The interaction of plutonium with bacteria in the repository environment

Abstract

Microorganisms in the nuclear waste repository environment may interact with plutonium through (i) sorption, (ii) intracellular accumulation, and (iii) transformation of chemical speciation. These interactions may retard or enhance the mobility of Pu by precipitation reactions, biocolloid formation, or production of more soluble species. Current and planned radioactive waste repository environments, such as deep subsurface halite and granite formations, are considered extreme relative to life processes in the near-surface terrestrial environment. There is a paucity of information on the biotransformation of radionuclides by microorganisms present in such extreme environments. In order to gain a better understanding of the interaction of plutonium with microorganisms present in the waste repository sites we investigated a pure culture (Halomonas sp.) and a mixed culture of bacteria (Haloarcula sinaiiensis, Marinobacter hydrocarbonoclasticus, Altermonas sp., and a g-proteobacterium) isolated from the Waste Isolation Pilot Plant (WIPP) site and an Acetobacterium sp. from alkaline groundwater at the Grimsel Test Site in Switzerland.