Based on laboratory studies, Georgia Institute of Technology researchers report promising results using bacterial species from three genera isolated from subsurface soils collected at a U.S. Department of Energy (DOE) Field Research Center site in Oak Ridge, Tenn. Researchers conducted preliminary screenings of many bacterial isolates and found several candidate strains that released inorganic phosphate after hydrolyzing an organo-phosphate source the researchers provided.
The bioremediation research project, funded for three years by DOE’s Environmental Remediation Sciences Division, is in its early stages. Research team member Melanie Beazley, a Ph.D. student in the Georgia Tech School of Earth and Atmospheric Sciences, will present preliminary findings on March 30 at the 231st American Chemical Society National Meeting in Atlanta.
"These organisms release phosphate into the medium, but the precipitation (of uranium phosphate) occurs chemically," explained Assistant Professor of Earth and Atmospheric Sciences Martial Taillefert, co-director of the study. "That is the biomineralization of uranium and the novelty of this approach."
The process begins when the bacteria – from the genera Rhanella, Bacillus and possibly Arthrobacter– degrade an organo-phosphate compound such as glycerol-3-phosphate (G3P) or phytic acid (IP6), which can be present in subsurface soils."During their growth, the organisms liberate phosphate they derive from the organo-phosphate compound," said project co-director Patricia Sobecky, an associate professor of biology. "The free phosphate is released to the surrounding media, which is a solution in the lab. Then we conduct assays to see how much uranium is mineralized by the phosphate released by the bacteria."
Sobecky and her Ph.D. student Robert Martinez are conducting the microbiological and physiological component of the research, while Taillefert and Beazley study the uranium chemistry and analyze distribution of different forms of uranium during incubation in the lab.
"The devil’s in the details with the chemistry of uranium: There are numerous forms of uranium in the environment, which are all influenced by the natural properties of soils and groundwater," Taillefert said.
Sobecky added, "What we’re doing now is optimizing the assay conditions and the techniques to analyze the distribution of uranium species in the lab."
Traditionally, DOE has funded research investigating the chemical reduction of uranium contamination. But there are two approaches to immobilizing uranium. One strategy reduces uranium (VI) to uranium (IV), which is, in principle, immobile. But the uranium can re-oxidize even with traces of oxygen from rainwater seeping into the groundwater. The Georgia Tech approach biomineralizes uranium (VI) into an insoluble form of uranium via phosphate precipitation.
As they work toward a bioremediation strategy that will work in the field, researchers must design a mechanism to deal with competing organisms in the soil that might sequester the free phosphate, Sobecky noted. Though their current grant does not cover the cost of a field study, researchers hope to obtain funds in the future to test their strategy at Oak Ridge and potentially other DOE sites. Uranium contamination is a concern at DOE sites because it can migrate to groundwater in surrounding areas, Taillefert noted.
"At this point, we know the organisms we’re studying are active in precipitating uranium phosphate," he said. "…. Now we need to determine how chemically stable it is."
Researchers also have learned that when the bacteria are releasing phosphate from G3P, the bacteria can tolerate the toxic uranium and can continue to grow once the uranium is precipitated by the released phosphate.
"Our challenge now is fine-tuning the conditions around the bacterium so eventually it can thrive and work chemically in a natural setting," Taillefert said.
Jane Sanders | EurekAlert!
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
19.07.2018 | Social Sciences
18.07.2018 | Life Sciences
18.07.2018 | Materials Sciences