Bacteria of the Burkholderia cepacia complex are cyanogenic under biofilm and colonial growth conditions

<p>Abstract</p> <p>Background</p> <p>The <it>Burkholderia cepacia </it>complex (Bcc) is a collection of nine genotypically distinct but phenotypically similar species. They show wide ecological diversity and include species that are used for promoting plant growth and bio-control as well species that are opportunistic pathogens of vulnerable patients. Over recent years the Bcc have emerged as problematic pathogens of the CF lung. <it>Pseudomonas aeruginosa </it>is another important CF pathogen. It is able to synthesise hydrogen cyanide (HCN), a potent inhibitor of cellular respiration. We have recently shown that HCN production by <it>P. aeruginosa </it>may have a role in CF pathogenesis. This paper describes an investigation of the ability of bacteria of the Bcc to make HCN.</p> <p>Results</p> <p>The genome of <it>Burkholderia cenocepacia </it>has 3 putative HCN synthase encoding (<it>hcnABC</it>) gene clusters. <it>B. cenocepacia </it>and all 9 species of the Bcc complex tested were able to make cyanide at comparable levels to <it>P. aeruginosa</it>, but only when grown surface attached as colonies or during biofilm growth on glass beads. In contrast to <it>P. aeruginosa </it>and other cyanogenic bacteria, cyanide was not detected during planktonic growth of Bcc strains.</p> <p>Conclusion</p> <p>All species in the Bcc are cyanogenic when grown as surface attached colonies or as biofilms.</p

Israel and a sports boycott: Antisemitic? Anti-Zionist?

The paper identifies and summarises the debates that surround the place of Israel in international sport and assesses how that place is increasingly being contested. The long-standing conflict between Israel and Palestine has begun to manifest in the world of sport with the paper sketching the debates of those calling for, and those opposed to, sport sanctions/boycott of Israel until the ‘Palestinian Question’ is resolved. Five related tasks are addressed: first, to summarise the call for sanctions/boycott emanating from the Boycott, Disinvestment and Sanctions movement. Second, to explore how this call is establishing itself in the world of sport. The responses of those opposed to any form of sanction/boycott are then considered. The confusion that surrounds the term antisemitism is addressed and the relationship between (anti-) Zionism and antisemitism unpacked. The discussion concludes with an assessment of the claim made by the Israeli state, and its supporters, that any action against the country’s participation in international sport would be an act of antisemitism. Offering a timely, integrated summary of the heated debates that surround the Israel/Palestine conflict, the paper contributes to a wider discussion on the relationship between sport and politics

Cyanide and the cystic fibrosis pathogens Pseudomonas aeruginosa and Burkholderia cenocepacia

Most cystic fibrosis (CF) sufferers will die before reaching their mid thirties as a result of life long bacterial lung infection. Pseudomonas aeruginosa is the most important respiratory pathogen in CF patients; factors implicated in its pathogenesis include alginate over production, pyocyanin, and extracellular proteases. It is also capable of synthesising hydrogen cyanide, but the role of this potent inhibitor of cellular respiration has not yet been assessed in CF infection. Cyanide concentration was measured in sputum from CF and non-CF bronchiectasis patients with and without P. aeruginosa lung infection using a cyanide ion sensing electrode. Cyanide was detected in sputum from 19/25 patients with current P. aeruginosa infection, whereas it was not detected in any of the 10 patients without this organism (p<O.01). Maximum levels were 130IJM (mean Ç'ñSE: 72 Ç'ñ 6.6 IJM). Lung function data w~s examined for 21 P. aeruginosa-infected CF patients; the group with measurable sputum cyanide (n=11) had significantly poorer lung function than those without (FEV1% predicted: 26.8Ç'ñ3.8% versus 46.0Ç'ñ6.7%, p<O.01; FVC% predicted: 44.4Ç'ñ4.9% versus 60.1Ç'ñ7.7, p<O.05). The switch of P. aeruginosa to an alginate over producing, mucoid phenotype is a pivotal event in CF lung infection. Mucoidy usually results from loss of regulation of the alternate sigma factor AlgU via mutation in mucA, encoding an anti-sigmp factor. It is possible that this affects the expression of other virulence factors in addition to alginate. Thirteen mucA mutants were constructed in three wild type backgrounds and their level of cyanide, pyocyanin and elastase production was found to be 1/3 that of wild type strains. In addition, in contrast to wild type strains, mucA mutants showed a lack of suppression of cyanide and pyocyanin production in later stationary phase. The Burkholderia cepacia complex (Bcc) is another group of important CF pathogens. It was hypothesised that, like P. aeruginosa, they might also be cyanogenic. All 9 species of the Bcc complex were 'able to make cyanide at comparable levels to P. aeruginosa, but only when grown as surface attached colonies on agar plates or during biofilm growth on glass beads. In contrast to P. aeruginosa and other cyanogenic bacteria, cyanide was not detected during planktonic growth of Bcc strains. The data suggests that cyanide production by P. aeruginosa, and possibly members of the Bcc, is important in CF lung infection and that the CF relevant switch to mucoidy via mucA mutation affects the production of cyanide and other virulence factors in addition to alginate.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Metabolic profiling of Pseudomonas aeruginosa demonstrates that the anti-sigma factor MucA modulates osmotic stress tolerance

