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As part of the ongoing shift towards a circular economy, recent research has harnessed the potential of E. coli bacteria, utilizing them to produce bioelectricity.
The E. coli, short for Escherichia coli bacterium, typically doesn't enjoy a favorable reputation due to its association with food poisoning. However, it's important to recognize that this microorganism is not just a foe; it can also be a remarkable ally in various technological developments. One of the most recent breakthroughs is its role in harnessing bioelectricity from wastewater.
Traditionally, wastewater has been primarily utilized for compost and biogas production. However, scientists at the Ecole Polytechnique Fédérale de Lausanne (EPFL) have uncovered an innovative approach for utilizing this waste stream – generating renewable electricity.
Bioelectricity refers to the remarkable ability of certain microorganisms to produce electrical signals, specifically by transferring electrons extracellularly (EET) through their metabolic processes. These unique microorganisms, known as electrogenic, have the power to harness bioelectricity. Historically, the bacterium E. coli struggled to carry out this process efficiently.
However, owing to its resilience and ubiquity in diverse environments, E. coli has become one of the most extensively employed bacteria in genetic research. Its primary role is as a host for introducing foreign DNA strands from other organisms, enabling scientists to study their behavior in protein production—a field known as metabolic engineering.
The pioneering researchers at EPFL decided to harness the versatile nature of E. coli for a different purpose. By incorporating components from a bacterium named Shewanella oneidensis MR-1, a well-established electrogenic microorganism, they achieved a breakthrough: the ability to make E. coli bacteria generate bioelectricity from the organic matter found in wastewater. The crux of their success lay in optimizing a pathway for efficient electron transfer across the inner and outer membranes of the E. coli cells.
After demonstrating the system's efficacy within the controlled confines of a laboratory, the researchers tested it using wastewater from a Lausanne-based beer brewery. Surprisingly, the other bacteria in the mix failed to survive, while the modified E. coli managed to triple the typical efficiency seen in such renewable energy systems.
This marks a significant departure from the conventional practice of utilizing electricity to treat organic matter, as the new technique enables the generation of electricity rather than its consumption. The implications are profound; wastewater treatment systems could potentially evolve into small-scale, sustainable power plants in the future.
The potential of this approach extends beyond wastewater. It holds promise for a wide array of biotechnological advancements, including microbial batteries, electrosynthesis, and biosensors. Moreover, bacteria can be fine-tuned to generate varying levels of bioelectricity depending on the specific environment and type of processed organic matter.
In previous discussions, we've explored using bacteria to generate electricity, albeit in different contexts. One notable application involves a recently introduced biological battery featuring a seven-square-meter panel that can produce up to 15 Wh/day in any garden. Here, bacteria feed on irrigation water and the organic matter in the substrate, providing a self-sustaining energy source for illuminating green spaces and powering small sensors.
Another area of interest in bioelectricity involves a new generation of solar panels. Researchers have engineered E. coli bacteria to secrete lycopene, a natural pigment facilitating photosynthesis in this experimental domain. This innovation has led to a breakthrough in biogenic photovoltaic cell production, with the primary challenge being to ensure the bacteria's survival throughout the process.
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