Microbes Harvest Electrons: The Novel Process Discovered

Since scientists have discovered that certain microbes can draw their energy from electrical charges, researchers have wondered how they do it. Microbes Harvest Electrons

Bacteria have no mouth, so they need another way to get their fuel into their bodies. New research from Washington University in St. Louis shows how such a bacterium attracts electrons directly from an electrode source. The work from Arpita Bose's laboratory, assistant professor of biology in the arts and sciences, was published on 5 November in the journal mBio. Harvest Electrons

"The molecular basis of this process was hard to decipher until our work," Bose said. "This is mainly due to the complexity of the proteins involved in this process, so we now know for the first time how phototrophic microbes can capture electrons from solid and soluble substances." Harvest Electrons

Dinesh Gupta, a doctoral student in the Bose lab, is the first author of this new study. "I was excited to discover that these phototrophic bacteria use a new processing step to regulate the production of key electron transfer proteins involved in this process," said Gupta. "This study will help develop a bacterial platform where bacteria can access electricity and carbon dioxide to create value-added compounds such as biofuels." Microbes Harvest Electrons

The main task is to direct the current through the outer layer of the bacteria. This barrier is both non-conductive and impermeable to insoluble iron minerals and / or electrodes. Microbes Harvest Electrons

Bose and her co-workers, including Robert Kranz, a professor of biology, showed that the naturally occurring strain Rhodopseudomonas palustris TIE-1 forms a conduit for the uptake of electrons across the outer membrane. The bacterium relies on an iron-containing helper molecule called Deca-heme cytochrome c. By processing this protein, TIE-1 can form an essential bridge to its electron source.

Extracellular electron uptake (EEU) can help microbes survive under nutrient-poor conditions. Microbes Harvest Electrons

After documenting these mechanisms behind EEU, Bose hopes to use them as a biological marker for the identification of other strom-eating bacteria in the wild. The results will help researchers to understand the importance of this functionality for metabolic and microbial ecology.
Microbes Harvest Electrons

Journal Reference
Dinesh Gupta, Molly C. Sutherland, Karthikeyan Rengasamy, J. Mark Meacham, Robert G. Kranz, Arpita Bose. Photoferrotrophs Produce a PioAB Electron Conduit for Extracellular Electron Uptake. mBio, 2019; 10 (6) DOI: 10.1128/mBio.02668-19

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