Exploring the Potential of Cupriavidus metallidurans and Ochrobactrum anthropi for 241Am Bioaccumulation in Aqueous Solution

This study explores, for the first time, the bioaccumulation of americium-241 (241Am) by Cupriavidus metallidurans and Ochrobactrum anthropi, two bacterial strains previously investigated mainly for their interactions with other heavy metals and radionuclides. To the best of our knowledge, no prior studies have reported the use of these microorganisms for 241Am removal from aqueous solutions. The effects of initial 241Am concentration and solution pH on removal performance were evaluated through batch experiments. Kinetic analyses were performed using pseudo-first-order (PFO) and pseudo-second-order (PSO) models, with the PSO model providing a better fit, suggesting chemisorption as the rate-limiting step in the process. Initial 241Am concentrations ranged from 75 to 300 Bq mL−1, and both bacterial strains demonstrated comparable maximum bioaccumulation capacities of approximately 1.5 × 10−8 mmol g−1. However, O. anthropi exhibited superior resistance to 241Am, maintaining colony growth at activity levels up to 1200 Bq mL−1, compared to a threshold of 400 Bq mL−1 for C. metallidurans. These findings highlight the robustness and efficiency of these bacterial strains—particularly O. anthropic—in removing 241Am from liquid radioactive waste, offering promising implications for bioremediation technologies.