ECOTOXICOLOGICAL EFFECT OF MESOTRIONE ON ENZYME ACTIVITY AND MICROBIAL COMMUNITY IN AGRICULTURAL SOILS.

Multiple experiments were performed to evaluate the ecotoxicological effect of mesotrione on soil enzymatic activity, functional diversity, and genetic microbial biodiversity. The results showed that catalase and invertase activity initially increased with higher mesotrione concentration and then declined slightly. However, urease activity experienced a 11.9-23.2% reduction in comparison to control soil. The average well-color development (AWCD) was positively affected by the mesotrione treatment, the amount of carbohydrate, amino acid, and phenolic acid increased by 1.7-2.1, 1.1-1.6, and 1.7-2.5 times, respectively, when compared with the blank treatment. However, the utilization of carboxylic and acid amine was prohibited after applying 50-100 mg kg^-1 and 20-100 mg kg^-1 mesotrione. Denaturing gradient gel electrophoresis (DGGE) analysis showed that the shift in the bacterial community structure for different mesotrione treatments can be mainly attributed to an increment in band intensity, while the dissimilarity in the bacterial genetic structure decreased with increasing mesotrione content in the soil. Sequencing and phylogenetic analyses showed that the four bands in the denaturing gradient gel electrophoresis results were closely related to Bacillus subterraneus, Clostridium sp., and Bacillus sp. Obtained results show that abuse of mesotrione may pose a potential risk for soil microbial functioning. [ABSTRACT FROM AUTHOR]