This award is to support a collaborative project between Dr. John Stolz, Department of Biological Sciences, Duquesne University, Pittsburgh, Pennsylvania and Dr. Samy El-Aassar and Dr. Mahmoud Berekaa, both of the Department of Biology, Alexandria University, Alexandria, Egypt. The objective of this proposal is to assess microbial reduction of arsenic and selenium oxyanions in sediments from the Nile Delta from the Mediterranean to Beni-Suef in Upper Egypt. It will involve sediment enrichments using different electron donors and either arsenate or selenate as electron acceptors. Oxyanions of arsenic and selenium can be used in microbial anaerobic respiration as terminal electron acceptors, and therefore, isolation of such anaerobic bacteria will be sought. Different pristine and contaminated soils (including those impacted by industrial wastes) will be used as sources for enrichment of selenate and arsenate respiring bacteria. The development of biochemical (antibodies raised against specific subunits of the terminal reductase) and molecular probes (designed from the major conserved regions of the genes encoding the major subunit of reductase) for arsenate and selenate respiring bacteria will provide diagnostic tools for use in assessing the role of bacteria in the mobilization of selenate and arsenate in the natural environments.
Scope: Arsenic and selenium have become increasingly significant as environmental toxins in agricultural soils and drinking water. Their transformation (e.g., reduction and oxidation) and mobilization can be strongly influenced by microbial activities. The reduction of arsenate and selenate-respiring bacteria in numerous pristine and contaminated environments and their rapid appearance in enrichment culture suggest that these organisms are widespread in nature. This project is being supported under the US-Egypt Joint Fund Program, which provides grants to scientists and engineers in both countries to carry out these cooperative activities.
