Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
Environ Microbiol Rep. 2013 Jun;5(3):444-52. doi: 10.1111/1758-2229.12032.
Removal of selenium from groundwater was documented during injection of acetate into a uranium-contaminated aquifer near Rifle, Colorado (USA). Bioreduction of aqueous selenium to its elemental form (Se0) concentrated it within mineralized biofilms affixed to tubing used to circulate acetate-amended groundwater. Scanning and transmission electron microscopy revealed close association between Se0 precipitates and cell surfaces, with Se0 aggregates having a diameter of 50-60 nm. Accumulation of Se0 within biofilms occurred over a three-week interval at a rate of c. 9 mg Se0 m(-2) tubing day(-1). Removal was inferred to result from the activity of a mixed microbial community within the biofilms capable of coupling acetate oxidation to the reduction of oxygen, nitrate and selenate. Phylogenetic analysis of the biofilm revealed a community dominated by strains of Dechloromonas sp. and Thauera sp., with isolates exhibiting genetic similarity to the latter known to reduce selenate to Se0. Enrichment cultures of selenate-respiring microorganisms were readily established using Rifle site groundwater and acetate, with cultures dominated by strains closely related to D. aromatica (96-99% similarity). Predominance of Dechloromonas sp. in recovered biofilms and enrichments suggests this microorganism may play a role in the removal of selenium oxyanions present in Se-impacted groundwaters and sediments.
在科罗拉多州里弗尔附近受铀污染的含水层中注入乙酸盐时，有记录表明地下水的硒被去除。水相中硒被生物还原为其元素形式（Se0），在固定于用于循环添加了乙酸盐的地下水的管道上的矿化生物膜内浓缩。扫描和透射电子显微镜显示，Se0 沉淀物与细胞表面密切相关，Se0 聚集体的直径为 50-60nm。在三周的时间内，Se0 以约 9mg Se0 m(-2) 管道天(-1)的速率在生物膜内积累。据推断，去除是由于生物膜内混合微生物群落的活性所致，该群落能够将乙酸盐氧化与氧气、硝酸盐和硒酸盐的还原偶联。生物膜的系统发育分析表明，群落主要由 Dechloromonas sp.和 Thauera sp.的菌株组成，分离株与后者具有遗传相似性，后者已知将硒酸盐还原为 Se0。使用里弗尔现场地下水和乙酸盐很容易建立起硒酸盐呼吸微生物的富集培养物，培养物主要由与 D. aromatica（相似度为 96-99%）密切相关的菌株主导。回收的生物膜和富集物中 Dechloromonas sp.的优势表明，这种微生物可能在去除受硒影响的地下水和沉积物中存在的硒含氧阴离子方面发挥作用。
