Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Imaging electric charge propagating along microbial nanowires


The claim by UMass Amherst researchers that the microbe Geobacter produces tiny electrical wires has been mired in controversy for a decade, but a new collaborative study provides stronger evidence than ever to support their claims.

The claim by microbiologist Derek Lovley and colleagues at the University of Massachusetts Amherst that the microbe Geobacter produces tiny electrical wires, called microbial nanowires, has been mired in controversy for a decade, but the researchers say a new collaborative study provides stronger evidence than ever to support their claims.

UMass Amherst researchers recently provided stronger evidence than ever before to support their claim that the microbe Geobacter produces tiny electrical wires, called microbial nanowires, along which electric charges propagate just as they do in carbon nanotubes, a highly conductive man-made material.

Credit: UMass Amherst

UMass Amherst physicists working with Lovley and colleagues report in the current issue of Nature Nanotechnology that they've used a new imaging technique, electrostatic force microscopy (EFM), to resolve the biological debate with evidence from physics, showing that electric charges do indeed propagate along microbial nanowires just as they do in carbon nanotubes, a highly conductive man-made material.

Physicists Nikhil Malvankar and Sibel Ebru Yalcin, with physics professor Mark Tuominen, confirmed the discovery using EFM, a technique that can show how electrons move through materials. "When we injected electrons at one spot in the microbial nanowires, the whole filament lit up as the electrons propagated through the nanowire," says Malvankar.

Yalcin, now at Pacific Northwest National Lab, adds, "This is the same response that you would see in a carbon nanotube or other highly conductive synthetic nanofilaments. Even the charge densities are comparable. This is the first time that EFM has been applied to biological proteins. It offers many new opportunities in biology."

Lovley says the ability of electric current to flow through microbial nanowires has important environmental and practical implications. "Microbial species electrically communicate through these wires, sharing energy in important processes such as the conversion of wastes to methane gas. The nanowires permit Geobacter to live on iron and other metals in the soil, significantly changing soil chemistry and playing an important role in environmental cleanup. Microbial nanowires are also key components in the ability of Geobacter to produce electricity, a novel capability that is being adapted to engineer microbial sensors and biological computing devices."

He acknowledges that there has been substantial skepticism that Geobacter's nanowires, which are protein filaments, could conduct electrons like a wire, a phenomenon known as metallic-like conductivity. "Skepticism is good in science, it makes you work harder to evaluate whether what you are proposing is correct," Lovley points out. "It's always easier to understand something if you can see it. Drs. Malvankar and Yalcin came up with a way to visualize charge propagation along the nanowires that is so elegant even a biologist like me can easily grasp the mechanism."

Biologists have known for years that in biological materials, electrons typically move by hopping along discrete biochemical stepping-stones that can hold the individual electrons. By contrast, electrons in microbial nanowires are delocalized, not associated with just one molecule. This is known as metallic-like conductivity because the electrons are conducted in a manner similar to a copper wire.

Malvankar, who provided the first evidence for the metallic-like conductivity of the microbial nanowires in Lovley and Tuominen's labs in 2011, says, "Metallic-like conductivity of the microbial nanowires seemed clear from how it changed with different temperature or pH, but there were still many doubters, especially among biologists."

To add more support to their hypothesis, Lovley's lab genetically altered the structure of the nanowires, removing the aromatic amino acids that provide the delocalized electrons necessary for metallic-like conductivity, winning over more skeptics. But EFM provides the final, key evidence, Malvankar says.

"Our imaging shows that charges flow along the microbial nanowires even though they are proteins, still in their native state attached to the cells. Seeing is believing. To be able to visualize the charge propagation in the nanowires at a molecular level is very satisfying. I expect this technique to have an especially important future impact on the many areas where physics and biology intersect." he adds.

Tuominen says, "This discovery not only puts forward an important new principle in biology but also in materials science. Natural amino acids, when arranged correctly, can propagate charges similar to molecular conductors such as carbon nanotubes. It opens exciting opportunities for protein-based nanoelectronics that was not possible before."

Lovley and colleagues' microbial nanowires are a potential "green" electronics component, made from renewable, non-toxic materials. They also represent a new part in the growing field of synthetic biology, he says. "Now that we understand better how the nanowires work, and have demonstrated that they can be genetically manipulated, engineering 'electric microbes' for a diversity of applications seems possible."

One application currently being developed is making Geobacter into electronic sensors to detect environmental contaminants. Another is Geobacter-based microbiological computers. This work was supported by the Office of Naval Research, the U.S. Department of Energy and the National Science Foundation.

Janet Lathrop | Eurek Alert!
Further information:

More articles from Life Sciences:

nachricht Novel mechanisms of action discovered for the skin cancer medication Imiquimod
21.10.2016 | Technische Universität München

nachricht Second research flight into zero gravity
21.10.2016 | Universität Zürich

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>