Behavior of U(VI) in a simple prey (Yeast) - predator (Paramecium) food chain

Kozai, Naofumi   ; Onuki, Toshihiko; Koka, Masashi; Sato, Takahiro; Kamiya, Tomihiro; Esaka, Fumitaka  

To reveal the role of protozoa in migration of radionuclides in the environment, this study investigated behavior of U(VI) during culture of Paramecium sp. (P. bursaria) in media containing yeast on which U was sorbed. Paramecium was chosen as model protozoa because it is the most well known unicellular protozoa. After the contact of yeast cells with a U (VI) solution, U phosphates formed on yeast cells. P. bursaria cells were cultured with those yeast cells in an inorganic salt solution containing no phosphate. Only 3% of the presorbed U was dissolved from yeast cells into the liquid phases during the culture of Paramecium. As culture time advances, membranous precipitates formed. These membranous precipitates contained undigested and digested yeast cells and dense membranous organic substance filling gaps between those cells. In the membranous precipitates many particles of U phosphates which size and morphology are similar to those observed in the yeast cells were observed. These results suggest that the U immobilization effect of yeast cells was preserved in the prey-predator system