NDLI: Microbial studies of a selenium-contaminated mine site and potential for on-site remediation

Content Provider	Springer Nature Link
Author	Ktek Smith, Heather M. Crawford, Don L. Möller, Gregory Henson, Rachel A.
Copyright Year	2006
Abstract	Surface water Selenium (Se) concentrations are above regulatory standards at several active and inactive phosphate mine sites in the US Western Phosphate Resource Area. The focus of the present study was to examine the impacts of the microbial communities on the oxidation state of Se in overburden waste from the Smoky Canyon phosphate mine in Idaho, USA. Microbial populations were found that reduce soluble selenate (SeO 4 2− ) to insoluble elemental Se. Microcosm experiments were conducted for molecular genetic analysis of this microbial community by rRNA gene profiling. An acetone pretreatment step was developed to remove interfering pre-petroleum hydrocarbons from the samples prior to extraction. PCR was used to amplify 16S and 18S rRNA genes present in the microbial community DNA. The amplified products were subjected to denaturing gradient gel electrophoresis (DGGE). Isolates and excised DGGE bands were amplified and sequenced for identification to determine the relative importance of culturable isolates to the total microbial population. Analysis of samples from different sites at the mine showed how Se contamination and previous remediation treatments changed the microbial populations across the site. Members of the family Enterobacteriaceae were dominant among the selenate reducing isolates from the site containing high Se levels. In particular, Serratia fonticola was isolated repeatedly from contaminated Smoky Canyon Mine site samples. Packed column studies were performed with seleniferous waste rock fractions from Smoky Canyon Mine. Column amendments consisted of combinations of iron, compost, and whey. Eh, pH, and extractable Se measurements were taken. Tests with infiltrated water showed columns containing an organic amendment combined with iron metal were the most resistant to Se leaching. Iron-based compounds from the corroding metal are thought to strongly bind the Se reduced by microbial activity, thereby stabilizing the Se in an insoluble form. We conclude that long-term stabilization of selenium at contaminated mine sites may require reductive microbial processes combined with abiotic immobilization by iron, either natural or engineered, to stabilize the Se and retard re-oxidation and release. Iron-selenide or iron-selenite compounds are more stable and resistant to leaching, especially when removed from active weathering.
Starting Page	897
Ending Page	913
Page Count	17
File Format	PDF
ISSN	13675435
Journal	Journal of Industrial Microbiology and Biotechnology
Volume Number	33
Issue Number	11
e-ISSN	14765535
Language	English
Publisher	Springer-Verlag
Publisher Date	2006-06-28
Publisher Place	Berlin, Heidelberg
Access Restriction	Subscribed
Subject Keyword	Selenium Microbial Iron Molecular Remediation Microbial Genetics and Genomics Microbiology Bioinformatics Biochemistry Genetic Engineering Biotechnology
Content Type	Text
Resource Type	Article
Subject	Medicine Bioengineering Applied Microbiology and Biotechnology Biotechnology

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