Physiological aspects of atrazine degradation by higher marine fungi

The influence of glucose and NH₄NO₃ on the degradation of the herbicide atrazine was studied with the marine fungus Periconia prolifica Anastasiou. The bioaccumulation of¹⁴C-atrazine by fungal cultures was substantially increased at increased concentrations of glucose. Overall, 34.1% of the initial atrazine concentration was removed from the culture filtrate of the cultures grown in 0.5% (w/v) glucose and 0.007% (w/v) NH₄NO₃, and 40.4% of the initial atrazine concentration was removed when the same media contained 0.08% (w/v) NH₄NO₃. The majority of internalized radioactivity from both sets of cultures could be extracted from the mycelia as undegraded atrazine. However, examination of both the culture filtrates and mycelia of cultures grown under 0.5% (w/v) glucose and 0.08% (w/v) NH₄NO₃ revealed the presence of both dealkylated and dechlorinated hydrolysis products of atrazine. The fungal cultures, compared with uninoculated controls, showed a 5-fold increase in 2-chloro-4-ethylamino-6-amino-striazine (deisopropylatrazine), a 1.9-fold increase in 2-hydroxy-4-ethylamino-6-isopropylamino-s-triazine (hydroxyatrazine), and a 1.5-fold increase in other metabolites not extracted into ethyl acetate, suggesting two separate degradation pathways caused by a combination of metabolic and physicochemical interactions. Although mineralization of [ring-¹⁴C] atrazine did not occur under the conditions employed, considerable radioactivity was found in an unextractable form associated with cell fragments of Periconia cultures indicating further metabolism of the initial degradation products.