301
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Ferrando Chavez DL, Nejidat A, Herzberg M. Viscoelastic Properties of Extracellular Polymeric Substances Can Strongly Affect Their Washing Efficiency from Reverse Osmosis Membranes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:9206-9213. [PMID: 27404109 DOI: 10.1021/acs.est.6b01458] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The role of the viscoelastic properties of biofouling layers in their removal from the membrane was studied. Model fouling layers of extracellular polymeric substances (EPS) originated from microbial biofilms of Pseudomonas aeruginosa PAO1 differentially expressing the Psl polysaccharide were used for controlled washing experiments of fouled RO membranes. In parallel, adsorption experiments and viscoelastic modeling of the EPS layers were conducted in a quartz crystal microbalance with dissipation (QCM-D). During the washing stage, as shear rate was elevated, significant differences in permeate flux recovery between the three different EPS layers were observed. According to the amount of organic carbon remained on the membrane after washing, the magnitude of Psl production provides elevated resistance of the EPS layer to shear stress. The highest flux recovery during the washing stage was observed for the EPS with no Psl. Psl was shown to elevate the layer's shear modulus and shear viscosity but had no effect on the EPS adhesion to the polyamide surface. We conclude that EPS retain on the membrane as a result of the layer viscoelastic properties. These results highlight an important relation between washing efficiency of fouling layers from membranes and their viscoelastic properties, in addition to their adhesion properties.
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Affiliation(s)
- Diana Lila Ferrando Chavez
- The Jacob Blaustein Institutes for Desert Research, Zuckerberg Institute for Water Research, The Albert Katz International School of Desert Studies, Ben Gurion University of the Negev , Sede Boqer Campus, Midreshet Ben Gurion 84990, Israel
| | - Ali Nejidat
- The Jacob Blaustein Institutes for Desert Research, Zuckerberg Institute for Water Research, The Albert Katz International School of Desert Studies, Ben Gurion University of the Negev , Sede Boqer Campus, Midreshet Ben Gurion 84990, Israel
| | - Moshe Herzberg
- The Jacob Blaustein Institutes for Desert Research, Zuckerberg Institute for Water Research, The Albert Katz International School of Desert Studies, Ben Gurion University of the Negev , Sede Boqer Campus, Midreshet Ben Gurion 84990, Israel
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302
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Glutathione-Disrupted Biofilms of Clinical Pseudomonas aeruginosa Strains Exhibit an Enhanced Antibiotic Effect and a Novel Biofilm Transcriptome. Antimicrob Agents Chemother 2016; 60:4539-51. [PMID: 27161630 DOI: 10.1128/aac.02919-15] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 05/04/2016] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas aeruginosa infections result in high morbidity and mortality rates for individuals with cystic fibrosis (CF), with premature death often occurring. These infections are complicated by the formation of biofilms in the sputum. Antibiotic therapy is stymied by antibiotic resistance of the biofilm matrix, making novel antibiofilm strategies highly desirable. Within P. aeruginosa biofilms, the redox factor pyocyanin enhances biofilm integrity by intercalating with extracellular DNA. The antioxidant glutathione (GSH) reacts with pyocyanin, disrupting intercalation. This study investigated GSH disruption by assaying the physiological effects of GSH and DNase I on biofilms of clinical CF isolates grown in CF artificial sputum medium (ASMDM+). Confocal scanning laser microscopy showed that 2 mM GSH, alone or combined with DNase I, significantly disrupted immature (24-h) biofilms of Australian epidemic strain (AES) isogens AES-1R and AES-1M. GSH alone greatly disrupted mature (72-h) AES-1R biofilms, resulting in significant differential expression of 587 genes, as indicated by RNA-sequencing (RNA-seq) analysis. Upregulated systems included cyclic diguanylate and pyoverdine biosynthesis, the type VI secretion system, nitrate metabolism, and translational machinery. Biofilm disruption with GSH revealed a cellular physiology distinct from those of mature and dispersed biofilms. RNA-seq results were validated by biochemical and quantitative PCR assays. Biofilms of a range of CF isolates disrupted with GSH and DNase I were significantly more susceptible to ciprofloxacin, and increased antibiotic effectiveness was achieved by increasing the GSH concentration. This study demonstrated that GSH, alone or with DNase I, represents an effective antibiofilm treatment when combined with appropriate antibiotics, pending in vivo studies.
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303
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Chew SC, Kundukad B, Teh WK, Doyle P, Yang L, Rice SA, Kjelleberg S. Mechanical signatures of microbial biofilms in micropillar-embedded growth chambers. SOFT MATTER 2016; 12:5224-5232. [PMID: 27191395 DOI: 10.1039/c5sm02755a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Biofilms are surface-attached communities of microorganisms embedded in an extracellular matrix and are essential for the cycling of organic matter in natural and engineered environments. They are also the leading cause of many infections, for example, those associated with chronic wounds and implanted medical devices. The extracellular matrix is a key biofilm component that determines its architecture and defines its physical properties. Herein, we used growth chambers embedded with micropillars to study the net mechanical forces (differential pressure) exerted during biofilm formation in situ. Pressure from the biofilm is transferred to the micropillars via the extracellular matrix, and reduction of major matrix components decreases the magnitude of micropillar deflections. The spatial arrangement of micropillar deflections caused by pressure differences in the different biofilm strains may potentially be used as mechanical signatures for biofilm characterization. Hence, we submit that micropillar-embedded growth chambers provide insights into the mechanical properties and dynamics of the biofilm and its matrix.
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Affiliation(s)
- S C Chew
- Singapore Centre for Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Singapore.
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304
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Germoni LAP, Bremer PJ, Lamont IL. The effect of alginate lyase on the gentamicin resistance of Pseudomonas aeruginosa in mucoid biofilms. J Appl Microbiol 2016; 121:126-35. [PMID: 27061817 DOI: 10.1111/jam.13153] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 04/05/2016] [Accepted: 04/06/2016] [Indexed: 12/22/2022]
Abstract
AIMS Pseudomonas aeruginosa can secrete large amounts of alginate during chronic infections and this has been associated with high resistance to antibiotics. The major aim of this study was to investigate whether degradation of extracellular alginate by alginate lyase would increase the sensitivity of Ps. aeruginosa to gentamicin, an aminoglycoside antibiotic. METHODS AND RESULTS Degradation of alginate from Ps. aeruginosa was monitored using a spectrometric assay. Alginate lyase depolymerized alginate, but calcium and zinc cations at concentrations found in the cystic fibrosis lung reduced enzyme activity. Biofilms formed on agar were partially degraded by alginate lyase, but staining with crystal violet showed that the biomass of biofilms grown in liquid was not significantly affected by the enzyme. Viability testing showed that the sensitivity to gentamicin of biofilm bacteria and of bacteria released from biofilms was unaffected by alginate lyase. CONCLUSIONS Our results show that at least under the conditions used here alginate lyase does not affect gentamicin resistance of Ps. aeruginosa. SIGNIFICANCE AND IMPACT OF THE STUDY Our study indicates that alginate does not contribute to resistance to gentamicin and so does not provide support for the concept of treating patients with alginate lyase in order to increase the antibiotic sensitivity of Ps. aeruginosa.
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Affiliation(s)
- L A P Germoni
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - P J Bremer
- Department of Food Science, University of Otago, Dunedin, New Zealand
| | - I L Lamont
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
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305
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Staphylococcus aureus Protein A Mediates Interspecies Interactions at the Cell Surface of Pseudomonas aeruginosa. mBio 2016; 7:mBio.00538-16. [PMID: 27222468 PMCID: PMC4895107 DOI: 10.1128/mbio.00538-16] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
While considerable research has focused on the properties of individual bacteria, relatively little is known about how microbial interspecies interactions alter bacterial behaviors and pathogenesis. Staphylococcus aureus frequently coinfects with other pathogens in a range of different infectious diseases. For example, coinfection by S. aureus with Pseudomonas aeruginosa occurs commonly in people with cystic fibrosis and is associated with higher lung disease morbidity and mortality. S. aureus secretes numerous exoproducts that are known to interact with host tissues, influencing inflammatory responses. The abundantly secreted S. aureus staphylococcal protein A (SpA) binds a range of human glycoproteins, immunoglobulins, and other molecules, with diverse effects on the host, including inhibition of phagocytosis of S. aureus cells. However, the potential effects of SpA and other S. aureus exoproducts on coinfecting bacteria have not been explored. Here, we show that S. aureus-secreted products, including SpA, significantly alter two behaviors associated with persistent infection. We found that SpA inhibited biofilm formation by specific P. aeruginosa clinical isolates, and it also inhibited phagocytosis by neutrophils of all isolates tested. Our results indicate that these effects were mediated by binding to at least two P. aeruginosa cell surface structures—type IV pili and the exopolysaccharide Psl—that confer attachment to surfaces and to other bacterial cells. Thus, we found that the role of a well-studied S. aureus exoproduct, SpA, extends well beyond interactions with the host immune system. Secreted SpA alters multiple persistence-associated behaviors of another common microbial community member, likely influencing cocolonization and coinfection with other microbes. Bacteria rarely exist in isolation, whether on human tissues or in the environment, and they frequently coinfect with other microbes. However, relatively little is known about how microbial interspecies interactions alter bacterial behaviors and pathogenesis. We identified a novel interaction between two bacterial species that frequently infect together—Staphylococcus aureus and Pseudomonas aeruginosa. We show that the S. aureus-secreted protein staphylococcal protein A (SpA), which is well-known for interacting with host targets, also binds to specific P. aeruginosa cell surface molecules and alters two persistence-associated P. aeruginosa behaviors: biofilm formation and uptake by host immune cells. Because S. aureus frequently precedes P. aeruginosa in chronic infections, these findings reveal how microbial community interactions can impact persistence and host interactions during coinfections.
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306
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Scoffield J, Silo-Suh L. Glycerol metabolism promotes biofilm formation by Pseudomonas aeruginosa. Can J Microbiol 2016; 62:704-10. [PMID: 27392247 DOI: 10.1139/cjm-2016-0119] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Pseudomonas aeruginosa causes persistent infections in the airways of cystic fibrosis (CF) patients. Airway sputum contains various host-derived nutrients that can be utilized by P. aeruginosa, including phosphotidylcholine, a major component of host cell membranes. Phosphotidylcholine can be degraded by P. aeruginosa to glycerol and fatty acids to increase the availability of glycerol in the CF lung. In this study, we explored the role that glycerol metabolism plays in biofilm formation by P. aeruginosa. We report that glycerol metabolism promotes biofilm formation by both a chronic CF isolate (FRD1) and a wound isolate (PAO1) of P. aeruginosa. Moreover, loss of the GlpR regulator, which represses the expression of genes involved in glycerol metabolism, enhances biofilm formation in FRD1 through the upregulation of Pel polysaccharide. Taken together, our results suggest that glycerol metabolism may be a key factor that contributes to P. aeruginosa persistence by promoting biofilm formation.
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Affiliation(s)
- Jessica Scoffield
- a Department of Pediatric Dentistry, 1919 7th Avenue South, Room SDB 801, The University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Laura Silo-Suh
- b Department of Basic Medical Sciences, Mercer University, School of Medicine, Macon, GA 31207, USA
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307
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Baker P, Hill PJ, Snarr BD, Alnabelseya N, Pestrak MJ, Lee MJ, Jennings LK, Tam J, Melnyk RA, Parsek MR, Sheppard DC, Wozniak DJ, Howell PL. Exopolysaccharide biosynthetic glycoside hydrolases can be utilized to disrupt and prevent Pseudomonas aeruginosa biofilms. SCIENCE ADVANCES 2016; 2:e1501632. [PMID: 27386527 PMCID: PMC4928890 DOI: 10.1126/sciadv.1501632] [Citation(s) in RCA: 164] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 04/26/2016] [Indexed: 05/11/2023]
Abstract
Bacterial biofilms present a significant medical challenge because they are recalcitrant to current therapeutic regimes. A key component of biofilm formation in the opportunistic human pathogen Pseudomonas aeruginosa is the biosynthesis of the exopolysaccharides Pel and Psl, which are involved in the formation and maintenance of the structural biofilm scaffold and protection against antimicrobials and host defenses. Given that the glycoside hydrolases PelAh and PslGh encoded in the pel and psl biosynthetic operons, respectively, are utilized for in vivo exopolysaccharide processing, we reasoned that these would provide specificity to target P. aeruginosa biofilms. Evaluating these enzymes as potential therapeutics, we demonstrate that these glycoside hydrolases selectively target and degrade the exopolysaccharide component of the biofilm matrix. PelAh and PslGh inhibit biofilm formation over a 24-hour period with a half maximal effective concentration (EC50) of 69.3 ± 1.2 and 4.1 ± 1.1 nM, respectively, and are capable of disrupting preexisting biofilms in 1 hour with EC50 of 35.7 ± 1.1 and 12.9 ± 1.1 nM, respectively. This treatment was effective against clinical and environmental P. aeruginosa isolates and reduced biofilm biomass by 58 to 94%. These noncytotoxic enzymes potentiated antibiotics because the addition of either enzyme to a sublethal concentration of colistin reduced viable bacterial counts by 2.5 orders of magnitude when used either prophylactically or on established 24-hour biofilms. In addition, PelAh was able to increase neutrophil killing by ~50%. This work illustrates the feasibility and benefits of using bacterial exopolysaccharide biosynthetic glycoside hydrolases to develop novel antibiofilm therapeutics.
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Affiliation(s)
- Perrin Baker
- Program in Molecular Structure & Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
| | - Preston J. Hill
- Departments of Microbial Infection and Immunity, Microbiology, Center for Microbial Interface Biology, Ohio State University, Columbus, OH 43210, USA
| | - Brendan D. Snarr
- Departments of Medicine, Microbiology, and Immunology, McGill University, Montréal, Québec H3A 2B4, Canada
- Infectious Diseases and Immunity in Global Health Program, Centre for Translational Biology, McGill University Health Centre, Montréal, Québec H4A 3J1, Canada
| | - Noor Alnabelseya
- Program in Molecular Structure & Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Matthew J. Pestrak
- Departments of Microbial Infection and Immunity, Microbiology, Center for Microbial Interface Biology, Ohio State University, Columbus, OH 43210, USA
| | - Mark J. Lee
- Departments of Medicine, Microbiology, and Immunology, McGill University, Montréal, Québec H3A 2B4, Canada
- Infectious Diseases and Immunity in Global Health Program, Centre for Translational Biology, McGill University Health Centre, Montréal, Québec H4A 3J1, Canada
| | - Laura K. Jennings
- Department of Microbiology, University of Washington, Seattle, WA 98195, USA
| | - John Tam
- Program in Molecular Structure & Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
| | - Roman A. Melnyk
- Program in Molecular Structure & Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Matthew R. Parsek
- Department of Microbiology, University of Washington, Seattle, WA 98195, USA
| | - Donald C. Sheppard
- Departments of Medicine, Microbiology, and Immunology, McGill University, Montréal, Québec H3A 2B4, Canada
- Infectious Diseases and Immunity in Global Health Program, Centre for Translational Biology, McGill University Health Centre, Montréal, Québec H4A 3J1, Canada
| | - Daniel J. Wozniak
- Departments of Microbial Infection and Immunity, Microbiology, Center for Microbial Interface Biology, Ohio State University, Columbus, OH 43210, USA
| | - P. Lynne Howell
- Program in Molecular Structure & Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
- Corresponding author.
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308
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Sheppard DC, Howell PL. Biofilm Exopolysaccharides of Pathogenic Fungi: Lessons from Bacteria. J Biol Chem 2016; 291:12529-12537. [PMID: 27129222 DOI: 10.1074/jbc.r116.720995] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Exopolysaccharides play an important structural and functional role in the development and maintenance of microbial biofilms. Although the majority of research to date has focused on the exopolysaccharide systems of biofilm-forming bacteria, recent studies have demonstrated that medically relevant fungi such as Candida albicans and Aspergillus fumigatus also form biofilms during infection. These fungal biofilms share many similarities with those of bacteria, including the presence of secreted exopolysaccharides as core components of the extracellular matrix. This review will highlight our current understanding of fungal biofilm exopolysaccharides, as well as the parallels that can be drawn with those of their bacterial counterparts.
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Affiliation(s)
- Donald C Sheppard
- Departments of Medicine, Microbiology and Immunology, Research Institute of the McGill University Health Centre, McGill University, Montréal, Québec H4A 3J1; Infectious Diseases and Immunity in Global Health Program, Research Institute of the McGill University Health Centre, McGill University, Montréal, Québec H4A 3J1.
| | - P Lynne Howell
- Program in Molecular Structure & Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada.
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309
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Abstract
Microbes produce a biofilm matrix consisting of proteins, extracellular DNA, and polysaccharides that is integral in the formation of bacterial communities. Historical studies of polysaccharides revealed that their overproduction often alters the colony morphology and can be diagnostic in identifying certain species. The polysaccharide component of the matrix can provide many diverse benefits to the cells in the biofilm, including adhesion, protection, and structure. Aggregative polysaccharides act as molecular glue, allowing the bacterial cells to adhere to each other as well as surfaces. Adhesion facilitates the colonization of both biotic and abiotic surfaces by allowing the bacteria to resist physical stresses imposed by fluid movement that could separate the cells from a nutrient source. Polysaccharides can also provide protection from a wide range of stresses, such as desiccation, immune effectors, and predators such as phagocytic cells and amoebae. Finally, polysaccharides can provide structure to biofilms, allowing stratification of the bacterial community and establishing gradients of nutrients and waste products. This can be advantageous for the bacteria by establishing a heterogeneous population that is prepared to endure stresses created by the rapidly changing environments that many bacteria encounter. The diverse range of polysaccharide structures, properties, and roles highlight the importance of this matrix constituent to the successful adaptation of bacteria to nearly every niche. Here, we present an overview of the current knowledge regarding the diversity and benefits that polysaccharide production provides to bacterial communities within biofilms.
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310
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c-di-GMP and its Effects on Biofilm Formation and Dispersion: a Pseudomonas Aeruginosa Review. Microbiol Spectr 2016; 3:MB-0003-2014. [PMID: 26104694 DOI: 10.1128/microbiolspec.mb-0003-2014] [Citation(s) in RCA: 185] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Since its initial discovery as an allosteric factor regulating cellulose biosynthesis in Gluconacetobacter xylinus, the list of functional outputs regulated by c-di-GMP has grown. We have focused this article on one of these c-di-GMP-regulated processes, namely, biofilm formation in the organism Pseudomonas aeruginosa. The majority of diguanylate cyclases and phosphodiesterases encoded in the P. aeruginosa genome still remain uncharacterized; thus, there is still a great deal to be learned about the link between c-di-GMP and biofilm formation in this microbe. In particular, while a number of c-di-GMP metabolizing enzymes have been identified that participate in reversible and irreversible attachment and biofilm maturation, there is a still a significant knowledge gap regarding the c-di-GMP output systems in this organism. Even for the well-characterized Pel system, where c-di-GMP-mediated transcriptional regulation is now well documented, how binding of c-di-GMP by PelD stimulates Pel production is not understood in any detail. Similarly, c-di-GMP-mediated control of swimming, swarming and twitching also remains to be elucidated. Thus, despite terrific advances in our understanding of P. aeruginosa biofilm formation and the role of c-di-GMP in this process since the last version of this book (indeed there was no chapter on c-di-GMP!) there is still much to learn.
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311
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Parker D, Ahn D, Cohen T, Prince A. Innate Immune Signaling Activated by MDR Bacteria in the Airway. Physiol Rev 2016; 96:19-53. [PMID: 26582515 DOI: 10.1152/physrev.00009.2015] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Health care-associated bacterial pneumonias due to multiple-drug resistant (MDR) pathogens are an important public health problem and are major causes of morbidity and mortality worldwide. In addition to antimicrobial resistance, these organisms have adapted to the milieu of the human airway and have acquired resistance to the innate immune clearance mechanisms that normally prevent pneumonia. Given the limited efficacy of antibiotics, bacterial clearance from the airway requires an effective immune response. Understanding how specific airway pathogens initiate and regulate innate immune signaling, and whether this response is excessive, leading to host-induced pathology may guide future immunomodulatory therapy. We will focus on three of the most important causes of health care-associated pneumonia, Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella pneumoniae, and review the mechanisms through which an inappropriate or damaging innate immune response is stimulated, as well as describe how airway pathogens cause persistent infection by evading immune activation.
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Affiliation(s)
- Dane Parker
- Departments of Pediatrics and Pharmacology, Columbia University, New York, New York
| | - Danielle Ahn
- Departments of Pediatrics and Pharmacology, Columbia University, New York, New York
| | - Taylor Cohen
- Departments of Pediatrics and Pharmacology, Columbia University, New York, New York
| | - Alice Prince
- Departments of Pediatrics and Pharmacology, Columbia University, New York, New York
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312
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Biofilm formation mechanisms and targets for developing antibiofilm agents. Future Med Chem 2016; 7:493-512. [PMID: 25875875 DOI: 10.4155/fmc.15.6] [Citation(s) in RCA: 371] [Impact Index Per Article: 46.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Biofilms are communities of microorganisms that are attached to a surface and play a significant role in the persistence of bacterial infections. Bacteria within a biofilm are several orders of magnitude more resistant to antibiotics, compared with planktonic bacteria. Thus far, no drugs are in clinical use that specifically target bacterial biofilms. This is probably because until recently the molecular details of biofilm formation were poorly understood. Bacteria integrate information from the environment, such as quorum-sensing autoinducers and nutrients, into appropriate biofilm-related gene expression, and the identity of the key players, such as cyclic dinucleotide second messengers and regulatory RNAs are beginning to be uncovered. Herein, we highlight the current understanding of the processes that lead to biofilm formation in many bacteria.
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313
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Yu S, Su T, Wu H, Liu S, Wang D, Zhao T, Jin Z, Du W, Zhu MJ, Chua SL, Yang L, Zhu D, Gu L, Ma LZ. PslG, a self-produced glycosyl hydrolase, triggers biofilm disassembly by disrupting exopolysaccharide matrix. Cell Res 2015; 25:1352-67. [PMID: 26611635 PMCID: PMC4670989 DOI: 10.1038/cr.2015.129] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Revised: 10/10/2015] [Accepted: 10/10/2015] [Indexed: 01/07/2023] Open
Abstract
Biofilms are surface-associated communities of microorganism embedded in extracellular matrix. Exopolysaccharide is a critical component in the extracellular matrix that maintains biofilm architecture and protects resident biofilm bacteria from antimicrobials and host immune attack. However, self-produced factors that target the matrix exopolysaccharides, are still poorly understood. Here, we show that PslG, a protein involved in the synthesis of a key biofilm matrix exopolysaccharide Psl in Pseudomonas aeruginosa, prevents biofilm formation and disassembles existing biofilms within minutes at nanomolar concentrations when supplied exogenously. The crystal structure of PslG indicates the typical features of an endoglycosidase. PslG mainly disrupts the Psl matrix to disperse bacteria from biofilms. PslG treatment markedly enhances biofilm sensitivity to antibiotics and macrophage cells, resulting in improved biofilm clearance in a mouse implant infection model. Furthermore, PslG shows biofilm inhibition and disassembly activity against a wide range of Pseudomonas species, indicating its great potential in combating biofilm-related complications.
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Affiliation(s)
- Shan Yu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China,University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Tiantian Su
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan, Shandong 250100, China
| | - Huijun Wu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China,University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Shiheng Liu
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan, Shandong 250100, China
| | - Di Wang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Tianhu Zhao
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China,University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Zengjun Jin
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China,University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Wenbin Du
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Mei-Jun Zhu
- School of Food Science, Washington State University, Pullman, WA 99164-6120, USA
| | - Song Lin Chua
- Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Singapore 637551
| | - Liang Yang
- Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Singapore 637551
| | - Deyu Zhu
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan, Shandong 250100, China
| | - Lichuan Gu
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan, Shandong 250100, China,E-mail:
| | - Luyan Z Ma
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China,E-mail:
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314
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Lidor O, Al-Quntar A, Pesci EC, Steinberg D. Mechanistic analysis of a synthetic inhibitor of the Pseudomonas aeruginosa LasI quorum-sensing signal synthase. Sci Rep 2015; 5:16569. [PMID: 26593271 PMCID: PMC4655403 DOI: 10.1038/srep16569] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 10/14/2015] [Indexed: 01/24/2023] Open
Abstract
Pseudomonas aeruginosa is an opportunistic Gram-negative pathogen responsible for many human infections. LasI is an acyl-homoserine lactone synthase that produces a quorum-sensing (QS) signal that positively regulates numerous P. aeruginosa virulence determinants. The inhibition of the LasI protein is therefore an attractive drug target. In this study, a novel in silico to in vitro complementation was applied to screen thiazolidinedione-type compounds for their ability to inhibit biofilm formation at concentrations not affecting bacterial growth. The compound (z)-5-octylidenethiazolidine-2, 4-dione (TZD-C8) was a strong inhibitor of biofilm formation and chosen for further study. Structural exploration of in silico docking predicted that the compound had high affinity for the LasI activity pocket. The TZD-C8 compound was also predicted to create hydrogen bonds with residues Arg30 and Ile107. Site-directed mutagenesis (SDM) of these two sites demonstrated that TZD-C8 inhibition was abolished in the lasI double mutant PAO-R30D, I107S. In addition, in vitro swarming motility and quorum sensing signal production were affected by TZD-C 8, confirming this compound alters the cell to cell signalling circuitry. Overall, this novel inhibitor of P. aeruginosa quorum sensing shows great promise and validates our mechanistic approach to discovering inhibitors of LuxI-type acyl-homoserine lactone synthases.
