Bacteria dance the electric slide, officially named electrokinesis by the USC geobiologists who discovered the phenomenon.
Their study, published online today in PNAS Early Edition, describes what appears to be an entirely new bacterial behavior.
The metal-metabolizing Shewanella oneidensis microbe does not just cling to metal in its environment, as previously thought. Instead, it harvests electrochemical energy obtained upon contact with the metal and swims furiously for a few minutes before landing again.
Electrokinesis is more than a curiosity. Laboratory director and co-author Kenneth Nealson, the Wrigley Professor of Geobiology at USC and discoverer of Shewanella, hopes to boost the power of microbe-based fuel cells enough to produce usable energy.
The discovery of electrokinesis does not achieve that goal directly, but it should help researchers to better tune the complex living engines of microbial fuel cells.
"To optimize the bacteria is far more complicated than to optimize the fuel cell," Nealson said.
Electrokinesis was discovered in 2007 by Nealson's graduate student Howard Harris, an undergraduate at the time.
Nealson had given Harris what seemed an ideal assignment for a double major in cinema and biophysics.
"I had asked him if he would just take some movies of these bacteria doing what they do," Nealson said.
Filming through a microscope is hardly simple, but with the help of co-author and biophysics expert Moh El-Naggar, assistant professor of physics and astronomy at USC, Harris was able to make a computer analysis of a time-lapse sequence of bacteria near metal oxide particles.
"Every time the bacteria were around these particles … there was a great deal of swimming activity," Nealson recalled.
Harris then discovered that bacteria displayed the same behavior around the electrode of a battery. The swimming stopped when the electrode turned off, suggesting that the activity was electrical in origin.
As is often true with discoveries, this one raises more questions than it answers. Two in particular intrigue the researchers:
Why do the bacteria expend valuable energy swimming around?
How do the bacteria find the metal and return to it? Do they sense it through an electric field or the behavior of other bacteria?
Nealson and his team so far have only educated guesses.
For the first question, Nealson believes that the bacteria may swim away from the metal because they have too many competitors.
Bacteria get energy in two steps: by absorbing dissolved nutrients and then by converting those nutrients into biologically useful forms of energy through respiration, or the loss of electrons to an electron acceptor such as iron or manganese (humans also respire through the loss of electrons to oxygen, one of the most powerful electron acceptors).
"If electrons don't flow, it doesn't matter how much food you have," Nealson said.
However, he added, "in some environments, the food is much more precious than the electron acceptors."
If a metal surface became too crowded for bacteria to absorb nutrients easily, they might want to swim away and come back.
For the second question, Harris and co-author Mandy Ward, assistant professor of research in earth sciences at USC, are planning other experiments to understand exactly how Shewanella find electron acceptors.
They expect the experiments to keep Harris busy through his doctoral thesis.
The other co-authors on the PNAS paper were Orianna Bretschger of the J. Craig Venter Institute in San Diego, Margaret Romine of Pacific Northwest National Laboratory, and Anna Obraztsova, staff scientist in the Nealson laboratory at USC.
Carl Marziali | EurekAlert!
Fingerprint' technique spots frog populations at risk from pollution
27.03.2017 | Lancaster University
Parallel computation provides deeper insight into brain function
27.03.2017 | Okinawa Institute of Science and Technology (OIST) Graduate University
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
27.03.2017 | Earth Sciences
27.03.2017 | Life Sciences
27.03.2017 | Life Sciences