title: Accumulation and efflux of polychlorinated biphenyls in Escherichia coli.
abstract: Polychlorinated biphenyls (PCBs) are environmental pollutants that have been associated with numerous adverse health effects in human and animals. Hydroxylated PCBs (HPCBs) are the product of the oxidative metabolism of PCBs. The presence of hydroxyl groups in HPCBs makes these compounds more hydrophilic than the parent PCBs. One of the best approaches to break down and remove these contaminants is bioremediation; an environmentally friendly process that uses microorganisms to degrade hazardous chemicals into non-toxic ones. In this study, we investigated the cellular accumulation and toxicity of selected PCBs and HPCBs in Gram-negative bacteria, using Escherichia coli as a model organism. We found that none of the five PCBs tested were toxic to E. coli, presumably due to their limited bioavailability. Nevertheless, different HPCBs tested showed different levels of toxicity. Furthermore, we demonstrated that the primary multidrug efflux system in E. coli, AcrAB-TolC, facilitated the efflux of HPCBs out of the cell. Since AcrAB-TolC is constitutively expressed in E. coli and is conserved in all sequenced Gram-negative bacterial genomes, our results suggest that the efflux activities of multidrug resistant pumps may affect the accumulation and degradation of PCBs in Gram-negative bacteria.
authors.affiliation: Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055, USA.
authors.forename: Shen
authors.initials: S
authors.lastname: Geng
authors.forename: Jun
authors.initials: J
authors.lastname: Fang
authors.forename: Kendrick B
authors.initials: KB
authors.lastname: Turner
authors.forename: Sylvia
authors.initials: S
authors.lastname: Daunert
authors.forename: Yinan
authors.initials: Y
authors.lastname: Wei
mesh_terms: D001692:Biological Transport; D004785:Environmental Pollutants / Q000378:metabolism* / Q000633:toxicity*; D004926:Escherichia coli / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry; D026901:Membrane Transport Proteins / Q000378:metabolism; D008958:Models, Molecular; D011078:Polychlorinated Biphenyls / Q000378:metabolism* / Q000633:toxicity*
chemical_list: D004785:Environmental Pollutants; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D011078:Polychlorinated Biphenyls