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Affiliation(s)
- O. Lidor
- Biofilm Research Laboratory, Institute of Dental Sciences, Faculty of Dental Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - A. Al-Quntar
- Biofilm Research Laboratory, Institute of Dental Sciences, Faculty of Dental Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
- Institute of Drug Research, School of Pharmacy, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - E. C. Pesci
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, USA
| | - D. Steinberg
- Biofilm Research Laboratory, Institute of Dental Sciences, Faculty of Dental Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
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315
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Rybtke M, Hultqvist LD, Givskov M, Tolker-Nielsen T. Pseudomonas aeruginosa Biofilm Infections: Community Structure, Antimicrobial Tolerance and Immune Response. J Mol Biol 2015; 427:3628-45. [DOI: 10.1016/j.jmb.2015.08.016] [Citation(s) in RCA: 132] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 08/18/2015] [Accepted: 08/20/2015] [Indexed: 02/07/2023]
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316
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Vidya P, Smith L, Beaudoin T, Yau YCW, Clark S, Coburn B, Guttman DS, Hwang DM, Waters V. Chronic infection phenotypes of Pseudomonas aeruginosa are associated with failure of eradication in children with cystic fibrosis. Eur J Clin Microbiol Infect Dis 2015; 35:67-74. [DOI: 10.1007/s10096-015-2509-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 10/09/2015] [Indexed: 01/10/2023]
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317
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Abstract
Allelic exchange is an efficient method of bacterial genome engineering. This protocol describes the use of this technique to make gene knockouts and knock-ins, as well as single-nucleotide insertions, deletions and substitutions, in Pseudomonas aeruginosa. Unlike other approaches to allelic exchange, this protocol does not require heterologous recombinases to insert or excise selective markers from the target chromosome. Rather, positive and negative selections are enabled solely by suicide vector-encoded functions and host cell proteins. Here, mutant alleles, which are flanked by regions of homology to the recipient chromosome, are synthesized in vitro and then cloned into allelic exchange vectors using standard procedures. These suicide vectors are then introduced into recipient cells by conjugation. Homologous recombination then results in antibiotic-resistant single-crossover mutants in which the plasmid has integrated site-specifically into the chromosome. Subsequently, unmarked double-crossover mutants are isolated directly using sucrose-mediated counter-selection. This two-step process yields seamless mutations that are precise to a single base pair of DNA. The entire procedure requires ∼2 weeks.
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318
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Vital-Lopez FG, Reifman J, Wallqvist A. Biofilm Formation Mechanisms of Pseudomonas aeruginosa Predicted via Genome-Scale Kinetic Models of Bacterial Metabolism. PLoS Comput Biol 2015; 11:e1004452. [PMID: 26431398 PMCID: PMC4592021 DOI: 10.1371/journal.pcbi.1004452] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 07/14/2015] [Indexed: 12/28/2022] Open
Abstract
A hallmark of Pseudomonas aeruginosa is its ability to establish biofilm-based infections that are difficult to eradicate. Biofilms are less susceptible to host inflammatory and immune responses and have higher antibiotic tolerance than free-living planktonic cells. Developing treatments against biofilms requires an understanding of bacterial biofilm-specific physiological traits. Research efforts have started to elucidate the intricate mechanisms underlying biofilm development. However, many aspects of these mechanisms are still poorly understood. Here, we addressed questions regarding biofilm metabolism using a genome-scale kinetic model of the P. aeruginosa metabolic network and gene expression profiles. Specifically, we computed metabolite concentration differences between known mutants with altered biofilm formation and the wild-type strain to predict drug targets against P. aeruginosa biofilms. We also simulated the altered metabolism driven by gene expression changes between biofilm and stationary growth-phase planktonic cultures. Our analysis suggests that the synthesis of important biofilm-related molecules, such as the quorum-sensing molecule Pseudomonas quinolone signal and the exopolysaccharide Psl, is regulated not only through the expression of genes in their own synthesis pathway, but also through the biofilm-specific expression of genes in pathways competing for precursors to these molecules. Finally, we investigated why mutants defective in anthranilate degradation have an impaired ability to form biofilms. Alternative to a previous hypothesis that this biofilm reduction is caused by a decrease in energy production, we proposed that the dysregulation of the synthesis of secondary metabolites derived from anthranilate and chorismate is what impaired the biofilms of these mutants. Notably, these insights generated through our kinetic model-based approach are not accessible from previous constraint-based model analyses of P. aeruginosa biofilm metabolism. Our simulation results showed that plausible, non-intuitive explanations of difficult-to-interpret experimental observations could be generated by integrating genome-scale kinetic models with gene expression profiles.
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Affiliation(s)
- Francisco G. Vital-Lopez
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research and Materiel Command, Fort Detrick, Maryland, United States of America
| | - Jaques Reifman
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research and Materiel Command, Fort Detrick, Maryland, United States of America
- * E-mail:
| | - Anders Wallqvist
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research and Materiel Command, Fort Detrick, Maryland, United States of America
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319
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Penesyan A, Kumar SS, Kamath K, Shathili AM, Venkatakrishnan V, Krisp C, Packer NH, Molloy MP, Paulsen IT. Genetically and Phenotypically Distinct Pseudomonas aeruginosa Cystic Fibrosis Isolates Share a Core Proteomic Signature. PLoS One 2015; 10:e0138527. [PMID: 26431321 PMCID: PMC4592193 DOI: 10.1371/journal.pone.0138527] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 09/01/2015] [Indexed: 01/05/2023] Open
Abstract
The opportunistic pathogen Pseudomonas aeruginosa is among the main colonizers of the lungs of cystic fibrosis (CF) patients. We have isolated and sequenced several P. aeruginosa isolates from the sputum of CF patients and compared them with each other and with the model strain PAO1. Phenotypic analysis of CF isolates showed significant variability in colonization and virulence-related traits suggesting different strategies for adaptation to the CF lung. Genomic analysis indicated these strains shared a large set of core genes with the standard laboratory strain PAO1, and identified the genetic basis for some of the observed phenotypic differences. Proteomics revealed that in a conventional laboratory medium PAO1 expressed 827 proteins that were absent in the CF isolates while the CF isolates shared a distinctive signature set of 703 proteins not detected in PAO1. PAO1 expressed many transporters for the uptake of organic nutrients and relatively few biosynthetic pathways. Conversely, the CF isolates expressed a narrower range of transporters and a broader set of metabolic pathways for the biosynthesis of amino acids, carbohydrates, nucleotides and polyamines. The proteomic data suggests that in a common laboratory medium PAO1 may transport a diverse set of “ready-made” nutrients from the rich medium, whereas the CF isolates may only utilize a limited number of nutrients from the medium relying mainly on their own metabolism for synthesis of essential nutrients. These variations indicate significant differences between the metabolism and physiology of P. aeruginosa CF isolates and PAO1 that cannot be detected at the genome level alone. The widening gap between the increasing genomic data and the lack of phenotypic data means that researchers are increasingly reliant on extrapolating from genomic comparisons using experimentally characterized model organisms such as PAO1. While comparative genomics can provide valuable information, our data suggests that such extrapolations may be fraught with peril.
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Affiliation(s)
- Anahit Penesyan
- Department of Chemistry and Biomolecular Sciences, Faculty of Science and Engineering, Macquarie University, Sydney, New South Wales, Australia
| | - Sheemal S. Kumar
- Department of Chemistry and Biomolecular Sciences, Faculty of Science and Engineering, Macquarie University, Sydney, New South Wales, Australia
| | - Karthik Kamath
- Department of Chemistry and Biomolecular Sciences, Faculty of Science and Engineering, Macquarie University, Sydney, New South Wales, Australia
| | - Abdulrahman M. Shathili
- Department of Chemistry and Biomolecular Sciences, Faculty of Science and Engineering, Macquarie University, Sydney, New South Wales, Australia
| | - Vignesh Venkatakrishnan
- Department of Chemistry and Biomolecular Sciences, Faculty of Science and Engineering, Macquarie University, Sydney, New South Wales, Australia
| | - Christoph Krisp
- Department of Chemistry and Biomolecular Sciences, Faculty of Science and Engineering, Macquarie University, Sydney, New South Wales, Australia
- Australian Proteome Analysis Facility, Macquarie University, Sydney, New South Wales, Australia
| | - Nicolle H. Packer
- Department of Chemistry and Biomolecular Sciences, Faculty of Science and Engineering, Macquarie University, Sydney, New South Wales, Australia
| | - Mark P. Molloy
- Department of Chemistry and Biomolecular Sciences, Faculty of Science and Engineering, Macquarie University, Sydney, New South Wales, Australia
- Australian Proteome Analysis Facility, Macquarie University, Sydney, New South Wales, Australia
| | - Ian T. Paulsen
- Department of Chemistry and Biomolecular Sciences, Faculty of Science and Engineering, Macquarie University, Sydney, New South Wales, Australia
- * E-mail:
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320
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Jennings LK, Storek KM, Ledvina HE, Coulon C, Marmont LS, Sadovskaya I, Secor PR, Tseng BS, Scian M, Filloux A, Wozniak DJ, Howell PL, Parsek MR. Pel is a cationic exopolysaccharide that cross-links extracellular DNA in the Pseudomonas aeruginosa biofilm matrix. Proc Natl Acad Sci U S A 2015; 112:11353-8. [PMID: 26311845 PMCID: PMC4568648 DOI: 10.1073/pnas.1503058112] [Citation(s) in RCA: 384] [Impact Index Per Article: 42.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Biofilm formation is a complex, ordered process. In the opportunistic pathogen Pseudomonas aeruginosa, Psl and Pel exopolysaccharides and extracellular DNA (eDNA) serve as structural components of the biofilm matrix. Despite intensive study, Pel's chemical structure and spatial localization within mature biofilms remain unknown. Using specialized carbohydrate chemical analyses, we unexpectedly found that Pel is a positively charged exopolysaccharide composed of partially acetylated 1→4 glycosidic linkages of N-acetylgalactosamine and N-acetylglucosamine. Guided by the knowledge of Pel's sugar composition, we developed a tool for the direct visualization of Pel in biofilms by combining Pel-specific Wisteria floribunda lectin staining with confocal microscopy. The results indicate that Pel cross-links eDNA in the biofilm stalk via ionic interactions. Our data demonstrate that the cationic charge of Pel is distinct from that of other known P. aeruginosa exopolysaccharides and is instrumental in its ability to interact with other key biofilm matrix components.
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Affiliation(s)
- Laura K Jennings
- Department of Microbiology, University of Washington, Seattle, WA 98195
| | - Kelly M Storek
- Department of Microbiology, University of Washington, Seattle, WA 98195
| | - Hannah E Ledvina
- Department of Microbiology, University of Washington, Seattle, WA 98195
| | - Charlène Coulon
- Equipe Biochimie des Produits Aquatiques, Université du Littoral-Côte d'Opale, 62327 Boulogne-sur-mer, France
| | - Lindsey S Marmont
- Program in Molecular Structure and Function, The Hospital for Sick Children, Toronto, ON, Canada M5G 0A1; Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, ON, Canada M5S 1A8
| | - Irina Sadovskaya
- Equipe Biochimie des Produits Aquatiques, Université du Littoral-Côte d'Opale, 62327 Boulogne-sur-mer, France
| | - Patrick R Secor
- Department of Microbiology, University of Washington, Seattle, WA 98195
| | - Boo Shan Tseng
- Department of Microbiology, University of Washington, Seattle, WA 98195
| | - Michele Scian
- School of Pharmacy, University of Washington, Seattle, WA, 98195
| | - Alain Filloux
- Division of Cell and Molecular Biology, Faculty of Natural Science, Center for Molecular Microbiology and Infection, Imperial College London, London SW7 2AZ, United Kingdom
| | - Daniel J Wozniak
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH 43210; Department of Microbiology, The Ohio State University, Columbus, OH 43210; Center for Microbial Interface Biology, The Ohio State University, Columbus, OH 43210
| | - P Lynne Howell
- Program in Molecular Structure and Function, The Hospital for Sick Children, Toronto, ON, Canada M5G 0A1; Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, ON, Canada M5S 1A8
| | - Matthew R Parsek
- Department of Microbiology, University of Washington, Seattle, WA 98195;
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321
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Visaggio D, Pasqua M, Bonchi C, Kaever V, Visca P, Imperi F. Cell aggregation promotes pyoverdine-dependent iron uptake and virulence in Pseudomonas aeruginosa. Front Microbiol 2015; 6:902. [PMID: 26379660 PMCID: PMC4552172 DOI: 10.3389/fmicb.2015.00902] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 08/17/2015] [Indexed: 11/13/2022] Open
Abstract
In Pseudomonas aeruginosa the Gac signaling system and the second messenger cyclic diguanylate (c-di-GMP) participate in the control of the switch between planktonic and biofilm lifestyles, by regulating the production of the two exopolysaccharides Pel and Psl. The Gac and c-di-GMP regulatory networks also coordinately promote the production of the pyoverdine siderophore, and the extracellular polysaccharides Pel and Psl have recently been found to mediate c-di-GMP-dependent regulation of pyoverdine genes. Here we demonstrate that Pel and Psl are also essential for Gac–mediated activation of pyoverdine production. A pel psl double mutant produces very low levels of pyoverdine and shows a marked reduction in the expression of the pyoverdine-dependent virulence factors exotoxin A and PrpL protease. While the exopolysaccharide-proficient parent strain forms multicellular planktonic aggregates in liquid cultures, the Pel and Psl-deficient mutant mainly grows as dispersed cells. Notably, artificially induced cell aggregation is able to restore pyoverdine-dependent gene expression in the pel psl mutant, in a way that appears to be independent of iron diffusion or siderophore signaling, as well as of recently described contact-dependent mechanosensitive systems. This study demonstrates that cell aggregation represents an important cue triggering the expression of pyoverdine-related genes in P. aeruginosa, suggesting a novel link between virulence gene expression, cell–cell interaction and the multicellular community lifestyle.
