Highlights

Horizontal Gene Transfer (HGT)

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News - 2008
News - Pre 2008

News - 2009

• 10/22/09 - Protein Sequences Help Scientists Decipher Uranium Bioremediation Processes. Native microbes in subsurface environments interact with contaminants, play a role in modifying contaminant mobility in the subsurface environment and can be used as part of biology-based remediation strategies. A multi-disciplinary, multi-institution team of investigators working at a field research site in Rifle, CO (a former uranium mill tailings site managed by the DOE Office of Legacy Management) characterized the genomes of the dominant microbial populations and the proteins they expressed (proteomics), demonstrating that an understanding of cell metabolism can be used to diagnose the status of subsurface microbial communities involved in uranium bioremediation and as monitors of environmental processes in general. Changes in microbial central metabolism, energy generation and microbial strain composition over time reflected the changing geochemical conditions stimulated in situ during the field test. The results yielded important insights into the functioning of subsurface microbial communities, providing mechanistic information that can used to inform models of uranium bioremediation. This “proteogenomic” approach enables scientists to study the mechanistic basis for the growth and functioning of active microbes and microbial communities in the environment. Reference: Appl. Environ. Microbiol., 2009, 75(20): 6591-6599.
• 10/02/09 - Visualizing Microbial Activity in the Subsurface. The transport of metal and radionuclide contaminants in groundwater can be greatly influenced by microbial activity. Geophysical methods provide a way to detect microbial activity across larger spatial scales in subsurface environments than can be accomplished by point source drilling-intensive techniques. Detection of in situ microbial activity is important for developing realistic conceptual models of contaminant fate and transport at DOE sites. Results obtained from researchers at Lawrence Berkeley National Laboratory, Pacific Northwest National Laboratory and the University of California at Berkeley working at a field test site in Rifle, CO show that geophysics techniques can detect geochemical changes attributable to specific microbial activities in the subsurface across large spatial areas at field sites. These techniques provide a more spatially resolved assessment of microbial activity in the subsurface and can be used to inform conceptual and quantitative models of contaminant transport in the subsurface. Reference: Environ. Sci. Technol., 2009, 43(17): 6717-6723
• 8/21/09 - Common mineral alters fate of mercury in contaminated sediments. Mercury (Hg) contamination in the environment is of significant concern due to its toxicity. DOE’s Oak Ridge site recognizes mercury contamination as one of its most challenging environmental remediation problems. In particular, ionic mercury (Hg[II]) can be transformed by anaerobic bacteria in anoxic soils and sediments to methylmercury (MeHg), a potent neurotoxin. MeHg accumulates in ecological food chains and can be readily detected in fish tissues in contaminated streams and rivers. Reducing the levels of Hg(II) in contaminated soils decreases the potential for forming MeHg. Researchers at Rutgers University and Pacific Northwest National Laboratory show that Hg(II) can be reduced to elemental Hg(0) by magnetite, a mineral commonly found in anoxic sediments. The results demonstrate a potentially important mechanism of Hg(II) reduction needed to better understand the fate of Hg in contaminated environments and improve predictions of MeHg production in anoxic sediments. Reference: Environ. Sci. Technol., 2009, 43(14): 5307-5313.
• 7/29/09 - Six ERSP-funded Research Articles Published in July 15th Edition of ES&T. Subsurface contamination stemming from post Cold War Era uranium processing remains as one of DOE’s most problematic remediation challenges. The Environmental Remediation Sciences Program (ERSP) funds basic interdisciplinary research on the fate and transport of priority metal and radionuclide contaminants in the subsurface at DOE sites. Six separate ERSP-funded research articles appear the latest edition of the journal Environmental Science & Technology. The journal is an authoritative source of environmental process science read by a broad range of environmental researchers and professionals. The articles discuss a range of findings including new mechanisms of mercury reduction, uranium sorption to nanosized iron minerals, mobility of nanosized zerovalent iron, a new uranium immobilization technique and computer simulations of biomass development, mineral transformation and changes in local hydrology and geochemistry during field tests of in situ uranium bioremediation. The combined findings advance the mission of the ERSP to understand the coupled physical, chemical and biological processes impacting the mobility of priority contaminants at DOE sites so that decision-making for environmental remediation and long term stewardship can be informed by science-based information. Reference: Environ. Sci. Technol., 2009, 43(14):5161-5550.
• 7/27/09 - DOE Funded Researchers Win R&D 100 Award for design of GeoChip. A team of investigators led by Jizhong Zhou of the University of Oklahoma has been selected to receive an R&D 100 Award for development of the GeoChip, a tool for screening functional characteristics of complex microbial communities in the environment. The GeoChip is microarray of DNA probes that allows detection of over 10,000 genes involved in functional traits including metal reduction, stress tolerance, nutrient acquisition, and degradation of carbon compounds by wide range of microbes. Joint funding for development of the GeoChip was provided by the Genomics:GTL and Environmental Remediation Sciences Programs.
• 7/10/09 - Clay Minerals Affect Technetium (⁹⁹Tc) Mobility in the Environment. ⁹⁹Tc is a major risk driver at DOE sites due to its long half life, high solubility and potential for possible uptake into the foodchain as a phosphate analog. Researchers at Miami University-Ohio, Pacific Northwest National Laboratory and Argonne National Laboratory have found that ferrous iron, produced by metal reducing bacteria, within clay minerals, can readily reduce ⁹⁹Tc to an insoluble form thereby removing it from solution. Once reduced much of the immobilized ⁹⁹Tc remains physically protected from potential oxidants, that would otherwise remobilize the contaminant, inside clay particle aggregates. ⁹⁹Tc is a product of nuclear reactions and is found in the subsurface at some DOE sites due to inadvertent disposal of wastes stemming from Cold War era production of nuclear weapons. Clay minerals are common components of soils and sediments. The results indicate that bioreduced clay minerals could naturally play an important role in reducing ⁹⁹Tc mobility at key biologically active interfaces in soils and sediments in the environment or within bioremediation strategies aimed at limiting ⁹⁹Tc transport in groundwater at contaminated sites.
  Reference: Chemical Geology, 2009, 264:127-138.
• 5/5/09 - Outstanding Student Paper Award. Illenia Battiato from the University of California-San Diego received an Outstanding Student Paper Award from the American Geophysical Union (AGU) for her work on “Mixing induced precipitation phenomena: Range of applicability of macroscopic equations”. The award is associated with the Hydrology section of AGU and was presented at the Fall 2008 Meeting in San Francisco. Illenia’s research is affiliated with a SciDAC project led by PNNL in association with UCSD collaborators. Reference: EOS 2009, 90(18):159.
• 4/17/09 - PNNL Scientist Chosen as the Henry Darcy Distinguished Lecturer. Each year an outstanding ground water professional is chosen by a panel of scientists and engineers as the National Ground Water Research and Education Foundation’s (NGWREF) Darcy Lecturer to share his or her work with their peers and students at Universities throughout the country and internationally. The 2010 honoree, the 24th and the first from a DOE Laboratory, is Dr. Timothy Scheibe, a staff scientist in the Hydrology Technical Group at Pacific Northwest National Laboratory. Scheibe has made major contributions to the field of groundwater modeling. His multidisciplinary and integrative approaches to computational modeling have brought new insights into the scaling of geochemical processes affecting contaminant transport and innovative methods to couple genome-based mechanistic understanding of biological processes with traditional groundwater modeling codes.

