Construction of a synthetic microbial consortium for bifenthrin biodegradation via cooperative metabolism and...

Bifenthrin is a highly toxic and persistent pyrethroid insecticide whose residues threaten ecosystem safety and human health. Although microbial remediation is a promising strategy, the degradation efficiency of individual strains is often limited by steric hindrance from the intermediate bifenthrin alcohol. In this study, Pseudomonas aeruginosa strain PA (PA) and Paracoccus pantotrophus strain PP (PP) were isolated from contaminated soil and constructed into a synthetic consortium (PA+PP), which synergistically enhanced bifenthrin degradation. The consortium exhibited a notably higher degradation rate constant than either strain alone (k₃ = 0.26 d^-1 > k₁ = 0.15 d^-1> k₂ = 0^.10 d^-1). Under the optimized assay conditions, bifenthrin was introduced into the aqueous MSM system at a nominal initial concentration of 100 mg/L using an acetone stock solution and dispersed with 0.1% Tween 80, resulting in 92.38% removal within 7 days. Mechanistic analysis revealed a metabolic action specificity: PA served as the hydrolyzer, cleaving the ester bond of bifenthrin to generate bifenthrin alcohol and trifluorochloro-chrysanthemic acid, while PP, as the oxidizer, efficiently degraded bifenthrin alcohol, thereby relieving steric hindrance on PA hydrolases and establishing an essential cooperative degradation partnership. Additionally, PA-secreted extracellular polymeric substances (EPS), which are rich in polysaccharides, proteins, and humic-like components, promoted bifenthrin adsorption and electron transfer, thereby optimizing the local microenvironment for synergistic activity. This study elucidates a previously unreported cooperative mechanism between PA and PP, offering a mechanistic basis for designing effective microbial consortia to remediate bifenthrin pollution. These findings help optimize the microbial degradation efficiency of bifenthrin and other pyrethroids, providing theoretical support for developing engineered inoculants for environmental bioremediation.