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An experimental study on reduction of U (VI) by anaerobic bacteria, Shewanella putrefaciens, is first reported here in China. The experimental conditions were: 35℃ and pH = 7.0—7.4, corresponding to a physicochemical environments in which the sandstone-hosted in- terlayer oxidation-zone type uranium deposit formed in Northwest China’s Xinjiang. Bacteria adopted in the present experiment, Shewanella putrefaciens, occur extensively in natural envi- ronment. Our study shows that nano-crystal precipitates of uraninite quickly occurred on the surface of the cells within one week. It was found that the pitchblende was characterized by a random arrangement of uraninite nanocrystals (2—4 nm) in it, significantly different from natural pitchblende in which uraninite nanocrystals are arranged in order. Finally, a possible mechanism of uranium biomineralization by microorganisms in the deposits is discussed. Our investigation may supply a technical train of thoughts for bioremediation of nuclear-contaminated water envi- ronments and for underground dissolving extraction of the sandstone-hosted uranium ores.
An experimental study on reduction of U (VI) by anaerobic bacteria, Shewanella putrefaciens, is first reported here in in. The experimental conditions were: 35 ° C and pH = 7.0-7.4, corresponding to a physicochemical environments in which the sandstone-hosted in - terlayer oxidation-zone type uranium deposit formed in Northwest China’s Xinjiang. Bacteria adopted in the present experiment, Shewanella putrefaciens, occur extensively in natural envi- ronment. Our study shows that nano-crystal precipitates of uran quickly complete on the surface of the cells Within one week. It was found that the pitchblende was characterized by a random arrangement of uranium nanocrystals (2-4 nm) in it, significantly different from natural pitchblend in which uraninite nanocrystals are arranged in order. Finally, a possible mechanism of uranium biomineralization by microorganisms in the deposits is discussed. Our investigation may supply a technical train of thoughts for bioremed iation of nuclear-contaminated water envi- ronments and for underground dissolving extraction of the sandstone-hosted uranium ores.