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

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-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-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-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