Casu
- Department of Surgical Science, OBL Oral Biotechnology Laboratory, University of Cagliari, 09124 Cagliari, Italy; (A.S.); (C.C.); (S.F.); (G.O.)
| | - Sara Fais
- Department of Surgical Science, OBL Oral Biotechnology Laboratory, University of Cagliari, 09124 Cagliari, Italy; (A.S.); (C.C.); (S.F.); (G.O.)
| | - Germano Orrù
- Department of Surgical Science, OBL Oral Biotechnology Laboratory, University of Cagliari, 09124 Cagliari, Italy; (A.S.); (C.C.); (S.F.); (G.O.)
| | - Barbara Pisano
- Department of Medical Sciences and Public Health, University of Cagliari, Cittadella Universitaria, 09042 Monserrato, Italy; (B.P.); (M.P.)
| | - Monica Piras
- Department of Medical Sciences and Public Health, University of Cagliari, Cittadella Universitaria, 09042 Monserrato, Italy; (B.P.); (M.P.)
| | - Mariusz Jaremko
- Division of Biological and Environmental Sciences and Engineering (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia;
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5
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Lees RS, Ismail HM, Logan RAE, Malone D, Davies R, Anthousi A, Adolfi A, Lycett GJ, Paine MJI. New insecticide screening platforms indicate that Mitochondrial Complex I inhibitors are susceptible to cross-resistance by mosquito P450s that metabolise pyrethroids. Sci Rep 2020; 10:16232. [PMID: 33004954 PMCID: PMC7530702 DOI: 10.1038/s41598-020-73267-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 09/11/2020] [Indexed: 12/01/2022] Open
Abstract
Fenazaquin, pyridaben, tolfenpyrad and fenpyroximate are Complex I inhibitors offering a new mode of action for insecticidal malaria vector control. However, extended exposure to pyrethroid based products such as long-lasting insecticidal nets (LLINs) has created mosquito populations that are largely pyrethroid-resistant, often with elevated levels of P450s that can metabolise and neutralise diverse substrates. To assess cross-resistance liabilities of the Complex I inhibitors, we profiled their susceptibility to metabolism by P450s associated with pyrethroid resistance in Anopheles gambiae (CYPs 6M2, 6P3, 6P4, 6P5, 9J5, 9K1, 6Z2) and An. funestus (CYP6P9a). All compounds were highly susceptible. Transgenic An. gambiae overexpressing CYP6M2 or CYP6P3 showed reduced mortality when exposed to fenpyroximate and tolfenpyrad. Mortality from fenpyroximate was also reduced in pyrethroid-resistant strains of An. gambiae (VK7 2014 and Tiassalé 13) and An. funestus (FUMOZ-R). P450 inhibitor piperonyl butoxide (PBO) significantly enhanced the efficacy of fenpyroximate and tolfenpyrad, fully restoring mortality in fenpyroximate-exposed FUMOZ-R. Overall, results suggest that in vivo and in vitro assays are a useful guide in the development of new vector control products, and that the Complex I inhibitors tested are susceptible to metabolic cross-resistance and may lack efficacy in controlling pyrethroid resistant mosquitoes.
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Affiliation(s)
- Rosemary S Lees
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Hanafy M Ismail
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Rhiannon A E Logan
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - David Malone
- Innovative Vector Control Consortium, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Rachel Davies
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Amalia Anthousi
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Adriana Adolfi
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Gareth J Lycett
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK.
| | - Mark J I Paine
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK.
