Engineering Bioelectric Bacteria to Produce Renewable Energy

E. coli (Escherichia coli) is not often associated with renewable energy production. This bacteria is widely known as a food contaminant and causes of illness, but it might become a source of electricity and a tool for wastewater treatment.   

 

Modified E. coli at the Swiss Federal Institute of Technology Lausanne. Image used courtesy of Jamani Caillet (CC-BY-SA 4.0)

Researchers at the Swiss Federal Institute of Technology Lausanne (EPFL) have created a method to bioengineer the bacteria so that it can produce electricity without the aid of other chemicals. They have found that the modified E. coli can outperform alternatives by improving its ability to metabolize organic substances. 

Other microbes are capable of producing electricity, but their ability to do so is frequently contingent on the presence of specific chemicals or other idiosyncratic environmental conditions that ultimately limit utility and application. 
 

The Role of Extracellular Electron Transfer

Even though E. coli is naturally capable of producing electricity, researchers wanted to re-engineer it so that it was not subject to limitations such as needing specific chemicals to generate electricity. 

To this end, the research team at EPFL integrated specific electrical capabilities from other bacteria into E. coli so that it is now capable of creating higher rates of electricity generation with fewer limiting conditions. 

Researchers used the Shewanella oneidensis MR-1 bacteria to help increase E. coli’s capacities for electricity generation. This bacteria is known for its ability to generate electricity, so by integrating parts of this bacteria into the E. coli, researchers were able to create a uniquely effective combination of abilities.

Extracellular electron transfer (EET) is a natural process by which bacteria can produce electricity. It is a process of respiration that allows a microorganism to transfer electrons from the inside of the cell to compounds in the environment surrounding the cell. 

 

Diagram of direct and indirect extracellular electron transfer (EET). Image used courtesy of ResearchGate

 

So the team at EPFL was able to expand E. coli’s pre-existing capabilities to now exhibit enhanced EET. The data from their testing has quantified the significance of this improvement. The modified E. coli was able to produce three times as much electrical current generation compared to previously used methods. 

 

Applications To Organic Waste Processing 

This innovation is significant because there are a number of possible applications, many of which can make clean energy contributions. 

The research team began testing their newly modified E. coli in wastewater from a local brewery in Lausanne. They found that the bioengineered E. coli flourished exponentially by feeding off the waste in this water. 

 

Magnified E. coli found in wastewater. Image used courtesy of USGS

 

Processing wastewater is an energy-intensive process, so the fact that the modified E. coli can not only complete this process without needing additional energy but also generate electricity while doing so is promising. The obvious net positive makes this development compelling on a small scale, but large-scale applications could be a transformative step toward net zero emissions. 

Wastewater treatment alone contributes over 45 million tons of greenhouse gases to the atmosphere every year in the United States. Wastewater is not the only possible application. 

The modified E. coli, capable of producing electricity from a variety of sources, can be used in electrosynthesis, biosensor technologies, and microbial fuel cells. And that list is hardly exhaustive. As this breakthrough unfolds in real time, researchers will map out other novel uses. 

Because E. coli has an intrinsic genetic flexibility, it will be possible to customize it, thus making its versatility a core strength. 

Bioelectric microbes have been receiving significant attention in the research community, and this E. coli advancement is another development that can be adapted and applied toward the move to sustainable energy.