Degradation of atrazine by Pseudomonas sp and Achromobacter sp isolated from Brazilian agricultural soil

Atrazine is a herbicide used worldwide to control weeds in maize, sorghum and sugarcane crops. This study presents two bacteria isolated from Brazilian soil samples with atrazine application history. The isolates, identified as Pseudomonas sp. and Achromobacter sp., showed potential to degrade atrazine in solid medium. Pseudomonas sp. exhibited all the six atz genes that encode enzymes of the degradation process. This isolate was capable of degrading 99% of atrazine in vitro after 24 h of incubation. Achromobacter sp. presented only atzA, atzB and atzC genes, which are responsible for the first steps of the degradation pathway, and showed a different degradation profile. The three initial metabolites formed by atrazine degradation were detected in samples containing both Pseudomonas sp. and Achromobacter sp., suggesting atrazine transformation. By Northern Blot assay, atzA, atzB, atzC and atzD genes were differentially expressed in the presence of atrazine in Pseudomonas sp., however, this difference was not observed in Achromobacter sp. This study confirms the worldwide dispersion of atz genes.