Expression of organophosphohydrolase in recombinant Escherichia coli and its purification and immobilization by one-step method

Abstract:

[Background] As a kind of broad-spectrum insecticides, organophosphorus compounds have caused serious environmental pollution due to their high dosage, strong toxicity and non-degradability. [Objective] To degrade the organophosphorus compounds, organophosphohydrolase (OpdA) was immobilized on NiCo2O4 and the properties of the catalyst in degrading organophosphorus compounds were investigated. [Methods] Specifically, histidine tag (His-tag) was introduced into OpdA to construct His-tagged OpdA, and the His-tagged OpdA was efficiently expressed in Escherichia coli Rosetta(DE3) using pET-28a(+) as vector under the induction of 1.0 mmol/L isopropyl-β-D-thiogalactopyranoside. The immobilized OpdA (OpdA@NiCo2O4) was prepared by one-step purification and immobilization method. [Results] NiCo2O4 was prepared by hydrothermal treatment and calcination. Based on the coordination between the transition metal ions on the surface of NiCo2O4 and the imidazole group of histidine on the surface of enzyme, one-step purification and immobilization of His-tagged OpdA were achieved. OpdA@NiCo2O4 with high stability was obtained under optimized conditions, and then it was applied for organophosphorus compounds degradation. The high degradation efficiency of organophosphorus compounds was realized by cascade reaction in the presence of NaBH4 under the optimal degradation conditions. [Conclusion] In conclusion, one-step purification and immobilization of recombinant enzyme were achieved, and it’s also proved that this study provides a safe, efficient and environmental new way for the degradation of organophosphorus compounds.