Ana Muñoz

Soil bioremediation of atrazine pesticide by two strains of soil microorganism

Bioremediation is used in agricultural soils to solve pesticide contamination problems. To maintain soil ecosystems, it is important to avoid the use of foreign microorganisms for soil bioremediation. We used two autochthonous bacteria, Pseudomonas synxantha BS2 and Pseudomonas cedrella BS4, to degrade atrazine pesticide in a previously contaminated soil. These two bacteria had previously been isolated from the same soil. The atrazine degradation in sterile and non-sterile soils was measured by HPLC. Soils were inoculated with both bacteria separately, with their respective non-inoculated controls. After 20 days, more than 20% of the atrazine had been degraded in the sterile soil inoculated with Pseudomonas cedrella BS4, and more than 30% in the nonsterile soil. Inoculating sterile and non-sterile soils with Pseudomonas synxantha BS2 reduced the pesticide halflife by 50 days with respect to the non-inoculated soils. The non-biological degradation of atrazine in sterile noninoculated soil was 14%. The implementation of bioremediation with selected bacteria contributed to improving atrazine degradation in the studied soil, without altering the soils microbial ecosystem.