Genomic analysis of the Bacillus megaterium Mes11: New insights into nitroreductase genes associated with the degradation of mesotrione

Mesotrione is among the most recently marketed herbicides belonging to triketone family and applied on maize crops. A Bacillus megaterium Mes11 strain isolated from an agricultural soil was able completely transform 1 mM of mesotrione, alone or in a mixture with nicosulfuron and/or S-metolachlor herbicides, 5 h. Its complete genome contains one circular chromosome (5,191,612 bp) nine plasmids (from 45,372 169,684 bp). Genome analysis revealed that 10 genes encoded oxygen-insensitive nitroreductases which only (NfrA2) shown be involved first step mesotrione transformation « cellulo ». Indeed, quantitative reverse-transcription PCR demonstrated NfrA2 expression concomitant transformation, showing maximum 6-fold increase after 4 h exposure this single molecule. As opposed nicosulfuron, presence led significant 12 24-fold same time exposure, binary ternary mixtures, respectively. These results highlight, for time, physiological role » environmental B. bioremediation mesotrione-contaminated ecosystems.