Atrazine- tolerant native microorganisms isolated from agricultural soils in the department of Cordoba, Colombia

Abstract

The objective of the present study was to identify and evaluate atrazine tolerant native microorganisms isolated from a soil destined to the maize crop for ensiling, where this pesticide is usually used as preemergence. To determine their tolerance, they were subjected to growth at different concentrations of atrazine, different temperatures (30 ° C, 37 ° C and 40 ° C) and pH (5.0, 6.0 and 9.0). The results show native strains that tolerated concentrations of 1000 ppm atrazine, identified as Pseudomonas sp (strain 1L1a), Pseudomona sp (strain 1L2), Streptomyces sp and Arthrobacterium sp, which show higher growth at 37 °C (7. 98E+06 CFU/mL), lower at 30 °C (3.63E+06 CFU/mL) and tolerance at 40 °C (5.80E+06 CFU/mL). The strain Streptomyces sp reached its highest growth (4.73E+06 UFC/mL) at pH 9.0, while Pseudomonas sp strain 1L1a (3.43E+06 UFC/mL), Arthrobacter sp (3.40E+06 UFC/mL) and Pseudomonas sp strain 1L2a (2.63E+06 CFU/mL) was at pH 6.0. All microorganisms showed sensitivity to pH 5.0. The growths reached at different temperatures and pH are in agreement with the adaptation to the tropical climate predominant in the region and related to the genus of microorganisms. The study indicates that the native strains are able to tolerate high concentrations of atrazine and to mineralize it in soils with low content of organic matter and nutrients.

Keywords

• Microorganismos
• pesticida
• suelo
• biorremediación.