Functional display of triphenylmethane reductase for dye removal on the surface of Escherichia coli using N-terminal domain of ice nucleation protein

• TMR displayed on the surface of E. coli using INP-mediated display system.
• TMR whole cell biocatalyst exhibited excellent activity and stability.
• The engineered strain provides an attractive way for low-cost dye degradation.

Traditional biological treatment for triphenylmethane dye effluent is stuck with the inaccessibility of dye molecules to intracellular dye-degrading enzyme, thus a high-efficiency and low-cost method for dye decolorization is highly desirable. Here we established a bioremediation approach to display triphenylmethane reductase (TMR) on the surface of Escherichia coli (E. coli) using N-terminal of ice nucleation protein as anchoring motif for triphenylmethane dye decolorization for the first time. Approximately 85% of recombinant protein positioning on the surface of E. coil cells exhibited high activity and stability. The optimal temperature and pH of the surface-displayed TMR are 50 °C and 8.5, respectively. Comparing with other reported microorganisms, the decolorization rate for malachite green of this engineered strain is the highest so far, reaching 640 μmol min−1 g−1 dry weight cells. These results indicate that this engineered E. coli strain is a very promising candidate for synthetic dye removal.

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