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6
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Rivera Aguayo P, Bruna Larenas T, Alarcón Godoy C, Cayupe Rivas B, González-Casanova J, Rojas-Gómez D, Caro Fuentes N. Antimicrobial and Antibiofilm Capacity of Chitosan Nanoparticles against Wild Type Strain of Pseudomonas sp. Isolated from Milk of Cows Diagnosed with Bovine Mastitis. Antibiotics (Basel) 2020; 9:antibiotics9090551. [PMID: 32872146 PMCID: PMC7558502 DOI: 10.3390/antibiotics9090551] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 08/22/2020] [Accepted: 08/26/2020] [Indexed: 12/19/2022] Open
Abstract
Bovine mastitis (BM) is the most prevalent bacterial infection in the livestock sector, affecting the dairy industry greatly. The prevention and treatment of this disease is mainly made via antibiotics, but the increasing antimicrobial resistance of pathogens has affected the efficiency of conventional drugs. Pseudomonas sp. is one of the pathogens involved in this infection. The therapeutic rate of cure for this environmental mastitis-causing pathogen is practically zero, regardless of treatment. Biofilm formation has been one of the main virulence mechanisms of Pseudomonas hence presenting resistance to antibiotic therapy. We have manufactured chitosan nanoparticles (NQo) with tripolyphosphate (TPP) using ionotropic gelation. These NQo were confronted against a Pseudomonas sp. strain isolated from milk samples of cows diagnosed with BM, to evaluate their antimicrobial and antibiofilm capacity. The NQo showed great antibacterial effect in the minimum inhibitory concentrations (MIC), minimum bactericidal concentration (MBC) and disk diffusion assays. Using sub lethal concentrations, NQo were tested for inhibition of biofilm formation. The results show that the nanoparticles exhibited biofilm inhibition and were capable of eradicate pre-existing mature biofilm. These findings indicate that the NQo could act as a potential alternative to antibiotic treatment of BM.
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Affiliation(s)
- Paula Rivera Aguayo
- Centro de Investigación Austral Biotech, Facultad de Ciencias, Universidad Santo Tomas, Avenida Ejército 146, Santiago 8370003, Chile; (P.R.A.); (T.B.L.); (C.A.G.); (B.C.R.)
| | - Tamara Bruna Larenas
- Centro de Investigación Austral Biotech, Facultad de Ciencias, Universidad Santo Tomas, Avenida Ejército 146, Santiago 8370003, Chile; (P.R.A.); (T.B.L.); (C.A.G.); (B.C.R.)
| | - Carlos Alarcón Godoy
- Centro de Investigación Austral Biotech, Facultad de Ciencias, Universidad Santo Tomas, Avenida Ejército 146, Santiago 8370003, Chile; (P.R.A.); (T.B.L.); (C.A.G.); (B.C.R.)
| | - Bernardita Cayupe Rivas
- Centro de Investigación Austral Biotech, Facultad de Ciencias, Universidad Santo Tomas, Avenida Ejército 146, Santiago 8370003, Chile; (P.R.A.); (T.B.L.); (C.A.G.); (B.C.R.)
| | - Jorge González-Casanova
- Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Santiago 8910060, Chile;
| | - Diana Rojas-Gómez
- Escuela de Nutrición y Dietética, Facultad de Medicina, Universidad Andres Bello, Santiago 7591538, Chile;
| | - Nelson Caro Fuentes
- Centro de Investigación Austral Biotech, Facultad de Ciencias, Universidad Santo Tomas, Avenida Ejército 146, Santiago 8370003, Chile; (P.R.A.); (T.B.L.); (C.A.G.); (B.C.R.)
