Green synthesis of gold nanoparticles by engineered Escherichia coli for photodegradation of p-nitrophenol

Gold nanoparticles (AuNPs) are widely employed in the environmental, energy, and biomedical fields. The green synthesis of AuNPs is significant for reducing the hazardous chemicals and toxic byproducts of traditional synthesis procedures. In this study, engineered Escherichia coli (E. coli-GolR) capable of heterologous production of the gold-reducing protein (GolR) were constructed. Uniform and stable loading of AuNPs on E. coli-GolR were demonstrated by characterization. Experiments using live-dead cell labeling showed that E. coli-GolR was able to withstand the toxicity of AuIII. Within 5 min, 3 mM of 4-nitrophenol (4-NP) could be totally broken down by the acquired AuNPs@E. coli-GolR. More importantly, the AuNPs@E. coli-GolR could be recycled at least ten times, significantly decreasing the cost of their application. This work broadens the possibilities for using AuNPs by offering fresh insights into the microbial production of AuNPs.