Inhibition of NO3- and NO2- reduction by microbial Fe(III) reduction:: Evidence of a reaction between NO2- and cell surface-bound Fe2+
Inhibition of NO3- and NO2- reduction by microbial Fe(III) reduction:: Evidence of a reaction between NO2- and cell surface-bound Fe2+
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DOI：
10.1128/aem.71.9.5267-5274.2005
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发表时间：
2005-09-01
影响因子：
4.4
通讯作者：
Picardal, FW
中科院分区：
文献类型：
--
作者：
Coby, AJ;Picardal, FW
最近的一项研究(D.C.Cooper，F.W.Picardal，A.Schimmelmann和A.J.Coby，App.环境。微生物。69：3517-3525,2003)表明，在针铁矿存在的情况下，腐败希瓦氏菌200对NO3-和NO2-(NOx-)的还原受到抑制。解释这一发现的假设机制涉及通过Fe2+和NO2-之间的表面催化的非生物反应在电池上形成Fe(III)(Hyr)氧化物涂层。然后，这种涂层可以通过物理地阻止进入细胞的运输来抑制NOx-的还原。尽管之前研究中的数据与这样的解释一致，但这一假设在很大程度上是投机性的。在目前的工作中，这一假设得到了验证，并通过一些实验探索了它的环境意义。在包括针铁矿、赤铁矿和含铁天然沉积物在内的多种Fe(III)(Hydr)氧化物的还原过程中，观察到类似于3mMNO3-还原的抑制作用。细胞经Fe2+和NO2-处理后，氧还原和富马酸还原受到抑制，说明对其他可溶性电子受体的利用也受到抑制。反硝化副球藻对Fe2+的吸附抑制了NOx还原，表明Fe(II)能降低非铁还原细菌对可溶性电子受体的利用率。针铁矿或细胞吸附的Fe2+能将NO2-化学还原为N2O，但Fe2+水溶液对NO2-的还原速率不大。透射电子显微镜和扫描电子显微镜显示，经Fe2+和NO2-处理的细胞表面有一层电子致密、富铁的涂层。这种涂层的形成和效果突显了地下发生的生物地球化学反应的复杂性。
A recent study (D. C. Cooper, F. W. Picardal, A. Schimmelmann, and A.J. Coby, Appl. Environ. Microbiol. 69:3517-3525, 2003) has shown that NO3- and NO2- (NOx-) reduction by Shewanella putrefaciens 200 is inhibited in the presence of goethite. The hypothetical mechanism offered to explain this finding involved the formation of a Fe(III) (hydr)oxide coating on the cell via the surface-catalyzed, abiotic reaction between Fe2+ and NO2-. This coating could then inhibit reduction of NOx- by physically blocking transport into the cell. Although the data in the previous study were consistent with such an explanation, the hypothesis was largely speculative. In the current work, this hypothesis was tested and its environmental significance explored through a number of experiments. The inhibition of similar to 3 mM NO3- reduction was observed during reduction of a variety of Fe(III) (hydr)oxides, including goethite, hematite, and an iron-bearing, natural sediment. Inhibition of oxygen and fumarate reduction was observed following treatment of cells with Fe2+ and NO2-, demonstrating that utilization of other soluble electron acceptors could also be inhibited. Previous adsorption of Fe2+ onto Paracoccus denitrificans inhibited NOx- reduction, showing that Fe(II) can reduce rates of soluble electron acceptor utilization by non-iron-reducing bacteria. NO2- was chemically reduced to N2O by goethite or cell-sorbed Fe2+, but not at appreciable rates by aqueous Fe2+. Transmission and scanning electron microscopy showed an electron-dense, Fe-enriched coating on cells treated with Fe2+ and NO2-. The formation and effects of such coatings underscore the complexity of the biogeochemical reactions that occur in the subsurface.