Kinetics of U(VI) reduction by a dissimilatory Fe(III)-reducing bacterium under non-growth conditions

• Published in: Biotechnology and bioengineering 1997-08, Vol.55 (3), p.490-496
• Main Authors: Truex, Michael J., Peyton, Brent M., Valentine, Nancy B., Gorby, Yuri A.
• Format: Article
• Language: English
• Subjects: Bacteriology; Biological and medical sciences; Biology of microorganisms of confirmed or potential industrial interest; Biotechnology; Fundamental and applied biological sciences. Psychology; kinetics; Metabolism. Enzymes; metal reduction; Microbiology; Mission oriented research; Physiology and metabolism; precipitation; Shewanella; uranium
• ISSN: 0006-3592; 1097-0290
• DOI: 10.1002/(SICI)1097-0290(19970805)55:3<490::AID-BIT4>3.0.CO;2-7

Dissimilatory metal‐reducing microorganisms may be useful in processes designed for selective removal of uranium from aqueous streams. These bacteria can use U(VI) as an electron acceptor and thereby reduce soluble U(VI) to insoluble U(IV). While significant research has been devoted to demonstrating and describing the mechanism of dissimilatory metal reduction, the reaction kinetics necessary to apply this for remediation processes have not been adequately defined. In this study, pure culture Shewanella alga strain BrY reduced U(VI) under non‐growth conditions in the presence of excess lactate as the electron donor. Initial U(VI) concentrations ranged from 13 to 1680 μM. A maximum specific U(VI) reduction rate of 2.37 μmole‐U(VI)/(mg‐biomass h) and Monod half‐saturation coefficient of 132 μM‐U(VI) were calculated from measured U(VI) reduction rates. U(VI) reduction activity was sustained at 60% of this rate for at least 80 h. The initial presence of oxygen at a concentration equal to atmospheric saturation at 22°C delays but does not prevent U(VI) reduction. The rate of U(VI) reduction by BrY is comparable or better than rates reported for other metal reducing species. BrY reduces U(VI) at a rate that is 30% of its Fe(III) reduction rate. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 490–496, 1997.