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Results for “Pyocyanine”

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At least 73 records · Page 4Linked to original sources

PubMed1991

[Preliminary investigation of effect of pyocyanin on common bacteria in burn wound].

Pyocyanin was extracted from culture medium of Ps. aeruginosa by Frank's method. Minimum inhibitory concentration (MIC) & minimum bactericidal concentration (MBC) of pyocyanin for 6 species of bacteria isolated from burn wounds were determined. The results of MIC & MBC: S. aureus 12.5 micrograms/ml, 50 micrograms/ml; E. coli 25 micrograms/ml, 100 micrograms/ml; P. vulgaris 50 micrograms/ml, 200 micrograms/ml; C. freundii 100 micrograms/ml, 400 micrograms/ml; S. epidermidis 12.5 micrograms/ml, 50 micrograms/ml; no inhibitory effect on Ps. aeruginosa. According to the laboratory results and clinical findings, the authors believe that when there is a dominant growth of Ps. aeruginosa in burn wounds there may be pyocyanin production to inhibit or kill other species of bacteria.

Burns↗

PubMed1977

Pyocyanine production by Pseudomonas aeruginosa.

Dextrose enhanced the growth of P. aeruginosa but suppressed the biosynthesis of pyocyanine. The preformed pigment could be released from dead cells. Pigmentation was not correlated directly with number of viable organisms in the culture. High concentration of maltose likewise inhibited pyocyanine production. Maltose contained in medium used for pyocyanine production by P. aeruginosa should be kept in low concentration or omitted.

Culture Media↗

PubMedDate not supplied

[Effect of pyocyanin on the intensity of KMnO4-induced protein chemiluminescence].

Pyocyanin being added to protein solutions influenced the intensity of the subsequent chemiluminescence caused by KMnO4. The amplitude of chemiluminescence for albumin, peptone and peroxidase decreased by 38, 39 and 42%, respectively. Pyocyanin had only a minor effect on the chemiluminescence of alcohol dehydrogenase; it decreased the intensity of the reaction by 7%. The reaction of chemiluminescence for cytochrome c and lysozyme did not change in the presence of pyocyanin.

Bacterial Proteins↗

PubMed1997

The Involvement of Plastoquinone in the Pyocyanine-mediated Cyclic Electron Transport around Photosystem I.

2,5 dibromo-3-methyl-5-isopropyl-p-benzoquinone (DBMIB), an inhibitor of plastoquinone, inhibited photosystem I cyclic electron transport mediated by pyocyanine of low concentration, but had no effect on that mediated by phenazine methosulphate (PMS). In the presence of pyocyanine, the thylakoids displayed a transient post-illumination increase in chlorophyll fluorescence which resembled that displayed in leaves. The above results indicate the involvement of plastoquinone in the pyocyanine-mediated cyclic electron transport around photosystem I.

Journal Article↗

PubMed2025

Role of AprA and pyocyanin from Pseudomonas aeruginosa on Staphylococcus aureus tolerance to silver.

The opportunistic pathogens Staphylococcus aureus and Pseudomonas aeruginosa are often found together causing persistent infections where they exhibit complex interactions that affect their virulence and resistance to treatment. We sought to clarify how interactions between these organisms affect their resistance to the antimicrobial metal silver (AgNO3). As previous work showed that cell-free supernatant from P. aeruginosa enhances the resistance of S. aureus, we aimed to identify the exact factor(s) responsible for this increase. Using molecular weight cutoff filters and proteomics, we identified the protein AprA and pyocyanin as the responsible factors. Transposon-mediated disruption of aprA led to the production of supernatant which could not enhance the silver tolerance of S. aureus. These findings suggest that the protease AprA from P. aeruginosa plays an important role in increasing the tolerance of S. aureus to AgNO3 via in part by mediating the levels of pyocyanin which in turn reduces Ag2+ to detoxify it.

Pseudomonas aeruginosa↗

PubMed2000

Concentrations of the Pseudomonas aeruginosa toxin pyocyanin in human ear secretions.

Pseudomonas aeruginosa is the most common bacterium in chronic otitis media. Several extracellular factors have been described. Pyocyanin (Pyo) is the blue pigment that gives the bacterium its name "the pyocyanous bacteria". Pyo is known to have an inhibitory effect on the activity of cilia. It is a zwitterion that might easily penetrate biological membranes. Samples of ear secretions for culture and analysis of the concentration of Pyo were collected from 17 patients with different ear infections. Concentrations varied from 3 to 2714 nmol/g, with a mean of 905 nmol/g. For comparison, concentrations were also measured in bacteriological filtrates of P. aeruginosa obtained from wounds and urine specimens. Concentrations in filtrates varied from 13 to 8114 nmol/g, mean 1968 nmol/g. The results indicate that pyocyanin might act as virulence factor that compromises ciliary function and enables the microorganism to establish itself within the ear.

Adolescent↗

PubMed1987

Medium for the simultaneous detection of pyocyanin and fluorescein pigments of Pseudomonas aeruginosa.

