Characterization of Cesium Uptake Mediated by a Potassium Transport System of Bacteria in a Soil Conditioner

We found that bacteria in a commercial soil conditioner sold in Ishinomaki, Miyagi, exhibited concentrative and saturable cesium ion (Cs+) uptake in the natural range of pH and temperature. The concentration of intracellular Cs+ could be condensed at least a few times higher compared with the outside medium of the cells. This uptake appeared to be mediated by a K+ transport system, since Cs+ uptake was dose-dependently inhibited by potassium ion (K+). Eadie-Hofstee plot analysis indicated that the Cs+ uptake involved a single saturable process. The maximum uptake amount (J(max)) was the same in the presence and absence of K+, suggesting that Cs+ and K+ uptakes were competitive with respect to each other. These bacteria might be useful for bioremediation of cesium-contaminated soil.