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Affiliation(s)
- Daniela Visaggio
- Department of Biology and Biotechnology "Charles Darwin", Sapienza University of Rome Rome, Italy ; Department of Sciences, Universita degli Studi Roma Tre Rome, Italy
| | - Martina Pasqua
- Department of Biology and Biotechnology "Charles Darwin", Sapienza University of Rome Rome, Italy
| | - Carlo Bonchi
- Department of Sciences, Universita degli Studi Roma Tre Rome, Italy
| | - Volkhard Kaever
- Research Core Unit Metabolomics, Institute of Pharmacology, Hannover Medical School Hannover, Germany
| | - Paolo Visca
- Department of Sciences, Universita degli Studi Roma Tre Rome, Italy
| | - Francesco Imperi
- Department of Biology and Biotechnology "Charles Darwin", Sapienza University of Rome Rome, Italy ; Pasteur Institute - Cenci Bolognetti Foundation, Sapienza University of Rome Rome, Italy
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322
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Periasamy S, Nair HAS, Lee KWK, Ong J, Goh JQJ, Kjelleberg S, Rice SA. Pseudomonas aeruginosa PAO1 exopolysaccharides are important for mixed species biofilm community development and stress tolerance. Front Microbiol 2015; 6:851. [PMID: 26347731 PMCID: PMC4542536 DOI: 10.3389/fmicb.2015.00851] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 08/04/2015] [Indexed: 12/31/2022] Open
Abstract
Pseudomonas aeruginosa PAO1 produces three polysaccharides, alginate, Psl, and Pel that play distinct roles in attachment and biofilm formation for monospecies biofilms. Considerably less is known about their role in the development of mixed species biofilm communities. This study has investigated the roles of alginate, Psl, and Pel during biofilm formation of P. aeruginosa in a defined and experimentally informative mixed species biofilm community, consisting of P. aeruginosa, Pseudomonas protegens, and Klebsiella pneumoniae. Loss of the Psl polysaccharide had the biggest impact on the integration of P. aeruginosa in the mixed species biofilms, where the percent composition of the psl mutant was significantly lower (0.06%) than its wild-type (WT) parent (2.44%). In contrast, loss of the Pel polysaccharide had no impact on mixed species biofilm development. Loss of alginate or its overproduction resulted in P. aeruginosa representing 8.4 and 18.11%, respectively, of the mixed species biofilm. Dual species biofilms of P. aeruginosa and K. pneumoniae were not affected by loss of alginate, Pel, or Psl, while the mucoid P. aeruginosa strain achieved a greater biomass than its parent strain. When P. aeruginosa was grown with P. protegens, loss of the Pel or alginate polysaccharides resulted in biofilms that were not significantly different from biofilms formed by the WT PAO1. In contrast, overproduction of alginate resulted in biofilms that were comprised of 35-40% of P. aeruginosa, which was significantly higher than the WT (5-20%). Loss of the Psl polysaccharide significantly reduced the percentage composition of P. aeruginosa in dual species biofilms with P. protegens (<1%). Loss of the Psl polysaccharide significantly disrupted the communal stress resistance of the three species biofilms. Thus, the polysaccharide composition of an individual species significantly impacts mixed species biofilm development and the emergent properties of such communities.
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Affiliation(s)
- Saravanan Periasamy
- Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore Singapore
| | - Harikrishnan A S Nair
- Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore Singapore ; Interdisciplinary Graduate School, Nanyang Technological University, Singapore Singapore
| | - Kai W K Lee
- Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore Singapore
| | - Jolene Ong
- Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore Singapore ; School of Biological Sciences, Nanyang Technological University, Singapore Singapore
| | - Jie Q J Goh
- Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore Singapore ; School of Biological Sciences, Nanyang Technological University, Singapore Singapore
| | - Staffan Kjelleberg
- Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore Singapore ; School of Biological Sciences, Nanyang Technological University, Singapore Singapore ; School of Biotechnology and Biomolecular Sciences, Centre for Marine Bio-Innovation, University of New South Wales, Sydney, NSW Australia
| | - Scott A Rice
- Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore Singapore ; School of Biological Sciences, Nanyang Technological University, Singapore Singapore ; School of Biological, Earth and Environmental Sciences, Centre for Marine Bio-Innovation, University of New South Wales, Sydney, NSW Australia
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323
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Diken E, Ozer T, Arikan M, Emrence Z, Oner ET, Ustek D, Arga KY. Genomic analysis reveals the biotechnological and industrial potential of levan producing halophilic extremophile, Halomonas smyrnensis AAD6T. SPRINGERPLUS 2015; 4:393. [PMID: 26251777 PMCID: PMC4523562 DOI: 10.1186/s40064-015-1184-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 07/27/2015] [Indexed: 01/21/2023]
Abstract
Halomonas smyrnensis AAD6T is a gram negative, aerobic, and moderately halophilic bacterium, and is known to produce high levels of levan with many potential uses in foods, feeds, cosmetics, pharmaceutical and chemical industries due to its outstanding properties. Here, the whole-genome analysis was performed to gain more insight about the biological mechanisms, and the whole-genome organization of the bacterium. Industrially crucial genes, including the levansucrase, were detected and the genome-scale metabolic model of H. smyrnensis AAD6T was reconstructed. The bacterium was found to have many potential applications in biotechnology not only being a levan producer, but also because of its capacity to produce Pel exopolysaccharide, polyhydroxyalkanoates, and osmoprotectants. The genomic information presented here will not only provide additional information to enhance our understanding of the genetic and metabolic network of halophilic bacteria, but also accelerate the research on systematical design of engineering strategies for biotechnology applications.
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Affiliation(s)
- Elif Diken
- />Department of Bioengineering, Marmara University, Goztepe, 34722 Istanbul, Turkey
| | - Tugba Ozer
- />Department of Bioengineering, Marmara University, Goztepe, 34722 Istanbul, Turkey
| | - Muzaffer Arikan
- />Department of Genetics, Institute for Experimental Medicine, Istanbul University, Capa, 34093 Istanbul, Turkey
| | - Zeliha Emrence
- />Department of Genetics, Institute for Experimental Medicine, Istanbul University, Capa, 34093 Istanbul, Turkey
| | - Ebru Toksoy Oner
- />Department of Bioengineering, Marmara University, Goztepe, 34722 Istanbul, Turkey
| | - Duran Ustek
- />Department of Medical Genetics, School of Medicine, REMER, Medipol University, 34810 Istanbul, Turkey
| | - Kazim Yalcin Arga
- />Department of Bioengineering, Marmara University, Goztepe, 34722 Istanbul, Turkey
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324
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Liang ZX. The expanding roles of c-di-GMP in the biosynthesis of exopolysaccharides and secondary metabolites. Nat Prod Rep 2015; 32:663-83. [PMID: 25666534 DOI: 10.1039/c4np00086b] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The cyclic dinucleotide c-di-GMP has emerged in the last decade as a prevalent intracellular messenger that orchestrates the transition between the motile and sessile lifestyles of many bacterial species. The motile-to-sessile transition is often associated with the formation of extracellular matrix-encased biofilm, an organized community of bacterial cells that often contributes to antibiotic resistance and host-pathogen interaction. It is increasingly clear that c-di-GMP controls motility, biofilm formation and bacterial pathogenicity partially through regulating the production of exopolysaccharides (EPS) and small-molecule secondary metabolites. This review summarizes our current understanding of the regulation of EPS biosynthesis by c-di-GMP in a diversity of bacterial species and highlights the emerging role of c-di-GMP in the biosynthesis of small-molecule secondary metabolites.
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Affiliation(s)
- Zhao-Xun Liang
- Division of Structural Biology & Biochemistry, School of Biological Sciences, Nanyang Technological University, Singapore 637551.
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325
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Visualizing and quantifying Pseudomonas aeruginosa infection in the hindbrain ventricle of zebrafish using confocal laser scanning microscopy. J Microbiol Methods 2015; 117:85-94. [PMID: 26188283 DOI: 10.1016/j.mimet.2015.07.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 07/08/2015] [Accepted: 07/09/2015] [Indexed: 02/06/2023]
Abstract
Pseudomonas aeruginosa colonizes surfaces using a stepwise process that involves several phases, including attachment, production of exopolysaccharides, formation of microcolonies and the eventual development of biofilms. This process has been extensively characterized in vitro using both light and electron microscopic techniques. However, our ability to visualize this process in situ at the site of infection has been limited by the nature of the vertebrate models available. The optically clear zebrafish (Danio rerio) is an emerging model well suited for imaging bacterial infections. In this study, we infected the hindbrain ventricle of 54 h post-fertilization zebrafish with P. aeruginosa PAO1 and visualized and quantified microcolony formation using confocal laser scanning microscopy and image analyses. In comparison to wildtype PAO1, infection with a P. aeruginosa mutant deficient in the ability to produce the exopolysaccharide Psl caused less zebrafish mortality and fewer, smaller microcolonies per zebrafish at both 18 h and 29 h post-infection. The work presented here demonstrates reproducible in situ visualization and quantification methods for determining the extent of P. aeruginosa infection in a vertebrate model. We demonstrate how this model system can be manipulated to understand the effect of virulence factors on pathogenicity. Furthermore, this model can be adapted to study biofilm formation in situ, thereby extending our understanding of how bacterial persistence leads to chronic infections.
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326
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Bouffartigues E, Moscoso JA, Duchesne R, Rosay T, Fito-Boncompte L, Gicquel G, Maillot O, Bénard M, Bazire A, Brenner-Weiss G, Lesouhaitier O, Lerouge P, Dufour A, Orange N, Feuilloley MGJ, Overhage J, Filloux A, Chevalier S. The absence of the Pseudomonas aeruginosa OprF protein leads to increased biofilm formation through variation in c-di-GMP level. Front Microbiol 2015; 6:630. [PMID: 26157434 PMCID: PMC4477172 DOI: 10.3389/fmicb.2015.00630] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 06/09/2015] [Indexed: 11/13/2022] Open
Abstract
OprF is the major outer membrane porin in bacteria belonging to the Pseudomonas genus. In previous studies, we have shown that OprF is required for full virulence expression of the opportunistic pathogen Pseudomonas aeruginosa. Here, we describe molecular insights on the nature of this relationship and report that the absence of OprF leads to increased biofilm formation and production of the Pel exopolysaccharide. Accordingly, the level of c-di-GMP, a key second messenger in biofilm control, is elevated in an oprF mutant. By decreasing c-di-GMP levels in this mutant, both biofilm formation and pel gene expression phenotypes were restored to wild-type levels. We further investigated the impact on two small RNAs, which are associated with the biofilm lifestyle, and found that expression of rsmZ but not of rsmY was increased in the oprF mutant and this occurs in a c-di-GMP-dependent manner. Finally, the extracytoplasmic function (ECF) sigma factors AlgU and SigX displayed higher activity levels in the oprF mutant. Two genes of the SigX regulon involved in c-di-GMP metabolism, PA1181 and adcA (PA4843), were up-regulated in the oprF mutant, partly explaining the increased c-di-GMP level. We hypothesized that the absence of OprF leads to a cell envelope stress that activates SigX and results in a c-di-GMP elevated level due to higher expression of adcA and PA1181. The c-di-GMP level can in turn stimulate Pel synthesis via increased rsmZ sRNA levels and pel mRNA, thus affecting Pel-dependent phenotypes such as cell aggregation and biofilm formation. This work highlights the connection between OprF and c-di-GMP regulatory networks, likely via SigX (ECF), on the regulation of biofilm phenotypes.
