Featured Research

from universities, journals, and other organizations

Mechanism of novel biological electron transfer revealed

Date:
March 19, 2013
Source:
University of Massachusetts at Amherst
Summary:
When researchers discovered that the bacterium Geobacter sulfurreducens conducts electricity very effectively along metallic-like “microbial nanowires,” they found physicists quite comfortable with the idea of such a novel biological electron transfer mechanism, but not biologists.

The bacterium Geobacter sulfurreducens conducts electricity very effectively along metallic-like pili dubbed "microbial nanowires" by discoverers at UMass Amherst. They recently determined the impact of this conductivity on the biology of the bacterium, confirming an assumption in their earlier work that real metallic-like conductivity is taking place.
Credit: UMass Amherst

When researchers at the University of Massachusetts Amherst led by microbiologist Derek Lovley discovered that the bacterium Geobacter sulfurreducens conducts electricity very effectively along metallic-like "microbial nanowires," they found physicists quite comfortable with the idea of such a novel biological electron transfer mechanism, but not biologists.

"For biologists, Geobacter's behavior represents a paradigm shift. It goes against all that we are taught about biological electron transfer, which usually involves electrons hopping from one molecule to another," Lovley says. "So it wasn't enough for us to demonstrate that the microbial nanowires are conductive and to show with physics the conduction mechanism, we had to determine the impact of this conductivity on the biology."

"We have now identified key components that make these hair-like pili we call nanowires conductive and have demonstrated their importance in the biological electron transport. This time we relied more on genetics. I think most biologists are more comfortable with genetics rather than physics," Lovley adds.

"From my perspective, this is huge. It really clinches a big question. We overturned the major objection the biologists were making and confirmed the assumption in our earlier work, that real metallic-like conductivity is taking place."

Findings are described in an early online issue of mBio, the open-access journal of the American Society for Microbiology. In addition to Lovley, the UMass Amherst team includes first author Madeline Vargas, with Nikhil Malvankar, Pier-Luc Tremblay, Ching Leang, Jessica Smith, Pranav Patel, Oona Snoeyenbos-West and Kelly Nevin.

In 2011, Lovely's group discovered a fundamental, previously unknown property of pili in Geobacter. They found that electrons are transported along the pili via the same metallic-like conductivity found in synthetic organic materials used in electronics. Electrons are conducted over remarkable distances, thousands of times the cell's length. But exactly how the pili accomplished this wasn't clear.

They knew that the conductivity of synthetic conducting organic materials can be attributed to aromatic ringed structures which share electrons, suspended in a kind of a cloud that allows the overlapping electrons to easily flow. It seemed possible that amino acids, which have similar aromatic rings, might serve the same function in biological protein structures like pili. Lovley's team looked for likely aromatic amino acid targets and then substituted non-aromatic amino acids for the aromatic ones to see if this reduced the conductivity of the pili.

It worked. The re-engineered pili with non-aromatic compounds substituted for aromatic ones looked perfect and unchanged under a microscope, but now they no longer functioned as wires. "This new strain is really bad at what Geobacter does best," Lovley says. "Geobacter is known for its ability to grow on iron minerals and for generating electric current in microbial fuel cells, but without conductive pili those capabilities are greatly diminished."

"What we did is equivalent to pulling the copper out of an extension cord," he adds. "The cord looks the same, but it can't conduct electricity anymore."

The ability of protein filaments to conduct electrons in this way not only has ramifications for scientists' basic understanding of natural microbial processes but practical implications for environmental cleanup and the development of renewable energy sources as well, he adds. Lovley's UMass Amherst lab has already been working with federal agencies and industry to use Geobacter to clean up groundwater contaminated with radioactive metals or petroleum and to power electronic monitoring devices with current generated by Geobacter.

His group has also recently shown that Geobacter uses its nanowires to feed electrons to other microorganisms that can produce methane gas. This is an important step in the conversion of organic wastes to methane, which can then be burned to produce electricity.

As more states, including national leader Massachusetts, pass laws to prevent hospitals, universities, hotels and large restaurants from disposing of food waste in landfills, Geobacter's role in producing methane could be part of the solution for how to deal with this waste. The Massachusetts law goes into effect in 2014. "Waste to methane is a well developed green energy strategy in Europe and is almost certain to become more important here in Massachusetts in the near future," Lovley notes.


Story Source:

The above story is based on materials provided by University of Massachusetts at Amherst. Note: Materials may be edited for content and length.


Journal Reference:

  1. M. Vargas, N. S. Malvankar, P.-L. Tremblay, C. Leang, J. A. Smith, P. Patel, O. Synoeyenbos-West, K. P. Nevin, D. R. Lovley. Aromatic Amino Acids Required for Pili Conductivity and Long-Range Extracellular Electron Transport in Geobacter sulfurreducens. mBio, 2013; 4 (2): e00105-13 DOI: 10.1128/mBio.00105-13

Cite This Page:

University of Massachusetts at Amherst. "Mechanism of novel biological electron transfer revealed." ScienceDaily. ScienceDaily, 19 March 2013. <www.sciencedaily.com/releases/2013/03/130319124300.htm>.
University of Massachusetts at Amherst. (2013, March 19). Mechanism of novel biological electron transfer revealed. ScienceDaily. Retrieved September 2, 2014 from www.sciencedaily.com/releases/2013/03/130319124300.htm
University of Massachusetts at Amherst. "Mechanism of novel biological electron transfer revealed." ScienceDaily. www.sciencedaily.com/releases/2013/03/130319124300.htm (accessed September 2, 2014).

Share This




More Matter & Energy News

Tuesday, September 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Australian Airlines Relax Phone Ban Too

Australian Airlines Relax Phone Ban Too

Reuters - Business Video Online (Aug. 26, 2014) Qantas and Virgin say passengers can use their smartphones and tablets throughout flights after a regulator relaxed a ban on electronic devices during take-off and landing. As Hayley Platt reports the move comes as the two domestic rivals are expected to post annual net losses later this week. Video provided by Reuters
Powered by NewsLook.com
Hurricane Marie Brings Big Waves to California Coast

Hurricane Marie Brings Big Waves to California Coast

Reuters - US Online Video (Aug. 26, 2014) Huge waves generated by Hurricane Marie hit the Southern California coast. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Chinese Researchers Might Be Creating Supersonic Submarine

Chinese Researchers Might Be Creating Supersonic Submarine

Newsy (Aug. 26, 2014) Chinese researchers have expanded on Cold War-era tech and are closer to building a submarine that could reach the speed of sound. Video provided by Newsy
Powered by NewsLook.com
Breakingviews: India Coal Strained by Supreme Court Ruling

Breakingviews: India Coal Strained by Supreme Court Ruling

Reuters - Business Video Online (Aug. 26, 2014) An acute coal shortage is likely to be aggravated as India's supreme court declared government coal allocations illegal, says Breakingviews' Peter Thal Larsen. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

More Coverage


Biological Wires Carry Electricity Thanks to Special Amino Acids

Mar. 12, 2013 Slender bacterial nanowires require certain key amino acids in order to conduct electricity, according to a new ... read more
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins