Evaluation of Europium Biosorption Using Deinococcus radiodurans

The efficacy of a biosorption-based approach using living cells of Deinococcus radiodurans for recovery of Eu3+ from aquatic systems has been investigated. The effects of four variables including pH, culture media constituents, inoculum age and initial Eu3+ concentration were evaluated. Among five different media compositions tested, the combination of tryptone, glucose, yeast extract (TGY), cystine and NaCl showed highest removal of Eu3+ by the Deinococcus species. Similarly, maximum biosorption of Eu3+ was achieved at pH 6. Further, at the optimized condition of pH 6 and inoculum age of 45 h with TGY + cystine+NaCl culture media, 81% of Eu+3 was removed within 3 h at an initial Eu+3 concentration of 150 mg L-1. The appearance of EuPO4 peak in the XRD analysis of the D. radiodurans culture further indicated that biosorption of Eu(3+)occurred onto the PO4 functional group of the microbial cell wall. The high Eu+3 biosorption efficiency by D. radiodurans may constitute an effective and eco-friendly alternative strategy to recover Eu+3 from contaminated environment.