Biosorption behavior and mechanism of thorium on Streptomyces sporoverrucosus dwc-3

To understand the impact of microorganisms on the fate of thorium in soils, we have investigated the thorium biosorption behavior and mechanism on the living and dead cells of Streptomyces sporoverrucosus dwc-3, isolated from soils in China. The living cells need more time (24 h) to reach equilibrium than dead cells (24 h). The biosorption is greatly dependent on pH and ionic strength for the two kinds of cells. SEM and TEM indicate that thorium initially bind with the cell surface which is probably controlled by ion-exchange, evidence by PIXE, and inner-sphere complexation mechanism and then accumulated in the cytoplasm.