An engineered microorganism can simultaneously detoxify cadmium, chlorpyrifos, and γ‐hexachlorocyclohexane. (9th December 2015) - Yang, Chao
Abstract : Many ecosystems are currently co‐contaminated with heavy metals such as cadmium (Cd 2+ ) and pesticides such as chlorpyrifos (CP) and γ‐hexachlorocyclohexane (γ‐HCH). A feasible approach to remediate the combined pollution of heavy metals and pesticides is the use of γ‐HCH degrading bacteria endowed with CP hydrolysis and heavy metal biosorption capabilities. In this work, a recombinant microorganism capable of simultaneously detoxifying Cd 2+, CP, and γ‐HCH was constructed by display of synthetic phytochelatins (EC20) and methyl parathion hydrolase (MPH) fusion protein on the cell surface of the γ‐HCH degrading Sphingobium japonicum UT26 using the truncated ice nucleation protein (INPNC) as an anchoring motif. The surface localization of INPNC–EC20–MPH was verified by cell fractionation, Western blot analysis, immunofluorescence microscopy, and proteinase accessibility experiment. Expression of EC20 on the cell surface not only improved Cd 2+ binding but also alleviated the cellular toxicity of Cd 2+ . As expected, the rates of CP and γ‐HCH degradation were reduced in the presence of Cd 2+ for cells without EC20 expression. However, expression of EC20 (higher Cd 2+ accumulation) significantly restored the levels of CP and γ‐HCH degradation. These results demonstrated that surface display of EC20 enhanced not only Cd 2+ accumulation but also protected the recombinant strain against the toxic effects of Cd 2+ on CP and γ‐HCH degradation.