The electrically conductive bacteria are a secret for small batteries, great medical advances

The electrically conductive bacteria are a secret for small batteries, great medical advances

An atomic model for the microbial nanowires that conduct electricity is in the foreground, while two bacteria are seen in the electron micrograph in the background, surrounded by nanowires. Credit: Edward H. Egelman

Scientists have made a surprising discovery about how strange bacteria that live in soil and sediments can conduct electricity. Researchers determined that bacteria do so through an unprecedented biological structure never seen in nature, a structure that scientists can co-opt to miniaturize electronics, create powerful but small batteries, build wireless pacemakers and develop a large amount of other medical devices. advances.

Scientists believed that Geobacter sulfurreducens conducts electricity through common, hair-like appendages called pili. Instead, a researcher at the University of Virginia School of Medicine and his collaborators have determined that bacteria transmit electricity through immaculately ordered fibers, made from a completely different protein. These proteins surround a core of metal-containing molecules, such as an electrical wire that contains metallic wires. This "nanowire", however, is 100,000 times smaller than the width of a human hair.

Researchers believe that this small but neat structure could be tremendously useful for everything from taking advantage of the power of bioenergy to eliminating pollution and creating biological sensors. Actually it could serve as the bridge between electronics and living cells.

"There are all kinds of implanted medical devices that are connected to the tissue, such as pacemakers with wires, and this could lead to applications where you have miniature devices that are actually connected by these protein filaments," said Edward H. Egelman, Ph. UVA. RE. "Now we can imagine the miniaturization of many electronic devices generated by bacteria, which is quite surprising."

Small but effective

Geobacter bacteria play an important role in the soil, which includes facilitating the exchange of minerals and even cleaning up radioactive waste. They survive in environments without oxygen, and use nanowires to get rid of excess electrons in what can be considered their equivalent to breathing. These nanowires have fascinated scientists, but it is only now that researchers at UVA, Yale and the University of California, Irvine, have been able to determine how G. sulfurreducens uses these organic cables to transmit electricity.

"The technology [to understand nanowires] it did not exist until about five years ago, when advances in cryoelectron microscopy allowed a high resolution, "said Egelman, from the Department of Biochemistry and Molecular Genetics at UVA. We have one of these instruments here in the UVA, and, therefore, the ability to really understand the structure of these filaments at the atomic level. … So this is just one of the many mysteries that we have now been able to solve using this technology, like the virus that can survive in boiling acid, and there will be others. "

Bacterial nanowire mystery solved

The nanowires are projected from bacteria to facilitate the transfer of electrons. Credit: Yale University

He noted that by understanding the natural world, even at the smallest scales, scientists and manufacturers can get many valuable ideas and useful ideas. "An example that comes to mind is spider silk, which is made of proteins like these nanowires, but is stronger than steel," he said. "Through billions of years of evolution, nature has developed materials that have extraordinary qualities, and we want to take advantage of that."

The researchers have published their findings in the scientific journal. Cell. The authors of the study were Fengbin Wang, Yangqi Gu, J. Patrick O & # 39; Brien, Sophia M. Yi, Sibel Ebru Yalcin, Vishok Srikanth, Shen Cong, Dennis Vu, Nicole L. Ing, Allon I. Hochbaum, Egelman and Nikhil S. Malvankar.

Biological cables carry electricity thanks to special amino acids.

More information:
Fengbin Wang et al, Structure of microbial nanowires reveals stacked hemes that carry electrons over micrometers, Cell (2019). DOI: 10.1016 / j.cell.2019.03.029

Journal information:

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The electrically conductive bacteria are a secret for small batteries, the great medical advances (2019, April 4)
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