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Project ID: PA721

Title: Enrichment, biochemical, and molecular techniques for assessing microbial arsenic reduction

Focus Categories: Non Point Pollution, Groundwater

Keywords: arsenic, bacteria, enrichment culture, biochemical probes, molecular probes, arsenate reductase

Start Date: 09/01/2001

End Date: 08/31/2003

Federal Funds: $109,048

Non-Federal Matching Funds: $109,048

Congressional District: 14

Principal Investigators:
John F. Stolz
Professor, Duquesne University

Partha Basu
Assistant Professor, Duquesne University


Arsenic is a naturally occurring element that in elevated concentrations can cause skin lesions, cancer (e.g., bladder, kidney, lung and skin), diabetes, and cardiovascular disease. It has also been shown to act as an endocrine disruptor, affecting the glucocorticoid receptor. Arsenicosis is a global problem that is primarily caused by the consumption of arsenic-contaminated groundwater. The recent USGS NAWQA survey has identified several regions in the United States that are at risk including areas in the northeast, midwest, and southwest. Pennsylvania has its share of "hotspots" that contain ppm (micrograms/gram) concentrations of arsenic. With the recent adoption of the 0.01 mg/L standard for arsenic in drinking water by the U.S. Environmental Protection Agency, it has been estimated that some 3000 municipalities in the U.S. have drinking water that exceeds this level. In addition, 30% of Superfund sites have indicated arsenic as a "contaminant of concern". Although there are many sources of arsenic (i.e., geothermal, anthropogenic) the most common cause of elevated arsenic levels in ground water is arsenic release from iron oxide. Iron-reducing bacteria have been implicated in the release of arsenic from the Ganges Delta in Bangladesh. The reduction and mobilization of arsenic adsorbed to ferric or aluminum hydroxides by an iron- and arsenate-respiring bacterium (i.e., Sulfurospirillum barnesii) have recently been demonstrated. Thus, bacteria that grow by using arsenate as a terminal electron acceptor may play a crucial role in the transformation and mobilization of arsenic in groundwater. It has become imperative, therefore, that effective methods be developed for the identification of these organisms in the environment. The purpose of this proposal is to improve enrichment culture methods and develop biochemical and molecular techniques for the identification of arsenate-respiring bacteria in order to assess microbial arsenic mobilization. Specific studies proposed include 1) formulation of enrichment media for culturing freshwater arsenate-respiring bacteria from arsenic-contaminated NAWQA sites in Pennsylvania, and 2) design and development of biochemical and molecular probes for the detection of Gram positive arsenate-respiring bacteria. The results will provide an effective means for the detection of arsenate-respiring bacteria in natural environments and further our understanding of microbial mobilization of arsenic and its effect on water quality.

Progress/Completion Report PDF

U.S. Department of the Interior, U.S. Geological Survey
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Last Updated: Thursday June 24, 2004 3:18 PM
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