Chlorpyrifos degradation by consortium of actinobacteria isolated from contaminated environment

Abstract

The aim of this work was to demonstrate the efficiency of pure and mixed actinobacteria cultures isolated from Chilean (Streptomyces sp. Strain AC5 y AC7) and Argentinean (Streptomyces sp. A2, A5, A11, M7) contaminated sites for removing the insecticide chlorpyrifos (CP) from liquid medium. Preliminary actinobacteria tolerance assays were carried out in Petri plates containing solid minimal medium (MM) in the presence of CP at concentration of 1.66mgL−1. In most of cases, actinobacteria strains showed high tolerance levels to the pesticide. To determine the potential antagonistic effect of the actinobacteria strains, Petri dishes with solid starch casein medium were sown confronting individual strains with each other actinobacteria. No growth inhibition was observed, so, there were no responses to antagonism between the assayed strains. The ability of pure and mixed actinobacteria cultures to growth and remove CP in liquid MM wasevaluated determining growth (dry weight), pesticide removal (gas chromatography) and pH variation. After 72 h of incubation, the CP removal was 67?89% when individual strains were evaluated, 83% and 96% CP removal was observed in the mixed culture formed by Streptomyces sp. A2-A5-A11-M7 and Streptomyces sp. AC5-AC7, respectively. Finally, with the consortium constituted by six strains, 92% of CP was removed, the biomass was duplicated and the pH increase from 7.0 to 8.3. These microorganisms showed high degradation capacity to remove organophosphorus pesticides such as chlorpyrifos. Therefore actinobacterias isolated from contaminated sites could be recommended for bioremediation pesticides.