Chemical and Biological Degradation of Primary Metabolites of Atrazine by a Nocardia Strain

Abstract

The purpose of this paper is to elucidate the final degradative pathways of atrazine (I) by a Nocardia strain through experiments on the degradation of its metabolite, 4-amino-2-chloro-6-isopropylamino-1, 3, 5-triazine (IIa). This compound, in the bacterial medium, was transformed into several products identified as 2-chloro-4, 6-diamino-1, 3, 5-triazine (IIe), 4-amino-2-hydroxy-6-isopropylamino-1, 3, 5-triazine (VIII), 4-amino-1, 2-dihydro-1, 3, 5-triazin-2-one (IV) and dicyanodiamidine (VII). The formation of (IIc) was attributed to a microbial N-dealkylation, while the detection of (IV) and (VII) was attributed to a chemical degradation of the intermediate 4-amino-2-chloro-1, 3, 5-triazine (III). Compound (III) undergoes rapid hydrolysis and does not accumulate in the culture medium. On the basis of the microbial and chemical results, we propose a degradative pathway for atrazine.