Accumulation of radiocesium by fungi; Implication for radiocesium circulation in forest

Guido-Garcia, F.; Kimura, Tatsuki*; Sakamoto, Fuminori  ; Kozai, Naofumi   ; David, K.*; Grambow, B.*; Haruma, Toshikatsu  ; Yamaji, Keiko*

Mushrooms (fungi) accumulate radiocesium from soil and believed to control Cs circulation in forest. To elucidate mechanism of fungi-involving radiocesium circulation in forest, we investigated dissolution of mineral by a fungus mycelia (Phlebiopsis gigantean) and local concentration ratios of cesium to potassium, Cs/K, in fruit body of Lentinula edodes (shiitake). The tested fungus has higher ability than a siderophore-producing bacterium to dissolve minerals. Most of the Fe dissolved from minerals were found to be not stable complexes with organic substances. Cs/K values were almost constant in same fruit body specimen of shiitake, revealing that cesium is stored in proportion to potassium at any locations of a shiitake fruit body and there is no specific binding site for cesium in shiitake.