Springer Online Journal Archives 1860-2000
Energy, Environment Protection, Nuclear Power Engineering
Abstract Chelating agents produced by microorganisms enhance the dissolution of iron and increase its mobility and bioavailability. Since there are some similarities in the biological behavior of ferric, thorium and uranuyl ions, microorganisms resistant to thorium and uranium and capable of growing in their presence may produce sequestering agents for these metals in a manner similar to those produced for iron. Such complexation would increase the mobility and bioavailability of thorium and uranium in the environment.Pseudomonas aeruginosa species are resistant to certain heavy metals and have also been found in thorium, uranium and plutonium contaminated areas. In the present work, the ability ofP. aeruginosa to elaborate sequestering agents in medium containing thorium or uranium salts was tested. Addition of 10, 100, and 1,000 ppm of uranium or thorium to culture medium increased the lag period of the organism as the concentration of the metal increased. At concentrations of 1,000 ppm and higher, there was an extended lag period followed by reduction in growth. Uranium has a stronger inhibitory effect on growth of the organism than thorium at similar concentrations. Analyses of the culture media have shown, that relative to the control and under the experimental conditions used, the microorganisms have produced several new chelating agents for thorium and uranium. Some of the bacterially produced compounds resemble, but are not identical to the known iron chelating siderophores isolated from microorganisms, and some of their chemical properties are discussed in this report.
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