Uranium accumulation by a bacterium isolated from electroplating effluent

Pseudomonas MGF-48, a gram-negative, motile, oxidase-negative, catalase-positive, yellow-pigmented bacterium isolated from electroplating effluent, was found to accumulate uranium with high efficiency. Uptake of uranium was rapid and the amount increased in direct proportion to concentration, e.g., from 50 to 200 mg uranium per liter. The largest amount of uranium uptake was 174 mg per gram dry weight bacterial biomass and was observed to occur in stationary phase during incubation at 30 °C. Uptake was determined by flow injection analysis. Maximum uranium accumulation occurred at pH 6.5, with 86% of the uranium being taken up within 5 min of incubation. Release of uranium bound to the cells was accomplished by addition of sodium carbonate and EDTA solution (0.1 M), the cells were reusable, and served as a biosorbent. Cells immobilized in polyacrylamide gel took up 90% of the uranium. Pseudomonas MGF-48 showed excellent efficiency in biosorbing uranium, by both immobilized and free cells. The results of this study, compared with those of other reports of uranium accumulation by microorganisms, leads us to conclude that Pseudomonas MGF-48 shows excellent potential for bioremediating uranium-polluted aqueous effluents. This revised version was published online in July 2006 with corrections to the Cover Date.