TY - JOUR
T1 - Biogenic iron mineralization accompanying the dissimilatory reduction of hydrous ferric oxide by a groundwater bacterium
AU - Fredrickson, James K.
AU - Zachara, John M.
AU - Kennedy, David W.
AU - Dong, Hailang
AU - Onstott, Tullis C.
AU - Hinman, Nancy W.
AU - Li, Shu Mei
N1 - Funding Information:
This research was supported by the Natural and Accelerated Bioremediation Research Program (NABIR), Office of Biological and Environmental Research, U.S. Department of Energy (DOE). The continued support of Dr. F. J. Wobber is greatly appreciated. Pacific Northwest National Laboratory is operated for the DOE by Battelle Memorial Institute under Contract DE-AC06-76RLO 1830. We thank Dr. David Boone of Portland State Univ. for providing S. putrefaciens CN32 to us from the Subsurface Microbial Culture Collection and Dr. Yuri Gorby for helpful discussions. The Subsurface Microbial Culture Collection at Florida State University is supported by DOE Grant No. DE-FG05-90ER61039.
PY - 1998/10
Y1 - 1998/10
N2 - Dissimilatory iron-reducing bacteria (DIRB) couple the oxidation of organic matter or H2 to the reduction of iron oxides. The factors controlling the rate and extent of these reduction reactions and the resulting solid phases are complex and poorly understood. Batch experiments were conducted with amorphous hydrous ferric oxide (HFO) and the DIRB Shewanella putrefaciens, strain CN32, in well-defined aqueous solutions to investigate the reduction of HFO and formation of biogenic Fe(II) minerals. Lactate-HFO solutions buffered with either bicarbonate or 1,4-piperazinediethanesulfonic acid (PIPES) containing various combinations of phosphate and anthraquinone-2,6-disulfonate (AQDS), were inoculated with S. putrefaciens CN32. AQDS, a humic acid analog that can be reduced to dihydroanthraquinone by CN32, was included because of its ability to function as an electron shuttle during microbial iron reduction and as an indicator of pe. Iron reduction was measured with time, and the resulting solids were analyzed by X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) with energy-dispersive X-ray spectroscopy (EDS) and selected area electron diffraction (SAED). In HCO3- buffered medium with AQDS, HFO was rapidly and extensively reduced, and the resulting solids were dominated by ferrous carbonate (siderite). Ferrous phosphate (vivianite) was also present in HCO3- medium containing P, and fine-grained magnetite was present as a minor phase in HCO3- medium with or without P. In the PIPES-buffered medium, the rate and extent of reduction was strongly influenced by AQDS and P. With AQDS, HFO was rapidly converted to highly crystalline magnetite whereas in its absence, magnetite mineralization was slower and the final material less crystalline. In PIPES with both P and AQDS, a green rust type compound [Fe((6-x))(II)Fe(x)(III)(OH)12](x+)[(A2-)(x/2)·yH2O](x-) was the dominant solid phase formed; in the absence of AQDS a poorly crystalline product was observed. The measured pe and nature of the solids identified were consistent with thermodynamic considerations. The composition of aqueous media in which microbial iron reduction occurred strongly impacted the rate and extent of iron reduction and the nature of the reduced solids. This, in turn, can provide a feedback control mechanism on microbial metabolism. Hence, in sediments where geochemical conditions promote magnetite formation, two-thirds of the Fe(III) will be sequestered in a form that may not be available for anaerobic bacterial respiration.
AB - Dissimilatory iron-reducing bacteria (DIRB) couple the oxidation of organic matter or H2 to the reduction of iron oxides. The factors controlling the rate and extent of these reduction reactions and the resulting solid phases are complex and poorly understood. Batch experiments were conducted with amorphous hydrous ferric oxide (HFO) and the DIRB Shewanella putrefaciens, strain CN32, in well-defined aqueous solutions to investigate the reduction of HFO and formation of biogenic Fe(II) minerals. Lactate-HFO solutions buffered with either bicarbonate or 1,4-piperazinediethanesulfonic acid (PIPES) containing various combinations of phosphate and anthraquinone-2,6-disulfonate (AQDS), were inoculated with S. putrefaciens CN32. AQDS, a humic acid analog that can be reduced to dihydroanthraquinone by CN32, was included because of its ability to function as an electron shuttle during microbial iron reduction and as an indicator of pe. Iron reduction was measured with time, and the resulting solids were analyzed by X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) with energy-dispersive X-ray spectroscopy (EDS) and selected area electron diffraction (SAED). In HCO3- buffered medium with AQDS, HFO was rapidly and extensively reduced, and the resulting solids were dominated by ferrous carbonate (siderite). Ferrous phosphate (vivianite) was also present in HCO3- medium containing P, and fine-grained magnetite was present as a minor phase in HCO3- medium with or without P. In the PIPES-buffered medium, the rate and extent of reduction was strongly influenced by AQDS and P. With AQDS, HFO was rapidly converted to highly crystalline magnetite whereas in its absence, magnetite mineralization was slower and the final material less crystalline. In PIPES with both P and AQDS, a green rust type compound [Fe((6-x))(II)Fe(x)(III)(OH)12](x+)[(A2-)(x/2)·yH2O](x-) was the dominant solid phase formed; in the absence of AQDS a poorly crystalline product was observed. The measured pe and nature of the solids identified were consistent with thermodynamic considerations. The composition of aqueous media in which microbial iron reduction occurred strongly impacted the rate and extent of iron reduction and the nature of the reduced solids. This, in turn, can provide a feedback control mechanism on microbial metabolism. Hence, in sediments where geochemical conditions promote magnetite formation, two-thirds of the Fe(III) will be sequestered in a form that may not be available for anaerobic bacterial respiration.
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U2 - 10.1016/S0016-7037(98)00243-9
DO - 10.1016/S0016-7037(98)00243-9
M3 - Article
AN - SCOPUS:0032468301
SN - 0016-7037
VL - 62
SP - 3239
EP - 3257
JO - Geochimica et Cosmochimica Acta
JF - Geochimica et Cosmochimica Acta
IS - 19-20
ER -