title: Ecotoxicological assessment of soil microbial community tolerance to glyphosate.
abstract: Glyphosate is the most used herbicide worldwide. While contrasting results have been observed related with its impact on soil microbial communities, more studies are necessary to elucidate the potential effects of the herbicide. Differences in tolerance detected by Pollution Induced Community Tolerance (PICT) approach could reflect these effects. The objective of the present study was to assess the tolerance to glyphosate (the active ingredient and a commercial formulation) of contrasting soils with (H) and without (NH) history of exposure. The hypothesis of a higher tolerance in H soils due to a sustained selection pressure on community structure was tested through the PICT approach. Results indicated that tolerance to glyphosate is not consistent with previous history of exposure to the herbicide either for the active ingredient or for a commercial formulation. Soils of H and NH sites were also characterized in order to determine to what extent they differ in their functional diversity and structure of microbial communities. Denaturant Gradient Gel Electrophoresis (DGGE) and Quantitative Real Time PCR (Q-PCR) indicated high similarity of Eubacteria profiles as well as no significant differences in abundance, respectively, between H and NH sites. Community level physiological profiling (CLPP) indicated some differences in respiration of specific sources but functional diversity was very similar as reflected by catabolic evenness (E). These results support PICT assay, which ideally requires soils with differences in their exposure to the contaminant but minor differences in other characteristics. This is, to our knowledge, the first report of PICT approach with glyphosate examining tolerance at soil microbial community level.
authors.affiliation: Laboratorio de Biodiversidad Vegetal y Microbiana, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Campo Experimental J. Villarino, 2125 Zavalla, Argentina. Electronic address: marcalleg88@hotmail.com.
authors.forename: Marco
authors.initials: M
authors.lastname: Allegrini
authors.affiliation: Centro de Estudios de Recursos Naturales Renovables de la Zona Semiárida (CERZOS-CONICET), Departamento de Agronomía, Universidad Nacional del Sur, San Andrés 800, 8000 Bahía Blanca, Argentina.
authors.forename: María Celina
authors.initials: MC
authors.lastname: Zabaloy
authors.affiliation: Laboratorio de Biodiversidad Vegetal y Microbiana, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Campo Experimental J. Villarino, 2125 Zavalla, Argentina.
authors.forename: Elena del V
authors.initials: Edel V
authors.lastname: Gómez
mesh_terms: D000222:Adaptation, Physiological; D054750:Ecotoxicology; D004784:Environmental Monitoring; D005998:Glycine / Q000031:analogs & derivatives* / Q000633:toxicity; D006540:Herbicides / Q000633:toxicity*; D018570:Risk Assessment; D012987:Soil; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000633:toxicity*; D000097797:Glyphosate
chemical_list: D005998:Glycine; D006540:Herbicides; D012987:Soil; D012989:Soil Pollutants; D000097797:Glyphosate
keywords: DGGE profiles; Glyphosate; PICT assay; Q-PCR; Soil microbial community