Yale Scientists Discover That Light Accelerates Conductivity in Nature’s “Electric Grid”

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Bacteria Producing Nanowires Made Up of Cytochrome OmcS

Bacteria producing nanowires made up of cytochrome OmcS. Credit: Ella Maru Studio

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There is a global web of tiny bacteria-generated nanowires in the soil and oceans that “breathe” by exhaling excess electrons, composing an intrinsic electrical grid for the natural world.

In a new research study, <span class="glossaryLink" aria-describedby="tt" data-cmtooltip="

Yale University
Established in 1701, Yale University is a private Ivy League research university in New Haven, Connecticut. It is the third-oldest institution of higher education in the United States and is organized into fourteen constituent schools: the original undergraduate college, the Yale Graduate School of Arts and Sciences and twelve professional schools. It is named after British East India Company governor Elihu Yale.

” data-gt-translate-attributes=”[{"attribute":"data-cmtooltip", "format":"html"}]”>Yale University scientists found that light is a surprising ally in fostering this electronic activity within biofilm bacteria. They discovered that exposing bacteria-produced nanowires to light yielded an up to a 100-fold increase in electrical conductivity.

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The findings will be published today (September 7, 2022) in the journal <span class="glossaryLink" aria-describedby="tt" data-cmtooltip="

Nature Communications
Nature Communications is a peer-reviewed, open access, multidisciplinary, scientific journal published by Nature Research. It covers the natural sciences, including physics, biology, chemistry, medicine, and earth sciences. It began publishing in 2010 and has editorial offices in London, Berlin, New York City, and Shanghai.&nbsp;

” data-gt-translate-attributes=”[{"attribute":"data-cmtooltip", "format":"html"}]”>Nature Communications.

“The dramatic current increases in nanowires exposed to light show a stable and robust photocurrent that persists for hours,” said senior author Nikhil Malvankar, associate professor of Molecular Biophysics and Biochemistry (MBB) at Yale’s Microbial Sciences Institute on Yale’s West Campus.

The results could provide new insights as researchers pursue ways to exploit this hidden electrical current for a variety of purposes. For example, it could be used to help eliminate biohazard waste or create new renewable fuel sources.

Almost all living things breathe oxygen to eliminate excess electrons when converting nutrients into energy. However, soil bacteria living deep under oceans or buried underground do not have access to oxygen. Over billions of years, they have developed a way to respire by “breathing minerals,” like snorkeling, through tiny protein filaments called nanowires.

When these bacteria were exposed to light, the increase in electrical current surprised scientists because most of the bacteria tested live deep in the soil, far from the reach of light. Previous studies had shown that nanowire-producing bacteria grew faster when exposed to light.

 “Nobody knew how this happens,” Malvankar said.

In the new study, a Yale University team led by postdoctoral researcher Jens Neu and graduate student Catharine Shipps concluded that a metal-containing protein known as cytochrome OmcS — which makes up bacterial nanowires — acts as a natural photoconductor: the nanowires greatly facilitate electron transfer when biofilms are exposed to light.

“It is a completely different form of <span class="glossaryLink" aria-describedby="tt" data-cmtooltip="

photosynthesis
Photosynthesis is how plants and some microorganisms use sunlight to synthesize carbohydrates from carbon dioxide and water.

” data-gt-translate-attributes=”[{"attribute":"data-cmtooltip", "format":"html"}]”>photosynthesis,” Malvankar said. “Here, light is accelerating breathing by bacteria due to rapid electron transfer between nanowires.”

Malvankar’s lab is exploring how this insight into bacterial electrical conductivity could be used to spur growth in optoelectronics. This is a subfield of photonics that studies devices and systems that find and control light. They would like to use this technology to capture methane, a greenhouse gas known to be a significant contributor to global climate change.

Reference: 7 September 2022, Nature Communications.
DOI: 10.1038/s41467-022-32659-5

Other authors of the paper are Matthew Guberman-Pfeffer, Cong Shen, Vishok Srikanth, Sibel Ebru Yalcin from the Malvankar Lab at Yale; Jacob Spies, Professor Gary Brudvig, and Professor Victor Batista from the Yale Department of Chemistry; and Nathan Kirchhofer from Oxford Instruments.

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