Metabolic footprinting has shown enormous potential as a phenotyping tool and we are interested in applying it to understand the physiology of the opportunistic pathogen Pseudomonas aeruginosa during its chronic infection of the lungs of cystic fibrosis patients. The selection pressures of surviving in the CF lung environment lead to genetic adaptations of the bacterium. A common adaptation is mutation of the mucA gene, resulting in a loss-of-function mutation to the anti-sigma factor MucA, which leads to a mucoid phenotype as a consequence of the overproduction of the extracellular polysaccharide alginate. However, apart from the mucoid phenotype little is known about the overall metabolic and physiological changes caused by mucA mutation. We investigated the pleiotropic metabolic effects of this mutation using time-resolved metabolic footprinting (extracellular metabolomics), and found changes in various metabolites associated with osmotic tolerance, including glycine-betaine, trehalose and glutamate. Physiological experiments confirmed that the isogenic mucA22 mutant is less resistant to osmotic stress than the parental PA01 wild-type strain, but only in the stationary phase of growth. Quantitative comparison of the endometabolome of the cells showed differences in the accumulation of osmoprotective metabolites by the wild-type and mucA22 mutant strains, suggesting a switch in osmo-protectant preference from glycine-betaine to trehalose

A metabolic trade-off between phosphate and glucose utilization in Escherichia coli

Using full genome sequencing and metabolomics we show that adaptation to chronic nutrient starvation reduces metabolic flexibility inEscherichia coli.</p

Bacteria of the complex are cyanogenic under biofilm and colonial growth conditions-4

of possible homologues of the genes. The organisation of the locus is shown in the top left panel followed by the three sets of putative homologues; two of which are on chromosome two and one on chromosome three. The grey bars indicate the reading frame with the top being +/- 1, middle +/- 2 and bottom +/- 3; the arrows indicate if the genes are on the coding (left to right) or complement (right to left) strands. The percentage identity of the product of each putative gene to their HcnABChomologue is shown in labels underneath each panel. The Putative Bcc cyanide synthase proteins have conserved Fe-S (HcnA) and ADP binding motifs (HcnB and HcnC). ., . and . ClustalX alignments of putative J2315 cyanide synthase protein sequences with hydrogen cyanide synthases from (PAO1) and (PF-5). . Sequence of HcnA C-terminal from PAO1 and PF-5 aligned with putative proteins, BCAM01268a, BCAM0669 and BCAS0164. Diamonds indicate a potential Fe-S binding site at 4 cysteine residues in HcnA. . Sequence of the start of HcnB from PAO1 and PF-5 aligned with putative proteins BCAM01269, BCAM0668 and BCAS0163. . Sequence from the start of HcnC sequence from PAO1 and PF-5 aligned with putative proteins BCAM01268, BCAM0667 and BCAS0165. Arrows indicate eleven amino acid ADP-binding motif in HcnB and HcnC.<p><b>Copyright information:</b></p><p>Taken from "Bacteria of the complex are cyanogenic under biofilm and colonial growth conditions"</p><p>http://www.biomedcentral.com/1471-2180/8/108</p><p>BMC Microbiology 2008;8():108-108.</p><p>Published online 27 Jun 2008</p><p>PMCID:PMC2504479.</p><p></p

Bacteria of the complex are cyanogenic under biofilm and colonial growth conditions-3

Rapped in 1 ml 4 M NaOH. ., . and . cyanide concentration trapped in NaOH for PAO1, J2315 and K56-2 respectively. Solid bars: with glass beads, diagonal striped bars: without glass beads. Measurements are averages of 3 independent replicates with SE error bars.<p><b>Copyright information:</b></p><p>Taken from "Bacteria of the complex are cyanogenic under biofilm and colonial growth conditions"</p><p>http://www.biomedcentral.com/1471-2180/8/108</p><p>BMC Microbiology 2008;8():108-108.</p><p>Published online 27 Jun 2008</p><p>PMCID:PMC2504479.</p><p></p

Bacteria of the complex are cyanogenic under biofilm and colonial growth conditions-1

Oncentration of trapped cyanide normalised to the CFU count for the plate. Values are the averages of 3 independent replicates with SE error bars.<p><b>Copyright information:</b></p><p>Taken from "Bacteria of the complex are cyanogenic under biofilm and colonial growth conditions"</p><p>http://www.biomedcentral.com/1471-2180/8/108</p><p>BMC Microbiology 2008;8():108-108.</p><p>Published online 27 Jun 2008</p><p>PMCID:PMC2504479.</p><p></p

Bacteria of the complex are cyanogenic under biofilm and colonial growth conditions-0

of possible homologues of the genes. The organisation of the locus is shown in the top left panel followed by the three sets of putative homologues; two of which are on chromosome two and one on chromosome three. The grey bars indicate the reading frame with the top being +/- 1, middle +/- 2 and bottom +/- 3; the arrows indicate if the genes are on the coding (left to right) or complement (right to left) strands. The percentage identity of the product of each putative gene to their HcnABChomologue is shown in labels underneath each panel. The Putative Bcc cyanide synthase proteins have conserved Fe-S (HcnA) and ADP binding motifs (HcnB and HcnC). ., . and . ClustalX alignments of putative J2315 cyanide synthase protein sequences with hydrogen cyanide synthases from (PAO1) and (PF-5). . Sequence of HcnA C-terminal from PAO1 and PF-5 aligned with putative proteins, BCAM01268a, BCAM0669 and BCAS0164. Diamonds indicate a potential Fe-S binding site at 4 cysteine residues in HcnA. . Sequence of the start of HcnB from PAO1 and PF-5 aligned with putative proteins BCAM01269, BCAM0668 and BCAS0163. . Sequence from the start of HcnC sequence from PAO1 and PF-5 aligned with putative proteins BCAM01268, BCAM0667 and BCAS0165. Arrows indicate eleven amino acid ADP-binding motif in HcnB and HcnC.<p><b>Copyright information:</b></p><p>Taken from "Bacteria of the complex are cyanogenic under biofilm and colonial growth conditions"</p><p>http://www.biomedcentral.com/1471-2180/8/108</p><p>BMC Microbiology 2008;8():108-108.</p><p>Published online 27 Jun 2008</p><p>PMCID:PMC2504479.</p><p></p