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Affiliation(s)
- Emeline Bouffartigues
- EA 4312-Laboratory of Microbiology Signals and Microenvironment, University of Rouen - Normandy University Evreux, France
| | - Joana A Moscoso
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London London, UK
| | - Rachel Duchesne
- EA 4312-Laboratory of Microbiology Signals and Microenvironment, University of Rouen - Normandy University Evreux, France
| | - Thibaut Rosay
- EA 4312-Laboratory of Microbiology Signals and Microenvironment, University of Rouen - Normandy University Evreux, France
| | - Laurène Fito-Boncompte
- EA 4312-Laboratory of Microbiology Signals and Microenvironment, University of Rouen - Normandy University Evreux, France
| | - Gwendoline Gicquel
- EA 4312-Laboratory of Microbiology Signals and Microenvironment, University of Rouen - Normandy University Evreux, France
| | - Olivier Maillot
- EA 4312-Laboratory of Microbiology Signals and Microenvironment, University of Rouen - Normandy University Evreux, France
| | - Magalie Bénard
- Cell Imaging Platform of Normandy (PRIMACEN), Institute for Research and Innovation in Biomedicine, University of Rouen Mont-Saint-Aignan, France
| | - Alexis Bazire
- EA 3884-Laboratoire de Biotechnologie et Chimie Marines, Institut Universitaire Européen de la Mer, Université de Bretagne-Sud Lorient, France
| | - Gerald Brenner-Weiss
- Institute of Functional Interfaces, Karlsruhe Institute of Technology Karlsruhe, Germany
| | - Olivier Lesouhaitier
- EA 4312-Laboratory of Microbiology Signals and Microenvironment, University of Rouen - Normandy University Evreux, France
| | - Patrice Lerouge
- Glyco-MeV Laboratory, University of Rouen, Normandy University Mont-Saint-Aignan, France
| | - Alain Dufour
- EA 3884-Laboratoire de Biotechnologie et Chimie Marines, Institut Universitaire Européen de la Mer, Université de Bretagne-Sud Lorient, France
| | - Nicole Orange
- EA 4312-Laboratory of Microbiology Signals and Microenvironment, University of Rouen - Normandy University Evreux, France
| | - Marc G J Feuilloley
- EA 4312-Laboratory of Microbiology Signals and Microenvironment, University of Rouen - Normandy University Evreux, France
| | - Joerg Overhage
- Institute of Functional Interfaces, Karlsruhe Institute of Technology Karlsruhe, Germany
| | - Alain Filloux
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London London, UK
| | - Sylvie Chevalier
- EA 4312-Laboratory of Microbiology Signals and Microenvironment, University of Rouen - Normandy University Evreux, France
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327
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Wang Y, Hay ID, Rehman ZU, Rehm BHA. Membrane-anchored MucR mediates nitrate-dependent regulation of alginate production in Pseudomonas aeruginosa. Appl Microbiol Biotechnol 2015; 99:7253-65. [PMID: 25921805 DOI: 10.1007/s00253-015-6591-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2015] [Accepted: 03/25/2015] [Indexed: 10/23/2022]
Abstract
Alginates exhibit unique material properties suitable for medical and industrial applications. However, if produced by Pseudomonas aeruginosa, it is an important virulence factor in infection of cystic fibrosis patients. The alginate biosynthesis machinery is activated by c-di-GMP imparted by the inner membrane protein, MucR. Here, it was shown that MucR impairs alginate production in response to nitrate in P. aeruginosa. Subsequent site-specific mutagenesis of MucR revealed that the second MHYT sensor motif (MHYT II, amino acids 121-124) of MucR sensor domain was involved in nitrate sensing. We also showed that both c-di-GMP synthesizing and degrading active sites of MucR were important for alginate production. Although nitrate and deletion of MucR impaired alginate promoter activity and global c-di-GMP levels, alginate yields were not directly correlated with alginate promoter activity or c-di-GMP levels, suggesting that nitrate and MucR modulate alginate production at a post-translational level through a localized pool of c-di-GMP. Nitrate increased pel promoter activity in the mucR mutant while in the same mutant the psl promoter activity was independent of nitrate. Nitrate and deletion of mucR did not impact on swarming motility but impaired attachment to solid surfaces. Nitrate and deletion of mucR promoted the formation of biofilms with increased thickness, cell density, and survival. Overall, this study provided insight into the functional role of MucR with respect to nitrate-mediated regulation of alginate biosynthesis.
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Affiliation(s)
- Yajie Wang
- Institute of Fundamental Sciences, Massey University, Palmerston North, New Zealand
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328
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Wang S, Liu X, Liu H, Zhang L, Guo Y, Yu S, Wozniak DJ, Ma LZ. The exopolysaccharide Psl-eDNA interaction enables the formation of a biofilm skeleton in Pseudomonas aeruginosa. ENVIRONMENTAL MICROBIOLOGY REPORTS 2015; 7:330-40. [PMID: 25472701 PMCID: PMC4656019 DOI: 10.1111/1758-2229.12252] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 11/21/2014] [Indexed: 05/07/2023]
Abstract
A hallmark of bacterial biofilms is a self-produced extracellular matrix of exopolysaccharide, extracellular DNA (eDNA) and proteins that hold bacterial cells together in the community. However, interactions among matrix components and how the interactions contribute to the formation of matrix remain unclear. Here, we show the physical interaction between exopolysaccharide Psl and eDNA, the two key biofilm matrix components of the opportunistic pathogen Pseudomonas aeruginosa. The interaction allows the two components to combine to form a web of eDNA-Psl fibres, which resembles a biofilm skeleton in the centre of pellicles to give bacteria structural support and capability against agents targeted on one matrix component. The web of eDNA-Psl fibres was also found in flow-cell biofilms at microcolonies initiation stage. The colocalization of eDNA or Psl fibres with bacterial cell membrane stain suggests that fibre-like eDNA is likely derived from the lysis of dead bacteria in biofilms. Psl can interact with DNA from diverse sources, suggesting that P. aeruginosa has the ability to use DNA of other organisms (such as human neutrophils and other bacterial species) to form its own communities, which might increase the survival of P. aeruginosa in multispecies biofilms or within a human host.
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Affiliation(s)
- Shiwei Wang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Xi Liu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Hongsheng Liu
- School of Life Science, Liaoning University, Shenyang 110036, China
| | - Li Zhang
- School of Life Science, Liaoning University, Shenyang 110036, China
| | - Yuan Guo
- Center for Applied Geosciences, Eberhard Karls University Tuebingen, Tuebingen 72074, Germany
| | - Shan Yu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Daniel J. Wozniak
- Department of Microbial Infection and Immunity, Department of Microbiology, Center for Microbial Interface Biology, The Ohio State University, Columbus, OH 43210, USA
| | - Luyan Z. Ma
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
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329
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The Matrix Reloaded: Probing the Extracellular Matrix Synchronizes Bacterial Communities. J Bacteriol 2015; 197:2092-2103. [PMID: 25825428 DOI: 10.1128/jb.02516-14] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In response to chemical communication, bacterial cells often organize themselves into complex multicellular communities that carry out specialized tasks. These communities are frequently referred to as biofilms, which involve collective behavior of different cell types. Like cells of multicellular eukaryotes, the biofilm cells are surrounded by self-produced polymers that constitute the extracellular matrix (ECM), which binds them to each other and to the surface. In multicellular eukaryotes, it has been evident for decades that cell-ECM interactions control multiple cellular processes during development. While cells, both in biofilms and in multicellular eukaryotes, are surrounded by ECM and activate various genetic programs, until recently it has been unclear whether cell-ECM interactions are recruited in bacterial communicative behaviors. In this review, we will describe the examples reported thus far for ECM involvement in control of cell behavior throughout the different stages of biofilm formation. The studies presented in this review provide a newly emerging perspective of the bacterial ECM as an active player in regulation of biofilm development.
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330
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Whitney JC, Whitfield GB, Marmont LS, Yip P, Neculai AM, Lobsanov YD, Robinson H, Ohman DE, Howell PL. Dimeric c-di-GMP is required for post-translational regulation of alginate production in Pseudomonas aeruginosa. J Biol Chem 2015; 290:12451-62. [PMID: 25817996 DOI: 10.1074/jbc.m115.645051] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Indexed: 11/06/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic human pathogen that secretes the exopolysaccharide alginate during infection of the respiratory tract of individuals afflicted with cystic fibrosis and chronic obstructive pulmonary disease. Among the proteins required for alginate production, Alg44 has been identified as an inner membrane protein whose bis-(3',5')-cyclic dimeric guanosine monophosphate (c-di-GMP) binding activity post-translationally regulates alginate secretion. In this study, we report the 1.8 Å crystal structure of the cytoplasmic region of Alg44 in complex with dimeric self-intercalated c-di-GMP and characterize its dinucleotide-binding site using mutational analysis. The structure shows that the c-di-GMP binding region of Alg44 adopts a PilZ domain fold with a dimerization mode not previously observed for this family of proteins. Calorimetric binding analysis of residues in the c-di-GMP binding site demonstrate that mutation of Arg-17 and Arg-95 alters the binding stoichiometry between c-di-GMP and Alg44 from 2:1 to 1:1. Introduction of these mutant alleles on the P. aeruginosa chromosome show that the residues required for binding of dimeric c-di-GMP in vitro are also required for efficient alginate production in vivo. These results suggest that the dimeric form of c-di-GMP represents the biologically active signaling molecule needed for the secretion of an important virulence factor produced by P. aeruginosa.
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Affiliation(s)
- John C Whitney
- From the Program in Molecular Structure and Function, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada, the Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Gregory B Whitfield
- From the Program in Molecular Structure and Function, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada, the Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Lindsey S Marmont
- From the Program in Molecular Structure and Function, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada, the Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Patrick Yip
- From the Program in Molecular Structure and Function, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
| | - A Mirela Neculai
- From the Program in Molecular Structure and Function, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
| | - Yuri D Lobsanov
- From the Program in Molecular Structure and Function, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
| | - Howard Robinson
- the Photon Sciences Division, Brookhaven National Laboratory, Upton, New York 11973-5000, and
| | - Dennis E Ohman
- the Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center and McGuire Veterans Affairs Medical Center, Richmond, Virginia 23298-0678
| | - P Lynne Howell
- From the Program in Molecular Structure and Function, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada, the Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada,
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331
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Rafii F, Hart ME. Antimicrobial resistance in clinically important biofilms. World J Pharmacol 2015; 4:31-46. [DOI: 10.5497/wjp.v4.i1.31] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 10/22/2014] [Accepted: 12/17/2014] [Indexed: 02/06/2023] Open
Abstract
A biofilm contains a consortium of cohesive bacterial cells forming a complex structure that is a sedentary, but dynamic, community. Biofilms adhere on biotic and abiotic surfaces, including the surfaces of practically all medical devices. Biofilms are reported to be responsible for approximately 60% of nosocomial infections due to implanted medical devices, such as intravenous catheters, and they also cause other foreign-body infections and chronic infections. The presence of biofilm on a medical device may result in the infection of surrounding tissues and failure of the device, necessitating the removal and replacement of the device. Bacteria from biofilms formed on medical devices may be released and disperse, with the potential for the formation of new biofilms in other locations and the development of a systemic infection. Regardless of their location, bacteria in biofilms are tolerant of the activities of the immune system, antimicrobial agents, and antiseptics. Concentrations of antimicrobial agents sufficient to eradicate planktonic cells have no effect on the same microorganism in a biofilm. Depending on the microbial consortium or component of the biofilm that is involved, various combinations of factors have been suggested to explain the recalcitrant nature of biofilms toward killing by antibiotics. In this mini-review, some of the factors contributing to antimicrobial resistance in biofilms are discussed.
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332
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Ghadaksaz A, Fooladi AAI, Mahmoodzadeh Hosseini H, Amin M. The prevalence of some Pseudomonas virulence genes related to biofilm formation and alginate production among clinical isolates. J Appl Biomed 2015. [DOI: 10.1016/j.jab.2014.05.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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333
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Olsen I. Biofilm-specific antibiotic tolerance and resistance. Eur J Clin Microbiol Infect Dis 2015; 34:877-86. [PMID: 25630538 DOI: 10.1007/s10096-015-2323-z] [Citation(s) in RCA: 443] [Impact Index Per Article: 49.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 01/09/2015] [Indexed: 01/30/2023]
Abstract
Biofilms are heterogeneous structures composed of bacterial cells surrounded by a matrix and attached to solid surfaces. The bacteria here are 100 to 1,000 times more tolerant to antimicrobials than corresponding planktonic cells. Biofilms can be difficult to eradicate when they cause biofilm-related diseases, e.g., implant infections, cystic fibrosis, urinary tract infections, and periodontal diseases. A number of phenotypic features of the biofilm can be involved in biofilm-specific tolerance and resistance. Little is known about the molecular mechanisms involved. The current review deals with both phenotypic and molecular mechanisms of biofilm-specific antibiotic tolerance and resistance.
