During atrazine degradation by Rhodococcus sp, strain NI86/21, N-dealkylated metabolites and an hydroxy-isopropyl derivative are produced. The cytochrome P-450 system that is involved in degradation of thiocarbamate herbicides by strain NI86/21 (I. Nagy, G. Schoofs, F. Compernolle, P. Proost, J. Vanderleyden, and R. De Mot, J. Bacteriol. 177:676-687, 1995) is also required for atrazine degradation. Atrazine-degrading activity was conferred on the atrazine-negative strains, mutant FAJ2027 of Rhodococcus sp. strain NI86/21 and Rhodococcus erythropolis SQ1, upon transformation with the genes encoding the cytochrome P-450 system,