- Correspondence: ; Tel.: +56-22-3624720
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7
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Conceptual Model of Biofilm Antibiotic Tolerance That Integrates Phenomena of Diffusion, Metabolism, Gene Expression, and Physiology. J Bacteriol 2019; 201:JB.00307-19. [PMID: 31501280 DOI: 10.1128/jb.00307-19] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 08/28/2019] [Indexed: 01/14/2023] Open
Abstract
Transcriptomic, metabolomic, physiological, and computational modeling approaches were integrated to gain insight into the mechanisms of antibiotic tolerance in an in vitro biofilm system. Pseudomonas aeruginosa biofilms were grown in drip flow reactors on a medium composed to mimic the exudate from a chronic wound. After 4 days, the biofilm was 114 μm thick with 9.45 log10 CFU cm-2 These biofilms exhibited tolerance, relative to exponential-phase planktonic cells, to subsequent treatment with ciprofloxacin. The specific growth rate of the biofilm was estimated via elemental balances to be approximately 0.37 h-1 and with a reaction-diffusion model to be 0.32 h-1, or one-third of the maximum specific growth rate for planktonic cells. Global analysis of gene expression indicated lower transcription of ribosomal genes and genes for other anabolic functions in biofilms than in exponential-phase planktonic cells and revealed the induction of multiple stress responses in biofilm cells, including those associated with growth arrest, zinc limitation, hypoxia, and acyl-homoserine lactone quorum sensing. Metabolic pathways for phenazine biosynthesis and denitrification were transcriptionally activated in biofilms. A customized reaction-diffusion model predicted that steep oxygen concentration gradients will form when these biofilms are thicker than about 40 μm. Mutant strains that were deficient in Psl polysaccharide synthesis, the stringent response, the stationary-phase response, and the membrane stress response exhibited increased ciprofloxacin susceptibility when cultured in biofilms. These results support a sequence of phenomena leading to biofilm antibiotic tolerance, involving oxygen limitation, electron acceptor starvation and growth arrest, induction of associated stress responses, and differentiation into protected cell states.IMPORTANCE Bacteria in biofilms are protected from killing by antibiotics, and this reduced susceptibility contributes to the persistence of infections such as those in the cystic fibrosis lung and chronic wounds. A generalized conceptual model of biofilm antimicrobial tolerance with the following mechanistic steps is proposed: (i) establishment of concentration gradients in metabolic substrates and products; (ii) active biological responses to these changes in the local chemical microenvironment; (iii) entry of biofilm cells into a spectrum of states involving alternative metabolisms, stress responses, slow growth, cessation of growth, or dormancy (all prior to antibiotic treatment); (iv) adaptive responses to antibiotic exposure; and (v) reduced susceptibility of microbial cells to antimicrobial challenges in some of the physiological states accessed through these changes.
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8
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Klauck G, Serra DO, Possling A, Hengge R. Spatial organization of different sigma factor activities and c-di-GMP signalling within the three-dimensional landscape of a bacterial biofilm. Open Biol 2018; 8:180066. [PMID: 30135237 PMCID: PMC6119863 DOI: 10.1098/rsob.180066] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 07/18/2018] [Indexed: 12/25/2022] Open
Abstract
Bacterial biofilms are large aggregates of cells embedded in an extracellular matrix of self-produced polymers. In macrocolony biofilms of Escherichia coli, this matrix is generated in the upper biofilm layer only and shows a surprisingly complex supracellular architecture. Stratified matrix production follows the vertical nutrient gradient and requires the stationary phase σS (RpoS) subunit of RNA polymerase and the second messenger c-di-GMP. By visualizing global gene expression patterns with a newly designed fingerprint set of Gfp reporter fusions, our study reveals the spatial order of differential sigma factor activities, stringent control of ribosomal gene expression and c-di-GMP signalling in vertically cryosectioned macrocolony biofilms. Long-range physiological stratification shows a duplication of the growth-to-stationary phase pattern that integrates nutrient and oxygen gradients. In addition, distinct short-range heterogeneity occurs within specific biofilm strata and correlates with visually different zones of the refined matrix architecture. These results introduce a new conceptual framework for the control of biofilm formation and demonstrate that the intriguing extracellular matrix architecture, which determines the emergent physiological and biomechanical properties of biofilms, results from the spatial interplay of global gene regulation and microenvironmental conditions. Overall, mature bacterial macrocolony biofilms thus resemble the highly organized tissues of multicellular organisms.
