Variation in hydrogen cyanide production between different strains of Pseudomonas aeruginosa

Gilchrist, Francis J; Alcock, Alice; Belcher, John; Brady, Michael T.; Jones, Andrew M.; Smith, David; Španěl, Patrik; Webb, Kevin; Lenney, Warren

doi:10.1183/09031936.00166510

Cited by 51 publications

(69 citation statements)

References 39 publications

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“…There has been recent interest in using the cyanogenic properties of P. aeruginosa to develop a rapid method for its detection in CF patients (31,32). Although further work with a larger collection of strains is required, the reliability of this approach is brought into question by our findings.…”

Section: Discussioncontrasting

confidence: 51%

Strain-dependent diversity in the Pseudomonas aeruginosa quorum-sensing regulon

Chugani

Kim

Phattarasukol

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

100

112

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Quorum sensing allows bacteria to sense and respond to changes in population density. Acyl-homoserine lactones serve as quorumsensing signals for many Proteobacteria, and acyl-homoserine lactone signaling is known to control cooperative activities. Quorum-controlled activities vary from one species to another. Quorum-sensing controls a constellation of genes in the opportunistic pathogen Pseudomonas aeruginosa, which thrives in a number of habitats ranging from soil and water to animal hosts. We hypothesized that there would be significant variation in quorumsensing regulons among strains of P. aeruginosa isolated from different habitats and that differences in the quorum-sensing regulons might reveal insights about the ecology of P. aeruginosa. As a test of our hypothesis we used RNA-seq to identify quorumcontrolled genes in seven P. aeruginosa isolates of diverse origins. Although our approach certainly overlooks some quorum-sensingregulated genes we found a shared set of genes, i.e., a core quorum-controlled gene set, and we identified distinct, strain-variable sets of quorum-controlled genes, i.e., accessory genes. Some quorumcontrolled genes in some strains were not present in the genomes of other strains. We detected a correlation between traits encoded by some genes in the strain-variable subsets of the quorum regulons and the ecology of the isolates. These findings indicate a role for quorum sensing in extension of the range of habitats in which a species can thrive. This study also provides a framework for understanding the molecular mechanisms by which quorum-sensing systems operate, the evolutionary pressures by which they are maintained, and their importance in disparate ecological contexts.bacterial communication | systems biology | transcription control B acteria use quorum-sensing signals to communicate with each other and control gene expression in a cell density-dependent manner. Many species of Proteobacteria use diffusible acyl-homoserine lactones (AHLs) as quorum-sensing signals. AHLs are produced by signal synthase enzymes and are detected by signalspecific transcriptional regulators. AHL quorum-sensing circuits regulate a wide spectrum of phenotypes in a diverse array of α-, β-, and γ-Proteobacteria (1). Interspecies differences in quorum regulons often are a reflection of the diverse habitats that bacteria occupy, and quorum-controlled phenotypes often play a crucial role in niche persistence. The classic example is quorum control of luminescence in Vibrio fischeri, which allows this bacterium to discriminate between its free-living, low-populationdensity seawater habitat and its high-density symbiotic habitats, the light organs of certain fish and squid (2, 3). It is well established that there are species-specific differences in quorum regulons, but there is little information regarding the possibility of intraspecies strain-specific differences. We hypothesized that, particularly for versatile species that occupy diverse niches, there might be a shared core of quorum-controlled genes an...

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Section: Discussioncontrasting

confidence: 51%

Strain-dependent diversity in the Pseudomonas aeruginosa quorum-sensing regulon

Chugani

Kim

Phattarasukol

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

100

112

View full text Add to dashboard Cite

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“…HCN levels appear to be independent of bacterial load in sputum, suggesting that HCN production is strain-specific and/or a consequence of phenotypic shifts in the bacteria colonising the lung [11]. The former possibility is supported by the finding of varying degrees of HCN production amongst clinical isolates of P. aeruginosa when grown in culture [13,14,16,17]. Furthermore, HCN production is affected by the mucoid switch that P. aeruginosa commonly undergoes during chronic infection and is associated with a worsened prognosis [18].…”

Section: Introductionsupporting

confidence: 65%

Cyanide levels found in infected cystic fibrosis sputum inhibit airway ciliary function

