Electricity-eating microbes use electrons and fix carbon dioxide to grow

electricity eating bacteria
A Washington University team showed how a phototrophic microbe called Rhodopseudomonas palustris takes up electrons from conductive substances like metal oxides or rust to reduce carbon dioxide. Credit: Bose laboratory, Washington University

We have often seen our metal products catching rust and we usually apply some grease over it in order to prevent the rust over it. According to the study carried out by the researchers at the Washington University in St. Louis, it explains that there are certain bacteria’s which eat the electricity and transfer electrons to fix carbon dioxide to fuel its growth.

The research was lead by Prof. Arpita Bose, assistant professor of biology in Arts & Sciences, and Michael Guzman, a PhD candidate in her laboratory. The team showed how a naturally occurring strain of Rhodopseudomonas palustris takes up electrons from conductive substances like metal oxides or rust.

This is a continuation of the previous research carried by Bose, which states that R. palustris TIE-1 can consume electrons from rust proxies like poised electrodes, a process called extracellular electron uptake. R. palustris being phototrophic, it uses energy from light to carry out certain metabolic processes.

The new research explains the cellular sinks where this microbe dumps the electrons it eats from electricity. “It clearly shows for the first time how this activity—the ability for the organism to eat electricity—is connected to carbon dioxide fixation,” said Bose.

physiology of R palustris bacteria
Overview of the physiology of R. palustris.( Credit: Nature journal)

This special ability clearly shows the microbe’s natural ability for sustainable energy storage or other bioenergy applications which have caught the attention of the Department of Energy and Department of Defense.

Explaining the origins of the bacteria Bose says “R. palustris strains can be found in wild and exotic places like a rusty bridge in Woods Hole, Massachusetts where TIE-1 was isolated from. You can find these organisms everywhere. This suggests that extracellular electron uptake might be very common.

Co-researcher Guzzam adds “The main challenge is that it’s an anaerobe, so you need to grow it in an environment that doesn’t have oxygen in order for it to harvest light energy. But the flip side to that is that those challenges are met with a lot of versatility in this organism that a lot of other organisms don’t have.”

The researchers in their newspaper showed that the electrons from electricity enter into proteins in the membrane that are important for photosynthesis. Surprisingly, when they deleted the microbe’s ability to fix carbon dioxide, they observed a 90 percent reduction in its ability to consume electricity which means that it really want to fix carbon. This process is similar to the recharging of the battery.

Bose adds “The microbe uses electricity to charge its redox pool, storing up the electrons and making it highly reduced. To discharge it, the cell reduces carbon dioxide. The energy for all this comes from sunlight. The whole process keeps repeating itself, allowing the cell to make biomolecules with nothing more than electricity, carbon dioxide and sunlight. We hope that this ability to combine electricity and light to reduce carbon dioxide might be used to help find sustainable solutions to the energy crisis.

The new research answers basic science questions and provides plenty of opportunity for future bioenergy applications.

Published Researchhttps://www.nature.com/articles/s41467-019-09377-6


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