title: Mapping the Centimeter-Scale Spatial Variability of PAHs and Microbial Populations in the Rhizosphere of Two Plants.
abstract: Rhizoremediation uses root development and exudation to favor microbial activity. Thus it can enhance polycyclic aromatic hydrocarbon (PAH) biodegradation in contaminated soils. Spatial heterogeneity of rhizosphere processes, mainly linked to the root development stage and to the plant species, could explain the contrasted rhizoremediation efficiency levels reported in the literature. Aim of the present study was to test if spatial variability in the whole plant rhizosphere, explored at the centimetre-scale, would influence the abundance of microorganisms (bacteria and fungi), and the abundance and activity of PAH-degrading bacteria, leading to spatial variability in PAH concentrations. Two contrasted rhizospheres were compared after 37 days of alfalfa or ryegrass growth in independent rhizotron devices. Almost all spiked PAHs were degraded, and the density of the PAH-degrading bacterial populations increased in both rhizospheres during the incubation period. Mapping of multiparametric data through geostatistical estimation (kriging) revealed that although root biomass was spatially structured, PAH distribution was not. However a greater variability of the PAH content was observed in the rhizosphere of alfalfa. Yet, in the ryegrass-planted rhizotron, the Gram-positive PAH-degraders followed a reverse depth gradient to root biomass, but were positively correlated to the soil pH and carbohydrate concentrations. The two rhizospheres structured the microbial community differently: a fungus-to-bacterium depth gradient similar to the root biomass gradient only formed in the alfalfa rhizotron.
authors.affiliation: CNRS, LIEC UMR7360, Faculté des Sciences et Technologies, Bd des Aiguillettes, BP70239, 54506 Vandoeuvre-lès-Nancy, France.|Université de Lorraine, LIEC UMR7360, Faculté des Sciences et Technologies, Bd des Aiguillettes, BP 70239, 54506 Vandoeuvre-lès-Nancy, France.
authors.forename: Amélia
authors.initials: A
authors.lastname: Bourceret
authors.affiliation: CNRS, LIEC UMR7360, Faculté des Sciences et Technologies, Bd des Aiguillettes, BP70239, 54506 Vandoeuvre-lès-Nancy, France.|Université de Lorraine, LIEC UMR7360, Faculté des Sciences et Technologies, Bd des Aiguillettes, BP 70239, 54506 Vandoeuvre-lès-Nancy, France.
authors.forename: Corinne
authors.initials: C
authors.lastname: Leyval
authors.affiliation: MINES ParisTech, Centre de Géosciences Géostatistique, Ecole Nationale Supérieure des Mines de Paris, 35 Rue Saint-Honoré, 77305 Fontainebleau, France.
authors.forename: Chantal
authors.initials: C
authors.lastname: de Fouquet
authors.affiliation: CNRS, LIEC UMR7360, Faculté des Sciences et Technologies, Bd des Aiguillettes, BP70239, 54506 Vandoeuvre-lès-Nancy, France.|Université de Lorraine, LIEC UMR7360, Faculté des Sciences et Technologies, Bd des Aiguillettes, BP 70239, 54506 Vandoeuvre-lès-Nancy, France.
authors.forename: Aurélie
authors.initials: A
authors.lastname: Cébron
mesh_terms: D001419:Bacteria / Q000378:metabolism*; D002241:Carbohydrates / Q000032:analysis; D005658:Fungi / Q000378:metabolism*; D008129:Lolium / Q000382:microbiology*; D000455:Medicago sativa / Q000382:microbiology*; D018517:Plant Roots / Q000382:microbiology; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis*; D025341:Principal Component Analysis; D058441:Rhizosphere; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis
chemical_list: D002241:Carbohydrates; D011084:Polycyclic Aromatic Hydrocarbons; D012987:Soil; D012989:Soil Pollutants