Bacterial Reduction of Selenium in Coal Mine Tailings Pond Sediment
- Tariq Siddiquea,
- Joselito M. Arocena *ab,
- Ronald W. Thringa and
- Yiqiang Zhangc
- a Environmental Science and Engineering, Univ. of Northern British Columbia, 3333 University Way, Prince George, BC V2N 4Z9 Canada
b Canada Research Chair–Soil and Environmental Sciences, Univ. of Northern British Columbia, 3333 University Way, Prince George, BC V2N 4Z9 Canada
c Dep. of Environmental Sciences, Univ. of California, Riverside, CA 92521 USA. T. Siddique, present address, Dep. of Biological Sciences, University of Alberta, Edmonton, AB, Canada T6G 2E9
Sediment from a storage facility for coal tailings solids was assessed for its capacity to reduce selenium (Se) by native bacterial community. One Se6+–reducing bacterium Enterobacter hormaechei (Tar11) and four Se4+–reducing bacteria, Klebsiella pneumoniae (Tar1), Pseudomonas fluorescens (Tar3), Stenotrophomonas maltophilia (Tar6), and Enterobacter amnigenus (Tar8) were isolated from the sediment. Enterobacter hormaechei removed 96% of the added Se6+ (0.92 mg L−1) from the effluents when Se6+ was determined after 5 d of incubation. Analysis of the red precipitates showed that Se6+ reduction resulted in the formation of spherical particles (<1.0 μm) of Se0 as observed under scanning electron microscope (SEM) and confirmed by EDAX. Selenium speciation was performed to examine the fate of the added Se6+ in the sediment with or without addition of Enterobacter hormaechei cells. More than 99% of the added Se6+ (∼2.5 mg L−1) was transformed in the nonsterilized sediment (without Enterobacter hormaechei cells) as well as in the sterilized (heat-killed) sediment (with Enterobacter hormaechei cells). The results of this study suggest that the lagoon sediments at the mine site harbor Se6+– and Se4+–reducing bacteria and may be important sinks for soluble Se (Se6+ and Se4+). Enterobacter hormaechei isolated from metal-contaminated sediment may have potential application in removing Se from industrial effluents.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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