“Study of the effect of azospirillum brasilense AZ39 on the residuality of glyphosate used in corn crops”

CARDOZO, PATRICIA; SOSA, CARLOS; CARDENAS, MATÍAS; TRAVAGLIA, CLAUDIA; D'ERAMO, FABIANA; MORESSI, MARCELA

Congreso; 8vo Congreso Latinoamericano de pesticidas; 2021

STUDY OF THE EFFECT OF Azospirillum brasilense Az39 ON THE RESIDUALITY OF GLYPHOSATE USED IN CORN CROPSP. Cardozoa, C. Sosaa, M. Cardenasb, C. Travagliaa, F. D’Eramob, M. Moressib.a-Departamento de Ciencias Naturales, Facultad de Ciencias Exactas, Fisicoquimicas y Naturales, Universidad Nacional de Rio Cuarto. Rio Cuarto, Cordoba, Argentina.b-Departamento de Quimica, Facultad de Ciencias Exactas, Fisicoquimicas y Naturales, Universidad Nacional de Rio Cuarto. Rio Cuarto, Cordoba, Argentina.e-mail: mmoressi@exa.unrc.edu.arCurrently, there is an increasing need to expand to the maximum the knowledge of the physical-chemical characteristics, the form of action and the environmental impact of herbicides, in order to make a rational use of them1. In the development of a herbicide, aspects such as its chemical formula, its behavior within the plant to the impact on the environment should be studied, in order to offer the farmer effective and safe tools. Thus, studies related to forms of degradation of herbicides that remain as residues are important to achieve a minimum environmental impact 1.The time that a herbicide remains active in the soil, after it produced its effect, is called persistence. Any factor that alters the disappearance or decomposition of herbicides affects their persistence. Nowadays, different strategies are being developed to eliminate these substances in an economic and ecological way. Numerous studies have shown that soils contaminated with pesticides can be decontaminated by the action of specific microorganisms 2.In this work, an in vitro study was carried out on the interaction between the Rizo bacterium Azospirillum brasilense Az39 and glyphosate in order to determine if the microorganism was capable of reducing the accumulation of its residues.For the study, a bacterial inoculum was prepared using the Azospirillum brasilense Az39 strain, grown in LB liquid medium. From it, in vitro survival tests of the bacterial culture against glyphosate were performed, as well as its ability to use it as a carbon source. In the first case, a selective medium for nitrogen-fixing bacteria was used: NFb (nitrogen free broth), to which glyphosate sources were added. While for the second case, the same culture medium was prepared but without the addition of the carbon source, which was replaced by glyphosate. The concentration of glyphosate and AMPA was determined in these treatments where the culture medium conserved all the nutritional sources for the growth of A. brasilense Az39, representing the availability of nutrients that the bacteria usually have. Their quantification was carried out using HPLC Chromatography with MS / MS detection after derivatization with FMOC3.The obtained results showed a 30% decrease in the glyphosate concentration in the culture medium inoculated with A. brasilense compared to the treatment without bacterial inoculation. The treatment in which the Az39 culture was inactivated did not show significant differences with respect to the treatment without Az39. In the control treatment (-), neither glyphosate nor AMPA was detected. The ability of Azospirillum brasilense Az39 to use glyphosate as a carbon source was demonstrated, even in the presence of all its nutritional sources, which is promising for its degradation in the floor.Keywords: Azospirillum brasilense Az39, glyphosate, degradation of herbicides, HPLC MS/MS.References1-Alvear M., Lopez R., Rosas A., Espinoza N., Revista Cientifica Suelo y Nutricion Vegetal, (2006) 64-76. 2- Diez M. C., Journal of Soil Science and Plant Nutrient, 10 (2010) 244-267. 3-Ibañez M., Pozo O.J., Sancho J.V., Lopez F. J., Hernandez F., Journal of Chromatography A, 1081 (2005) 145-155.