Abstract
Adsorption of hexavalent uranium (U(VI)) by extracellular polymeric substances (EPS) has been studied, but the possibility of simultaneous U(VI) reduction mediated by EPS has not had experimental confirmation, as the reduction products have not yet been directly proven. Here, we reported the first direct evidence of lower-valent products of U(VI) immobilization by loosely associated EPS (laEPS) isolated from a fermenter strain of Klebsiella sp. J1 when the laEPS was exposed to H2. During the 120-min tests for similarly 86% adsorption under O2, N2, and H2, 8% more U was immobilized through a non-adsorptive pathway by the EPS for H2 than for N2 and O2. A set of solid-state characterization tools (FT-IR, XPS, EELS, and TEM-EDX) confirmed partial reduction of U(VI) to lower-valence U, with the main reduced form being uraninite (UIVO2) nanoparticles, and the results reinforced the role of the reduction in accelerating U immobilization and shaping the characteristics of immobilized U in terms of valency, size, and crystallization. The laEPS, mostly comprised of carbohydrate and protein, contained non-cytochrome enzymes and electron carriers that could be responsible for electron transfer to U(VI). Taken together, our results directly confirm that EPS was able to mediate partial U(VI) reduction in the presence of H2 through non-cytochrome catalysis and that reduction enhanced overall U immobilization. Our study fills in some gaps of the microbe-mediated U cycle and will be useful to understand and control U removal in engineered reactors and in-situ bioremediation.
| Original language | English (US) |
|---|---|
| Journal | Biotechnology and Bioengineering |
| DOIs | |
| State | Accepted/In press - Jan 1 2018 |
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Keywords
- Extracellular polymeric substances (EPS)
- H
- Nanoparticles
- Uranium reduction
ASJC Scopus subject areas
- Biotechnology
- Bioengineering
- Applied Microbiology and Biotechnology
Cite this
Direct solid-state evidence of H2-induced partial U(VI) reduction concomitant with adsorption by extracellular polymeric substances (EPS). / Li, Ang; Zhou, Chen; Liu, Zhuolin; Xu, Xiaoyin; Zhou, Yun; Zhou, Dandan; Tang, Youneng; Ma, Fang; Rittmann, Bruce.
In: Biotechnology and Bioengineering, 01.01.2018.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Direct solid-state evidence of H2-induced partial U(VI) reduction concomitant with adsorption by extracellular polymeric substances (EPS)
AU - Li, Ang
AU - Zhou, Chen
AU - Liu, Zhuolin
AU - Xu, Xiaoyin
AU - Zhou, Yun
AU - Zhou, Dandan
AU - Tang, Youneng
AU - Ma, Fang
AU - Rittmann, Bruce
PY - 2018/1/1
Y1 - 2018/1/1
N2 - Adsorption of hexavalent uranium (U(VI)) by extracellular polymeric substances (EPS) has been studied, but the possibility of simultaneous U(VI) reduction mediated by EPS has not had experimental confirmation, as the reduction products have not yet been directly proven. Here, we reported the first direct evidence of lower-valent products of U(VI) immobilization by loosely associated EPS (laEPS) isolated from a fermenter strain of Klebsiella sp. J1 when the laEPS was exposed to H2. During the 120-min tests for similarly 86% adsorption under O2, N2, and H2, 8% more U was immobilized through a non-adsorptive pathway by the EPS for H2 than for N2 and O2. A set of solid-state characterization tools (FT-IR, XPS, EELS, and TEM-EDX) confirmed partial reduction of U(VI) to lower-valence U, with the main reduced form being uraninite (UIVO2) nanoparticles, and the results reinforced the role of the reduction in accelerating U immobilization and shaping the characteristics of immobilized U in terms of valency, size, and crystallization. The laEPS, mostly comprised of carbohydrate and protein, contained non-cytochrome enzymes and electron carriers that could be responsible for electron transfer to U(VI). Taken together, our results directly confirm that EPS was able to mediate partial U(VI) reduction in the presence of H2 through non-cytochrome catalysis and that reduction enhanced overall U immobilization. Our study fills in some gaps of the microbe-mediated U cycle and will be useful to understand and control U removal in engineered reactors and in-situ bioremediation.
AB - Adsorption of hexavalent uranium (U(VI)) by extracellular polymeric substances (EPS) has been studied, but the possibility of simultaneous U(VI) reduction mediated by EPS has not had experimental confirmation, as the reduction products have not yet been directly proven. Here, we reported the first direct evidence of lower-valent products of U(VI) immobilization by loosely associated EPS (laEPS) isolated from a fermenter strain of Klebsiella sp. J1 when the laEPS was exposed to H2. During the 120-min tests for similarly 86% adsorption under O2, N2, and H2, 8% more U was immobilized through a non-adsorptive pathway by the EPS for H2 than for N2 and O2. A set of solid-state characterization tools (FT-IR, XPS, EELS, and TEM-EDX) confirmed partial reduction of U(VI) to lower-valence U, with the main reduced form being uraninite (UIVO2) nanoparticles, and the results reinforced the role of the reduction in accelerating U immobilization and shaping the characteristics of immobilized U in terms of valency, size, and crystallization. The laEPS, mostly comprised of carbohydrate and protein, contained non-cytochrome enzymes and electron carriers that could be responsible for electron transfer to U(VI). Taken together, our results directly confirm that EPS was able to mediate partial U(VI) reduction in the presence of H2 through non-cytochrome catalysis and that reduction enhanced overall U immobilization. Our study fills in some gaps of the microbe-mediated U cycle and will be useful to understand and control U removal in engineered reactors and in-situ bioremediation.
KW - Extracellular polymeric substances (EPS)
KW - H
KW - Nanoparticles
KW - Uranium reduction
UR - http://www.scopus.com/inward/record.url?scp=85045221511&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85045221511&partnerID=8YFLogxK
U2 - 10.1002/bit.26592
DO - 10.1002/bit.26592
M3 - Article
C2 - 29574765
AN - SCOPUS:85045221511
JO - Biotechnology and Bioengineering
JF - Biotechnology and Bioengineering
SN - 0006-3592
ER -