2005 Volume 6 Issue 1 Pages 107-110
Cs accumulation by Pseudomonas fluorescens was examined under conditions of growth and resting to elucidate the interaction between Cs and bacteria. In the growth condition, P. fluorescens was cultured in citric acid media containing 50 μM CsCl and 0, 0.1, 1.0, and 10 mM K for 64 h at 30°C. Adsorption and Aeorption behaviors of Cs were examined by the contact of the cells with 50 μM CsCl solution under the resting condition. Cs-accumulated P. fluorescens was exposed to a 1 CH3COONH4 solution to examine the reversibility of Cs accumulation. In the growth condition, P. fluorescens did not accumulate Cs irrespective of the presence of K. In the resting condition, the cells quickly adsorbed approximately 5 μmol Cs/gcell dry-weight and subsequently released approximately 90% of the adsorbed Cs with 1 M CH3COONH4. The amount of Cs adsorption by cells of P. fluorescens varied with changing pH and ionic strength of the solution. These results indicate that Cs accumulation by P. fluorescens occurs mainly by reversible adsorption on the cell walls, but not by intracellular accumulation under nutrient conditions.