Liu_2025_Chem.Eng.J_523_168754

The organophosphorus pesticide (OP) chlorpyrifos, recently listed as a persistent organic pollutant (POP), poses significant threats to ecosystems and human health due to its widespread use. Harnessing the quorum sensing (QS) mechanism for biodegradation is a promising approach, capable of removing environmental pollutants and facilitating ecological restoration. Herein, Pseudomonas aeruginosa PAO1 effectively degraded chlorpyrifos, achieving over 65.08% degradation in 9 days at a concentration of 50 mg.L1. This strain showed excellent colonization ability and efficient degradation performance in soil. Within 25 days, it achieved a degradation efficiency of over 54.49% for different concentrations of chlorpyrifos (10-50 mg.kg1). In addition, the presence of indigenous microorganisms effectively promoted the degradation of chlorpyrifos by PAO1. The las QS system was implicated in the regulation of chlorpyrifos biodegradation. Compared with the wild-type (WT) PAO1, the degradation rates of chlorpyrifos by the QS mutants deltalasI and deltalasR were significantly decreased. After complementation of the las knockout mutants, the degradation of chlorpyrifos was nearly restored to the WT level. When the exogenous QS signal molecule 3-oxo-C12-HSL (N-(3-oxo-dodecanoyl)-L-homoserine lactone) was introduced, the residual amounts of chlorpyrifos in the deltalasI strain significantly decreased. Moreover, under chlorpyrifos stress at concentrations of 50 mg.L1 and 100 mg.L1, the swarming abilities of WT and mutants deltalasI and deltalasR were significantly enhanced. A new degradation gene, est2098, was identified in PAO1, encoding a carboxylesterase with substantial catalytic activity against chlorpyrifos. This enzyme features a conserved domain (GXSXG) and a catalytic triad (Ser150, Glu243, and His273), with low sequence similarities (< 37.70%) with other known OP-degrading enzymes. The molecular docking and gene knockout experiments further validated its pivotal role in the degradation of chlorpyrifos. These results shed new light on the degradation mechanisms of P. aeruginosa PAO1 and provide potential candidates for chlorpyrifos bioremediation.