Radioactive yttrium isotopes (⁹⁰Y and ⁹¹Y) are produced during nuclear fission and are found in nuclear power plant waste effluents. Consequently, research exploring microbial interactions with yttrium has focused on immobilization of soluble yttrium via biosorption, bioaccumulation, and bioprecipitation.

Accumulation of ⁹⁰Y by bacteria (Schmidt and Dobberstein, 1957) and ⁹¹Y by bacteria and protozoa (Morgan, 1961) has been demonstrated. Alcaligenes eutrophus biofilms in flat membrane bioreactors were shown to precipitate yttrium and other metals as insoluble carbonates (Van Roy et al, 1997). Pseudomonas fluorescens grown with yttrium-complexed citrate as a sole carbon source accumulated yttrium intracellularly in a phosphate-deficient medium (Appanna and Huang, 1992a), and deposited the metal in an insoluble extracellular phosphate complex when grown in a phosphate-rich medium (Appanna and Huang, 1992b). The majority of accumulated yttrium in P. fluorescens appeared to be associated with the outer membrane (Appanna et al, 2001).

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Appana VD, Huang J. Microbial precipitation of yttrium. Microbios. 1992;72:129-36.

Morgan GB. The absorbtion of radioisotopes by certain microorganisms. Quart J Fla Acad Sci. 1961;24:94-100.

Van Roy S, Peys K, Dresselaers T, Diels L. The use of an Alcaligenes eutrophus biofilm in a membrane bioreactor for heavy metal recovery. Res Microbiol. 1997;148:526-528.