Combined microbiological test to assess changes in an organic matrix used to avoid agricultural soil contamination, exposed to an insecticide

Abstract

Combined microbiological and molecular test (BiologEcoplateTM , denaturing gradient gel electrophoresis (DGGE) and Real Time PCR (qPCR)) were carried out to evaluate the impact of repeated diazinon (DZN) applications at high concentration (40 mg kg-1) on microbial communities in a microcosm simulating the organic matrix (straw (50%): peat (25%): soil (25%) vv-1) of a pesticide biopurification system (PBS). Pesticide dissipation was also evaluated. After three successive exposures with DZN the dissipation efficiency was high; DZN dissipation clearly accelerated in the organic matrix, achieving 87%, 93% and 96% respectively after the three applications. The results obtained with BiologEcoplate TM showed that the physiological profiles of the community were not affected by the addition of DZN. On the other hand, molecular assays (DGGE and qPCR) demonstrated that the microbial structure (bacteria and fungi) remained relatively stable over time with high DZN doses compared to control. The results of the present study clearly demonstrate the high dissipation capacity of this biomixture and highlight the microbiological robustness of this biological system.