The microbial reduction of U（VI） by Bacillus sp. dwc-2, isolated from soil in Southwest China, was explored using transmission electron microscopy （TEIVI）, X-ray photoelectron spectros- copy （XPS） and X-ray abso...The microbial reduction of U（VI） by Bacillus sp. dwc-2, isolated from soil in Southwest China, was explored using transmission electron microscopy （TEIVI）, X-ray photoelectron spectros- copy （XPS） and X-ray absorption near edge spectroscopy （XANES）. Our studies indicated that approximately 16.0% of U（VI） at an initial concentration of 100 mg/L uranium nitrate could be reduced by Bacillus sp. dwc-2 at pH 8.2 under anaerobic conditions at room temperature. Additionally, natural organic matter （NOM） played an important role in enhancing the bioreduction of U（VI） by Bacillus sp. dwc-2. XPS results demonstrated that the uranium presented mixed valence states （U（VI） and U（IV）） after bioreduction, which was subse- quently confirmed by XANES. Furthermore, the TEM and high resolution transmission electron microscopy （HRTEM） analysis suggested that the reduced uranium was bioaccumulated mainly within the cell and as a crystalline structure on the cell wa11. These observations implied that the reduction of uranium may have a significant effect on its fate in the soil environment in which these bacterial strains occur.展开更多
基金supported by the National Natural Science Foundation(Nos.21071102,91126013)Joint Funds of National Natural Science Foundation and China Academy of Engineering Physics(NSAF,No.U1330125)+1 种基金the National High Technology Research and Development Program(863)of China(No.2012AA063503)the National Fund of China for Fostering Talents in Basic Science(No.J1210004)
文摘The microbial reduction of U（VI） by Bacillus sp. dwc-2, isolated from soil in Southwest China, was explored using transmission electron microscopy （TEIVI）, X-ray photoelectron spectros- copy （XPS） and X-ray absorption near edge spectroscopy （XANES）. Our studies indicated that approximately 16.0% of U（VI） at an initial concentration of 100 mg/L uranium nitrate could be reduced by Bacillus sp. dwc-2 at pH 8.2 under anaerobic conditions at room temperature. Additionally, natural organic matter （NOM） played an important role in enhancing the bioreduction of U（VI） by Bacillus sp. dwc-2. XPS results demonstrated that the uranium presented mixed valence states （U（VI） and U（IV）） after bioreduction, which was subse- quently confirmed by XANES. Furthermore, the TEM and high resolution transmission electron microscopy （HRTEM） analysis suggested that the reduced uranium was bioaccumulated mainly within the cell and as a crystalline structure on the cell wa11. These observations implied that the reduction of uranium may have a significant effect on its fate in the soil environment in which these bacterial strains occur.
