Ground-breaking research has harnessed the electricity-generating potential of a much-researched bacteria called Escherichia coli (E coli), which is commonly found in the guts of warm-blooded animals and is known to cause food poisoning and food-borne diseases, diagnostic effects of which range from modest to very severe.
The research has found that E. coli can generate electricity from wastewater, which opens avenues to the double benefits of utilising wastewater to generate electricity and putting the harmful bacteria on the leash to do so.
Researchers from Ecole Polytechnique Fédérale de Lausanne (EPFL), in Switzerland, harnessed the E coli bacteria through a process called extracellular electron transfer (EET) – a microbial metabolism that enables efficient electron transfer between microbial cells and extracellular solid materials.
While many bacteria are already known to generate electricity through this process, the latest research by the EPFL team demonstrated that a bioengineered E. coli can generate electricity many times more than others by metabolising a range of organic substrates, including – and especially – wastewater. This has proved E coli to be the most efficient “electric microbe”.
The key innovation used by the EPFL research team was to create an efficient EET pathway by integrating components of another electricity-generating bacterium called Shewanella oneidensis MR-1. The integration led to the opening of an optimised pathway for electron transfer, which traversed the inner and outer cell membranes in a much more enhanced manner than previously demonstrated, leading to a three-fold increase in electrical current generation compared to previous similar EET processes. The creation of a complete EET pathway by integrating components of another bacterium is a first in this domain of research, according to EPFL.
According to the study titled “Extracellular electron transfer pathways to enhance the electroactivity of modified Escherichia coli”, published in the journal Joule on September 8, the implications of this research point to more than just wastewater treatment to produce electricity – E coli’s potential to generate electricity from a wide range of sources also allows it to be used in microbial fuel cells, electrosynthesis, and biosensing; besides, its genetic flexibility can be exploited for sustainable technology development. According to Prof Ardemis Boghossian, from the Institute of Chemical Sciences and Engineering (ISIC), EPFL, whose team worked on this ground-breaking research, the team’s study found that instead of putting energy into the system to process organic waste, “we are producing electricity while processing organic waste at the same time – hitting two birds with one stone!”
The team tested the modified E coli on wastewater from a local brewery in Lausanne and found that while the hitherto known electric microbes could not survive the process, the modified, bioengineered E. coli did.