RAPID DEGRADATION OF ATRAZINE BY RHODOCOCCUS SP NI86/21 AND BY AN ATRAZINE-PERFUSED SOIL

Rapid mineralization of the s-triazine ring carbons of atrazine in the absence of other substrates was accomplished by a mixed microbial consortia in soil that had been extensively perfused with a solution of the herbicide. Most (83%) of the labeled s-triazine ring carbons were mineralized to (CO2)-C-14, and nearly all (93%) of the labeled carbon in the ethyl side chain of atrazine was also mineralized at a similar rate as the ring carbons to (CO2)-C-14. No metabolites accumulated in the broth; however, several metabolites were detected in small amounts after 72 h of incubation. One of these metabolites was identified as hydroxyatrazine. The degradation of atrazine by Rhodococcus sp. NI86/21 was also studied, and two metabolites, deisopropylatrazine and deethylatrazine, were identified by mass spectrometry. The major metabolite, deisopropylatrazine, contained 69% of the radiolabel of the parent atrazine, and the minor metabolite, deethylatrazine, accounted for 25% of the parent atrazine.