RING HYDROXYLATION OF N-METHYLCARBAMATE INSECTICIDES BY RHODOCOCCUS TE1

Rhodococcus TE1, a soil bacterial isolate shown previously to metaboli ze several thiocarbamate herbicides, organophosphorus insecticides, an d s-triazine herbicides, was found to degrade carbofuran (2,3-dihydro- 2,2-dimethyl-7-benzofuranyl N-methylcarbamate), propoxur (2-isopropoxy phenyl methylcarbamate), and carbaryl (l-naphthyl methylcarbamate) in a defined growth medium. The insecticides were cometabolized, serving neither as a carbon nor as a nitrogen source for growth. Oxygen was re quired for metabolism of the insecticides. Carbofuran, carbaryl, and p ropoxur were each converted to hydrophilic end-products 16 mass units larger in size than the respective parent compounds. On the basis of N MR and GC-MS analysis, the end-product of carbofuran metabolism was id entified as 5-hydroxycarbofuran. Hydroxylation of the aryl N-methylcar bamate insecticides was associated with a 77 kb plasmid whose loss res ulted in the inability to metabolize these compounds. Given the ubiqui ty of the rhodococci in soils, and the variety of pesticides degraded by strain TE1, it is likely that these Gram-positive bacteria contribu te significantly to the dissipation of pesticides in the environment.