Patented bioelectrodes have electrifying taste for waste
New research at Michigan State University (MSU) and published in the current issue of Nature Communications shows how Geobacter bacteria grow as films on electrodes and generate electricity – a process that’s ready to be scaled up to industrial levels.
The thick biofilm, a gelatin microbial dynamo of sorts, is a combination of cells loaded with cytochromes, metal-based proteins, and pili, hairlike protein filaments discovered and patented by MSU’s Gemma Reguera, associate professor of microbiology and MSU AgBioResearch scientist.
The biofilms are comparable to an electrical grid. Each cell is a power plant, generating electrical discharges that are delivered to the underlying electrode using a network of cytochromes and pili. The cytochromes are the transformers and towers supplying electricity to the city. The pili represent the sparse-but-mighty powerlines that connect the towers, even those far away from the power plant, to the grid.
Cytochromes and pili work together for shorter ranges – the first 10 layers of cells or so closest to the electrode. As more cells stack on the electrode, the efficiency of the cytochrome as electron carrier diminishes, and the pili do all of the work – discharging electrons 1,000 times faster than normal.
“The pili do all of the work after the first 10 layers, and allow the cells to continue to grow on the electrode, sometimes beyond 200 cell layers, while generating electricity,” said Reguera, who co-published the paper with MSU graduate student Rebecca Steidl and MSU postdoctoral student Sanela Lampa-Pastirk, who work in Reguera’s lab. “This is the first study to show how electrons can travel such long distances across thick biofilms; the pili are truly like powerlines, at the nanoscale.”
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