Biotransformation of s-Triazine Herbicides and Related Degradation Products in Liquid Cultures by the White Rot Fungus Phanerochaete chrysosporium

Abstract

: The ability of the white rot basidiomycete Phanerochaete chrysosporium to transform s-triazine herbicides has been investigated in laboratory experiments. The chlorinated metabolites formed during atrazine Ndealkylations were not further transformed by the fungus, whereas hydroxyatrazine was converted to an unknown product. P. chrysosporium was also able to carry out the N-dealkylation of the herbicides simazine, propazine and terbuthylazine. Herbicide metabolism was not supported by puriÐed peroxidases. The highest rates of herbicide N-dealkylation were obtained in liquid cultures maintained under moderate temperature allowing a long mycelium growing phase. Atrazine transformation was found to be supported by the mycelium, which contained signiÐcant amounts of microsomal cytochrome P450. Herbicide N-dealkylation was decreased in the presence of 1-aminobenzotriazole, in agreement with the involvement of P450 monooxygenases in atrazine metabolism.

Optimized Atrazine Degradation by Pleurotus ostreatus INCQS 40310: an Alternative for Impact Reduction of Herbicides Used in Sugarcane Crops

“…In general, soil fungi remove the ethyl group of atrazine before the removal of the isopropyl group [36,37]. ), regarding not only the optimal percentage of degradation (4,11,12) but also the results that showed minimum medium composition (1) and unidentified metabolites (13,16). Another interesting result was obtained from assay 4, which promoted 60% atrazine degradation after 20 days with the formation of DIHA, DEDIA, DIA, HA and DEA.…”

“…The degradation and mineralization of atrazine can occur through physical-chemical processes or by microorganism action. Previous studies reported in the literature have identified more than 15 metabolites resulting from atrazine degradation [9][10][11][12][13]. The main atrazine degradation products are hydroxylated and chlorinated compounds, including desethylatrazine (2-chloro-4-amino-6-isopropylamine-s-triazine, DEA), desisopropylatrazine (2-chloro-4-ethylamine-6-aminos-triazine, DIA), desethyldesisopropylatrazine (2-chloro-4,6-aminos-triazine, DEDIA), desethylhydroxyatrazine (2-hydroxy-4-amino-6-isopropylamine-s-triazine, DEHA), desisopropylhydroxyatrazine (2-hydroxy-4-ethylamine-6-amino-s-triazine, DIHA) and hydroxyatrazine (2-hydroxy-4-ethylamine-6-isopropylamine-s-triazine, HA).…”

“…Within the soil, the degradation of atrazine by fungi usually follows pathways that involve the sequential removal of the aromatic ring substituents, beginning with dealkylation, which is the first step in the degradation of this compound [12,15]. The application of fungi for the biodegradation of recalcitrant chemicals has been widely studied [16][17][18][19][20].…”

The Role of White-rot Fungi in Herbicide Transformation

“…According to da Silva Coelho-Moreira et al [75], enzymatic crude extracts supplied with combinations of veratryl alcohol H 2 O 2 and Mn 2+ did not degrade the herbicide, it is possible that DCPMU and DCPU can be further transformed by MnP. P. chrysosporium is also able to transform atrazine, its transformation product and other striazine herbicides [70]. The first and main step in the chlorinated-s-triazine degradation pathway by the fungus was mono-N-dealkylation.…”

“…MCPA and bentazon were degraded by P. chrysosporium at 65% and 75%, respectively, in 20 days [73]. P. chysosporium degraded isoproturon belonging to phenylurea groups [73,76], atrazine [70], and also diuron [82]. However, according to [57], no atrazine degradation was observed by this fungus in liquid cultures.…”