Cesium uptake by edible mushrooms and microorganisms isolated from mushroom substrata

¹ Division of Environmental Health, Kanagawa Prefectural Public Health Laboratory, Asahi-ku, Yokohama 241-0851, Japan
² Department of Radiological Health, National Institute of Public Health, Minato-ku, Tokyo 108-8638, Japan
³ Department of Microbiology, School of Pharmaceutical Sciences, Toho University, Funabashi, Chiba 274-8510, Japan

Abstract

The concentrations of ¹³⁷Cs and stable Cs were measured in wild mushrooms, mushroom substrata and soils from Mt.Fuji in Japan. We then studied the Cs uptake by the edible mushroom, Pleurotus ostreatus, through the cultured experiments using ¹³⁷Cs and/or a stable Cs tracer. ¹³⁷Cs concentrations in the fruiting bodies were 2-4 orders of magnitude higher than those in the wild mushrooms collected in Japan. It was demonstrated that ¹³⁷Cs and Cs were actively uptaken by the mushrooms depending on the ¹³⁷Cs or Cs concentration in the medium. We subsequently investigated the Cs sensitivity of microorganisms in the mushroom substrata and Cs uptake by actinomycetes, one of the soil microorganisms in mushroom substrata. The number of both bacteria and actinomycetes in the substrata decreased with increasing Cs concentration in the medium. Actinomycetes in the mushroom substrata were more sensitive to Cs than other bacteria. In the presence of 5mM CsCl, Cs uptake by several strains of actinomyces was generally high, and the growth was partially inhibited compared with the Cs resistant strains, Streptomyces lividans TK24 and Streptomyces sp. TOHO-2.