title: Role of the multidrug efflux systems of Pseudomonas aeruginosa in organic solvent tolerance.
abstract: Multidrug efflux pumps with a broad substrate specificity make a major contribution to intrinsic and acquired multiple antibiotic resistance in Pseudomonas aeruginosa. Using genetically defined efflux pump mutants, we investigated the involvement of the three known efflux systems, MexA-MexB-OprM, MexC-MexD-OprJ, and MexE-MexF-OprN, in organic solvent tolerance in this organism. Our results showed that all three systems are capable of providing some level of tolerance to organic solvents such as n-hexane and p-xylene. Expression of MexAB-OprM was correlated with the highest levels of tolerance, and indeed, this efflux system was a major contributor to the intrinsic solvent tolerance of P. aeruginosa. Intrinsic organic solvent tolerance was compromised by a protonophore, indicating that it is substantially energy dependent. These data suggest that the efflux of organic solvents is a factor in the tolerance of P. aeruginosa to these compounds and that the multidrug efflux systems of this organism can accommodate organic solvents, as well as antibiotics.
authors.affiliation: Department of Microbiology and Immunology, Queen's University, Kingston, Ontario K7L 3N6, Canada.
authors.forename: X Z
authors.initials: XZ
authors.lastname: Li
authors.forename: L
authors.initials: L
authors.lastname: Zhang
authors.forename: K
authors.initials: K
authors.lastname: Poole
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000502:physiology; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D004352:Drug Resistance, Microbial / Q000502:physiology; D018432:Drug Resistance, Multiple / Q000502:physiology*; D006838:Hydrocarbons / Q000494:pharmacology*; D007476:Ionophores / Q000494:pharmacology; D009154:Mutation; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D012997:Solvents / Q000494:pharmacology*
chemical_list: D001425:Bacterial Outer Membrane Proteins; D006838:Hydrocarbons; D007476:Ionophores; D012997:Solvents; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone