Adsorption of Th (IV) and Pu (IV) on the Surface of Pseudomonas fluorescens and Bacillus subtilis in the Presence of Desferrioxamine Siderophore

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Adsorption of Th (IV) and Pu (IV) on a Gram-negative bacterium Pseudomonas fluorescens and a Gram-positive bacterium Bacillus subtilis in the presence of siderophore desferrioxamine B (DFO) was studied. Thorium (IV) and Pu (IV) were dissociated from DFO during adsorption on the cells. Thorium (IV) adsorption on bacterial cells in the presence of DFO was larger than that of Pu (IV) because of the smaller stability of the Th (IV) -DFO complex than that of the Pu (IV) -DFO complex. On the other hand, adsorption of Pu (IV) was larger than that of Fe (III), wherein the stability of the Pu (IV) - and Fe (III) -DFO complex is comparable. P. fluorescens showed a higher affinity for Th (IV) and Pu (IV) than B, subtilis, though potentiometric titration of bacterial cells indicated that surfaces of P. fluorescens and B. subtilis cells showed similar proton binding properties.