Analysis of the Aspergillus fumigatus Biofilm Extracellular Matrix by Solid-State Nuclear Magnetic Resonance Spectroscopy

Reichhardt, Courtney; Ferreira, Jose A. G.; Joubert, Lydia‐Marie; Clemons, Karl V.; Stevens, David A.; Cegelski, Lynette

doi:10.1128/ec.00050-15

Cited by 75 publications

(79 citation statements)

References 42 publications

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“…This would suggest the locus of phage action is something specific for hyphae or extracellular matrix (Reichhardt et al, 2015). Consistent with this, our birefringence measurements and confocal microscopy studies indicate that Pf4 forms an ordered layer on Af biofilms.…”

Section: Discussionsupporting

confidence: 76%

Pf4 bacteriophage produced by Pseudomonas aeruginosa inhibits Aspergillus fumigatus metabolism via iron sequestration

et al. 2016

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Pseudomonas aeruginosa (Pa) and Aspergillus fumigatus (Af) are major human pathogens known to interact in a variety of disease settings, including airway infections in cystic fibrosis. We recently reported that clinical CF isolates of Pa inhibit the formation and growth of Af biofilms. Here, we report that the bacteriophage Pf4, produced by Pa, can inhibit the metabolic activity of Af biofilms. This phage-mediated inhibition was dose dependent, ablated by phage denaturation, and was more pronounced against preformed Af biofilm rather than biofilm formation. In contrast, planktonic conidial growth was unaffected. Two other phages, Pf1 and fd, did not inhibit Af, nor did supernatant from a Pa strain incapable of producing Pf4. Pf4, but not Pf1, attaches to Af hyphae in an avid and prolonged manner, suggesting that Pf4-mediated inhibition of Af may occur at the biofilm surface. We show that Pf4 binds iron, thus denying Af a crucial resource. Consistent with this, the inhibition of Af metabolism by Pf4 could be overcome with supplemental ferric iron, with preformed biofilm more resistant to reversal. To our knowledge, this is the first report of a bacterium producing a phage that inhibits the growth of a fungus and the first description of a phage behaving as an iron chelator in a biological system. †Present address:

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Section: Discussionsupporting

confidence: 76%

Pf4 bacteriophage produced by Pseudomonas aeruginosa inhibits Aspergillus fumigatus metabolism via iron sequestration

et al. 2016

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“…fumigatus has shown, in vivo and in vitro, the ability to form biofilms, or complex aggregates of organisms embedded within a polymer-rich extracellular matrix, which demonstrate increased antimicrobial resistance (32). Thus, there is a need for other therapeutic methods with mechanisms that differ from those of the common antifungal targets of ergosterol or cell wall biosynthesis.…”

mentioning

confidence: 99%

Effects of Iron Chelators on the Formation and Development of Aspergillus fumigatus Biofilm

Nazik

Penner

Ferreira

et al. 2015

Antimicrob Agents Chemother

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e Iron acquisition is crucial for the growth of Aspergillus fumigatus. A. fumigatus biofilm formation occurs in vitro and in vivo and is associated with physiological changes. In this study, we assessed the effects of Fe chelators on biofilm formation and development. Deferiprone (DFP), deferasirox (DFS), and deferoxamine (DFM) were tested for MIC against a reference isolate via a broth macrodilution method. The metabolic effects (assessed by XTT [2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide inner salt]) on biofilm formation by conidia were studied upon exposure to DFP, DFM, DFP plus FeCl 3 , or FeCl 3 alone. A preformed biofilm was exposed to DFP with or without FeCl 3 . The DFP and DFS MIC 50 against planktonic A. fumigatus was 1,250 M, and XTT gave the same result. DFM showed no planktonic inhibition at concentrations of <2,500 M. By XTT testing, DFM concentrations of <1,250 M had no effect, whereas 2,500 M increased biofilms forming in A. fumigatus or preformed biofilms (P < 0.01). DFP at 156 to 2,500 M inhibited biofilm formation (P < 0.01 to 0.001) in a dose-responsive manner. Biofilm formation with 625 M DFP plus any concentration of FeCl 3 was lower than that in the controls (P < 0.05 to 0.001). FeCl 3 at >625 M reversed the DFP inhibitory effect (P < 0.05 to 0.01), but the reversal was incomplete compared to the controls (P < 0.05 to 0.01). For preformed biofilms, DFP in the range of >625 to 1,250 M was inhibitory compared to the controls (P < 0.01 to 0.001). FeCl 3 at >625 M overcame inhibition by 625 M DFP (P < 0.001). FeCl 3 alone at >156 M stimulated biofilm formation (P < 0.05 to 0.001). Preformed A. fumigatus biofilm increased with 2,500 M FeCl 3 only (P < 0.05). In a strain survey, various susceptibilities of biofilms of A. fumigatus clinical isolates to DFP were noted. In conclusion, iron stimulates biofilm formation and preformed biofilms. Chelators can inhibit or enhance biofilms. Chelation may be a potential therapy for A. fumigatus, but we show here that chelators must be chosen carefully. Individual isolate susceptibility assessments may be needed.A spergillus fumigatus, the ubiquitous saprophytic mold, frequently causes respiratory tract infections, including invasive pulmonary aspergillosis and allergic bronchopulmonary aspergillosis (1). A. fumigatus disease occurs most frequently in immunocompromised individuals, such as bone marrow transplant and other neutropenic patients, solid organ transplant recipients (2), and in those with cystic fibrosis (1, 3), chronic granulomatous disease, or chronic obstructive pulmonary disease (1, 4). Despite therapeutic advances in the development and administration of antifungals, mortality from A. fumigatus infection remains high (5).A. fumigatus has shown, in vivo and in vitro, the ability to form biofilms, or complex aggregates of organisms embedded within a polymer-rich extracellular matrix, which demonstrate increased antimicrobial resistance (32). Thus, there is a need for other therapeutic methods with mechanisms that d...

