Batteries or Bacteria?

Illustration by Lily Xu

Illustration by Lily Xu

Imagine winding slimy tubes intertwined amongst each other, brown chewed up blobs of food and juices so acidic they have the ability to burn skin.  Although this inhospitable environment sounds repulsive to many, it is home to millions of bacterial cells. These gut bacterial cells play a vital role in the human body’s maintenance of health and defense against invaders. Out of these million, a select few have valuable and fascinating methods of electricity generation. Researchers at the University of California, Berkeley have recently found a bacterium located in the gut called Listeria Monocytogenes that possesses the ability to produce energy efficiently as a part of its simple metabolic processes. Due to our large dependence on fossil fuels and other sources of non-renewable energy that are both limited in supply and negatively impact the environment, it is imperative that we start utilizing and searching for methods of energy-generation that are not only sustainable and environmentally friendly, but efficient and relatively easy to harness.

Recent research focusing on Listeria Monocytogene bacteria, also known for its role in causing diarrhea, has pinpointed the specific process the bacterium uses to metabolize. Compared to other methods used to harness bioenergy and create fuel from bacteria, the process undergone by the Listeria Monocytogene bacteria involves a relatively inelaborate electron transfer chain. While humans generate fuel and generate electricity through ATP synthesis with the help of oxygen exhalation and nutrient intake, the metabolic processes of Listeria Monocytogenes are vastly different. When electrons are produced through the process of metabolism, these electrons need to be removed. Oxygen typically acts as a useful electron acceptor, but since oxygen is not abundantly present in the gut, bacteria must find another source for electron removal. Minerals such as iron and manganese are found in the gut and can also act as ideal electron acceptors for gut bacteria. The chain of chemical reactions induced from the transfer of electrons out of the cell and to a mineral is referred to as the extracellular electron transfer chain. This series of chemical reactions creates an electric current as electrons are passed from one reaction to another.

Although the process of electricity generation through gut bacteria happens on a microscopic scale, the applications of these bacteria to the realm of renewable energy production are infinite. Current methods of bioenergy generation using microbial fuel cells to turn organic matter into energy are important approaches, but they are often inefficient and costly because they require large amounts of organic matter, expensive equipment, and high waiting times for the energy to be generated.The electron transfer chain used by Listeria Monocytogenes is a much more straightforward process that easily be manipulated to produce measurable energy on a large scale. A microbial battery created by Berkeley researchers  by using a small sample of electrogenic Listeria Monocytogenes  was able to generate up to 500 microamps of energy. When applied to a large scale production of energy, the electric current generated by similar bacteria batteries could have the ability to generate quantities of power similar to that created by solar or wind energy. As our population and dependence on technology grows it is imperative that we allow renewable sources to produce the majority of our energy. The discovery of the electrogenic capabilities of bacteria will play a major role in these efforts because this bacteria is available to us in such abundant quantities and the mechanisms by which the bacteria produces energy are easy to harness for mass energy production.

As the search continues for new sources of power for our energy driven world, bacteria have the potential to play a large role in the sustainable production of electricity. More and more types of electrogenic bacteria are being discovered and their abundance is integral to the large-scale production of energy that will fuel the lives of future generations.

Edited by: Anhthi Luong

Illustrated by: Lily Xu

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