Monday, November 13, 2006
92-7

Heavy Metal Induced Inhibition of Nitrate Reductases.

Fritz Ntoko, Zachary Senwo, Robert Taylor, and Elica Moss. Alabama A&M University, 4900 Meridian St, Normal, AL 35762

Nitrate and heavy metals commonly found in groundwater are pollutants that constitute significant risk to humans when present in food and drinking water. Nitrate reductase (NR), catalyzes the initial step of the denitrification process. The sources include animals, plants and microorganisms. We did in vitro studies to evaluate and compare the activities of nitrate reductases from plant (corn), fungi (Aspergillus niger) and bacteria (Escherichia coli) in varied concentrations of Cd2+, Cu2+, Ni2+, Co2+, Cr6+, Fe2+, Zn2+, and Pb2+. The enzymes showed varied levels of sensitivity to metals at concentrations between 1mM and 10-4 mM. Nitrate reductase from corn was very sensitive to ten-fold changes in heavy metal concentrations. Nitrate reductase from E. coli showed low sensitivity to concentrations of six metals while that from A. niger showed higher sensitivity to four metals.  

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