Isolation and characterization of a metsulfuron-methyl degrading bacterium Methylopila sp. S113

The bacterium S113, capable of degrading metsulfuron-methyl, was isolated from metsulfuron-methyl-treated soil. The isolate was identified as Methylopila sp. according to its phenotypic features and 16S rDNA phylogenetic analysis. This strain could utilize metsulfuron-methyl as the sole carbon or nitrogen source. More than 97% of the 50 mg l−1 initially added metsulfuron-methyl was depleted after 72 h when a culture was inoculated with 104 cells l−1 of strain S113. This strain could also degrade bensulfuron-methyl, thifensulfuron-methyl and ethametsulfuron-methyl. Cell-free extract of S113 was able to metabolize metsulfuron-methyl and other sulfonylurea herbicides. The metsulfuron-methyl degrading enzyme(s) was(ere) constitutively expressed and was(ere) not induced by metsulfuron-methyl. Inoculation of strain S113 into soil was found to promote the removal of metsulfuron-methyl in soil.