Garbisu C, Gonzalez S, Yang W H, Yee B C, Carlson D L, Yee A, Smith N R, Otero R, Buchanan B B, Leighton T
Department of Plant Biology, University of California, Berkeley 94720, USA.
Biofactors. 1995 May;5(1):29-37.
We have demonstrated that the common soil bacterium, Bacillus subtilis, reduces selenite to an insoluble and much less toxic product--the red form of elemental selenium. Reduction was effected by an inducible system that appears to deposit elemental selenium between the cell wall and the plasma membrane. Glucose and sucrose supported selenite reduction. Although malate and citrate supported growth, no significant reduction of selenite occurred, indicating the importance of the redox state of the culture substrate. Selenite reduction in the millimolar concentration range (i.e., cultures supplemented with 1 mM selenite) was not affected by a ten-fold excess of nitrate or sulfate--compounds that serve as alternate electron acceptors and antagonize selenite reduction by anaerobic bacteria. Similarly, nitrite and sulfite did not significantly affect the rate or extent of selenite reduction. B.subtilis was able to grow and produce selenium (Se degree) at selenite concentrations ranging from 0.6 microM to 5 mM (50 ppb to 395 ppm selenium). At the lowest selenite concentration tested, 50 ppb selenium, B.subtilis removed 95% of the selenite from the liquid phase. The results suggest that selenite is reduced via an inducible detoxification system rather than dissimilatory electron transport. The findings establish the potential utility of B.subtilis for the bioremediation of selenite-polluted sites.
我们已经证明，常见的土壤细菌枯草芽孢杆菌能将亚硒酸盐还原为一种不溶性且毒性小得多的产物——红色单质硒。这种还原作用是由一种可诱导系统实现的，该系统似乎将单质硒沉积在细胞壁和质膜之间。葡萄糖和蔗糖能支持亚硒酸盐的还原。虽然苹果酸和柠檬酸盐能支持生长，但亚硒酸盐没有显著还原，这表明培养底物的氧化还原状态很重要。毫摩尔浓度范围内（即添加1 mM亚硒酸盐的培养物）的亚硒酸盐还原不受十倍过量硝酸盐或硫酸盐的影响，硝酸盐和硫酸盐是作为替代电子受体并抑制厌氧细菌亚硒酸盐还原的化合物。同样，亚硝酸盐和亚硫酸盐对亚硒酸盐还原的速率或程度也没有显著影响。枯草芽孢杆菌能够在0.6 microM至5 mM（50 ppb至395 ppm硒）的亚硒酸盐浓度范围内生长并产生硒（Se⁰）。在测试的最低亚硒酸盐浓度50 ppb硒时，枯草芽孢杆菌从液相中去除了95%的亚硒酸盐。结果表明，亚硒酸盐是通过一种可诱导的解毒系统而非异化电子传递被还原的。这些发现确立了枯草芽孢杆菌在亚硒酸盐污染场地生物修复中的潜在用途。
