First isolation and characterization of a bacterial strain that biotransforms the herbicide mesotrione.

The aim of this study was to find and characterize a fungal or bacterial strain capable of metabolizing mesotrione, a new selective herbicide for control of broad-leaved weeds in maize. This strain was isolated from cloud water and showed close phylogenetic relationship with strains belonging to the Bacillus genus, based on 16S rRNA gene alignment. Kinetics of mesotrione degradation were monitored by high-performance liquid chromatography and in situ(1)H nuclear magnetic resonance spectroscopy at different concentrations. Mesotrione was completely biotransformed even at 5 mmol l(-1) concentration. 2-Amino-4-methylsulfonyl benzoic acid (AMBA) was identified as one of the metabolites, but was not the major one. This study reports the first rapid mesotrione biotransformation by a pure bacterial strain and the formation of several metabolites including AMBA. This bacterium isolated from cloud water is the first pure strain capable of rapidly degrading mesotrione.