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Affiliation(s)
- I Olsen
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, P.O. Box 1052 Blindern, Oslo, 0316, Norway,
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334
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Seviour T, Hansen SH, Yang L, Yau YH, Wang VB, Stenvang MR, Christiansen G, Marsili E, Givskov M, Chen Y, Otzen DE, Nielsen PH, Geifman-Shochat S, Kjelleberg S, Dueholm MS. Functional amyloids keep quorum-sensing molecules in check. J Biol Chem 2015; 290:6457-69. [PMID: 25586180 DOI: 10.1074/jbc.m114.613810] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The mechanism by which extracellular metabolites, including redox mediators and quorum-sensing signaling molecules, traffic through the extracellular matrix of biofilms is poorly explored. We hypothesize that functional amyloids, abundant in natural biofilms and possessing hydrophobic domains, retain these metabolites. Using surface plasmon resonance, we demonstrate that the quorum-sensing (QS) molecules, 2-heptyl-3-hydroxy-4(1H)-quinolone and N-(3-oxododecanoyl)-l-homoserine lactone, and the redox mediator pyocyanin bind with transient affinity to functional amyloids from Pseudomonas (Fap). Their high hydrophobicity predisposes them to signal-amyloid interactions, but specific interactions also play a role. Transient interactions allow for rapid association and dissociation kinetics, which make the QS molecules bioavailable and at the same time secure within the extracellular matrix as a consequence of serial bindings. Retention of the QS molecules was confirmed using Pseudomonas aeruginosa PAO1-based 2-heptyl-3-hydroxy-4(1H)-quinolone and N-(3-oxododecanoyl)-l-homoserine lactone reporter assays, showing that Fap fibrils pretreated with the QS molecules activate the reporters even after sequential washes. Pyocyanin retention was validated by electrochemical analysis of pyocyanin-pretreated Fap fibrils subjected to the same washing process. Results suggest that QS molecule-amyloid interactions are probably important in the turbulent environments commonly encountered in natural habitats.
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Affiliation(s)
- Thomas Seviour
- From the Singapore Centre on Environmental Life Sciences Engineering (SCELSE) and
| | - Susan Hove Hansen
- the Center for Microbial Communities, Aalborg University, 9220 Aalborg East, Denmark
| | - Liang Yang
- From the Singapore Centre on Environmental Life Sciences Engineering (SCELSE) and
| | - Yin Hoe Yau
- the School of Biological Sciences (SBS), Nanyang Technological University, Singapore 637551, Singapore
| | - Victor Bochuan Wang
- From the Singapore Centre on Environmental Life Sciences Engineering (SCELSE) and the School of Materials Science and Engineering (MSE), Nanyang Technological University, Singapore 639798
| | - Marcel R Stenvang
- the Interdisciplinary Nanoscience Center (iNANO), Department of Molecular Biology and Genetics, Center for Insoluble Protein Structures (inSPIN), and
| | - Gunna Christiansen
- the Department of Biomedicine, Aarhus University, 8000 Aarhus C, Denmark
| | - Enrico Marsili
- From the Singapore Centre on Environmental Life Sciences Engineering (SCELSE) and
| | - Michael Givskov
- From the Singapore Centre on Environmental Life Sciences Engineering (SCELSE) and the Department of International Health, Immunology and Microbiology, University of Copenhagen, 1165 Copenhagen, Denmark, and
| | - Yicai Chen
- From the Singapore Centre on Environmental Life Sciences Engineering (SCELSE) and
| | - Daniel E Otzen
- the Interdisciplinary Nanoscience Center (iNANO), Department of Molecular Biology and Genetics, Center for Insoluble Protein Structures (inSPIN), and
| | - Per Halkjær Nielsen
- From the Singapore Centre on Environmental Life Sciences Engineering (SCELSE) and the Center for Microbial Communities, Aalborg University, 9220 Aalborg East, Denmark
| | - Susana Geifman-Shochat
- the School of Biological Sciences (SBS), Nanyang Technological University, Singapore 637551, Singapore
| | - Staffan Kjelleberg
- From the Singapore Centre on Environmental Life Sciences Engineering (SCELSE) and the Centre for Marine Bio-innovation and School of Biotechnology and Biomolecular Science, University of New South Wales, Mosman, New South Wales 2088, Australia
| | - Morten S Dueholm
- the Center for Microbial Communities, Aalborg University, 9220 Aalborg East, Denmark
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335
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Abdallah M, Benoliel C, Ferreira-Theret P, Drider D, Dhulster P, Chihib NE. Effect of culture conditions on the resistance of Pseudomonas aeruginosa biofilms to disinfecting agents. BIOFOULING 2015; 31:49-59. [PMID: 25569121 DOI: 10.1080/08927014.2014.993390] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The relationship between the environmental conditions of biofilm formation and resistance to disinfectants was studied. Anti-biofilm assays were performed against biofilms grown at 20, 30 and 37°C on stainless steel and polycarbonate, over 24 and 48 h. A rise in growth temperature increased the resistance of 24 h biofilms to disinfectants containing didecyldimethylammonium chloride and decreased it to a disinfectant containing alkyldimethylbenzylammonium chloride. The increase in growth temperature coupled with an incubation time of 24 h promoted increases in both matrix production and the membrane rigidity of sessile cells. An increase in incubation time also increased both matrix production and the membrane rigidity of sessile cells. Such phenomena resulted in an increased resistance to disinfectants of biofilms grown at 20 and 30°C. The resistance of 48 h biofilms to disinfectants decreased with an increase in growth temperature despite the increase in matrix production and the membrane rigidity of sessile cells.
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Affiliation(s)
- Marwan Abdallah
- a Laboratoire de Procédés Biologiques, Génie Enzymatique et Microbien (ProBioGEM), IUT A/Polytech'Lille , Université de Lille1-Science et Technologies , Villeneuve-d'Ascq , France
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336
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Draft Genome Sequence of the Biofilm-Producing Bacillus subtilis Strain B-1, Isolated from an Oil Field. GENOME ANNOUNCEMENTS 2014; 2:2/6/e01163-14. [PMID: 25502661 PMCID: PMC4263823 DOI: 10.1128/genomea.01163-14] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We report here the draft genome sequence of the Bacillus subtilis strain B-1, a strain known to form biofilms. The biofilm matrix mainly consists of the biopolymer γ-polyglutamate (γ-PGA). The sequence of the genome of this strain allows the study of specific genes involved in biofilm formation.
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337
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Whiteley CG, Lee DJ. Bacterial diguanylate cyclases: structure, function and mechanism in exopolysaccharide biofilm development. Biotechnol Adv 2014; 33:124-141. [PMID: 25499693 DOI: 10.1016/j.biotechadv.2014.11.010] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2014] [Revised: 11/24/2014] [Accepted: 11/24/2014] [Indexed: 10/24/2022]
Abstract
The ubiquitous bacterial cyclic di-guanosine monophosphate (c-di-GMP) emerges as an important messenger for the control of many bacterial cellular functions including virulence, motility, bioluminescence, cellulose biosynthesis, adhesion, secretion, community behaviour, biofilm formation and cell differentiation. The synthesis of this cyclic nucleotide arises from external stimuli on various signalling domains within the N-terminal region of a dimeric diguanylate cyclase. This initiates the condensation of two molecules of guanosine triphosphate juxtaposed to each other within the C-terminal region of the enzyme. The biofilm from pathogenic microbes is highly resistant to antimicrobial agents suggesting that diguanylate cyclase and its product - c-di-GMP - are key biomedical targets for the inhibition of biofilm development. Furthermore the formation and long-term stability of the aerobic granule, a superior biofilm for biological wastewater treatment, can be controlled by stimulation of c-di-GMP. Any modulation of the synthetic pathways for c-di-GMP is clearly advantageous in terms of medical, industrial and/or environmental bioremediation implications. This review discusses the structure and reaction of individual diguanylate cyclase enzymes with a focus on new directions in c-di-GMP research. Specific attention is made on the molecular mechanisms that control bacterial exopolysaccharide biofilm formation and aerobic granules.
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Affiliation(s)
- Chris G Whiteley
- Graduate Institute of Applied Science & Technology, National Taiwan University of Science and Technology, Taipei, Taiwan.
| | - Duu-Jong Lee
- Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan; Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan
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338
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Ochoa SA, Cruz-Córdova A, Rodea GE, Cázares-Domínguez V, Escalona G, Arellano-Galindo J, Hernández-Castro R, Reyes-López A, Xicohtencatl-Cortes J. Phenotypic characterization of multidrug-resistant Pseudomonas aeruginosa strains isolated from pediatric patients associated to biofilm formation. Microbiol Res 2014; 172:68-78. [PMID: 25530579 DOI: 10.1016/j.micres.2014.11.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 09/22/2014] [Accepted: 11/24/2014] [Indexed: 10/24/2022]
Abstract
BACKGROUND Pseudomonas aeruginosa is an opportunistic pathogen that has acquired several mechanisms of resistance to multiple groups of antibiotic agents and has been widely employed as a model organism for the study of biofilm formation. Many P. aeruginosa structures embedded in the extracellular matrix, such as exopolysaccharides (EPS), flagella, and type-IV pili (T4P), have been associated with biofilm formation. In this study, we assess biofilm formation by crystal violet quantification in clinical strains of multidrug-resistant (MDR) P. aeruginosa isolated from the Hospital Infantil de México Federico Gómez (HIMFG) associated to total and reducing EPS production (quantification by the anthrone and DNS method, respectively), twitching motility activity by T4P, and flagellar-mediated motility. RESULTS The determination of Minimum Inhibitory Concentration (MIC) showed that >50% of P. aeruginosa strains were resistant to 12 different antibiotics (TIC, CAZ, CTX, CRO, FEP, AZT, GM, CIP, LEV, PZT, IMP, and MEM). Total and reducing EPS analysis of the 58 biofilm-forming MDR P. aeruginosa strains showed heterogeneous values ranging from OD600 9.06 to 212.33, displaying a linear correlation with the production of total EPS (59.66μg/ml to 6000.33μg/ml; R(2)=0.89), and a higher correlation with reducing EPS (88.33μg/ml to 1100.66μg/ml; R(2)=0.96). T4P twitching motility showed a moderated linear correlation (2.00mm to 28.33mm; R(2)=0.74). Even though it has been demonstrated that flagella contribute to the initial stages of biofilm formation, crystal violet analysis showed a moderate correlation (R(2)=0.49) with flagellar-mediated motility in MDR P. aeruginosa under the tested conditions. In addition, PFGE profiles revealed two subgroups generating profiles group A, consisting of 89.63% (52/58) of the strains, and group B, consisting of 13.09% (6/58) of the strains. CONCLUSIONS Phenotypic analysis showed a correlation among the biofilms developed in the MDR P. aeruginosa strains with EPS (total and reducing) production, T4P-activity by twitching motility and flagellar-mediated motility.
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Affiliation(s)
- Sara A Ochoa
- Laboratorio de Investigación en Bacteriología Intestinal, Unidad de Hemato-Onocología e Investigación. Hospital Infantil de México Federico Gómez, Dr. Márquez 162, Col. Doctores, Delegación Cuauhtémoc, México, D.F. 06720, Mexico
| | - Ariadnna Cruz-Córdova
- Laboratorio de Investigación en Bacteriología Intestinal, Unidad de Hemato-Onocología e Investigación. Hospital Infantil de México Federico Gómez, Dr. Márquez 162, Col. Doctores, Delegación Cuauhtémoc, México, D.F. 06720, Mexico
| | - Gerardo E Rodea
- Laboratorio de Investigación en Bacteriología Intestinal, Unidad de Hemato-Onocología e Investigación. Hospital Infantil de México Federico Gómez, Dr. Márquez 162, Col. Doctores, Delegación Cuauhtémoc, México, D.F. 06720, Mexico
| | - Vicenta Cázares-Domínguez
- Laboratorio de Investigación en Bacteriología Intestinal, Unidad de Hemato-Onocología e Investigación. Hospital Infantil de México Federico Gómez, Dr. Márquez 162, Col. Doctores, Delegación Cuauhtémoc, México, D.F. 06720, Mexico
| | - Gerardo Escalona
- Laboratorio de Investigación en Bacteriología Intestinal, Unidad de Hemato-Onocología e Investigación. Hospital Infantil de México Federico Gómez, Dr. Márquez 162, Col. Doctores, Delegación Cuauhtémoc, México, D.F. 06720, Mexico
| | - José Arellano-Galindo
- Laboratorio de Infectología, Departamento de Infectología. Hospital Infantil de México Federico Gómez, Dr. Márquez 162, Col. Doctores, Delegación Cuauhtémoc, México, D.F. 06720, Mexico
| | - Rigoberto Hernández-Castro
- Departamento de Ecología de Agentes Patógenos, Hospital General "Dr. Manuel Gea González", Tlalpan, México, D.F. 14080, Mexico
| | - Alfonso Reyes-López
- Dirección de Investigación. Hospital Infantil de México Federico Gómez, Dr. Márquez 162, Col. Doctores, Delegación Cuauhtémoc, México, D.F. 06720, Mexico
| | - Juan Xicohtencatl-Cortes
- Laboratorio de Investigación en Bacteriología Intestinal, Unidad de Hemato-Onocología e Investigación. Hospital Infantil de México Federico Gómez, Dr. Márquez 162, Col. Doctores, Delegación Cuauhtémoc, México, D.F. 06720, Mexico.
