Phanerochaete chrysosporium-driven quinone redox cycling promotes degradation of imidacloprid

Abstract

This study systematically investigated the advanced oxidation processes driven by the white-rot fungus (WRF) Phanerochaete chrysosporium in the removal of the neonicotinoid pesticide imidacloprid (IMI). The quinone redox cycling driven by P. chrysosporium promotes the degradation of IMI in presence of Mn2+ and Fe (III)-oxalate. Results showed that the degradation efficiency varied with the type of quinine mediator, and gallic acid (GA) was a more effective mediator than 1,4-benzoquinone (BQ). The removal rate of IMI was increased by 1.8-fold in the presence of 100 μM of Mn2+ compared with that of the system without Mn2+. The addition of oxalic acid and EDTA promoted the degradation of IMI, and the effect of oxalic acid was more pronounced at the later stage (day 5 and day 6); the optimal Fe3+/oxalate ratio was 1:3. Time-course experiments revealed the maximum removal rates of IMI were 97.37%, 82.0% and 73.52% at the initial IMI concentration of 10, 20, and 30 mg/L, respectively, in the presence of 100 μM Mn2+, 100 μM Fe3+-300 μM of oxalate and 500 μM gallic acid. Under quinone redox cycling conditions, the good correlation between ·OH production rates and the enzymes activity was concluded, the quinines redox cycles promote enzyme activity, as well as the rate of ·OH production. Results from this study indicated the GA mediator-based system using P. chrysosporium offers a new method to advance the bio-oxidation process owing to its simple culture system, low-cost precursors, unique fungi, and degradation stability.