Assessment of the ecotoxicological impact of natural and synthetic β-triketone herbicides on the diversity and activity of the soil bacterial community using omic approaches

International audienceThe emergence of pesticides of natural origin appears as an environmental-friendly alternative to synthetic pes-ticides for managing weeds. To verify this assumption, leptospermone, a natural β-triketone herbicide, andsulcotrione, a synthetic one, were applied to soil microcosms at 0× (control), 1× or 10× recommended fielddose. The fate of these two herbicides (i.e. dissipation and formation of transformation products) was monitoredtoassessthescenarioofexposureofsoilmicroorganismstonaturalandsyntheticherbicides.Ecotoxicologicalim-pactof bothherbicides wasexploredbymonitoring soil bacterial diversity and activity usingnext-generation se-quencing of 16S rRNA gene amplicons and soil metabolomics. Both leptospermone and sulcotrione fullydissipated over the incubation period. During their dissipation, transformation products of natural and syntheticβ-triketone were detected. Hydroxy-leptospermone was almost completely dissipated by the end of the exper-iment, while CMBA, the major metabolite of sulcotrione, remained in soil microcosms. After 8 days of exposure,the diversity and structure of the soil bacterial community treated with leptospermone was significantly modi-fied, while less significant changes were observed for sulcotrione. For both herbicides, the diversity of the soilbacterial community was still not completely recovered by the end of the experiment (45 days). The combine