Uranium reduction and resistance to reoxidation under iron-reducing and sulfate-reducing conditions

Boonchayaanant, Benjaporn; Nayak, Dipti D.; Du, Xin; Criddle, Craig S.

doi:10.1016/j.watres.2009.07.013

Cited by 32 publications

(26 citation statements)

References 49 publications

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“…At that site, continuous U(VI) reduction was observed until the dominant microbial communities shifted from Fe-reducing bacteria to sulfate-reducing bacteria, at which point U(VI) reduction slowed, ceased, or rebounded (1,5). Furthermore, the greatest rate of reduction of uranium was observed under Fe-reducing conditions, consistent with previous work showing that Fe-reducing conditions were more favorable for uranium reduction in a laboratory bioreduction experiment (2).…”

Section: Resultssupporting

confidence: 88%

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Microbial Functional Gene Diversity with a Shift of Subsurface Redox Conditions during In Situ Uranium Reduction

Liang

Nostrand

N'guessan

et al. 2012

Appl Environ Microbiol

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ABSTRACTTo better understand the microbial functional diversity changes with subsurface redox conditions duringin situuranium bioremediation, key functional genes were studied with GeoChip, a comprehensive functional gene microarray, in field experiments at a uranium mill tailings remedial action (UMTRA) site (Rifle, CO). The results indicated that functional microbial communities altered with a shift in the dominant metabolic process, as documented by hierarchical cluster and ordination analyses of all detected functional genes. The abundance ofdsrABgenes (dissimilatory sulfite reductase genes) and methane generation-relatedmcrgenes (methyl coenzyme M reductase coding genes) increased when redox conditions shifted from Fe-reducing to sulfate-reducing conditions. The cytochrome genes detected were primarily fromGeobactersp. and decreased with lower subsurface redox conditions. Statistical analysis of environmental parameters and functional genes indicated that acetate, U(VI), and redox potential (Eh) were the most significant geochemical variables linked to microbial functional gene structures, and changes in microbial functional diversity were strongly related to the dominant terminal electron-accepting process following acetate addition. The study indicates that the microbial functional genes clearly reflect thein situredox conditions and the dominant microbial processes, which in turn influence uranium bioreduction. Microbial functional genes thus could be very useful for tracking microbial community structure and dynamics during bioremediation.

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Section: Resultssupporting

confidence: 88%

“…were in high abundance. Several different species of Clostridium have been shown to reduce U(VI) to U(IV) to various degrees (2,24), and the hypothesis was proposed that U(VI) reduction occurred through hydrogenases and other enzymes (9). However, hydrogenase genes derived from Clostridium sp.…”

Section: Figmentioning

confidence: 99%

Microbial Functional Gene Diversity with a Shift of Subsurface Redox Conditions during In Situ Uranium Reduction

Liang

Nostrand

N'guessan

et al. 2012

Appl Environ Microbiol

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“…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.…”

Section: (Oh)]mentioning

confidence: 99%

“…In open atmospheric systems, under oxygenic conditions, and with pH values lower than 3, U(VI) is present exclusively in the form of hexavalent uranyl cation, UO 2 2ϩ , which is the most bioavailable form of U (15,16). Circumneutral pH favors the formation of positively charged uranyl hydroxide, [(UO 2 ) 3 …”

mentioning

confidence: 99%

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

Kulkarni

Misra

Gupta

et al. 2016

Appl Environ Microbiol

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Deinococcus radiodurans and Escherichia coli expressing either PhoN, a periplasmic acid phosphatase, or PhoK, an extracellular alkaline phosphatase, were evaluated for uranium (U) bioprecipitation under two specific geochemical conditions (GCs): (i) a carbonate-deficient condition at near-neutral pH (GC1), and (ii) a carbonate-abundant condition at alkaline pH (GC2). Transmission electron microscopy revealed that recombinant cells expressing PhoN/PhoK formed cell-associated uranyl phosphate precipitate under GC1, whereas the same cells displayed extracellular precipitation under GC2. These results implied that the cell-bound or extracellular location of the precipitate was governed by the uranyl species prevalent at that particular GC, rather than the location of phosphatase. MINTEQ modeling predicted the formation of predominantly positively charged uranium hydroxide ions under GC1 and negatively charged uranyl carbonate-hydroxide complexes under GC2. Both microbes adsorbed 6-to 10-fold more U under GC1 than under GC2, suggesting that higher biosorption of U to the bacterial cell surface under GC1 may lead to cell-associated U precipitation. In contrast, at alkaline pH and in the presence of excess carbonate under GC2, poor biosorption of negatively charged uranyl carbonate complexes on the cell surface might have resulted in extracellular precipitation. The toxicity of U observed under GC1 being higher than that under GC2 could also be attributed to the preferential adsorption of U on cell surfaces under GC1. This work provides a vivid description of the interaction of U complexes with bacterial cells. The findings have implications for the toxicity of various U species and for developing biological aqueous effluent waste treatment strategies. IMPORTANCEThe present study provides illustrative insights into the interaction of uranium (U) complexes with recombinant bacterial cells overexpressing phosphatases. This work demonstrates the effects of aqueous speciation of U on the biosorption of U and the localization pattern of uranyl phosphate precipitated as a result of phosphatase action. Transmission electron microscopy revealed that location of uranyl phosphate (cell associated or extracellular) was primarily influenced by aqueous uranyl species present under the given geochemical conditions. The data would be useful for understanding the toxicity of U under different geochemical conditions. Since cell-associated precipitation of metal facilitates easy downstream processing by simple gravitybased settling down of metal-loaded cells, compared to cumbersome separation techniques, the results from this study are of considerable relevance to effluent treatment using such cells. Bioremediation strategies, such as bioreduction (1-3), biosorption (4-8), bioaccumulation (9, 10), and bioprecipitation (5, 11, 12, 13), have been studied for their potential to immobilize U from solutions. There is also a large body of work on microbial interactions with uranium relevant to environmental in situ bioremediation. The...

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“…Furthermore, 300A sediment slurry and 300A sediment slurry amended with Fh were used to evaluate their impact on overall U(VI) immobilization. (7,32,75). Sediment incubation was carried out anaerobically at room temperature (22 Ϯ 2°C).…”

Section: R1 Was Limited To Fe(iii) Nitrilotriacetic Acid [Fe(iii)-ntamentioning

confidence: 99%

Fe(III) Reduction and U(VI) Immobilization by Paenibacillus sp. Strain 300A, Isolated from Hanford 300A Subsurface Sediments

Ahmed

Cao

McLean

et al. 2012

Appl Environ Microbiol

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Uranium reduction and resistance to reoxidation under iron-reducing and sulfate-reducing conditions

Cited by 32 publications

References 49 publications

Microbial Functional Gene Diversity with a Shift of Subsurface Redox Conditions during In Situ Uranium Reduction

Microbial Functional Gene Diversity with a Shift of Subsurface Redox Conditions during In Situ Uranium Reduction

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

Fe(III) Reduction and U(VI) Immobilization by Paenibacillus sp. Strain 300A, Isolated from Hanford 300A Subsurface Sediments

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