Metabolization and degradation kinetics of the urban-use pesticide fipronil by white rot fungus Trametes versicolor

Abstract

Fipronil is a recalcitrant phenylpyrazole-based pesticide used for flea/tick treatment and termite control that is distributed in urban aquatic environments via stormwater and contributes to stream toxicity. We discovered that fipronil is rapidly metabolized (t = 4.2 d) by the white rot fungus Trametes versicolor to fipronil sulfone and multiple previously unknown fipronil transformation products, lowering fipronil concentration by 96.5%. Using an LC-QTOF-MS untargeted metabolomics approach, we identified four novel fipronil fungal transformation products: hydroxylated fipronil sulfone, glycosylated fipronil sulfone, and two compounds with unresolved structures. These results are consistent with identified enzymatic detoxification pathways wherein conjugation with sugar moieties follows initial ring functionalization (hydroxylation). The proposed pathway is supported by kinetic evidence of transformation product formation. Fipronil loss by sorption, hydrolysis, and photolysis was negligible. When T. versicolor was exposed to the cytochrome P450 enzyme inhibitor 1-aminobenzotriazole, oxidation of fipronil and production of hydroxylated and glycosylated transformation products significantly decreased (p = 0.038, 0.0037, 0.0023, respectively), indicating that fipronil is metabolized intracellularly by cytochrome P450 enzymes. Elucidating fipronil transformation products is critical because pesticide target specificity can be lost via structural alteration, broadening classes of impacted organisms. Integration of fungi in engineered natural treatment systems could be a viable strategy for pesticide removal from stormwater runoff.

Biochar-augmented biofilters to improve pollutant removal from stormwater – can they improve receiving water quality?

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Degradation of the herbicide paraquat by macromycetes isolated from southeastern Mexico

“…The strain ECS-79 was identified as Trametes versicolor. There are several reports on the degradation potential of this species and together with P. chrysosporium, is one of the most frequently studied macromycete species regarding the degradation of xenobiotic compounds such as aromatic polycyclic hydrocarbons (anthracene and naphthalene) (Marco-Urrea et al 2010;Jelic et al 2012;Wolfand et al 2016;Kamei 2017). This paper represents the first study that analyses the breakdown of the herbicide paraquat by both of these strains.…”

Fungi as a toolbox for sustainable bioremediation of pesticides in soil and water

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