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MICROBIAL SEQUESTRATION OF LEAD AND OTHER HEAVY METALS
Citation:
DAVIS-HOOVER, W. J., S. A. ABDRASHITOVA, R. DEVEREUX, M. A. LLYUSHCHENKO, AND D. FELDHAKE. MICROBIAL SEQUESTRATION OF LEAD AND OTHER HEAVY METALS. Presented at 15th Annual AEHS Meeting West Coast Conference on Soils, Sediment & Water, San Diego, CA, March 14 - 17, 2005.
Impact/Purpose:
to present information
Description:
Human activity resulting in heavy metal contamination is a worldwide concern. Lead is a potent neurotoxin that can cause heart problems, kidney damage, and mental retardation. Mercury causes toxicity based on its form and route of exposure. Effects range from allergic reactions to internal organ and neurological damage to death. Bacteria can concentrate or bioaccumulate heavy metals, biotransform metals to less toxic forms, and can be used to bioremediate contaminated sediments. Pseudomonas aeruginosa CHL-004 is a lead resistant environmental isolate which concentrates lead from liquid and solid media. Generally, bacteria accumulate heavy metals by sorption to exopolymers or other cell components, or bacteria transport heavy metals and bioaccumulate them intracellularly. CHL-004 is unusual; it sequesters lead intracellularly as a lead-phosphorus complex within discrete inclusion bodies. The heavy metal resistance capabilities of CHL-004 are being investigated using classical microbiology and molecular biology techniques. The culture is being screened for the presence of homologs of previously described heavy metal resistance genes using PCR primers targeting czc genes (cadmium, zinc, and cobalt resistance), ars genes (arsenic and antimony), and the merA gene (mercuric reductase). The transport and accumulation of lead by CHL-004 is also being investigated to determine the mechanisms of lead resistance, transport and intracellular storage. These methods will also be used to examine the heavy metal resistance and mercury volatilization ability of several strains isolated from contaminated sediments in Pavlodar, Kazakhstan. Mercury contamination at this location is widespread, occurring within a chloralkali plant, at nearby off-site waste storage, in evaporation ponds, and in Balkyldak Lake. The Irtysh River, a major river in Kazakhstan and a drinking water source, is threatened by a plume of mercury-contaminated groundwater. These strains are adapted to cold temperatures and could be useful for in situ bioremediation at this site and other sites where temperatures are low.