title: Synthesis of novel palladium(0) nanocatalysts by microorganisms from heavy-metal-influenced high-alpine sites for dehalogenation of polychlorinated dioxins.
abstract: In a search for new aqueous-phase systems for catalyzing reactions of environmental and industrial importance, we prepared novel biogenerated palladium (Pd) nanocatalysts using a "green" approach based on microorganisms isolated from high-alpine sites naturally impacted by heavy metals. Bacteria and fungi were enriched and isolated from serpentinite-influenced ponds (Totalp region, Parsenn, near Davos, Graubünden, Switzerland). Effects on growth dynamics were monitored using an automated assay in 96-well microtiter plates, which allowed for simultaneous cultivation and on-line analysis of Pd(II)- and Ni(II)-mediated growth inhibition. Microorganisms from Totalp ponds tolerated up to 3mM Pd(II) and bacterial isolates were selected for cultivation and reductive synthesis of Pd(0) nanocatalysts at microbial interfaces. During reduction of Pd(II) with formate as the electron donor, Pd(0) nanoparticles were formed and deposited in the cell envelope. The Pd(0) catalysts produced in the presence of Pd(II)-tolerant Alpine Pseudomonas species were catalytically active in the reductive dehalogenation of model polychlorinated dioxin congeners. This is the first report which shows that Pd(0) synthesized in the presence of microorganisms catalyzes the reductive dechlorination of polychlorinated dibenzo-p-dioxins (PCDDs). Because the "bioPd(0)" catalyzed the dechlorination reactions preferably via non-lateral chlorinated intermediates, such a pathway could potentially detoxify PCDDs via a "safe route". It remains to be determined whether the microbial formation of catalytically active metal catalysts (e.g., Zn, Ni, Fe) occurs in situ and whether processes involving such catalysts can alter the fate and transport of persistent organic pollutants (POPs) in Alpine habitats.
authors.affiliation: Institute of Applied Microbiology, Research Centre for BioSystems, Land Use, and Nutrition (IFZ), Justus-Liebig-Universität Giessen, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Schlüter
authors.affiliation: Institute of Applied Microbiology, Research Centre for BioSystems, Land Use, and Nutrition (IFZ), Justus-Liebig-Universität Giessen, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Hentzel
authors.affiliation: Institute of Applied Microbiology, Research Centre for BioSystems, Land Use, and Nutrition (IFZ), Justus-Liebig-Universität Giessen, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Suarez
authors.affiliation: Institute of Chemistry, Research Group Food and Environmental Chemistry, Martin-Luther-Universität Halle-Wittenberg, Germany.
authors.forename: Mandy
authors.initials: M
authors.lastname: Koch
authors.affiliation: Institute of Chemistry, Research Group Food and Environmental Chemistry, Martin-Luther-Universität Halle-Wittenberg, Germany.
authors.forename: Wilhelm G
authors.initials: WG
authors.lastname: Lorenz
authors.affiliation: Institute of Soil Science and Soil Conservation, Research Centre for BioSystems, Land Use, and Nutrition (IFZ), Justus-Liebig-Universität Giessen, Germany.
authors.forename: Leonard
authors.initials: L
authors.lastname: Böhm
authors.affiliation: Institute of Soil Science and Soil Conservation, Research Centre for BioSystems, Land Use, and Nutrition (IFZ), Justus-Liebig-Universität Giessen, Germany.
authors.forename: Rolf-Alexander
authors.initials: RA
authors.lastname: Düring
authors.affiliation: Institute of Ecology, Universität Innsbruck, Austria.
authors.forename: Karin A
authors.initials: KA
authors.lastname: Koinig
authors.affiliation: Institute of Applied Microbiology, Research Centre for BioSystems, Land Use, and Nutrition (IFZ), Justus-Liebig-Universität Giessen, Germany. Electronic address: michael.bunge@umwelt.uni-giessen.de.
authors.forename: Michael
authors.initials: M
authors.lastname: Bunge
mesh_terms: D001419:Bacteria / Q000235:genetics / Q000378:metabolism*; D055162:Biocatalysis; D004269:DNA, Bacterial / Q000235:genetics; D004271:DNA, Fungal / Q000235:genetics; D021901:DNA, Intergenic / Q000235:genetics; D004147:Dioxins / Q000378:metabolism*; D005658:Fungi / Q000235:genetics / Q000378:metabolism*; D053768:Metal Nanoparticles / Q000032:analysis*; D008969:Molecular Sequence Data; D010165:Palladium / Q000378:metabolism*; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000378:metabolism*; D013557:Switzerland
chemical_list: D004269:DNA, Bacterial; D004271:DNA, Fungal; D021901:DNA, Intergenic; D004147:Dioxins; D012336:RNA, Ribosomal, 16S; D012989:Soil Pollutants; D010165:Palladium
keywords: Catalysts; Dehalogenation; Nanoparticles; Palladium; Serpentinite; Totalp