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339
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Wu D, Huang W, Duan Q, Li F, Cheng H. Sodium houttuyfonate affects production of N-acyl homoserine lactone and quorum sensing-regulated genes expression in Pseudomonas aeruginosa. Front Microbiol 2014; 5:635. [PMID: 25505457 PMCID: PMC4244979 DOI: 10.3389/fmicb.2014.00635] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Accepted: 11/05/2014] [Indexed: 12/11/2022] Open
Abstract
Quorum sensing (QS) is a means of cell-to-cell communication that uses diffusible signaling molecules that are sensed by the population to determine population density, thus allowing co-ordinate gene regulation in response to population density. In Pseudomonas aeruginosa, production of the QS signaling molecule, N-acyl homoserine lactone (AHL), co-ordinates expression of key factors of pathogenesis, including biofilm formation and toxin secretion. It is predicted that the inhibition of AHL sensing would provide an effective clinical treatment to reduce the expression of virulence factors and increase the effectiveness of antimicrobial agents. We previously demonstrated that sodium houttuyfonate (SH), commonly used in traditional Chinese medicine to treat infectious diseases, can effectively inhibit QS-regulated processes, including biofilm formation. Here, using a model system, we demonstrate that SH causes the dose-dependent inhibition of AHL production, through down-regulation of the AHL biosynthesis gene, lasI. Addition of SH also resulted in down-regulation of expression of the AHL sensor and transcriptional regulator, LasR, and inhibited the production of the QS-regulated virulence factors, pyocyanin and LasA. These results suggest that the antimicrobial activity of SH may be due to its ability to disrupt QS in P. aeruginosa.
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Affiliation(s)
- Daqiang Wu
- Laboratory of Microbiology and Immunology, School of Chinese and Western Integrative Medicine, Anhui University of Chinese Medicine Hefei, China
| | - Weifeng Huang
- Laboratory of Microbiology and Immunology, School of Chinese and Western Integrative Medicine, Anhui University of Chinese Medicine Hefei, China
| | - Qiangjun Duan
- Laboratory of Microbiology and Immunology, School of Chinese and Western Integrative Medicine, Anhui University of Chinese Medicine Hefei, China
| | - Fang Li
- School of Pharmacy, Anhui University of Chinese Medicine Hefei, China
| | - Huijuan Cheng
- Laboratory of Microbiology and Immunology, School of Chinese and Western Integrative Medicine, Anhui University of Chinese Medicine Hefei, China
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340
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Pseudomonas aeruginosa adaptation in the nasopharyngeal reservoir leads to migration and persistence in the lungs. Nat Commun 2014; 5:4780. [PMID: 25179232 DOI: 10.1038/ncomms5780] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 07/23/2014] [Indexed: 12/27/2022] Open
Abstract
Chronic bacterial infections are a key feature of a variety of lung conditions. The opportunistic bacterium, Pseudomonas aeruginosa, is extremely skilled at both colonizing and persisting in the airways of patients with lung damage. It has been suggested that the upper airways (including the paranasal sinuses and nasopharynx) play an important role as a silent reservoir of bacteria. Over time, P. aeruginosa can adapt to its niche, leading to increased resistance in the face of the immune system and intense therapy regimes. Here we describe a mouse inhalation model of P. aeruginosa chronic infection that can be studied for at least 28 days. We present evidence for adaptation in vivo, in terms of genotype and phenotype including antibiotic resistance. Our data suggest that there is persistence in the upper respiratory tract and that this is key in the establishment of lung infection. This model provides a unique platform for studying evolutionary dynamics and therapeutics.
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341
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Barnes RJ, Bandi RR, Chua F, Low JH, Aung T, Barraud N, Fane AG, Kjelleberg S, Rice SA. The roles of Pseudomonas aeruginosa extracellular polysaccharides in biofouling of reverse osmosis membranes and nitric oxide induced dispersal. J Memb Sci 2014. [DOI: 10.1016/j.memsci.2014.04.046] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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342
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Coordination of swarming motility, biosurfactant synthesis, and biofilm matrix exopolysaccharide production in Pseudomonas aeruginosa. Appl Environ Microbiol 2014; 80:6724-32. [PMID: 25172852 DOI: 10.1128/aem.01237-14] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Biofilm formation is a complex process in which many factors are involved. Bacterial swarming motility and exopolysaccharides both contribute to biofilm formation, yet it is unclear how bacteria coordinate swarming motility and exopolysaccharide production. Psl and Pel are two key biofilm matrix exopolysaccharides in Pseudomonas aeruginosa. This opportunistic pathogen has three types of motility, swimming, twitching, and swarming. In this study, we found that elevated Psl and/or Pel production reduced the swarming motility of P. aeruginosa but had little effect on swimming and twitching. The reduction was due to decreased rhamnolipid production with no relation to the transcription of rhlAB, two key genes involved in the biosynthesis of rhamnolipids. Rhamnolipid-negative rhlR and rhlAB mutants synthesized more Psl, whereas exopolysaccharide-deficient strains exhibited a hyperswarming phenotype. These results suggest that competition for common sugar precursors catalyzed by AlgC could be a tactic for P. aeruginosa to balance the synthesis of exopolysaccharides and rhamnolipids and to control bacterial motility and biofilm formation inversely because the biosynthesis of rhamnolipids, Psl, and Pel requires AlgC to provide the sugar precursors and an additional algC gene enhances the biosynthesis of Psl and rhamnolipids. In addition, our data indicate that the increase in RhlI/RhlR expression attenuated Psl production. This implied that the quorum-sensing signals could regulate exopolysaccharide biosynthesis indirectly in bacterial communities. In summary, this study represents a mechanism that bacteria utilize to coordinate swarming motility, biosurfactant synthesis, and biofilm matrix exopolysaccharide production, which is critical for biofilm formation and bacterial survival in the environment.
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343
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Baker P, Ricer T, Moynihan PJ, Kitova EN, Walvoort MTC, Little DJ, Whitney JC, Dawson K, Weadge JT, Robinson H, Ohman DE, Codée JDC, Klassen JS, Clarke AJ, Howell PL. P. aeruginosa SGNH hydrolase-like proteins AlgJ and AlgX have similar topology but separate and distinct roles in alginate acetylation. PLoS Pathog 2014; 10:e1004334. [PMID: 25165982 PMCID: PMC4148444 DOI: 10.1371/journal.ppat.1004334] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2014] [Accepted: 07/08/2014] [Indexed: 02/05/2023] Open
Abstract
The O-acetylation of polysaccharides is a common modification used by pathogenic organisms to protect against external forces. Pseudomonas aeruginosa secretes the anionic, O-acetylated exopolysaccharide alginate during chronic infection in the lungs of cystic fibrosis patients to form the major constituent of a protective biofilm matrix. Four proteins have been implicated in the O-acetylation of alginate, AlgIJF and AlgX. To probe the biological function of AlgJ, we determined its structure to 1.83 Å resolution. AlgJ is a SGNH hydrolase-like protein, which while structurally similar to the N-terminal domain of AlgX exhibits a distinctly different electrostatic surface potential. Consistent with other SGNH hydrolases, we identified a conserved catalytic triad composed of D190, H192 and S288 and demonstrated that AlgJ exhibits acetylesterase activity in vitro. Residues in the AlgJ signature motifs were found to form an extensive network of interactions that are critical for O-acetylation of alginate in vivo. Using two different electrospray ionization mass spectrometry (ESI-MS) assays we compared the abilities of AlgJ and AlgX to bind and acetylate alginate. Binding studies using defined length polymannuronic acid revealed that AlgJ exhibits either weak or no detectable polymer binding while AlgX binds polymannuronic acid specifically in a length-dependent manner. Additionally, AlgX was capable of utilizing the surrogate acetyl-donor 4-nitrophenyl acetate to catalyze the O-acetylation of polymannuronic acid. Our results, combined with previously published in vivo data, suggest that the annotated O-acetyltransferases AlgJ and AlgX have separate and distinct roles in O-acetylation. Our refined model for alginate acetylation places AlgX as the terminal acetlytransferase and provides a rationale for the variability in the number of proteins required for polysaccharide O-acetylation. Bacteria utilize many defense strategies to protect themselves against external forces. One mechanism used by the bacterium Pseudomonas aeruginosa is the production of the long sugar polymer alginate. The bacteria use this polymer to form a biofilm – a barrier to protect against antibiotics and the host immune response. During its biosynthesis alginate undergoes a chemical modification whereby acetate is added to the polymer. Acetylation of alginate is important as this modification makes the bacterial biofilm less susceptible to recognition and clearance by the host immune system. In this paper we present the atomic structure of AlgJ; one of four proteins required for O-acetylation of the polymer. AlgJ is structurally similar to AlgX, which we have shown previously is also required for alginate acetylation. To understand why both enzymes are required for O-acetylation we functionally characterized the proteins and found that although AlgJ exhibits acetylesterase activity – catalyzing the removal of acetyl groups from a surrogate substrate – it does not bind to short mannuornic acid polymers. In contrast, AlgX bound alginate in a length-dependent manner and was capable of transfering acetate from a surrogate substrate onto alginate. This has allowed us to not only understand how acetate is added to alginate, but increases our understanding of how acetate is added to other bacterial sugar polymers.
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Affiliation(s)
- Perrin Baker
- Program in Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Tyler Ricer
- Program in Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Patrick J. Moynihan
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Elena N. Kitova
- Alberta Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada
| | | | - Dustin J. Little
- Program in Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - John C. Whitney
- Program in Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Karen Dawson
- Program in Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Joel T. Weadge
- Program in Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Howard Robinson
- Photon Sciences Division, Brookhaven National Laboratory, Upton, New York, United States of America
| | - Dennis E. Ohman
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center and McGuire Veterans Affairs Medical Center, Richmond, Virginia, United States of America
| | - Jeroen D. C. Codée
- Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands
| | - John S. Klassen
- Alberta Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Anthony J. Clarke
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - P. Lynne Howell
- Program in Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
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344
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Chew SC, Kundukad B, Seviour T, van der Maarel JRC, Yang L, Rice SA, Doyle P, Kjelleberg S. Dynamic remodeling of microbial biofilms by functionally distinct exopolysaccharides. mBio 2014; 5:e01536-14. [PMID: 25096883 PMCID: PMC4128364 DOI: 10.1128/mbio.01536-14] [Citation(s) in RCA: 115] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 07/07/2014] [Indexed: 12/24/2022] Open
Abstract
Biofilms are densely populated communities of microbial cells protected and held together by a matrix of extracellular polymeric substances. The structure and rheological properties of the matrix at the microscale influence the retention and transport of molecules and cells in the biofilm, thereby dictating population and community behavior. Despite its importance, quantitative descriptions of the matrix microstructure and microrheology are limited. Here, particle-tracking microrheology in combination with genetic approaches was used to spatially and temporally study the rheological contributions of the major exopolysaccharides Pel and Psl in Pseudomonas aeruginosa biofilms. Psl increased the elasticity and effective cross-linking within the matrix, which strengthened its scaffold and appeared to facilitate the formation of microcolonies. Conversely, Pel reduced effective cross-linking within the matrix. Without Psl, the matrix becomes more viscous, which facilitates biofilm spreading. The wild-type biofilm decreased in effective cross-linking over time, which would be advantageous for the spreading and colonization of new surfaces. This suggests that there are regulatory mechanisms to control production of the exopolysaccharides that serve to remodel the matrix of developing biofilms. The exopolysaccharides were also found to have profound effects on the spatial organization and integration of P. aeruginosa in a mixed-species biofilm model of P. aeruginosa-Staphylococcus aureus. Pel was required for close association of the two species in mixed-species microcolonies. In contrast, Psl was important for P. aeruginosa to form single-species biofilms on top of S. aureus biofilms. Our results demonstrate that Pel and Psl have distinct physical properties and functional roles during biofilm formation. Importance: Most bacteria grow as biofilms in the environment or in association with eukaryotic hosts. Removal of biofilms that form on surfaces is a challenge in clinical and industrial settings. One of the defining features of a biofilm is its extracellular matrix. The matrix has a heterogeneous structure and is formed from a secretion of various biopolymers, including proteins, extracellular DNA, and polysaccharides. It is generally known to interact with biofilm cells, thus affecting cell physiology and cell-cell communication. Despite the fact that the matrix may comprise up to 90% of the biofilm dry weight, how the matrix properties affect biofilm structure, maturation, and interspecies interactions remain largely unexplored. This study reveals that bacteria can use specific extracellular polymers to modulate the physical properties of their microenvironment. This in turn impacts biofilm structure, differentiation, and interspecies interactions.
