Environmental impact of synthetic and natural ?-triketone herbicides: detection, microbial adaptation, biodegradation and toxicity.. soil metagenome

Conventional agricultural practices rely on uses of effective synthetic pesticides for managing weeds. Nowadays, there is more concern about the possibility of adverse effects of these substances on human health and ecosystems. Risk assessment and ecotoxicological monitoring of pesticides, including their main degradation products, are already required within the framework of European legislation. As a consequence, there is a need for a new generations of less environmentally dangerous molecules, such as lower impact pesticides, biopesticides and natural product-based pesticides. b-triketone natural herbicides, as many naturals products, are considered as biodegradable and less toxic than synthetic ones. However, studies on the fate and effects of natural products in the soil and water environment are practically non-existing. In this context, TRICETOX project aims to evaluate the possible risks and adverse effects of leptospermone, on microbial community applied at recommended field dose and ten times recommended field dose using a microcosm approach. In a first phase, dissipation kinetics of leptospermone was monitored in order to characterize the scenario of exposure of soil microorganisms. The impact of leptospermone on soil microbial community was investigated directly from DNA soil extracts using new molecular tools based on (i) qPCR targeting 16S rRNA gene sequences to estimate the abundances of total bacteria and phylum specific groups and (ii) pyrosequencing to get further insight in possible effect of leptospermone on genetic diversity of bacterial community.