Discovery of Fundidesulfovibrio terrae: A Carbon-Recycling Bacterium with Unique Electrical Abilities

Researchers have identified a new soil bacterium, Fundidesulfovibrio terrae, capable of recycling carbon dioxide and producing valuable chemicals using electricity. This bacterium exhibits an unusual ability to both export and absorb electrical energy while converting carbon dioxide into acetate, an organic compound important for industry.

This discovery reveals a previously unknown microbial strategy that could support future carbon-neutral technologies and sustainable chemical production.

Bidirectional Electron Transfer Unveiled

The research team isolated F. terrae from paddy soil. They found it can perform bidirectional extracellular electron transfer, meaning it can move electrons both out of and into its cells. While most organisms generate energy through internal chemical reactions, some microbes have developed the ability to electrically interact with their environment, exchanging electrons with solid materials like minerals or electrodes.

This adaptation aids their survival in oxygen-limited environments and influences global biogeochemical cycles.

Laboratory experiments demonstrated that F. terrae can directly transfer electrons to iron minerals, reducing iron compounds without requiring chemical mediators. The bacterium achieved a reduction efficiency exceeding 60 percent. Electrochemical measurements further confirmed its ability to both donate and accept electrons from electrodes, forming stable biofilms for continuous electrical interaction.

Electrifying Carbon Fixation

One significant finding was the bacterium's capacity to use electricity for carbon fixation. When supplied with electrons from an electrode and carbon dioxide as the sole carbon source, F. terrae converted carbon dioxide into acetate. This occurred via the Wood-Ljungdahl pathway, an efficient microbial carbon fixation mechanism.

The system produced acetate concentrations over 11 millimolar, showing effective conversion of electrical energy into organic products.

The Molecular Mechanism

Genomic and biochemical analyses indicated that specialized c-type cytochromes are crucial for this electrical communication, acting as molecular conduits for electron transport across cell membranes. The bacterium also appears to utilize conductive pili structures, functioning like microscopic wires for efficient electron flow between cells and external surfaces.

Broader Ecological and Industrial Implications

This discovery expands the understanding of sulfate-reducing bacteria, known for their roles in sulfur cycling, corrosion, and environmental remediation. The newly identified bidirectional electron transfer mechanism suggests these bacteria may have broader roles in ecosystems and bioelectrochemical systems than previously recognized.

The findings have significant implications for sustainable energy applications. Microbial electrosynthesis systems, which use microbes to convert electricity and carbon dioxide into fuels or chemicals, are gaining interest for reducing greenhouse gas emissions.

F. terrae offers a potential new biological resource for developing environmentally friendly manufacturing technologies.

Further studies are needed to optimize electrosynthesis performance and understand the organisms' function in various environments. However, this discovery highlights the potential of electroactive microorganisms for connecting renewable energy with carbon recycling.