title: Functional and structural responses of soil N-cycling microbial communities to the herbicide mesotrione: a dose-effect microcosm approach.
abstract: Microbial communities driving the nitrogen cycle contribute to ecosystem services such as crop production and air, soil, and water quality. The responses to herbicide stress of ammonia-oxidizing and ammonia-denitrifying microbial communities were investigated by an analysis of changes in structure-function relationships. Their potential activities, abundances (quantitative PCR), and genetic structure (denaturing gradient gel electrophoresis) were assessed in a microcosm experiment. The application rate (1 × FR, 0.45 μg g(-1) soil) of the mesotrione herbicide did not strongly affect soil N-nutrient dynamics or microbial community structure and abundances. Doses of the commercial product Callisto® (10 × FR and 100 × FR) or pure mesotrione (100 × FR) exceeding field rates induced short-term inhibition of nitrification and a lasting stimulation of denitrification. These effects could play a part in the increase in soil ammonium content and decrease in nitrate contents observed in treated soils. These functional impacts were mainly correlated with abundance shifts of ammonia-oxidizing Bacteria (AOB) and Archaea (AOA) or denitrifying bacteria. The sustained restoration of nitrification activity, from day 42 in the 100 × FR-treated soils, was likely promoted by changes in the community size and composition of AOB, which suggests a leading role, rather than AOA, for soil nitrification restoration after herbicide stress. This ecotoxicological community approach provides a nonesuch multiparameter assessment of responses of N-cycling microbial guilds to pesticide stress.
authors.affiliation: INRA UR 251 PESSAC, Centre Versailles-Grignon, RD 10, 78026, Versailles cedex, France. olivier.crouzet@versailles.inra.fr.
authors.forename: Olivier
authors.initials: O
authors.lastname: Crouzet
authors.affiliation: Ecologie Microbienne, INRA USC 1193 - CNRS UMR 5557, 69622, Villeurbanne, France.|Ecologie Microbienne, Université de Lyon, Université Lyon 1, 69622, Villeurbanne, France.
authors.forename: Franck
authors.initials: F
authors.lastname: Poly
authors.affiliation: CNRS UMR 6023 LMGE, Campus de Cézeaux, 63171, Aubière cedex, France.|Clermont Université, Université Blaise Pascal, 63000, Clermont-Ferrand, France.
authors.forename: Frédérique
authors.initials: F
authors.lastname: Bonnemoy
authors.affiliation: Agroécologie, INRA, UMR 1347, 17 rue Sully, BP 86510, 21065, Dijon cedex, France.
authors.forename: David
authors.initials: D
authors.lastname: Bru
authors.affiliation: CNRS UMR 6023 LMGE, Campus de Cézeaux, 63171, Aubière cedex, France.|Clermont Université, Université Blaise Pascal, 63000, Clermont-Ferrand, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Batisson
authors.affiliation: CNRS UMR 6023 LMGE, Campus de Cézeaux, 63171, Aubière cedex, France.|Clermont Université, Université Blaise Pascal, 63000, Clermont-Ferrand, France.
authors.forename: Jacques
authors.initials: J
authors.lastname: Bohatier
authors.affiliation: Agroécologie, INRA, UMR 1347, 17 rue Sully, BP 86510, 21065, Dijon cedex, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Philippot
authors.affiliation: CNRS UMR 6023 LMGE, Campus de Cézeaux, 63171, Aubière cedex, France.|Clermont Université, Université Blaise Pascal, 63000, Clermont-Ferrand, France.
authors.forename: Clarisse
authors.initials: C
authors.lastname: Mallet
mesh_terms: D000641:Ammonia; D001105:Archaea / Q000187:drug effects / Q000235:genetics; D020562:Betaproteobacteria / Q000187:drug effects / Q000235:genetics; D003512:Cyclohexanones / Q000633:toxicity*; D058645:Denaturing Gradient Gel Electrophoresis; D004305:Dose-Response Relationship, Drug; D017753:Ecosystem; D006540:Herbicides / Q000633:toxicity*; D059013:Microbial Consortia / Q000187:drug effects* / Q000235:genetics; D058465:Nitrification; D058458:Nitrogen Cycle / Q000187:drug effects*; D010084:Oxidation-Reduction; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology
chemical_list: D003512:Cyclohexanones; D006540:Herbicides; D012987:Soil; C432907:mesotrione; D000641:Ammonia
keywords: Ammonia oxidizers; Denitrifiers; Herbicide; Microbial ecotoxicology; Soil microcosms