To help simplify the identification of Pseudomonas aeruginosa by clinical microbiology laboratories, the authors developed a new medium, pyocyanin-fluorescein agar (PFA), which enhances the production of both Pseudomonas pigments simultaneously. Production of pigments on PFA was equivalent to production on a pyocyanin agar (P agar) and a fluorescein agar (F agar) used in combination and was superior to either P agar or F agar used alone. The medium is simple to prepare and it detected pigment in 94% of P. aeruginosa isolates tested.

Culture Media↗

PubMed2006

The phenazine pyocyanin is a terminal signalling factor in the quorum sensing network of Pseudomonas aeruginosa.

Certain members of the fluorescent pseudomonads produce and secrete phenazines. These heterocyclic, redox-active compounds are toxic to competing organisms, and the cause of these antibiotic effects has been the focus of intense research efforts. It is largely unknown, however, how pseudomonads themselves respond to - and survive in the presence of - these compounds. Using Pseudomonas aeruginosa DNA microarrays and quantitative RT-PCR, we demonstrate that the phenazine pyocyanin elicits the upregulation of genes/operons that function in transport [such as the resistance-nodulation-cell division (RND) efflux pump MexGHI-OpmD] and possibly in redox control (such as PA2274, a putative flavin-dependant monooxygenase), and downregulates genes involved in ferric iron acquisition. Strikingly, mexGHI-opmD and PA2274 were previously shown to be regulated by the PA14 quorum sensing network that controls the production of virulence factors (including phenazines). Through mutational analysis, we show that pyocyanin is the physiological signal for the upregulation of these quorum sensing-controlled genes during stationary phase and that the response is mediated by the transcription factor SoxR. Our results implicate phenazines as signalling molecules in both P. aeruginosa PA14 and PAO1.

Bacterial Proteins↗

PubMed1992

Effect of pyocyanine, a pigment of Pseudomonas aeruginosa, on production of reactive nitrogen intermediates by murine alveolar macrophages.

In this study we investigated the effect of pyocyanine, a pigment produced by Pseudomonas aeruginosa, on production of reactive nitrogen intermediates by macrophages. We found that addition of pyocyanine to cultures of murine alveolar macrophages inhibited the capacity of these cells to produce reactive nitrogen intermediates (measured as nitrite) in a dose-dependent manner without altering cell viability, cytokine-induced Ia expression, or production of tumor necrosis factor.

Animals↗

PubMed1995

Pyocyanin from Pseudomonas aeruginosa inhibits prostacyclin release from endothelial cells.

Pseudomonas aeruginosa pneumonia causes a vasculitis of small pulmonary arteries. While the fully developed lesion demonstrates vessel wall necrosis, the early lesion is remarkable for preservation of viable endothelium despite vessel wall invasion by bacteria. Pyocyanin, an exoproduct of P. aeruginosa, markedly inhibited prostacyclin production by pulmonary artery endothelial cells without causing cell lysis. Pyocyanin might after vascular homeostasis in the absence of cytolysis.

Animals↗

PubMed1969

Biosynthesis of pyocyanine by a paraffin hydrocarbon-oxidizing strain of Pseudomonas aeruginosa.

A paraffin-oxidizing bacterium, designated as Pseudomonas aeruginosa ATS-14, was isolated from soil samples obtained from the Athabasca "tar sands." This strain utilized kerosene as the only carbon source of energy and produced a high concentration of pyocyanine in the culture medium. Aromatic carbons were not attacked, but C(10) to C(17)n-alkanes were readily oxidized by the pseudomonad and formed pyocyanine. The highest yield of the pigment was obtained from hexadecane and heptadecane.

Alkanes↗

PubMed1974

Phenotype recognition of pyocyanine mutants in pseudomonas aeruginosa.

Certain classes of pyocyanine mutants in Pseudomonas aeruginosa escape detection when screened in the presence of wild-type or other mutant cells. A technique is described for recognizing mutant phenotypes after cells are in individual agar wells. The procedure eliminates cross-feeding phenomena as well as the masking of mutant phenotypes by diffusing pyocyanine produced by nearby clones.

Agar↗

PubMed1991

Effect of Pseudomonas aeruginosa-derived pyocyanin and 1-hydroxyphenazine on pulmonary mucociliary clearance monitored scintigraphically in the baboon model.

The effect of products of the bacterium Pseudomonas aeruginosa on mucociliary lung clearance has been monitored in vivo in the baboon model by scintigraphy. Clearance was found to be inhibited by both 1-hydroxyphenazine and pyocyanin, and a dose-effect was illustrated by the former. This confirms previous in vitro results as well as results from work on guinea-pigs, and holds good prospects for the use of the baboon model under anesthesia in such investigations.

Aerosols↗

PubMed2006

Pyocyanin isolated from a marine microbial population: synergistic production between two distinct bacterial species and mode of action.

