Hunter William J
United States Department of Agriculture, Agricultural Research Service, 2150-D Centre Ave, Fort Collins, CO 80526-8119, USA.
Curr Microbiol. 2007 May;54(5):376-81. doi: 10.1007/s00284-006-0474-y. Epub 2007 May 4.
A bacterium that reduces the soluble selenium oxyanions, selenate and selenite, to insoluble elemental red selenium (Se(0)) was isolated from a laboratory reactor developed to remove selenate from groundwater. Gene sequence alignment of the 16S rRNA allowed identification of the isolate as Azospira oryzae. Biochemical and morphologic characterization confirm the identification. The isolate reduces selenate and selenite to Se(0) under microaerophilic and denitrifying conditions but not under aerobic conditions. It does not use selenate or selenite as terminal e(-) donors. Se oxyanion reduction causes the formation of Se nanospheres that are 0.25 +/- 0.04 microm in diameter. Nanospheres may be associated with the cells or free in the medium. The enzymatic activity associated with the reduction of selenate has a molecular mass of approximately 500 kD, and the enzymatic activity associated with the reduction of selenite has a mass of approximately 55 kD. Selenite reduction was inhibited by tungsten. The molecular masses of these activities were different from those associated with the reduction of dimethylsulfoxide, sulfate, and nitrite. This bacterium, or perhaps its enzymes or DNA, might be useful for the remediation of waters contaminated with Se oxyanions.
从一个用于去除地下水中硒酸盐的实验室反应器中分离出一种细菌，它能将可溶性硒氧阴离子硒酸盐和亚硒酸盐还原为不溶性元素态红色硒（Se(0)）。通过对16S rRNA的基因序列比对，鉴定该分离菌为米氏固氮螺菌。生化和形态学特征证实了这一鉴定结果。该分离菌在微需氧和反硝化条件下能将硒酸盐和亚硒酸盐还原为Se(0)，但在有氧条件下不能。它不将硒酸盐或亚硒酸盐用作末端电子供体。硒氧阴离子的还原导致形成直径为0.25±0.04微米的硒纳米球。纳米球可能与细胞相关或游离于培养基中。与硒酸盐还原相关的酶活性分子量约为500 kD，与亚硒酸盐还原相关的酶活性分子量约为55 kD。钨抑制亚硒酸盐的还原。这些活性的分子量与与二甲基亚砜、硫酸盐和亚硝酸盐还原相关的分子量不同。这种细菌，或者其酶或DNA，可能对修复受硒氧阴离子污染的水体有用。