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Affiliation(s)
| | - Binu Kundukad
- BioSystems and Micromechanics IRG, Singapore-MIT Alliance for Research and Technology, National University of Singapore, Singapore
| | - Thomas Seviour
- Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore
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345
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Zarnowski R, Westler WM, Lacmbouh GA, Marita JM, Bothe JR, Bernhardt J, Lounes-Hadj Sahraoui A, Fontaine J, Sanchez H, Hatfield RD, Ntambi JM, Nett JE, Mitchell AP, Andes DR. Novel entries in a fungal biofilm matrix encyclopedia. mBio 2014; 5:e01333-14. [PMID: 25096878 PMCID: PMC4128356 DOI: 10.1128/mbio.01333-14] [Citation(s) in RCA: 203] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 07/10/2014] [Indexed: 12/31/2022] Open
Abstract
Virulence of Candida is linked with its ability to form biofilms. Once established, biofilm infections are nearly impossible to eradicate. Biofilm cells live immersed in a self-produced matrix, a blend of extracellular biopolymers, many of which are uncharacterized. In this study, we provide a comprehensive analysis of the matrix manufactured by Candida albicans both in vitro and in a clinical niche animal model. We further explore the function of matrix components, including the impact on drug resistance. We uncovered components from each of the macromolecular classes (55% protein, 25% carbohydrate, 15% lipid, and 5% nucleic acid) in the C. albicans biofilm matrix. Three individual polysaccharides were identified and were suggested to interact physically. Surprisingly, a previously identified polysaccharide of functional importance, β-1,3-glucan, comprised only a small portion of the total matrix carbohydrate. Newly described, more abundant polysaccharides included α-1,2 branched α-1,6-mannans (87%) associated with unbranched β-1,6-glucans (13%) in an apparent mannan-glucan complex (MGCx). Functional matrix proteomic analysis revealed 458 distinct activities. The matrix lipids consisted of neutral glycerolipids (89.1%), polar glycerolipids (10.4%), and sphingolipids (0.5%). Examination of matrix nucleic acid identified DNA, primarily noncoding sequences. Several of the in vitro matrix components, including proteins and each of the polysaccharides, were also present in the matrix of a clinically relevant in vivo biofilm. Nuclear magnetic resonance (NMR) analysis demonstrated interaction of aggregate matrix with the antifungal fluconazole, consistent with a role in drug impedance and contribution of multiple matrix components. Importance: This report is the first to decipher the complex and unique macromolecular composition of the Candida biofilm matrix, demonstrate the clinical relevance of matrix components, and show that multiple matrix components are needed for protection from antifungal drugs. The availability of these biochemical analyses provides a unique resource for further functional investigation of the biofilm matrix, a defining trait of this lifestyle.
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Affiliation(s)
- Robert Zarnowski
- Department of Medicine, Infectious Diseases, University of Wisconsin, Madison, Wisconsin, USA
| | - William M Westler
- National Magnetic Resonance Facility at Madison, University of Wisconsin, Madison, Wisconsin, USA
| | | | - Jane M Marita
- Dairy Forage Research Center, U.S. Department of Agriculture, Madison, Wisconsin, USA
| | - Jameson R Bothe
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin, USA
| | | | - Anissa Lounes-Hadj Sahraoui
- Université du Littoral Côte d'Opale, Unité de Chimie Environnementale at Interactions sur le Vivant, Calais, France
| | - Joël Fontaine
- Université du Littoral Côte d'Opale, Unité de Chimie Environnementale at Interactions sur le Vivant, Calais, France
| | - Hiram Sanchez
- Department of Medicine, Infectious Diseases, University of Wisconsin, Madison, Wisconsin, USA
| | - Ronald D Hatfield
- Dairy Forage Research Center, U.S. Department of Agriculture, Madison, Wisconsin, USA
| | | | | | - Aaron P Mitchell
- Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
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346
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Turner KH, Everett J, Trivedi U, Rumbaugh KP, Whiteley M. Requirements for Pseudomonas aeruginosa acute burn and chronic surgical wound infection. PLoS Genet 2014; 10:e1004518. [PMID: 25057820 PMCID: PMC4109851 DOI: 10.1371/journal.pgen.1004518] [Citation(s) in RCA: 236] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 06/04/2014] [Indexed: 12/29/2022] Open
Abstract
Opportunistic infections caused by Pseudomonas aeruginosa can be acute or chronic. While acute infections often spread rapidly and can cause tissue damage and sepsis with high mortality rates, chronic infections can persist for weeks, months, or years in the face of intensive clinical intervention. Remarkably, this diverse infectious capability is not accompanied by extensive variation in genomic content, suggesting that the genetic capacity to be an acute or a chronic pathogen is present in most P. aeruginosa strains. To investigate the genetic requirements for acute and chronic pathogenesis in P. aeruginosa infections, we combined high-throughput sequencing-mediated transcriptome profiling (RNA-seq) and genome-wide insertion mutant fitness profiling (Tn-seq) to characterize gene expression and fitness determinants in murine models of burn and non-diabetic chronic wound infection. Generally we discovered that expression of a gene in vivo is not correlated with its importance for fitness, with the exception of metabolic genes. By combining metabolic models generated from in vivo gene expression data with mutant fitness profiles, we determined the nutritional requirements for colonization and persistence in these infections. Specifically, we found that long-chain fatty acids represent a major carbon source in both chronic and acute wounds, and P. aeruginosa must biosynthesize purines, several amino acids, and most cofactors during infection. In addition, we determined that P. aeruginosa requires chemotactic flagellar motility for fitness and virulence in acute burn wound infections, but not in non-diabetic chronic wound infections. Our results provide novel insight into the genetic requirements for acute and chronic P. aeruginosa wound infections and demonstrate the power of using both gene expression and fitness profiling for probing bacterial virulence. Soft tissue infections, such as those in burns, bed sores, and diabetic ulcers, are a significant healthcare and economic burden in the developed and developing world. The opportunistic pathogen P. aeruginosa can cause both acute and chronic infections, and the trajectory of these two types of infections is vastly different. We used high-throughput sequencing to profile P. aeruginosa genome-wide gene expression and mutant fitness during mouse model acute and non-diabetic chronic wound infections. Using these data, we show that wounds are nutrient-rich growth environments in which long-chain fatty acids are a primary source of carbon and energy. We also show that the ability to travel along spatio-chemical gradients by chemotaxis is critical for bacterial fitness and virulence in acute but not chronic infections. Our results demonstrate the utility of simultaneous mutant fitness and gene expression profiling to discover critical functions in complex growth environments.
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Affiliation(s)
- Keith H. Turner
- Department of Molecular Biosciences, Institute of Cellular and Molecular Biology, Center for Infectious Disease, The University of Texas at Austin, Austin, Texas, United States of America
| | - Jake Everett
- Department of Surgery, Texas Tech University Health Sciences Center, Lubbock, Texas, United States of America
| | - Urvish Trivedi
- Department of Surgery, Texas Tech University Health Sciences Center, Lubbock, Texas, United States of America
| | - Kendra P. Rumbaugh
- Department of Surgery, Texas Tech University Health Sciences Center, Lubbock, Texas, United States of America
| | - Marvin Whiteley
- Department of Molecular Biosciences, Institute of Cellular and Molecular Biology, Center for Infectious Disease, The University of Texas at Austin, Austin, Texas, United States of America
- * E-mail:
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347
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Bouffartigues E, Duchesne R, Bazire A, Simon M, Maillot O, Dufour A, Feuilloley M, Orange N, Chevalier S. Sucrose favors Pseudomonas aeruginosa pellicle production through the extracytoplasmic function sigma factor SigX. FEMS Microbiol Lett 2014; 356:193-200. [PMID: 24861220 DOI: 10.1111/1574-6968.12482] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 05/16/2014] [Accepted: 05/16/2014] [Indexed: 11/28/2022] Open
Abstract
Pseudomonas aeruginosa biofilm formation was increased by addition of sucrose to Luria-Bertani medium, whereas addition of NaCl to a final similar osmolarity and use of maltose instead of sucrose, were ineffective. In a previous study, we showed that the extracytoplasmic sigma factor SigX is activated in the presence of sucrose. The sucrose-mediated pellicle increase was abolished in a sigX mutant strain. Sucrose addition led to an increase in pel expression and cyclic-diguanylate (c-di-GMP) pool level production. Interestingly, these two phenotypes were strongly decreased in a sigX mutant. Since pel is not known as a SigX-target, we suspect SigX to be involved in the c-di-GMP production. We found that expression of the diguanylate cyclase PA4843 gene was increased in the presence of sucrose at least partly through SigX activity. Our study shows that sucrose itself rather than osmolarity favours the biofilm mode of P. aeruginosa through the activation of SigX.
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Affiliation(s)
- Emeline Bouffartigues
- Laboratoire de Microbiologie Signaux et Microenvironnement (LMSM), EA 4312, Normandie Université, Université de Rouen, Rouen, France
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348
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Serra DO, Hengge R. Stress responses go three dimensional - the spatial order of physiological differentiation in bacterial macrocolony biofilms. Environ Microbiol 2014; 16:1455-71. [PMID: 24725389 PMCID: PMC4238805 DOI: 10.1111/1462-2920.12483] [Citation(s) in RCA: 124] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 03/28/2014] [Indexed: 11/30/2022]
Abstract
In natural habitats, bacteria often occur in multicellular communities characterized by a robust extracellular matrix of proteins, amyloid fibres, exopolysaccharides and extracellular DNA. These biofilms show pronounced stress resistance including a resilience against antibiotics that causes serious medical and technical problems. This review summarizes recent studies that have revealed clear spatial physiological differentiation, complex supracellular architecture and striking morphology in macrocolony biofilms. By responding to gradients of nutrients, oxygen, waste products and signalling compounds that build up in growing biofilms, various stress responses determine whether bacteria grow and proliferate or whether they enter into stationary phase and use their remaining resources for maintenance and survival. As a consequence, biofilms differentiate into at least two distinct layers of vegetatively growing and stationary phase cells that exhibit very different cellular physiology. This includes a stratification of matrix production with a major impact on microscopic architecture, biophysical properties and directly visible morphology of macrocolony biofilms. Using Escherichia coli as a model system, this review also describes our detailed current knowledge about the underlying molecular control networks – prominently featuring sigma factors, transcriptional cascades and second messengers – that drive this spatial differentiation and points out directions for future research.
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Affiliation(s)
- Diego O Serra
- Institute of Biology/Microbiology, Humboldt Universität zu Berlin, Chausseestr. 117, Berlin, 10115, Germany
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349
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Deletion mutant library for investigation of functional outputs of cyclic diguanylate metabolism in Pseudomonas aeruginosa PA14. Appl Environ Microbiol 2014; 80:3384-93. [PMID: 24657857 DOI: 10.1128/aem.00299-14] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We constructed a library of in-frame deletion mutants targeting each gene in Pseudomonas aeruginosa PA14 predicted to participate in cyclic di-GMP (c-di-GMP) metabolism (biosynthesis or degradation) to provide a toolkit to assist investigators studying c-di-GMP-mediated regulation by this microbe. We present phenotypic assessments of each mutant, including biofilm formation, exopolysaccharide (EPS) production, swimming motility, swarming motility, and twitch motility, as a means to initially characterize these mutants and to demonstrate the potential utility of this library.
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350
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Okegbe C, Price-Whelan A, Dietrich LEP. Redox-driven regulation of microbial community morphogenesis. Curr Opin Microbiol 2014; 18:39-45. [PMID: 24607644 DOI: 10.1016/j.mib.2014.01.006] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2013] [Revised: 01/13/2014] [Accepted: 01/20/2014] [Indexed: 12/22/2022]
Abstract
During growth on surfaces, diverse microbial communities display topographies with captivating patterns. The quality and quantity of matrix excreted by resident cells play major roles in determining community architecture. Two current publications indicate that the cellular redox state and respiratory activity are important parameters affecting matrix output in the divergent bacteria Pseudomonas aeruginosa and Bacillus subtilis. These and related studies have identified regulatory proteins with the potential to respond to changes in redox state and respiratory electron transport and modulate the activity of the signal transduction pathways that control matrix production. These developments hint at the critical mechanistic links between environmental sensing and community behavior, and provide an exciting new context within which to interpret the molecular details of biofilm structure determination.
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Affiliation(s)
- Chinweike Okegbe
- Department of Biological Sciences, Columbia University, New York, NY 10027, United States
| | - Alexa Price-Whelan
- Department of Biological Sciences, Columbia University, New York, NY 10027, United States
| | - Lars E P Dietrich
- Department of Biological Sciences, Columbia University, New York, NY 10027, United States.
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