Marine microbial populations collected from the Hawaiian Islands were screened for antimicrobial activity. A blue metabolite was identified from mixed cell cultures, but production was not evident in pure cultures. Experiments designed to probe the synergistic role of the microorganisms are presented. Full characterization of the blue natural product, pyocyanin, is provided including corrections made to 1H and 13C-NMR assignments of the molecule misreported in the chemical literature and yeast transcriptome analysis. The transcriptional effects were consistent with the compound's purported role as an inducer of oxidative stress and damage and illustrates the overall potential of the method to reveal the primary biological/cellular effects of a natural product. The experiments outlined here might serve as a general paradigm for identification of natural products arising from microbial communities and investigation of their respective interactions.

Bacteria↗

PubMed2004

The role of pyocyanin in Pseudomonas aeruginosa infection.

Pyocyanin (PCN) is a blue redox-active secondary metabolite that is produced by Pseudomonas aeruginosa. PCN is readily recovered in large quantities in sputum from patients with cystic fibrosis who are infected by P. aeruginosa. Despite in vitro studies demonstrating that PCN interferes with multiple cellular functions, its importance during clinical infection is uncertain. This is partially caused by the difficulty in defining the contribution of PCN among the numerous virulence factors produced by P. aeruginosa during infection. In addition, few cellular pathways that are affected by PCN are known. This review briefly highlights recent advances that might clarify the role of PCN in P. aeruginosa pathogenesis.

Animals↗

PubMed1999

Pseudomonas aeruginosa UV-A-induced lethal effect: influence of salts, nutritional stress and pyocyanine.

The presence of NaCl in plating media shows an important protection against the Pseudomonas aeruginosa UV-A-induced lethal effect, contrasting with the known sensitizing action of salts on UV-A-irradiated Escherichia coli cells. MgSO4 exhibits a similar protection, but lower concentrations than for NaCl are needed to achieve the same effect. NaCl protection from lethal effects involves an osmotic mechanism, while MgSO4 could act by a different process. On the other hand, when cells grown in a complete medium are then incubated for 20 min in a synthetic medium and irradiated with UV-A, a very marked protection is obtained. This protection is dependent on protein synthesis, since treatment with tetracycline, during the nutritional stress, blocks its induction. These results offer a new example of cross-protection among different stressing agents. In our experimental conditions, natural phenazines of P. aeruginosa are not present in the cells, ruling out the possibility that these pigments act as photosensitizers. Conversely, pyocyanine (the major phenazine produced by this microorganism) prevents the UV-A killing effect in a concentration-dependent way when present in the irradiation media. Finally, UV-A irradiation induces, as in E. coli, the accumulation of guanosine tetraphosphate and guanosine pentaphosphate, although the physiological meaning of this finding has yet to be determined.

Culture Media↗

PubMed1997

The global activator GacA of Pseudomonas aeruginosa PAO positively controls the production of the autoinducer N-butyryl-homoserine lactone and the formation of the virulence factors pyocyanin, cyanide, and lipase.

The global activator GacA, a highly conserved response regulator in Gram-negative bacteria, is required for the production of exoenzymes and secondary metabolites in Pseudomonas spp. The gacA gene of Pseudomonas aeruginosa PAO1 was isolated and its role in cell-density-dependent gene expression was characterized. Mutational inactivation of gacA resulted in delayed and reduced formation of the cell-density signal N-butyryl-L-homoserine lactone (BHL), of the cognate transcriptional activator RhIR (VsmR), and of the transcriptional activator LasR, which is known to positively regulate RhIR expression. Amplification of gacA on a multicopy plasmid caused precocious and enhanced production of BHL, RhIR and LasR. In parallel, the gacA gene dosage markedly influenced the BHL/RhIR-dependent formation of the cytotoxic compounds pyocyanin and cyanide and the exoenzyme lipase. However, the concentrations of another known cell-density signal of P. aeruginosa, N-oxododecanoyl-L-homoserine lactone, did not always match BHL concentrations. A model accounting for these observations places GacA function upstream of LasR and RhIR in the complex, cell-density-dependent signal-transduction pathway regulating several exoproducts and virulence factors of P. aeruginosa via BHL.

4-Butyrolactone↗

PubMed2006

Pseudomonas aeruginosa pyocyanin inactivates lung epithelial vacuolar ATPase-dependent cystic fibrosis transmembrane conductance regulator expression and localization.

Pseudomonas aeruginosa (PA) is a major pathogen causing morbidity and ultimately mortality in patients afflicted with cystic fibrosis (CF) lung disease. One important virulence factor, pyocyanin (PCN), is a blue, redox-active compound that is secreted in such copious amounts by PA in the CF lungs that it determines the colour of expectorated sputum. In this study, we discovered that physiological concentrations of PCN inactivate the airway epithelial vacuolar ATPase, resulting in reduced expression and trafficking of the cystic fibrosis transmembrane conductance regulator in cultured lung and primary nasal epithelial cells. Our study supports the notion that PCN contributes significantly to the pathogenesis of CF and other bronchiectasis patients infected by PA.

Calcium Channels, L-Type↗