title: Bacterial reduction of selenium in coal mine tailings pond sediment.
abstract: Sediment from a storage facility for coal tailings solids was assessed for its capacity to reduce selenium (Se) by native bacterial community. One Se(6+)-reducing bacterium Enterobacter hormaechei (Tar11) and four Se(4+)-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 Se(6+) (0.92 mg L(-1)) from the effluents when Se(6+) was determined after 5 d of incubation. Analysis of the red precipitates showed that Se(6+) reduction resulted in the formation of spherical particles (<1.0 microm) of Se(0) as observed under scanning electron microscope (SEM) and confirmed by EDAX. Selenium speciation was performed to examine the fate of the added Se(6+) in the sediment with or without addition of Enterobacter hormaechei cells. More than 99% of the added Se(6+) (approximately 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 Se(6+)- and Se(4+)-reducing bacteria and may be important sinks for soluble Se (Se(6+) and Se(4+)). Enterobacter hormaechei isolated from metal-contaminated sediment may have potential application in removing Se from industrial effluents.
authors.affiliation: Environmental Science and Engineering, Univ. of Northern British Columbia, 3333 University Way, Prince George, BC V2N 4Z9 Canada.
authors.forename: Tariq
authors.initials: T
authors.lastname: Siddique
authors.forename: Joselito M
authors.initials: JM
authors.lastname: Arocena
authors.forename: Ronald W
authors.initials: RW
authors.lastname: Thring
authors.forename: Yiqiang
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D001419:Bacteria / Q000235:genetics / Q000378:metabolism*; D001673:Biodegradation, Environmental; D003032:Coal Mining; D019015:Geologic Sediments; D010802:Phylogeny; D064586:Selenic Acid; D012643:Selenium / Q000378:metabolism*; D018036:Selenium Compounds / Q000378:metabolism; D018038:Sodium Selenite / Q000378:metabolism; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000378:metabolism*; D014877:Water Pollution, Chemical / Q000517:prevention & control
chemical_list: D018036:Selenium Compounds; D014874:Water Pollutants, Chemical; D012643:Selenium; D018038:Sodium Selenite; D064586:Selenic Acid