title: Quantification of Pseudomonas aeruginosa hydrogen cyanide production by a polarographic approach.
abstract: Pseudomonas aeruginosa is an opportunistic pathogen responsible for numerous infections acquired in hospital especially in persons whose immune systems are weakened, such as with patient suffering from AIDS or cystic fibrosis. This bacterium produces a great diversity of virulence factors among them hydrogen cyanide (HCN) which is one of the most potent and toxic. A precise quantification of HCN or CN(-) ion is essential to understand the involvement of this toxin in the pathogenesis of P. aeruginosa. In the present study, we present a new technique based on a polarographic approach to measure the production kinetics of HCN/CN(-) by P. aeruginosa strains, in several media commonly used in microbiology labs. The method was validated using mutants (hcnB- and hcnC-) which are unable to produce detectable HCN/CN(-). The kinetics of HCN/CN(-) production by P. aeruginosa in Luria Bertani (LB) medium showed a parabolic shape with a peak observed at 4, 5 and 8h for strains PA14, PAO1 and MPAO1, respectively. When bacteria were grown in ordinary nutrient broth (ONB) 2.5% medium, a less adapted medium for bacterial growth, the general profile of the kinetics was conserved but peak production was delayed (10 and 12h for PAO1 and MPAO1, respectively). When the bacteria were cultured in minimum medium MMC, bacterial growth was particularly slow and HCN/CN(-) production was markedly reduced. Taken together, this new polarographic method appears as a useful technique to detect and quantify HCN/CN(-) in routine media where the bacteria can express and regulate high amounts of toxins. With this method, we demonstrate that HCN/CN(-) production by P. aeruginosa is maximal at the end of the exponential growth phase and depends on the richness of the growth medium used.
authors.affiliation: Laboratory of Microbiology Signals and Microenvironment LMSM EA 4312, University of Rouen, 55 rue Saint Germain, 27000 Evreux, France.
authors.forename: Anne-Sophie
authors.initials: AS
authors.lastname: Blier
authors.forename: Julien
authors.initials: J
authors.lastname: Vieillard
authors.forename: Eloïse
authors.initials: E
authors.lastname: Gerault
authors.forename: Audrey
authors.initials: A
authors.lastname: Dagorn
authors.forename: Tony
authors.initials: T
authors.lastname: Varacavoudin
authors.forename: Franck
authors.initials: F
authors.lastname: Le Derf
authors.forename: Nicole
authors.initials: N
authors.lastname: Orange
authors.forename: Marc
authors.initials: M
authors.lastname: Feuilloley
authors.forename: Olivier
authors.initials: O
authors.lastname: Lesouhaitier
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D006856:Hydrogen Cyanide / Q000032:analysis* / Q000378:metabolism*; D011048:Polarography / Q000379:methods*; D011552:Pseudomonas Infections / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000737:chemistry / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D037521:Virulence Factors
chemical_list: D001426:Bacterial Proteins; D037521:Virulence Factors; D006856:Hydrogen Cyanide