title: Inhibition of staphylococcal biofilm formation by nitrite.
abstract: Several environmental stresses have been demonstrated to increase polysaccharide intercellular adhesin (PIA) synthesis and biofilm formation by the human pathogens Staphylococcus aureus and Staphylococcus epidermidis. In this study we characterized an adaptive response of S. aureus SA113 to nitrite-induced stress and show that it involves concomitant impairment of PIA synthesis and biofilm formation. Transcriptional analysis provided evidence that nitrite, either as the endogenous product of respiratory nitrate reduction or after external addition, causes repression of the icaADBC gene cluster, mediated likely by IcaR. Comparative microarray analysis revealed a global change in gene expression during growth in the presence of 5 mM sodium nitrite and indicated a response to oxidative and nitrosative stress. Many nitrite-induced genes are involved in DNA repair, detoxification of reactive oxygen and nitrogen species, and iron homeostasis. Moreover, preformed biofilms could be eradicated by the addition of nitrite, likely the result of the formation of toxic acidified nitrite derivatives. Nitrite-mediated inhibition of S. aureus biofilm formation was abrogated by the addition of nitric oxide (NO) scavengers, suggesting that NO is directly or indirectly involved. Nitrite also repressed biofilm formation of S. epidermidis RP62A.
authors.affiliation: Microbial Genetics, University of Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany.
authors.forename: Steffen
authors.initials: S
authors.lastname: Schlag
authors.forename: Christiane
authors.initials: C
authors.lastname: Nerz
authors.forename: Timo A
authors.initials: TA
authors.lastname: Birkenstock
authors.forename: Florian
authors.initials: F
authors.lastname: Altenberend
authors.forename: Friedrich
authors.initials: F
authors.lastname: Götz
mesh_terms: D001422:Bacterial Adhesion / Q000187:drug effects / Q000502:physiology; D018441:Biofilms / Q000187:drug effects*; D017353:Gene Deletion; D007700:Kinetics; D009566:Nitrates / Q000378:metabolism; D009573:Nitrites / Q000494:pharmacology*; D010084:Oxidation-Reduction; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013211:Staphylococcus aureus / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D013212:Staphylococcus epidermidis / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D014158:Transcription, Genetic
chemical_list: D009566:Nitrates; D009573:Nitrites