Evaluación de la tolerancia al pesticida glifosato de la microbiota aislada de la Laguna de Colta.

Abstract

The agricultural activity influences in the water quality deterioration due to the pesticides incorporation used for the crops protection. The purpose of this researching was to evaluate the glyphosate tolerance of isolated microorganisms of water samples from the Colta Lagoon; taking 12 samples of 10 mL around the lagoon, PCA with glyphosate, those were incubated at room temperature and 35º C during 24 hours or until growing was observed. The microorganism’s isolation was carried out based on a representative characteristic. Three replicas were realized; the last replica was seeded for exhaustion. The Gram staining was carried out, showing positive Gram (63%) at room temperature and negative Gram (33%), and at 35ºC positive Gram (47%) and negative Gram (56%) in the Agar PCA medium distilled water; while in the PCA medium, lagoon water, the two temperatures showed 50% positive Gram and 50% negative Gram; however, in the PCA medium with glyphosate the 58% of positive Gram were determined at room temperature and 42% of negative Gram, and at 35ºC 64% of positive Gram and 36% of negative Gram. To determine the tolerance, the clones were cultivated in the PCA medium with glyphosate to concentrations (1; 2; 3; 4; 5 mL/100 mL), obtaining thirteen clones in 5 mL/1000 mL concentration, and tolerance tests to the Paraquat in three concentrations (1; 2; 3 mL/100 mL), obtaining nine clones in 3 mL/1000 mL concentration. The antibiotic resistance evaluation was carried out, obtaining higher sensibility to the Oxacillin. During this study it was concluded that isolated bacteria show more tolerance to the glyphosate, allowing them to adapt they to contaminated environments with glyphosate, the tolerance presented by the bacteria be used for the bioremediation, however, it is recommended to realize a greater evaluation to obtain more exact results.