Dechlorination of atrazine by a Rhizobium sp. isolate

A Rhizobium sp, strain, named PATR, was isolated from an agricultural soil and found to actively degrade the herbicide atrazine. Incubation of PATR in a basal liquid medium containing 30 mg of atrazine liter(-1) resulted in the rapid consumption of the herbicide and the accumulation of hydroxyatrazine as the only metabolite detected after 8 days of culture, Experiments performed with ring-labeled [C-14]atrazine indicated no mineralization, The enzyme responsible for the hydroxylation of atrazine was partially purified and found to consist of four 50-kDa subunits. Its synthesis in PATR was constitutive. This new atrazine hydrolase demonstrated 92% sequence identity through a 24-amino-acid fragment with atrazine chlorohydrolase AtzA produced by Pseudomonas sp. strain ADP.