Simultaneous Reduction of Nitrate and Selenate by Cell Suspensions of Selenium-Respiring Bacteria
Simultaneous Reduction of Nitrate and Selenate by Cell Suspensions of Selenium-Respiring Bacteria
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通过硒呼吸细菌的细胞悬浮液同时还原硝酸盐和硒酸盐
DOI：
10.1128/aem.65.10.4385-4392.1999
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发表时间：
1999
影响因子：
4.4
通讯作者：
J. Stolz
中科院分区：
文献类型：
--
作者：
R. Oremland;J. S. Blum;Allana Burns Bindi;P. Dowdle;M. Herbel;J. Stolz
摘要 当细胞用硝酸盐、硫代硫酸盐、砷酸盐或富马酸盐作为电子受体培养时，巴氏硫螺菌的洗涤细胞悬浮液会还原硒酸盐 [Se(VI)]。当电子供体浓度受到限制时，Se(VI) 生长的细胞中整个细胞中 Se(VI) 的还原量大约是硝酸盐生长的细胞中观察到的四倍；相应地，硝酸盐生长的细胞中硝酸盐的还原量比 Se(VI) 生长的细胞高约 11 倍。然而，在两种情况下都观察到硝酸盐和 Se(VI) 同时减少。在非限制电子供体浓度下，用等摩尔硝酸盐和硒酸盐悬浮的硝酸盐生长的细胞实现了氮和硒氧阴离子的完全还原去除，其中大部分硝酸盐还原先于硒酸盐还原。氯霉素不会抑制这些减少。呼吸 Se(VI) 的卤碱嗜碱性芽孢杆菌也给出了类似的结果，但其 Se(VI) 还原酶在硝酸盐生长的细胞中不是组成型的。呼吸亚硒酸盐的硒还原芽孢杆菌没有观察到 Se(VI) 的还原。巴氏沙门氏菌细胞膜制剂的动力学实验结果表明，在硝酸盐生长的细胞中存在组成型硒酸盐和硝酸盐还原，以及诱导型高亲和力硝酸还原酶，该酶对硒酸盐也具有低亲和力。在毫摩尔硝酸盐存在的情况下，微摩尔 Se(VI) 的同时还原表明这些生物体可能在生物修复富含硝酸盐的含硒农业废水中具有功能性用途。 75 Se-硒酸盐示踪剂的结果表明，这些生物体可以将环境Se(VI)浓度降低至符合关于将硒氧阴离子释放到环境中的新法规的水平。
ABSTRACT Washed-cell suspensions of Sulfurospirillum barnesiireduced selenate [Se(VI)] when cells were cultured with nitrate, thiosulfate, arsenate, or fumarate as the electron acceptor. When the concentration of the electron donor was limiting, Se(VI) reduction in whole cells was approximately fourfold greater in Se(VI)-grown cells than was observed in nitrate-grown cells; correspondingly, nitrate reduction was ∼11-fold higher in nitrate-grown cells than in Se(VI)-grown cells. However, a simultaneous reduction of nitrate and Se(VI) was observed in both cases. At nonlimiting electron donor concentrations, nitrate-grown cells suspended with equimolar nitrate and selenate achieved a complete reductive removal of nitrogen and selenium oxyanions, with the bulk of nitrate reduction preceding that of selenate reduction. Chloramphenicol did not inhibit these reductions. The Se(VI)-respiring haloalkaliphile Bacillus arsenicoselenatis gave similar results, but its Se(VI) reductase was not constitutive in nitrate-grown cells. No reduction of Se(VI) was noted for Bacillus selenitireducens, which respires selenite. The results of kinetic experiments with cell membrane preparations of S. barnesii suggest the presence of constitutive selenate and nitrate reduction, as well as an inducible, high-affinity nitrate reductase in nitrate-grown cells which also has a low affinity for selenate. The simultaneous reduction of micromolar Se(VI) in the presence of millimolar nitrate indicates that these organisms may have a functional use in bioremediating nitrate-rich, seleniferous agricultural wastewaters. Results with75Se-selenate tracer show that these organisms can lower ambient Se(VI) concentrations to levels in compliance with new regulations proposed for release of selenium oxyanions into the environment.