Nair

Shoemark

Chan³

et al. 2014

Eur Respir J

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We have previously reported cyanide at concentrations of up to 150 mM in the sputum of cystic fibrosis patients infected with Pseudomonas aeruginosa and a negative correlation with lung function. Our aim was to investigate possible mechanisms for this association, focusing on the effect of pathophysiologically relevant cyanide levels on human respiratory cell function.Ciliary beat frequency measurements were performed on nasal brushings and nasal air-liquid interface (ALI) cultures obtained from healthy volunteers and cystic fibrosis patients.Potassium cyanide decreased ciliary beat frequency in healthy nasal brushings (n56) after 60 min (150 mM: 47% fall, p,0.0012; 75 mM: 32% fall, p,0.0001). Samples from cystic fibrosis patients (n53) showed similar results (150 mM: 55% fall, p50.001). Ciliary beat frequency inhibition was not due to loss of cell viability and was reversible. The inhibitory mechanism was independent of ATP levels. KCN also significantly inhibited ciliary beat frequency in ALI cultures, albeit to a lesser extent. Ciliary beat frequency measurements on ALI cultures treated with culture supernatants from P. aeruginosa mutants defective in virulence factor production implicated cyanide as a key component inhibiting the ciliary beat frequency.If cyanide production similarly impairs mucocilliary clearance in vivo, it could explain the link with increased disease severity observed in cystic fibrosis patients with detectable cyanide in their airway. @ERSpublications Cyanide levels detectable in sputum inhibit ciliary function

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“…There is also evidence that hydrogen cyanide is an important biomarker for bacterial infections. It was recently confirmed that the bacterium Pseudomonas aeruginosa (PA) produces substantial amounts of HCN [18,19], enough to be detectable in the breath of patients infected with PA [5,18]. Children with cystic fibrosis often develop a chronic PA infection and it is crucial to detect this infection as early as possible to allow for complete eradication.…”

Section: Introductionmentioning

confidence: 99%

“…Children with cystic fibrosis often develop a chronic PA infection and it is crucial to detect this infection as early as possible to allow for complete eradication. Current microbiological methods for PA diagnosis rely on sputum samples, which are difficult to obtain from young children, or are very invasive (bronchoscopy) or unreliable (cough swabs) [5,18,19]. A rapid, reliable and non-invasive method for detection of systemic HCN is therefore needed, and breath analysis is a viable candidate.…”

Section: Introductionmentioning

confidence: 99%

Background levels and diurnal variations of hydrogen cyanide in breath and emitted from skin

et al. 2011

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PostprintThis is the accepted version of a paper published in Journal of Breath Research. This paper has been peer-reviewed but does not include the final publisher proof-corrections or journal pagination. Abstract. The hydrogen cyanide (HCN) concentration in exhaled human breath and skin gas samples collected with different sampling techniques was measured using nearinfrared cavity ring-down spectroscopy. The median baseline HCN concentrations in samples provided by 19 healthy volunteers 2-4 hours after the last meal depended on the employed sampling technique: 6.5 parts per billion by volume (ppbv) in mixed (dead space and end-tidal) mouth-exhaled breath collected to a gas sampling bag, 3.9 ppbv in end-tidal mouth-exhaled breath, 1.3 ppbv in end-tidal nose-exhaled breath, 1.0 ppbv in unwashed skin, and 0.6 ppbv in washed skin samples. Diurnal measurements showed that elevated HCN levels are to be expected in mouth-exhaled breath samples after food and drink intake, which suggests HCN generation in the oral cavity. The HCN concentrations in end-tidal nose-exhaled breath and skin gas samples correlated and it is concluded that these concentrations best reflect systemic HCN levels.

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Variation in hydrogen cyanide production between different strains of Pseudomonas aeruginosa

Cited by 51 publications

References 39 publications

Strain-dependent diversity in the Pseudomonas aeruginosa quorum-sensing regulon

Strain-dependent diversity in the Pseudomonas aeruginosa quorum-sensing regulon

Cyanide levels found in infected cystic fibrosis sputum inhibit airway ciliary function

Background levels and diurnal variations of hydrogen cyanide in breath and emitted from skin

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