Characterization of atrazine degrading bacteria isolated from Argentinean agricultural soils

CUADRADO, V; MERINI, LJ; GIULIETTI, AM

Mar del Plata - Buenos Aires

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (S.A.I.B.).; 2007

The herbicide atrazine is widely employed in agriculture. Its physicochemical properties and extensive use increase the risk of soil and water contamination. The purpose of this work was the enrichment, isolation and characterization of microorganisms able to degrade atrazine, from agricultural fields (20 years of atrazine use) of Argentina Humid Pampa. Enrichments in liquid media were established, using atrazine as sole N and/or C source. 30 microbial strains were purified and genetically characterized by sequencing the 16S rDNA gene. Characterization of catabolic microbial associations was also carried out. Growth and catabolic performance were determined in liquid media with different atrazine concentrations, and kinetic parameters were calculated. Atrazine and its main metabolites were detected by HPLC. Results showed a great degrading microflora diversity: 63% of the isolates belonged to the phylum Proteobacteria (mainly Alphaproteobacteria), 30% were Actinobacteria and 7% Firmicutes. Three different bacteria associations were the more efficient in degradation, with 100% removal at concentrations between 25 and 500 ppm, although with different degradation rates. Herbicide degradation was facilitated by the combined activities of consortia members, due to their synergistic enzymatic activities. These cultivable microorganisms become potential candidates for bioremediation trials.