|495-2||Involvement of cytochrome P450 in the degradation of diuron by Ganoderma lucidum|
|Autores:||Jaqueline da Silva Coelho-moreira (UEM - Universidade Estadual de Maringá) ; Caroline Aparecida Vaz de Araújo (UEM - Universidade Estadual de Maringá) ; Cristina Giatti Marques de Souza (UEM - Universidade Estadual de Maringá) ; Adelar Bracht (UEM - Universidade Estadual de Maringá) ; Rosane Marina Peralta (UEM - Universidade Estadual de Maringá) |
White-rot fungi are Basidiomycetes which have been evaluated for their potential in the remediation of contaminated sites due to their great ability to degrade a wide variety of pollutant molecules. Intra and extracellular enzymatic systems have been associated with xenobiotic metabolism by white-rot fungi. Pesticides are persistent molecules highly employed in agriculture to control broad-leaf weeds in the crops. These, and other xenobiotic molecules, are degraded by several microorganisms; however, the enzymatic system involved in this process has not always been identified. In this work, we cultivated the white-rot fungus Ganoderma lucidum in the presence of the herbicide diuron and evaluated the involvement contents of cytochrome P450 in the degradation of diuron. Liquid medium was prepared using a corn cob extract, mineral solution and glucose (1%) added or not of diuron (174 µg by culture). The cytochrome P450 inhibitors ABT (1-aminobenzotriazole) and PB (piperonylbutoxide) were added to cultures in the final concentration of 1 mM and 0.5 mM, respectively. After cultivation, residual diuron and its metabolites in the mycelia were extracted with acetonitrile and evaluated by HPLC. The presence of diuron and its metabolites, DCPMU [1-(3,4-Dichlorophenyl)-3-methylurea] and DCPU [(3,4-Dichlorophenyl)urea], were observed in filtrates and mycelial extract. Around 6.5% (11.4 µg) of diuron was found in the mycelial extract on 5 day of cultivation, decreasing during the cultivation. The degradation products DCPMU and DCPU had the maximal contents on 15 day (4.18 and 1.92 µg, respectively), which coincided with the maximal biomass production (110 mg). These results suggest that the fungal herbicide degradation may occur intracellularly by the uptake of the molecule into the fungal cell. In culture filtrates with addition of the cytochrome P450 inhibitors (ABT and PB), a higher diuron amount was found (122.5 and 105μg by culture, respectively) compared with control cultures without the inhibitors (77.5 μg). Also, ABT and PB inhibited the production of the degradation products from diuron (DCPMU and DCPU) by more than 50% after 15 days of incubation. Thus, these results demonstrate strong evidence of the cytochrome P-450 involvement in the degradation of diuron by the white-rot fungus G. lucidum.
Palavras-chave: white-rot fungi, Ganoderma lucidum, herbicide, cytochrome P-450