Grantee Research Project Results
2000 Progress Report: The Biochemistry and Molecular Biology of Microbial Selenate and Arsenate Transformation
EPA Grant Number: R826105Title: The Biochemistry and Molecular Biology of Microbial Selenate and Arsenate Transformation
Investigators: Stolz, John F.
Institution: Duquesne University , United States Geological Survey
Current Institution: Duquesne University
EPA Project Officer: Hahn, Intaek
Project Period: October 1, 1997 through September 30, 2000
Project Period Covered by this Report: October 1, 1999 through September 30, 2000
Project Amount: $273,119
RFA: Exploratory Research - Environmental Biology (1997) RFA Text | Recipients Lists
Research Category: Biology/Life Sciences , Aquatic Ecosystems
Objective:
The mobilization of toxic elements and heavy metals in the environment can be strongly influenced by microbial activity. Sulfurospirillum barnesii, has the ability to couple the oxidation of organic matter to the reduction of selenate and arsenate, compounds which have become significant environmental toxins. The hypothesis to be tested is that S. barnesii has separate pathways for arsenate and selenate reduction but that the selenate reductase is a less substrate-specific enzyme, capable of reducing a wide range of substrates. The objective of this proposal is to purify and characterize (Km, Vmax, substrate specificity, absorption spectrum, mid-point potential) the two reductases and associated cytochromes, and develop biochemical and molecular probes based on the selenate reductase that can be used to detect S. barnesii in nature. The probes also will be used to determine the relatedness of these reductases from other bacterial species.Progress Summary:
We are near completion of the characterization of the dissimilatory arsenate reductase (DAsR). The complex represents a unique enzyme system that includes a hydrogenase. It was therefore necessary to take several additional approaches to its purification. We now have the methodology to routinely purify active DAsR. Work also continues on the purification of the dissimilatory selenate reductase, however, we are not as far along as initially anticipated. The same methods developed for the DAsR are being used to purify the DSeR.We have also continued work on the characterization of new strains of arsenate- and selenate- respiring bacteria. The selenate-respirer isolated from the Dead Sea was found to be a member of the halobacteriales (Gram negative, salt-loving, eubacteria). This group is comprised of salt-loving fermentative anaerobes. However, we have identified cytochromes in the cells when they are grown on either nitrate or selenate. A manuscript describing and naming this organism (Selenohalobacter shriftii) has been submitted. We also are continuing to characterize the freshwater Bacillus isolated from the Ohio River. The student working on this will defend her master's thesis this October. We also now have a Gram positive bacterium from Ohio River sediments that grows rapidly on 20 mM arsenate. Work is underway to characterize this organism.
Future Activities:
We anticipate completion of the characterization of the dissimilatory arsenate reductase, testing of the antibodies, and preliminary characterization of the dissimilatory selenate reductase during the no-cost extension.Journal Articles on this Report : 3 Displayed | Download in RIS Format
| Other project views: | All 12 publications | 8 publications in selected types | All 5 journal articles |
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Blum JS, Stolz JF, Oren A, Oremland RS. Selenihalanaerobacter shriftii gen. nov., sp nov., a halophilic anaerobe from Dead Sea sediments that respires selenate. Archives of Microbiology 2001;175(3):208-219. |
R826105 (2000) R826105 (Final) |
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Oremland RS, Blum JS, Bindi AB, Dowdle PR, Herbel M, Stolz JF. Simultaneous reduction of nitrate and selenate by cell suspensions of Selenium-respiring bacteria. Applied Environmental Microbiology 1999;65(10):4385-4392. |
R826105 (1999) R826105 (2000) R826105 (Final) |
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Stolz JF, Oremland RS. Bacterial respiration of arsenic and selenium. FEMS Microbiology Reviews, Volume 23, Issue 5, October 1999, Pages 615-627. |
R826105 (1999) R826105 (2000) R826105 (Final) |
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Supplemental Keywords:
heavy metals, ecology, soil, water, enzymes, indicators, bioremediation., Scientific Discipline, Waste, Ecosystem Protection/Environmental Exposure & Risk, Environmental Microbiology, Fate & Transport, Biochemistry, Bioremediation, Ecological Risk Assessment, Molecular Biology/Genetics, microbiology, microbial selenate, fate and transport, aerobic degradation, biodegradation, arsenate compounds, oligonucleotide probes, biotechnology, reductases, sulfurospirillum barnesii, oligobacteria, heavy metalsRelevant Websites:
http://www.home.cc.duq.edu/~stolz/Research.html
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.