title: Development of analytical methodologies to assess recalcitrant pesticide bioremediation in biobeds at laboratory scale.
abstract: To assess recalcitrant pesticide bioremediation it is necessary to gradually increase the complexity of the biological system used in order to design an effective biobed assembly. Each step towards this effective biobed design needs a suitable, validated analytical methodology that allows a correct evaluation of the dissipation and bioconvertion. Low recovery yielding methods could give a false idea of a successful biodegradation process. To address this situation, different methods were developed and validated for the simultaneous determination of endosulfan, its main three metabolites, and chlorpyrifos in increasingly complex matrices where the bioconvertor basidiomycete Abortiporus biennis could grow. The matrices were culture media, bran, and finally a laboratory biomix composed of bran, peat and soil. The methodology for the analysis of the first evaluated matrix has already been reported. The methodologies developed for the other two systems are presented in this work. The targeted analytes were extracted from fungi growing over bran in semisolid media YNB (Yeast Nitrogen Based) with acetonitrile using shaker assisted extraction, The salting-out step was performed with MgSO4 and NaCl, and the extracts analyzed by GC-ECD. The best methodology was fully validated for all the evaluated analytes at 1 and 25mgkg(-1) yielding recoveries between 72% and 109% and RSDs <11% in all cases. The application of this methodology proved that A. biennis is able to dissipate 94% of endosulfan and 87% of chlorpyrifos after 90 days. Having assessed that A. biennis growing over bran can metabolize the studied pesticides, the next step faced was the development and validation of an analytical procedure to evaluate the analytes in a laboratory scale biobed composed of 50% of bran, 25% of peat and 25% of soil together with fungal micelium. From the different procedures assayed, only ultrasound assisted extraction with ethyl acetate allowed recoveries between 80% and 110% with RSDs <18%. Linearity, recovery, precision, matrix effect and LODs/LOQs of each method were studied for all the analytes: endosulfan isomers (α & β) and its metabolites (endosulfan sulfate, ether and diol) as well as for chlorpyrifos. In the first laboratory evaluation of these biobeds endosulfan was bioconverted up to 87% and chlorpyrifos more than 79% after 27 days.
authors.affiliation: Cátedra de Farmacognosia, Facultad de Química, Universidad de la República, Gral. Flores 2124, Montevideo CP 11800, Uruguay; Laboratorio de Microbiología, Laboratorio Tecnológico del Uruguay (LATU), Parque Industrial Municipal Barrio Anglo, Fray Bentos CP 65000, Uruguay. Electronic address: arivero@latu.org.uy.
authors.forename: Anisleidy
authors.initials: A
authors.lastname: Rivero
authors.affiliation: Polo Agroalimentario y Agroindustrial, Departamento de Química del Litoral, CENUR Litoral Norte Sede Paysandú, Universidad de la República, Ruta 3km 363, Paysandú CP 60000, Uruguay. Electronic address: sniell@cup.edu.uy.
authors.forename: Silvina
authors.initials: S
authors.lastname: Niell
authors.affiliation: Cátedra de Microbiología, Facultad de Química, Universidad de la República, Gral. Flores 2124, Montevideo CP 11800, Uruguay. Electronic address: mcerdeir@fq.edu.uy.
authors.forename: M Pía
authors.initials: MP
authors.lastname: Cerdeiras
authors.affiliation: Cátedra de Farmacognosia, Facultad de Química, Universidad de la República, Gral. Flores 2124, Montevideo CP 11800, Uruguay; Polo Agroalimentario y Agroindustrial, Departamento de Química del Litoral, CENUR Litoral Norte Sede Paysandú, Universidad de la República, Ruta 3km 363, Paysandú CP 60000, Uruguay. Electronic address: heinzen@fq.edu.uy.
authors.forename: Horacio
authors.initials: H
authors.lastname: Heinzen
authors.affiliation: Cátedra de Farmacognosia, Facultad de Química, Universidad de la República, Gral. Flores 2124, Montevideo CP 11800, Uruguay. Electronic address: cs@fq.edu.uy.
authors.forename: María Verónica
authors.initials: MV
authors.lastname: Cesio
mesh_terms: D001673:Biodegradation, Environmental; D004390:Chlorpyrifos; D010575:Pesticides; D012987:Soil; D012989:Soil Pollutants
chemical_list: D010575:Pesticides; D012987:Soil; D012989:Soil Pollutants; D004390:Chlorpyrifos
keywords: Basidiomycete; Bioremediation; Method validation; Recalcitrant pesticides