Degradación de Imidacloprid por Cladosporium cladosporioides: cinética, vías metabólicas y toxicidad

Abstract

Imidacloprid is one of the most popular and widely used neonicotinoid insecticides, despite reports of its adverse effects on non-target organisms. It is persistent in soil, with a half-life of 100 days and due to its high solubility easily contaminates water bodies around the world. Therefore, it is crucial to remove imidacloprid from contaminated environments and identify alternatives for treating agricultural liquid waste. This study presents the first report of imidacloprid degradation by the native fungus Cladosporium cladosporioides. The isolate was identified by analysis of the ITS region sequences (ITS1 and ITS4) and based on morphological characteristics. Degradation kinetics were performed using concentrations of 20, 40, and 100 mg L⁻¹ of imidacloprid in the presence of glucose as a carbon source. After 10 days, the fungus degraded 71%, 56%, and 30% of the initial concentration, respectively. The maximum degradation rate was of 2.66 mg L⁻¹ d⁻¹ for 40 mg L⁻¹. Biomass development and laccase activity patterns were both coincident with the degradation kinetics. Transformation products as 5-hydroxyimidacloprid, imidacloprid olefin, and 6-chloronicotinic acid, were identified by LC-MS/MS and FTIR, suggesting a possible metabolic degradation pathway. These products exhibited lower toxicity, on Eisenia fetida avoidance tests, than imidacloprid. This research is the first step toward the future application of C. cladosporioides in the treatment of liquid effluents to prevent pollution and remediate contaminated environments.