Cometabolism of Cr(VI) by Shewanella oneidensis MR-1 produces cell-associated reduced chromium and inhibits growth
Cometabolism of Cr(VI) by Shewanella oneidensis MR-1 produces cell-associated reduced chromium and inhibits growth
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DOI：
10.1002/bit.10725
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发表时间：
2003-09-20
影响因子：
3.8
通讯作者：
Criddle, CS
中科院分区：
文献类型：
--
作者：
Middleton, SS;Bencheikh-Latmani, R;Criddle, CS
微生物还原是一种很有前途的铬修复策略，但竞争电子受体的影响仍然知之甚少。我们研究了铬酸盐（Cr（VI））减少在间歇培养的希瓦氏菌oneidensis MR-1在有氧和无菌条件下，在没有额外的电子受体。生长和Cr（VI）去除模式表明共代谢减少;在没有硝酸盐或氧气的情况下，MR-1减少Cr（VI），但没有任何增加活细胞计数和速率逐渐下降时，细胞呼吸。只有一小部分（1.6%）的电子从乳酸转移到铬（VI）。48小时的转化能力（Tc）为0.78毫克（15 mumoles）铬（VI）减少。[mg蛋白质]（-1）作为单一加标添加高水平Cr（VI）。对于低水平的Cr（VI）依次加入，Tc增加到3.33毫克（64 mumoles）Cr（VI）减少。[mg蛋白质]（-1），表明其在较高浓度下受到毒性的限制。在反硝化和好氧生长过程中，MR-1减少Cr（VI），在反硝化条件下的速率要快得多。Cr（VI）在6 μ M时对硝酸盐还原没有影响，在45 μ M时强烈抑制，在200 μ M以上停止硝酸盐还原。Cr（VI）在60 μ M时对需氧生长没有影响，但在150 μ M以上时严重抑制生长。可能在Cr（VI）毒性中起作用的因素是细胞内还原的铬。透射电子显微镜（TEM）和电子能量损失谱（EELS）暴露于Cr（VI）的cryofying细胞显示减少铬沉淀细胞外的细胞表面上，第一次，作为电子致密的圆球细胞内。(C)2003 Wiley Periodicals，Inc.
Microbial reduction is a promising strategy for chromium remediation, but the effects of competing electron acceptors are still poorly understood. We investigated chromate (Cr(VI)) reduction in batch cultures of Shewanella oneidensis MR-1 under aerobic and denitrifying conditions and in the absence of an additional electron acceptor. Growth and Cr(VI) removal patterns suggested a cometabolic reduction; in the absence of nitrate or oxygen, MR-1 reduced Cr(VI), but without any increase in viable cell counts and rates gradually decreased when cells were respiked. Only a small fraction (1.6%) of the electrons from lactate were transferred to Cr(VI). The 48-h transformation capacity (Tc) was 0.78 mg (15 mumoles) Cr(VI) reduced . [mg protein](-1) for high levels of Cr(VI) added as a single spike. For low levels of Cr(VI) added sequentially, Tc increased to 3.33 mg (64 mumoles) Cr(VI) reduced . [mg protein](-1), indicating that it is limited by toxicity at higher concentrations. During denitrification and aerobic growth, MR-1 reduced Cr(VI), with much faster rates under denitrifying conditions. Cr(VI) had no effect on nitrate reduction at 6 muM, was strongly inhibitory at 45 muM, and stopped nitrate reduction above 200 muM. Cr(VI) had no effect on aerobic growth at 60 muM, but severely inhibited growth above 150 muM. A factor that likely plays a role in Cr(VI) toxicity is intracellular reduced chromium. Transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) of denitrifying cells exposed to Cr(VI) showed reduced chromium precipitates both extracellularly on the cell surface and, for the first time, as electron-dense round globules inside cells. (C) 2003 Wiley Periodicals, Inc.