Alginate Overproduction Affects<i>Pseudomonas aeruginosa</i>Biofilm Structure and Function

Hentzer, Morten; Teitzel, Gail; Balzer, Grant J.; Heydorn, Arne; Molin, Søren; Givskov, Michael; Parsek, Matthew R.

doi:10.1128/jb.183.18.5395-5401.2001

Cited by 599 publications

(545 citation statements)

References 55 publications

(51 reference statements)

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“…Fourier transform infrared spectroscopy (FTIR) demonstrated that alginate was associated with biofilms of this mucoid strain. Similar results were obtained using a mutant derivative of the nonmucoid strain P. aeruginosa PAO1 engineered to overproduce alginate (25,60). On the other hand, results using wild-type P. aeruginosa PAO1 and PA14 showed that alginate was not associated with biofilms (72) and that a second polysaccharide likely encoded by a separate polysaccharide biosynthetic gene cluster may provide the extracellular matrix material for those cells (18,19,29).…”

supporting

confidence: 69%

“…P. aeruginosa pulmonary infections are considered biofilm-associated diseases, where the bacteria colonize the surface of pulmonary tissue (36), are often encapsulated in extracellular polysaccharide matrix material (25,36,48), secrete quorumsensing signaling compounds (58), and have increased resistance to antibiotics (reviewed in reference 59) and to host defenses (2,30,45). Mutations in the cystic fibrosis transmembrane regulator of CF patients lead to physiological alteration of pulmonary fluid, with the most characteristic manifestation being the increased concentrations of thick pulmonary mucus that includes DNA and actin from lysed neutrophils (38).…”

mentioning

confidence: 99%

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Calcium-Induced Virulence Factors Associated with the Extracellular Matrix of MucoidPseudomonas aeruginosaBiofilms

Sarkisova¹,

Patrauchan

Berglund³

et al. 2005

J Bacteriol

199

173

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Pseudomonas aeruginosa colonizes the pulmonary tissue of patients with cystic fibrosis (CF), leading to biofilm-associated infections. The pulmonary fluid of CF patients usually contains elevated concentrations of cations and may contain the P. aeruginosa redox-active pigment pyocyanin, which is known to disrupt calcium homeostasis of host cells. Since divalent cations are important bridging ions for bacterial polysaccharides and since they may play regulatory roles in bacterial gene expression, we investigated the effect of calcium ions on the extracellular matrix constituents of P. aeruginosa biofilms. For mucoid strain P. aeruginosa FRD1, calcium addition (1.0 and 10 mM as CaCl 2 ) resulted in biofilms that were at least 10-fold thicker than biofilms without added calcium. Scanning confocal laser microscopy showed increased spacing between cells for the thick biofilms, and Fourier transform infrared spectroscopy revealed that the material between cells is primarily alginate. An algD transcriptional reporter demonstrated that calcium addition caused an eightfold increase in alg gene expression in FRD1 biofilms. Calcium addition also resulted in increased amounts of three extracellular proteases (AprA, LasB, and PrpL). Immunoblots of the biofilm extracellular material established that AprA was harbored within the biofilm extracellular matrix. An aprA deletion mutation and a mutation in gene for a putative P. aeruginosa calmodulin-like protein did not significantly affect calcium-induced biofilm structure. Two-dimensional gel electrophoresis showed increased amounts of phenazine biosynthetic proteins in FRD1 biofilms and in calcium-amended planktonic cultures. Spectrochemical analyses showed that the calcium addition causes a three-to fivefold increase in pyocyanin production. These results demonstrate that calcium addition affects the structure and extracellular matrix composition of mucoid P. aeruginosa biofilms, through increased expression and stability of bacterial extracellular products. The calcium-induced extracellular matrix of mucoid P. aeruginosa consists primarily of the virulence factor alginate and also harbors extracellular proteases and perhaps pyocyanin, a biomolecule that may further disrupt cellular calcium levels.

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supporting

confidence: 69%

mentioning

confidence: 99%

Calcium-Induced Virulence Factors Associated with the Extracellular Matrix of MucoidPseudomonas aeruginosaBiofilms

Sarkisova¹,

Patrauchan

Berglund³

et al. 2005

J Bacteriol

199

173

View full text Add to dashboard Cite

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“…2B). This corresponds to observations done in surface-attached biofilms, where biofilms formed by mucoid P. aeruginosa have been shown to be more difficult to eradicate than the corresponding wild-type biofilms (18), while the MIC values for planktonic cultures were comparable (10). Deletion of the algD gene in the mucA background resulted in nonmucoid No statistical differences in survival were observed between the two strains upon antimicrobial treatment.…”

Section: Resultsmentioning

confidence: 99%

“…Biofilms of mucoid P. aeruginosa strains are more tolerant to antibiotics than wild-type biofilms (10), and mucoidy has been implicated in increased tolerance to host immune responses (11).…”

mentioning

confidence: 99%

Importance of the Exopolysaccharide Matrix in Antimicrobial Tolerance of Pseudomonas aeruginosa Aggregates

