6533b86dfe1ef96bd12ca69d

RESEARCH PRODUCT

Ecotoxicological impact of oxamyl on the abundance and diversity of bacterial communities in an agricultural soil adapted to enhanced degradation

subject

description

Pesticides are largely applied to crops and end up on soils where they may affect non-target soil microorgan-isms involved in important ecosystem functions. Although in the past two decades microbial-ecology and –ecotoxicology were revolutionized by the incredible developments of molecular methods applied to nucleic acids (both DNA and RNA), within the EU regulation the current evaluation of the ecotoxicological effects of pesticides on soil microorganisms relies on single broad test (i.e. carbon mineralization), non-sensitive enough to detect shifts in diversity and function of microorganisms. Within the framework of the Love-to-Hate IAPP EU project, we tested the interest for combining high throughput sequencing and microbial functional measure-ments to assess the ecotoxicological effect of the carbamate oxamyl on the diversity abundance and activity of microorganisms in soils previously exposed to this nematicide. Oxamyl was rapidly mineralized concomitantly to a significant increase of the abundance of oxamyl-degraders. Bacterial diversity and composition for the overall microbial community were not affected by oxamyl exposure. However, when analyzing the active mi-crobial community by a RNA based approach, α-diversity indices were significantly higher than those of overall microbial community. Additionally, a significant effect on the composition of microbial communities was ob-served over time. Likewise, the most abundant bacterial groups remained constant for the overall microbial community but significantly shifted for the active Bacteroidetes and Gemmatimonadetes bacterial groups. Further analysis to detect the OTUs responsible for these significant differences led to the identification of seven different species belonging to the Proteobacteria, Acidobacteria and Actinobacteria bacterial groups. To conclude, the effects of oxamyl on the soil bacterial community were exclusively observed when analysing the active microbial communities and abundance of oxamyl degrading microorganisms. It emphasizes the need to focus on functional based analysis to better understand the ecotoxicological effects of pesticides on soil micro-bial communities.