• 4/6/09 - LBNL Earth Scientist Named Geological Society Distinguished Lecturer. Dr. Susan Hubbard, a staff scientist in the Earth Sciences Division at Lawrence Berkeley National Laboratory, has been chosen to serve as the 2010 Geological Society of America's (GSA) Birdsall-Dreiss Lecturer. The endowed lectureship is made to one person annually by the GSA Hydrogeology Division based on two criteria. The nominee must be (1) a renowned scientist whose publication record and research have had national and international impact in the field of hydrogeology and (2) an outstanding speaker. Hubbard is the 32nd GSA Birdsall-Dreiss Lecturer, and the first from a DOE national laboratory. Hubbard has made major contributions to the field of Hydrogeophysics through her research which is sponsored by DOE’s Office of Biological and Environmental Research.

• 3/4/09 - Genomics Improves Contaminant Transport Simulations. Microbes profoundly affect the mobility of contaminants in the environment but current transport models over-simplify predictions of microbial activity in situ. DOE-funded researchers at Pacific Northwest National Lab and the Universities of Toronto and Massachusetts have coupled a genome-scale metabolic model of a uranium-reducing microorganism, Geobacter sulfurreducens, to the reactive transport code HYDROGEOCHEM to better predict the in situ bioremediation of uranium at the Rifle, CO test site. This enabled the researchers to integrate field tests and laboratory investigations and to demonstrate important advances between current empirical methods of simulating microbial activity and the new genome-scale metabolic modeling approach. The new, genome-based approach better predicts the coupled physical, chemical, and biological processes influencing the mobility of contaminants in the environment. The approach can be extended to other natural environments and other microbes or microbial communities. It also demonstrates the importance of studying environmentally relevant microbes to describe important microbially-mediated processes in the environment.
  Reference: Microbial Biotechnology., 2009, 2(2): 274-286.

• 1/12/09 - Organic Carbon Supply Influences Uranium Bioremediation. Addition of organic carbon compounds to uranium-contaminated environments stimulates the activity of microorganisms resulting in the removal of uranium from groundwater. Researchers at LBNL have shown that competing biogeochemical reactions driven by the rate of organic carbon supply strongly influence uranium mobility during biostimulation and must be carefully optimized to ensure the sustainability of the remediation technique. At low organic carbon supply rates, desorption of uranium from sediments increases soluble uranium concentrations while higher rates stimulate conditions necessary for removal of soluble uranium via microbial bioreduction in laboratory column experiments. Further increases in organic carbon supply rate lead to formation of uranium-carbonate complexes that may drive uranium reoxidation thereby increasing soluble uranium concentrations. The results illustrate that uranium bioremediation processes are more complicated than previously thought and organic carbon supply rates will need to be optimized to balance several competing biogeochemical processes to ensure uranium immobilization over long time frames.
  Reference: Environ. Sci. Technol., 2008, 42(23): 8901-8907.