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Affiliation(s)
- Gisela Klauck
- Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, Berlin 10115, Germany
| | - Diego O Serra
- Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, Berlin 10115, Germany
| | - Alexandra Possling
- Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, Berlin 10115, Germany
| | - Regine Hengge
- Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, Berlin 10115, Germany
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9
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Costa AM, Mergulhão FJ, Briandet R, Azevedo NF. It is all about location: how to pinpoint microorganisms and their functions in multispecies biofilms. Future Microbiol 2017; 12:987-999. [PMID: 28745517 DOI: 10.2217/fmb-2017-0053] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Multispecies biofilms represent the dominant mode of life for the vast majority of microorganisms. Bacterial spatial localization in such biostructures governs ecological interactions between different populations and triggers the overall community functions. Here, we discuss the pros and cons of fluorescence-based techniques used to decipher bacterial species patterns in biofilms at single cell level, including fluorescence in situ hybridization and the use of genetically modified bacteria that express fluorescent proteins, reporting the significant improvements of those techniques. The development of tools for spatial and temporal study of multispecies biofilms will allow live imaging and spatial localization of cells in naturally occurring biofilms coupled with metabolic information, increasing insight of microbial community and the relation between its structure and functions.
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Affiliation(s)
- Angela M Costa
- LEPABE, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Porto, Portugal.,i3S - Instituto de Investigação e Inovação em Saúde, University of Porto, Portugal.,INEB - Institute of Biomedical Engineering, University of Porto, Porto, Portugal
| | - Filipe J Mergulhão
- LEPABE, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Porto, Portugal
| | - Romain Briandet
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Nuno F Azevedo
- LEPABE, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Porto, Portugal
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11
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Gel-Entrapped Staphylococcus aureus Bacteria as Models of Biofilm Infection Exhibit Growth in Dense Aggregates, Oxygen Limitation, Antibiotic Tolerance, and Heterogeneous Gene Expression. Antimicrob Agents Chemother 2016; 60:6294-301. [PMID: 27503656 DOI: 10.1128/aac.01336-16] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 08/03/2016] [Indexed: 11/20/2022] Open
Abstract
An experimental model that mimicked the structure and characteristics of in vivo biofilm infections, such as those occurring in the lung or in dermal wounds where no biomaterial surface is present, was developed. In these infections, microbial biofilm forms as cell aggregates interspersed in a layer of mucus or host matrix material. This structure was modeled by filling glass capillary tubes with an agarose gel that had been seeded with Staphylococcus aureus bacteria and then incubating the gel biofilm in medium for up to 30 h. Confocal microscopy showed that the bacteria formed in discrete pockets distributed throughout the gel matrix. These aggregates enlarged over time and also developed a size gradient, with the clusters being larger near the nutrient- and oxygen-supplied interface and smaller at greater depths. Bacteria entrapped in gels for 24 h grew slowly (specific growth rate, 0.06 h(-1)) and were much less susceptible to oxacillin, minocycline, or ciprofloxacin than planktonic cells. Microelectrode measurements showed that the oxygen concentration decreased with depth into the gel biofilm, falling to values less than 3% of air saturation at depths of 500 μm. An anaerobiosis-responsive green fluorescent protein reporter gene for lactate dehydrogenase was induced in the region of the gel where the measured oxygen concentrations were low, confirming biologically relevant hypoxia. These results show that the gel biofilm model captures key features of biofilm infection in mucus or compromised tissue: formation of dense, distinct aggregates, reduced specific growth rates, local hypoxia, and antibiotic tolerance.
