Plutonium occurs naturally on Earth in trace amounts, but tons of plutonium have been produced in nuclear reactors and the U. S. Department of Energy has plutonium storage sites in seventeen states across the U.S.A. Plutonium emits alpha, beta, gamma, and neutron radiation and isotopes have half-lives as long as 2 x 104 years. Consequently, plutonium is considered to be a potential carcinogen and mutagen (ToxFAQS: Plutonium). Plutonium has no known biological function, and research investigating microbial interactions with plutonium has focused on bioremediation of waste sites and environments contaminated with plutonium.

Plutonium can exist in oxidation states from III to VI under aqueous conditions, and different oxidation states predominate in different environments (Ibrahim and Culp, 1989). Dissimilatory plutonium reduction has not been documented, but Rusin et al (1994) reported the solubilization of plutonium oxides from soil by iron-reducing bacteria, which may represent reductive dissolution of plutonium. Yong and Macaskie (1998) demonstrated the potential for a Citrobacter sp. expressing surface phosphatase activity to mineralize Pu(IV) in an insoluble complex with lanthanum and phosphate. Microbacterium flavescens JG-9 was shown to accumulate Pu(IV) via siderophore-mediated uptake (John et al, 2001). Aspergillus niger grown on a solid medium containing plutonium transported plutonium from the medium to aerial spores (Beckert and Au, 1976). Immobilization of soluble plutonium using bacteria as biosorbents has been explored (Meyer et al, 1979; Panak et al, 2001).

For more information:

Search Medline for plutonium metabolism AND bacteria

Beckert WF, Au FHF. Plutonium uptake by a soil fungus and transport to its spores. Transuranium Nuclides in the Environment, Proc. Symp. 1976;337-45.

Yong P, Macaskie LE. bioaccumulation of lanthanum, uranium and thorium, and use of a model system to develop a method for the biologically-mediated removal of plutonium from solution. J. Chem. Technol. Biotechnol. 1998;71:15-26.

Panak PJ, Nitsche H. Interaction of aerobic soil bacteria with plutonium(VI). Radiochim. Act. 2001;89:499-504.

Rusin PA, Quintana L, Brainard JR, Strietelmeier BA, Tiat CD, Ekberg SA, Palmer PD, Newton TW, Clark DL. Solubilization of plutonium hydrous oxide by iron-reducing bacteria. Environ. Sci. Technol. 1994;28:1686-90.


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