Goltermann

Tolker‐Nielsen

2017

Antimicrob Agents Chemother

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Pseudomonas aeruginosa is an opportunistic pathogen that can infect the lungs of cystic fibrosis (CF) patients and persist in the form of antibiotic-tolerant aggregates in the mucus. It has recently been suggested that such aggregates are formed due to restricted bacterial motility independent of the production of extracellular matrix components, and that they do not rely on an extracellular matrix for antimicrobial tolerance. However, we show here that biofilm matrix overexpression, as displayed by various clinical isolates, significantly protects P. aeruginosa aggregates against antimicrobial treatment. Alginate-overproducing mucA mutant bacteria growing in aggregates showed highly increased antibiotic tolerance compared to wild-type bacteria in aggregates. Deletion of algD in the mucA mutant strain abrogated alginate production and reversed the antibiotic tolerance displayed by the aggregates to a level similar to that observed for aggregates formed by the wild type. The P. aeruginosa ΔwspF and ΔyfiR mutant strains both overproduce Pel and Psl exopolysaccharide, and when these bacteria grew in aggregates, they showed highly increased antibiotic tolerance compared to wild-type bacteria growing in aggregates. However, the ΔwspF and ΔyfiR mutant strains, deficient in Pel/Psl production due to additional ΔpelA ΔpslBCD deletions, formed aggregates that displayed antibiotic tolerance levels close to those of wild-type aggregates. These results suggest that biofilm matrix components, such as alginate, Pel, and Psl, do play a role in the tolerance toward antimicrobials when bacteria grow as aggregates.

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“…Biofilm protects the cell against mercury toxicity Many bacteria are embedded in an extracellular polymeric substance matrix composed of polysaccharides, proteins, and nucleic acids (Flemming and Wingender, 2001). The surfaceattached communities (biofilms) increase resistance to antimicrobial agents compared to the resistance of free-swimming organisms (Hentzer et al, 2001) probably due to decreased metabolic activity within the depths of a biofilm (Spoering and Lewis, 2001) and to binding and sequestration of antimicrobial agents by biofilm components, such as negatively charged phosphate, sulfate, and carboxylic acid groups (Hunt, 1986). As biofilms facilitate sorption of heavy metals, they are capable of removing heavy metal ions from bulk liquid (Liehr et al 1994;Labrenz et al, 2000).…”

Section: The Mercury Uptake Is Ph-dependentmentioning

confidence: 99%

Stoichiometry and kinetics of mercury uptake by photosynthetic bacteria

2017

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Mercury adsorption on the cell surface and intracellular uptake by bacteria represent the key first step in the production and accumulation of highly toxic mercury in living organisms. In this work, the biophysical characteristics of the mercury bioaccumulation are studied in intact cells of photosynthetic bacteria by use of analytical (dithizone) assay and physiological photosynthetic markers (pigment content, fluorescence induction and membrane potential) to determine the amount of mercury ions bound to the cell surface and taken up by the cell. It is shown that the Hg(II) uptake mechanism 1) has two kinetically distinguishable components, 2) includes co-opted influx through heavy metal transporters since the slow component is inhibited by Ca 2+ channel blockers, 3) shows complex pH-dependence demonstrating the competition of ligand binding of Hg(II) ions with H + ions (low pH) and high tendency of complex formation of Hg(II) with hydroxyl ions (high pH) and 4) is not a passive but an energy-dependent process as evidenced by light-activation and inhibition by protonophore. Photosynthetic bacteria can accumulate Hg(II) in amounts much (about 10 5 ) greater than their own masses by well defined strong and weak binding sites with equilibrium binding constants in the range of 1 (μM) -1 and 1 (mM) -1 , respectively. The strong binding sites are attributed to sulfhydryl groups as the uptake is blocked by use of sulfhydryl modifying agents and their number is much (two orders of magnitude) smaller than the number of weak binding sites. Biofilms developed by some bacteria (e.g. Rvx. gelatinosus) increase the mercury binding capacity further by a factor of about five. Photosynthetic bacteria in the light act as sponge of Hg(II) and can be potentially used for biomonitoring and bioremediation of mercury contaminated aqueous cultures.2

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Alginate Overproduction AffectsPseudomonas aeruginosaBiofilm Structure and Function

Cited by 599 publications

References 55 publications

Calcium-Induced Virulence Factors Associated with the Extracellular Matrix of MucoidPseudomonas aeruginosaBiofilms

Calcium-Induced Virulence Factors Associated with the Extracellular Matrix of MucoidPseudomonas aeruginosaBiofilms

Importance of the Exopolysaccharide Matrix in Antimicrobial Tolerance of Pseudomonas aeruginosa Aggregates

Stoichiometry and kinetics of mercury uptake by photosynthetic bacteria

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