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12
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Serra DO, Klauck G, Hengge R. Vertical stratification of matrix production is essential for physical integrity and architecture of macrocolony biofilms of Escherichia coli. Environ Microbiol 2015; 17:5073-88. [PMID: 26234179 PMCID: PMC5014196 DOI: 10.1111/1462-2920.12991] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 07/15/2015] [Indexed: 12/22/2022]
Abstract
Bacterial macrocolony biofilms grow into intricate three-dimensional structures that depend on self-produced extracellular polymers conferring protection, cohesion and elasticity to the biofilm. In Escherichia coli, synthesis of this matrix - consisting of amyloid curli fibres and cellulose - requires CsgD, a transcription factor regulated by the stationary phase sigma factor RpoS, and occurs in the nutrient-deprived cells of the upper layer of macrocolonies. Is this asymmetric matrix distribution functionally important or is it just a fortuitous by-product of an unavoidable nutrient gradient? In order to address this question, the RpoS-dependent csgD promoter was replaced by a vegetative promoter. This re-wiring of csgD led to CsgD and matrix production in both strata of macrocolonies, with the lower layer transforming into a rigid 'base plate' of growing yet curli-connected cells. As a result, the two strata broke apart followed by desiccation and exfoliation of the top layer. By contrast, matrix-free cells at the bottom of wild-type macrocolonies maintain colony contact with the humid agar support by flexibly filling the space that opens up under buckling areas of the macrocolony. Precisely regulated stratification in matrix-free and matrix-producing cell layers is thus essential for the physical integrity and architecture of E. coli macrocolony biofilms.
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Affiliation(s)
- Diego O Serra
- Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, Berlin, 10115, Germany
| | - Gisela Klauck
- Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, Berlin, 10115, Germany
| | - Regine Hengge
- Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, Berlin, 10115, Germany
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13
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Modeling microbial growth and dynamics. Appl Microbiol Biotechnol 2015; 99:8831-46. [DOI: 10.1007/s00253-015-6877-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Revised: 07/13/2015] [Accepted: 07/16/2015] [Indexed: 12/11/2022]
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14
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Bridier A, Sanchez-Vizuete P, Guilbaud M, Piard JC, Naïtali M, Briandet R. Biofilm-associated persistence of food-borne pathogens. Food Microbiol 2014; 45:167-78. [PMID: 25500382 DOI: 10.1016/j.fm.2014.04.015] [Citation(s) in RCA: 291] [Impact Index Per Article: 29.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2014] [Revised: 04/15/2014] [Accepted: 04/27/2014] [Indexed: 12/19/2022]
Abstract
Microbial life abounds on surfaces in both natural and industrial environments, one of which is the food industry. A solid substrate, water and some nutrients are sufficient to allow the construction of a microbial fortress, a so-called biofilm. Survival strategies developed by these surface-associated ecosystems are beginning to be deciphered in the context of rudimentary laboratory biofilms. Gelatinous organic matrices consisting of complex mixtures of self-produced biopolymers ensure the cohesion of these biological structures and contribute to their resistance and persistence. Moreover, far from being just simple three-dimensional assemblies of identical cells, biofilms are composed of heterogeneous sub-populations with distinctive behaviours that contribute to their global ecological success. In the clinical field, biofilm-associated infections (BAI) are known to trigger chronic infections that require dedicated therapies. A similar belief emerging in the food industry, where biofilm tolerance to environmental stresses, including cleaning and disinfection/sanitation, can result in the persistence of bacterial pathogens and the recurrent cross-contamination of food products. The present review focuses on the principal mechanisms involved in the formation of biofilms of food-borne pathogens, where biofilm behaviour is driven by its three-dimensional heterogeneity and by species interactions within these biostructures, and we look at some emergent control strategies.
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Affiliation(s)
| | - P Sanchez-Vizuete
- Inra, UMR 1319 Micalis, Jouy-en-Josas, France; AgroParisTech, UMR Micalis, Massy, France
| | - M Guilbaud
- Inra, UMR 1319 Micalis, Jouy-en-Josas, France; AgroParisTech, UMR Micalis, Massy, France
| | - J-C Piard
- Inra, UMR 1319 Micalis, Jouy-en-Josas, France; AgroParisTech, UMR Micalis, Massy, France
| | - M Naïtali
- Inra, UMR 1319 Micalis, Jouy-en-Josas, France; AgroParisTech, UMR Micalis, Massy, France
| | - R Briandet
- Inra, UMR 1319 Micalis, Jouy-en-Josas, France; AgroParisTech, UMR Micalis, Massy, France.
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