Uranium reduction and microbial community development in response to stimulation with different electron donors

Abstract

Stimulating microbial reduction of soluble U(VI) to less soluble U(IV) shows promise as an in situ bioremediation strategy for uranium contaminated groundwater, but the optimal electron donors for promoting this process have yet to be identified. The purpose of this study was to better understand how the addition of various electron donors to uraniumcontaminated subsurface sediments affected U(VI) reduction and the composition of the microbial community. The simple electron donors, acetate or lactate, or the more complex donors, hydrogen-release compound (HRC) or vegetable oil, were added to the sediments incubated in flow-through columns. The composition of the microbial communities was evaluated with quantitative PCR probing specific 16S rRNA genes and functional genes, phospholipid fatty acid analysis, and clone libraries. All the electron donors promoted U(VI) removal, even though the composition of the microbial communities was different with each donor. In general, the overall biomass, rather than the specific bacterial species, was the factor most related to U(VI) removal. -Vegetable oil and HRC were more effective in stimulating U(VI) removal than acetate. These results suggest that the addition of more complex organic electron donors could be an excellent option for in situ bioremediation of uranium-contaminated groundwater.

Interaction of Uranium with Bacterial Cell Surfaces: Inferences from Phosphatase-Mediated Uranium Precipitation

“…However, under strongly alkaline conditions, negatively charged uranyl-carbonate complexes, like [UO 2 (CO 3 ) 2 ] 2Ϫ and [UO 2 (CO 3 ) 3 ] 4Ϫ , predominate (17)(18)(19). It is important to understand how these different U species interact with bacterial cellular surfaces, especially for designing biological wastewater treatment systems.…”

Uranium Bioreduction and Biomineralization

“…The extent of U(VI) reduction was found to be higher with methanol than with glucose and much higher with glucose as compared to ethanol (Madden et al, 2009). Vegetable oil and HRC were more effective in stimulating U(VI) removal than acetate (Barlett et al, 2012a).…”

“…Among them, acetate is the most common electron donor used in both laboratory and field experiments, followed by ethanol, lactate, and glucose (Francis et al, 1988;Finneran et al, 2002;Luo et al, 2007;Shelobolina et al, 2008;Barlett et al, 2012a). Other electron donors include benzoate, butyrate and butanol, and aromatic hydrocarbons such as toluene , hydrogen, formate, pyruvate, and fumarate (Finneran et al, 2002;Liu et al, 2002;Esteve-Núñez et al, 2004;Shelobolina et al, 2008;Marshall et al, 2009;Prakash et al, 2009;Junier et al, 2010).…”

“…Other electron donors include benzoate, butyrate and butanol, and aromatic hydrocarbons such as toluene , hydrogen, formate, pyruvate, and fumarate (Finneran et al, 2002;Liu et al, 2002;Esteve-Núñez et al, 2004;Shelobolina et al, 2008;Marshall et al, 2009;Prakash et al, 2009;Junier et al, 2010). Further, hydrogen release compounds (HRC), emulsified soybean oil (ESO), and emulsified vegetable oil (EVO) were also demonstrated to reduce U(VI) ( Gihring et al, 2011;Barlett et al, 2012a). Liu et al (2002) reported that H2 resulted in higher U(VI) reduction rates than lactate.…”

A Study on the Dissolution of Autunite Minerals by Facultative Bacteria in Bicarbonate Media

“…Recent investigations studied the formation of the biofilm by Shewanella Oneidensis MR-1 and found that the initial layer of the biofilm was produced by bacteria until the coverage of the surface and, consequently the formation of vertical towering biofilm structures (Thormann, Saville et al 2004). Furthermore, acetate and lactate have been reported to be less effective stimulants for U(VI) reduction, whereas more complex organic electron donors have been directly correlated to the ability of DMRB to reduce U(VI) (Barlett, Moon et al 2012). …”