Electricity is everywhere, even in your body. Cells, such as neurons, use electrical currents to control your movement, perception, and thought. Unlike copper wires that conduct electricity over a long distance, electrical transport in living organisms are limited to the micrometer scale, making exact measurements of those cellular currents hard to acquire. Metal electrodes are typically implanted adjacent to the cells to guide the electricity to external machines. One such example is brain-machine interfaces, which read neuron activity through electronic implants. However, a recent report from University of Antwerp on conductive cable bacteria might introduce a completely new interface between living organisms and electronics.

Cable bacteria are micro-organisms in the seafloor that form centimeter-long chains made of thousands of cells in a row. Previous studies have found that cable bacterial cells are connected internally by a network of parallel fibers that are continuous across cell-cell junctions. In this work, researchers extracted the fibers, attached them to tiny metal electrodes and measured their conductivity. Their findings showed that these fibers are able to conduct nanoampere currents over 1 centimeter (or 2000 adjacent cells), which is about 1000 times longer than the typical scale of electrical transport in other living organisms. Essentially, these bacteria use their own version of wires to conduct electricity throughout their entire assemblage.

This work introduced a new concept of ‘biological cables’ that can efficiently guides electrical currents over long distances, and operates in a way comparable to the copper wires. However, we still don’t know how the bacteria assemble thousands of cells in a row, and precisely control the orientation of the internal fibers. If we could one day manipulate these bacterial cells to grow in a specific design, shape, or pattern, the bacterial cables can potentially replace the less efficient and imprecise implantable electronics and enable new bio-electronic applications.

Managing Correspondent: Anqi Zhang

Original journal article: A highly conductive fibre network enables centimetre-scale electron transport in multicellular cable bacteria. Nature Communications.

Image Credit: UAntwerp

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