Laser Spectroscopic Studies of Interactions of U VI with Bacterial Phosphate Species

We have investigated the interactions of U VI with two bacterial phosphate‐containing species: Gram‐positive Bacillus sphaericus and Gram‐negative Psedomonas aeruginosa. The Gram‐positive B. sphaericus was investigated by using Raman spectroscopy and time‐resolved laser‐induced fluorescence spectroscopy (TRLFS). We found that living cells, spores, and intact heat‐killed cells complexed U VI (pH 4.5) through phosphate groups bound to their surfaces, while decomposed cells released H 2 PO 4 − and precipitated U VI as UO 2 (H 2 PO 4 ) 2 . TRLFS of U VI showed that Gram‐negative P. aeruginosa —genetically engineered to accumulate polyphosphate, subsequently degrade it, and secrete phosphate—precipitated U VI quantitatively at pH 4.5. The same bacterial strain, not induced to secrete phosphate, sorbed only a small amount of U VI . The use of a genetically engineered Gram‐negative bacterium , which accumulates polyphosphate, degrades it, and secretes phosphate, may be a promising method for bioremediation of actinides in aqueous media. It was found to precipitate U VI quantitatively at pH 4.5. The same bacterial strain, not induced to secrete phosphate, sorbed only a small amount of U VI . These results were compared to the interactions of U VI with a Gram‐positive phosphate‐containing bacterium.