title: [Effect of different levels of environmental oxygen on the biofilm production of Pseudomonas aeruginosa].
abstract: OBJECTIVE
  To investigate the relationship among oxygen concentration, quorum sensing system, type secretion system, and biofilm production of Pseudomonas aeruginosa.
  
  
  METHODS
  A total of 23 clinical strains of Pseudomonas aeruginosa were cultured at different levels of environmental oxygen for three days. Then biofilm mass and alginate were quantified. The expression levels of LasI and RhlI were detected by real time polymerase chain reaction (PCR). The secretion of exoenzyme S was examined by Western blot.
  
  
  RESULTS
  Both the biofilm mass (R=0.455, P=0.000) and alginate (R=0.367, P=0.000) were positively correlated with oxygen concentration. Real time PCR showed that the expression levels of LasI and RhlI were not significantly correlated with oxygen concentration (R=0.025, P=0.794; R=-0.044, P=0.653), the production of biofilm (R=0.001, P=0.990; R=0.011, P=0.909), or alginate(R=0.029, P=0.770; R=0.193, P=0.064). Western blot showed that the optimal oxygen concentration range for exoenzyme S secretion of Pseudomonas aeruginosa ranged 10% to 30%.
  
  
  CONCLUSIONS
  Hyperoxia can promote the production of biofilm and alginate by Pseudomonas aeruginosa. Las/Rhl system may not participate in biofilm production at the early stage due to the low bacteria amount. The increased production of biofilm may inhibit the expression of Type Secretion system and thus inhibit bacterial virulence.
authors.affiliation: Graduate School, CAMS and PUMC, Beijing 100730, China.
authors.forename: Dong-Qing
authors.initials: DQ
authors.lastname: Cui
authors.forename: Tie-Ying
authors.initials: TY
authors.lastname: Sun
authors.forename: Jian
authors.initials: J
authors.lastname: Li
authors.forename: Xiu-Qing
authors.initials: XQ
authors.lastname: Huang
mesh_terms: D000464:Alginates / Q000378:metabolism; D018441:Biofilms / Q000187:drug effects*; D010100:Oxygen / Q000378:metabolism*; D011550:Pseudomonas aeruginosa / Q000378:metabolism / Q000502:physiology*; D053038:Quorum Sensing / Q000187:drug effects / Q000502:physiology
chemical_list: D000464:Alginates; D010100:Oxygen