6533b831fe1ef96bd1298ac7

RESEARCH PRODUCT

Les herbicides β-tricétones : devenir et impact écotoxicologique dans les sols agricoles et caractérisation de souches bactériennes dégradantes

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P-triketone herbicides : fate and ecotoxicological impact in arable soils and characterization of degrading bacterial strains abstract :This work aims to describe the ecodynamics of synthetic (sulcotrione and mesotrione) and natural (leptospermone) -triketone herbicides and to estimate their ecotoxicological impact on the bacterial community in arable soils. The processes involved in the dissipation of these herbicides (adsorption and biodegradation) have been studied in soil microcosms. Two bacterial strains, Bradyrhizobium sp. SRl able to degrade sulcotrione and mesotrione, and Methylophilus sp. LS1 degrading leptospermone, have been isolated. A bank of 12 ooo mutants of Bradyrhizobium sp. SR1 was established allowing the selection of two Sul•mutants but interrupted genes didn't code for enzymes degrading sulcotrione. The ecotoxicological impact of synthetic (sulcotrione) and natural (leptospermone) triketones on soil bacterial community was estimated using metagenomics and metabolomic tools. Leptospermone transitory modified the diversity and composition of the bacterial community, in accordance with its persistence in soil. Sulcotrione did not modified neither the diversity nor the composition of the bacterial community. The combination of metagenomics and metabolomics is promising for the assessment of ecotoxicological impact of herbicides on soil microorganisms.