title: Molecular basis of tobacco-induced bacterial biofilms: an in vitro study.
abstract: OBJECTIVE
  To evaluate changes in the expression of biofilm-related genes when exposed to tobacco smoke and oxidative stress.
  
  
  METHODS
  Experimental, in vitro. Setting Laboratories of Rhinology and Microbiology, University of Pennsylvania.
  
  
  METHODS
  Bacterial biofilm mass was measured using crystal violet staining and measurement of the optical density. Biofilm-related genes of the Pseudomonas aeruginosa PAO1 strain (pilF, flgK, lasI, lasB, rhlA, and algC) were studied following repetitive exposure to exogenous tobacco smoke and hydrogen peroxide. This was done using a reporter plasmid.
  
  
  RESULTS
  After 1 exposure to smoke, there was no change in biofilm formation. However, after 2 and 3 exposures, the biofilm formed had an increased mass (P < .05). With respect to oxidative stress in the form of H(2)O(2), bacterial cultures demonstrated a dose- and time-dependent induction of biofilm formation compared with control conditions. Gene expression following repetitive smoke exposure demonstrated an increase in expression of pilF, flgK, algC, and lasI genes (P < .05); a decrease in rhlA (P < .05); and no significant change in the lasB gene (P = 0.1). Gene expression following H(2)O(2) exposure demonstrated an increase in pilF (P < .05), whereas the other genes failed to demonstrate a statistical change.
  
  
  CONCLUSIONS
  Repetitive tobacco smoke exposure leads to molecular changes in biofilm-related genes, and exposure to oxidative stress in the form of H(2)O(2) induces biofilm growth in PAO1. This could represent adaptative changes due to oxidative stress or chemically mediated through any of the several chemicals encountered in tobacco smoke and may explain increased biofilm formation in microbes isolated from smokers.
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Marcelo B
authors.initials: MB
authors.lastname: Antunes
authors.forename: John J
authors.initials: JJ
authors.lastname: Chi
authors.forename: Zhi
authors.initials: Z
authors.lastname: Liu
authors.forename: Natalia
authors.initials: N
authors.lastname: Goldstein-Daruech
authors.forename: James N
authors.initials: JN
authors.lastname: Palmer
authors.forename: Jun
authors.initials: J
authors.lastname: Zhu
authors.forename: Noam A
authors.initials: NA
authors.lastname: Cohen
mesh_terms: D018441:Biofilms; D015870:Gene Expression; D018384:Oxidative Stress; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000502:physiology*; D014028:Tobacco Smoke Pollution
chemical_list: D014028:Tobacco Smoke Pollution