The Applied Research Center (ARC) at Florida International University (FIU), in collaboration with the Pacific Northwest National Laboratory (PNNL), developed an original research manuscript that was accepted on March 14, 2012, for publication in a future issue of the international journal Chemical Geology. The manuscript was prepared by Yelena Katsenovich (FIU), Denny Carvajal (FIU-DOE Fellow), Dawn Wellman (PNNL) and Leonel Lagos (FIU), and is entitled, “Enhanced U(VI) release from autunite mineral by aerobic Arthrobacter sp. in the presence of aqueous bicarbonate.” The study provides a comprehensive explanation of the stability of autunite minerals in the oxidized conditions that exist at the Hanford Site and the environmental fate and transport of uranium in the subsurface. The research highlighted that the Arthrobacter G975, a bacterial strain previously isolated from Hanford soil, bio-enhanced the release of uranium(VI) from natural calcium-autunite in the presence of various concentrations of bicarbonate (up to 10 mM), even while not in direct contact with the mineral. This research is the first to investigate microbial dissolution of autunite in the aerobic conditions. Autunite and meta-autunite minerals are an important group of uranyl minerals that act as a sink for dissolved uranium (VI) in soils contaminated by actinides. Reported data suggests that indigenous microorganisms in subsurface environments play a major role in the mineral weathering process and can affect the mobility of heavy metals or radionuclides by dissolution and complexation reactions. This manuscript is the second publication accepted by a peer-reviewed journal to demonstrate the significance of bacteria–uranium interactions by focusing on the Arthrobacter sp. that is found in fairly large numbers in Hanford soil as well as other subsurface environments contaminated with radioactive materials. In December 2011, a paper entitled, “Assessment of the resistance to uranium (VI) exposure by Arthrobacter sp. isolated from Hanford Site soil” (Y.Katsenovich, D. Carvajal, R. Guduru, L. Lagos, C-z. Li), was accepted by the Geomicrobiology Journal. An additional publication entitled, “The effect of aqueous bicarbonate and calcium ion on uranium biosorption by G975 strain,” is being prepared for potential publication.
The main points of the newly accepted manuscript include the following:
Research collaboration between FIU and PNNL has included the involvement of 9 undergraduate and graduate FIU students (known as DOE Fellows) from the DOE-FIU Science and Technology Workforce Development Program (fellows.fiu.edu). Through this research work, the students have completed 3 master’s theses as well as initiated an additional 2 PhD theses. The DOE Fellows participate part-time during the school year with the hands-on research being performed at the Applied Research Center and intern during the summer at DOE sites, national laboratories, and DOE contractors. Specifically related to this research topic, DOE Fellow Denny Carvajal had the opportunity during the summer of 2010 to complete an internship at PNNL under the mentorship and supervision of PNNL scientists, where he performed research on the uranium toxicity to native microbial communities in the Hanford 300 Area groundwater. His final Summer Internship Technical Report can be found at http://fellows.fiu.edu/doc/Summer10Reports/Denny_Carvajal_Summer2010_Internship_Report.pdf.