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“…Similar to bacteria, fungi secrete polysaccharides, proteins, and lipids and form an extracellular matrix (biofilm) under stress conditions. A nuclear magnetic resonance (NMR) analysis of the A. fumigatus extracellular matrix indicated that modified polysaccharides are the main component (306), as found in Vibrio cholerae by those same authors. Although dioxygen diffusion is limited in bacterial (307) and fungal (308) biofilms, how these changes trigger differentiation at the cellular level is largely unknown.…”

Section: Transitions From Vegetative Growth To Asexual Developmentmentioning

confidence: 71%

Fungal Morphogenesis, from the Polarized Growth of Hyphae to Complex Reproduction and Infection Structures

Riquelme

Aguirre

Bartnicki-García

et al. 2018

Microbiol Mol Biol Rev

288

246

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SUMMARYFilamentous fungi constitute a large group of eukaryotic microorganisms that grow by forming simple tube-like hyphae that are capable of differentiating into more-complex morphological structures and distinct cell types. Hyphae form filamentous networks by extending at their tips while branching in subapical regions. Rapid tip elongation requires massive membrane insertion and extension of the rigid chitin-containing cell wall. This process is sustained by a continuous flow of secretory vesicles that depends on the coordinated action of the microtubule and actin cytoskeletons and the corresponding motors and associated proteins. Vesicles transport cell wall-synthesizing enzymes and accumulate in a special structure, the Spitzenkörper, before traveling further and fusing with the tip membrane. The place of vesicle fusion and growth direction are enabled and defined by the position of the Spitzenkörper, the so-called cell end markers, and other proteins involved in the exocytic process. Also important for tip extension is membrane recycling by endocytosis via early endosomes, which function as multipurpose transport vehicles for mRNA, septins, ribosomes, and peroxisomes. Cell integrity, hyphal branching, and morphogenesis are all processes that are largely dependent on vesicle and cytoskeleton dynamics. When hyphae differentiate structures for asexual or sexual reproduction or to mediate interspecies interactions, the hyphal basic cellular machinery may be reprogrammed through the synthesis of new proteins and/or the modification of protein activity. Although some transcriptional networks involved in such reprogramming of hyphae are well studied in several model filamentous fungi, clear connections between these networks and known determinants of hyphal morphogenesis are yet to be established.

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Analysis of the Aspergillus fumigatus Biofilm Extracellular Matrix by Solid-State Nuclear Magnetic Resonance Spectroscopy

Cited by 75 publications

References 42 publications

Pf4 bacteriophage produced by Pseudomonas aeruginosa inhibits Aspergillus fumigatus metabolism via iron sequestration

Pf4 bacteriophage produced by Pseudomonas aeruginosa inhibits Aspergillus fumigatus metabolism via iron sequestration

Effects of Iron Chelators on the Formation and Development of Aspergillus fumigatus Biofilm

Fungal Morphogenesis, from the Polarized Growth of Hyphae to Complex Reproduction and Infection Structures

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