title: Stimulation of pyrene mineralization in freshwater sediments by bacterial and plant bioaugmentation.
abstract: As a means to study the fate of polycyclic aromatic hydrocarbons (PAHs) in freshwater sediments, pyrene mineralization was examined in microcosms spiked with [14C]pyrene. Some microcosms were planted with reeds (Phragmites australis) and/or inoculated with a pyrene-degrading strain, Mycobacterium sp. 6PY1. Mineralization rates recorded over a 61 d period showed that reeds promoted a significant enhancement of pyrene degradation, which possibly resulted from a root-mediated increase of oxygen diffusion into the sediment layer, as indicated by in situ redox measurements. In inoculated microcosms, mineralization reached a higher level in the absence (8.8%) than in the presence of plants (4.4%). Mineralization activity was accompanied by the release of water-soluble pyrene oxidation products, the most abundant of which was identified as 4,5-diphenanthroic acid. Pyrene was recovered from plant tissues, including stems and leaves, at concentrations ranging between 40 and 240 microg/g of dry mass. Plants also accumulated labeled oxidation products likely derived from microbial degradation. Pyrene-degrading strains were 35-70-fold more abundant in inoculated than in noninoculated microcosms. Most of the pyrene-degrading isolates selected from the indigenous microflora were identified as Mycobacterium austroafricanum strains. Taken together, the results of this study show that plants or PAH-degrading bacteria enhance pollutant removal, but their effects are not necessarily cumulative.
authors.affiliation: Laboratoire de Biochimie et Biophysique des Systèmes Intégrés, Département de Réponse et Dynamique Cellulaires, CNRS UMR 5092, CEA-Grenoble, F-38054 Grenoble Cedex 9, France. yjouanneau@cea.fr
authors.forename: Yves
authors.initials: Y
authors.lastname: Jouanneau
authors.forename: John C
authors.initials: JC
authors.lastname: Willison
authors.forename: Christine
authors.initials: C
authors.lastname: Meyer
authors.forename: Serge
authors.initials: S
authors.lastname: Krivobok
authors.forename: Nathalie
authors.initials: N
authors.lastname: Chevron
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Besombes
authors.forename: Gérard
authors.initials: G
authors.lastname: Blake
mesh_terms: D001673:Biodegradation, Environmental; D005618:Fresh Water / Q000737:chemistry*; D019015:Geologic Sediments / Q000737:chemistry*; D008903:Minerals / Q000737:chemistry; D009161:Mycobacterium / Q000254:growth & development*; D006109:Poaceae / Q000254:growth & development*; D011721:Pyrenes / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D008903:Minerals; D011721:Pyrenes; D014874:Water Pollutants, Chemical; C030984:pyrene