Sustainable power generation from sewage with engineered microorganisms as electrocatalysts

Microbial fuel cells (MFCs) are an emerging technology that could degrade contaminants and produce electricity simultaneously with the assistance of microorganisms. However, key challenges remain for their practical implementation, including the lack of efficient and cost-effective catalysts at the cathode. Here we take advantage of a sustainable cathode biocatalyst to construct a high-performance MFC that allows fast treatment of sewage and competitive power output. Our catalyst design is built on the Escherichia coli cell, which, upon coupled gene and nano engineering, shows excellent oxygen reduction reaction activity (current density of 3.32 mA cm−2 and onset potential of 0.63 V versus the reversible hydrogen electrode) and accelerates the depollution of organic matter in sewage sludge. Remarkably, glucose consumption reaches a level as high as 19.4 mM in 100 h with a maximum power density of 334 μW cm−2. Combined characterizations and theoretical calculations reveal that the enabling chemistry is the unique configuration of the iron centre of intermembranous cytochrome c in cells. Our study not only opens a new path for the rational design of electrocatalysts but also suggests the feasibility of addressing environmental issues using MFCs. This study presents a microorganism electrocatalyst for the cathode of a microbial fuel cell that allows simultaneous electricity generation and treatment of sewage.