The bacteria might one day be used to clean up toxic chemicals left over from nuclear weapons production decades ago.
Using a unique combination of microscopes, researchers at Ohio State University and their colleagues were able to glimpse how the Shewanella oneidensis bacterium breaks down metal to chemically extract oxygen.
The study, published online this week in the journal Applied and Environmental Microbiology, provides the first evidence that Shewanella maneuvers proteins within the bacterial cell into its outer membrane to contact metal directly. The proteins then bond with metal oxides, which the bacteria utilize the same way we do oxygen.
The process is called respiration, and it’s how living organisms make energy, explained Brian Lower, assistant professor in the School of Environment and Natural Resources at Ohio State. We use the oxygen we breathe to release energy from our food. But in nature, bacteria don’t always have access to oxygen.
“Whether the bacteria are buried in the soil or underwater, they can rely on metals to get the energy they need,” Lower said. “It’s an ancient form of respiration.”
“This kind of respiration is fascinating from an evolutionary standpoint, but we’re also interested in how we can use the bacteria to remediate nasty compounds such as uranium, technetium, and chromium.”
The last two are byproducts of plutonium. The United States Department of Energy is sponsoring the work in order to uncover new methods for treating waste from nuclear weapons production in the 1960s and ‘70s.
Shewanella is naturally present in the soil, and can in fact be found at nuclear waste sites such as the Hanford site in the state of Washington, Lower explained.
With better knowledge of the bacterium’s abilities, scientists might one day engineer a Shewanella that would remediate such waste more efficiently.
“For instance, if you could enhance this bacterium’s ability to reduce uranium by having it make more of these key proteins, that could perhaps be one way to clean up these sites that are contaminated,” he said.
The danger at such waste sites is that the toxic metals are soluble, and so can leak into the local water supply. But these bacteria naturally convert the metals into an insoluble form. Though the metals would remain in place, they would be stable solids instead of unstable liquids.
For this study, Lower and his colleagues used an atomic force microscope (AFM) to test how the bacterium responded to the metallic mineral hematite.
An AFM works somewhat like a miniaturized phonograph needle: a tiny tip dangles from a cantilever above a surface that’s being studied. The cantilever measures how much the tip rises and falls as it’s dragged over the surface. It can measure features smaller than a nanometer (billionth of a meter), and detect atomic forces between the probe tip and the surface material.
They combined the AFM with an optical microscope to get a precise map of the bacteria’s location on the hematite.
Though the bacteria are very small -- several hundred thousand of them could fit inside the period at the end of a sentence -- they are still thousands of times bigger than the tip of an AFM probe. So the microscope was able to slide over the surface of individual bacteria to detect protein molecules on the cell surface and in contact with the metal.
The researchers coated their probe tip with antibodies for the protein OmcA, which they suspected Shewanella would use to “breathe” the metal.
Whenever the probe slid over an OmcA protein, the antibody coating would stick to the protein. By measuring the tiny increase in force needed to pull the two apart, the researchers could tell where on the bacteria surface the proteins were located.
The microscope detected OmcA all around the edges of the bacteria, wherever the cell membrane contacted the hematite -- which suggests that the protein does indeed enable the bacteria to “breathe” hematite. The protein was even present in a gelatinous ooze that was seeping from the bacteria. This suggests that Shewanella might create the ooze in order to obtain energy from a wider portion of the metal than it can directly touch, Lower said.
In the future, he and his partners want to test their new microscope technique on other types of cells. They also want to test whether Shewanella produces OmcA on the cell surface when exposed to uranium and technetium.
Lower’s coauthors on the paper hail from Corning, Inc.; Pacific Northwest National Laboratory; Johannes Kepler University of Linz, Austria; Ecole Polytechnique Fédérale de Lausanne, Switzerland; and Umeå University, Sweden.
Contact: Brian Lower, (614) 247-1676; Lower.firstname.lastname@example.org
Pam Frost Gorder | Newswise Science News
Further reports about: > AFM > Environmental Microbiology > Metals > Microscope > Microscopes > OmcA > Oxygen > Plutonium > Shewanella oneidensis > bacteria > cell surface > chromium > key protein > living organism > metal oxides > nuclear weapons production > respiration > soil bacteria > technetium > toxic chemicals > toxic metals > uranium
Link Discovered between Immune System, Brain Structure and Memory
26.04.2017 | Universität Basel
Researchers develop eco-friendly, 4-in-1 catalyst
25.04.2017 | Brown University
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
27.04.2017 | Earth Sciences
27.04.2017 | Materials Sciences
27.04.2017 | Materials Sciences