Kinetics of Indirect UO2 Oxidation by Mn(II)-Oxidizing Bacillus Spores

Chinni, S., Anderson, C., Ulrich, K.U., Veeramani, H., Sharp, J.O., Giammar, D.E., Bernier-Latmani, R. and Tebo, B.M. (2008) Kinetics of Indirect UO2 Oxidation by Mn(II)-Oxidizing Bacillus Spores. In: Goldschmidt 2008, Vancouver, Canada, 13-18 July 2008, A158.

Abstract

Reductive immobilization of U(VI) as U(IV)O2 has been widely explored as a feasible approach for remediating uranium contaminated sites. Many soil bacteria, including Bacillus sp., oxidize Mn(II) to Mn(IV) oxides which, in turn, chemically oxidize UO2 to U(VI), there by mobilizing uranium. We are investigating UO2 oxidation coupled to bacterially-catalyzed Mn(II) oxidation in order to better understand the environmental constraints controlling the stability of UO2 and the kinetics of UO2 oxidation. We have conducted experiments using spores of the Bacillus sp. strain SG-1 to investigate changes in the oxidation rate of synthetic and biogenic UO2 with varying concentrations of synthetic and biogenic MnO2, In addition, we also measured the changes in O2 uptake and the key parameters of the MichaelisMenten kinetics (Km and Vmax) associated with bacterial Mn(II) oxidation as concentrations of synthetic and biogenic UO2 varied. Biogenic MnO2 produced by Bacillus sp. SG-1 oxidized biogenic UO2 up to four times faster than synthetic UO2 and more effectively than synthetic MnO2. The rates of enzymatic Mn(II) oxidation as a function of Mn(II) concentration conformed to the Michaelis-Menten kinetics; rates of Mn(II) oxidation in the presence of different concentrations of U(IV) indicated a competitive type of inhibition where the Vmax values were unaffected by UO2 concentration, but the Km values increased with increasing UO2. This inhibition does not appear to be directly related to the properties of UO2 itself but rather to the formation of soluble UO2 2+ which inhibits the enzymatic Mn(II) oxidation.

• Item Type: Conference Proceedings
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Veeramani, Dr Harish
• Authors: Chinni, S., Anderson, C., Ulrich, K.U., Veeramani, H., Sharp, J.O., Giammar, D.E., Bernier-Latmani, R., and Tebo, B.M.
• College/School: College of Science and Engineering > School of Engineering > Infrastructure and Environment

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