ChpR-displaying bacteria for bioremediation of chlorpyrifos and TCP: A whole-cell biosorbent approach

The extensive use of chlorpyrifos (CPF) has led to significant water contamination, posing severe threats to aquatic ecosystems. This study presents a proof-of-concept for using surface-engineered bacteria as whole-cell biosorbents to remediate organophosphorus pesticide pollution and enhance water quality. We tested three outer membrane anchor motifs to display ChpR homologs on engineered bacteria. Only ice nucleation protein from Pseudomonas borealis (InaPb) successfully displayed these large proteins (up to 60 kDa) on the bacterial surface. Surface-engineered strains achieved complete adsorption of CPF at concentrations up to 100 µM and its toxic metabolite, 3,5,6-trichloro-2-pyridinol (TCP), at concentrations up to 1.6 µM in freshwater, with an optical density (OD₆₀₀) of 1.0. These strains also effectively removed CPF and TCP from soil leachates at various optical densities, with complete adsorption observed at OD₆₀₀ = 1.0, and demonstrated robust performance against the environmental matrix effects. Biosensing using a ChpR-based method and gas chromatography-mass spectrometry (GC-MS) analyses confirmed a significant reduction in the bioavailability and toxicity of CPF and TCP. This innovative approach offers a green and sustainable alternative to traditional remediation methods, highlighting the potential of engineered whole-cell biosorbents for improving water quality and reducing ecological risks in contaminated environments.