Biodegradation pathway and mechanism of new emerging pollutants neonicotinoids

Neonicotinoids (NEOs), a fourth-generation pesticide group, are extensively utilized for crop protection in agriculture. However, their excessive use can negatively impact the environment and human health. Biodegradation offers an eco-friendly method for eliminating these insecticides. This study employed bacterial strains Stutzerimonas sp. SA1 and Pseudomonas sp. SA3, isolated from pesticide-contaminated agricultural soil, to degrade the various NEOs including acetamiprid (AC), imidacloprid (IM), thiamethoxam (TH), and clothianidin (CL). Numerous intermediate compounds were detected during biodegradation, and potential pathways were discussed. The highest reduction of chemical oxygen demand of clothianidin (87 %) and acetamiprid (72 %) were observed in Stutzerimonas sp. SA1 and Pseudomonas sp. SA3 were AC 72 % and CL 66 % respectively. A bacterial consortium effectively breakdown the NEOs through the secretion of nitrile hydratase (NH) enzyme. Fourier-transform infrared spectroscopy results confirmed the presence of functional groups alkane and carbonyl in the NEOs residue. The Gas Chromatography Mass Spectrometry data revealed that the Stutzerimonas sp. SA1 has the highest potential of biodegradation efficiency (BE) AC (89 %) and IM (87 %) than the other NEOs respectively. The Pseudomonas sp. SA3 shoved the higher BE in the AC (90 %), IM (97 %) and TH (85 %) than the bacterium Stutzerimonas sp. SA1. The results suggest that these bacteria produce the degradative enzymes effectively and utilize the NEOs as a carbon source. The results suggest that these bacteria produce the NH degradative enzymes and utilize the NEOs as a carbon source. In conclusion, the strains Stutzerimonas sp. SA1 and Pseudomonas sp. SA3 were identified as potential candidate for the biomineralization and removal of NEOs contaminated environment.