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Formation of 2,4-D bound residues in soils: New insights into microbial metabolism

Abstract : The microbial contribution to the formation of bound residues in soils is studied by characterizing the metabolic activity of three microorganisms (Trametes versicolor, Fusarium solani and Ralstonia eutropha) on 14C-2,4- dichlorophenoxyacetic acid (2,4-D) during incubation in synthetic liquidmedia and soil. A fractionation protocol was applied to quantify the 14C-2,4-D thatwas incorporated into the biomass among biomolecular-like fractions. Successive fractionation of microbial biomass was implemented to break up and quantify the methanol/dichloromethane fraction (corresponding to the 14C-lipid-like fraction), the trichloroacetic acid fraction (or hydrolysed 14C-polysaccharide-like fraction) and the acid hydrolysable fraction (or the hydrolysed 14C-protein-like fraction). Relevant differences in the 2,4-D degradation and biomass radioactivity distribution among the three microorganisms were found. The 14C-protein-like fraction was the most consistent biomass fraction for reflecting the pesticide use capacity of the microorganisms under liquid and soil conditions. 2,4-D and its metabolite 4- chlorophenol were detected in methanol/dichloromethane and trichloroacetic acid fractions of the biomass of microorganisms exhibiting a low capacity to mineralize 2,4-D, thus proving that the microbial participation in the formation of bound residues while conserving the initial pesticide structure under natural soil conditions may be intimately associatedwith the lipid- and polysaccharide-like constituents. The fractionation protocol differentiates between 14C that is incorporated into biomass as a biomolecular constituent and the pesticide or its metabolites that accumulate in the biomass and thus correspond to the stricto sensu definition of bound residues.
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https://hal.archives-ouvertes.fr/hal-01607148
Déposant : Archive Ouverte Prodinra <>
Soumis le : lundi 2 octobre 2017 - 23:36:09
Dernière modification le : mardi 26 mai 2020 - 14:00:44

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Liliana Rocío Botero, Christian Mougin, Gustavo Peñuela, Enrique Barriuso Benito. Formation of 2,4-D bound residues in soils: New insights into microbial metabolism. Science of the Total Environment, Elsevier, 2017, 584-585, pp.715-722. ⟨10.1016/j.scitotenv.2017.01.105⟩. ⟨hal-01607148⟩

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