Cr(III) is indirectly oxidized by the Mn(II)-Oxidizing bacterium Bacillus sp strain SG-1
Cr(III) is indirectly oxidized by the Mn(II)-Oxidizing bacterium Bacillus sp strain SG-1
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DOI：
10.1021/es0615167
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发表时间：
2007-01-15
影响因子：
11.4
通讯作者：
Tebo, Bradley M.
中科院分区：
文献类型：
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作者：
Murray, Karen J.;Tebo, Bradley M.
锰氧化物是环境中唯一已知的铬(III)的氧化剂，对铬(III)的去向的预测一直基于具有良好特征的锰(III，IV)氧化物矿物的铬(III)氧化速率。然而，我们的研究表明，锰(II)氧化菌的存在可能会通过产生非常活跃的锰氧化物或氧化过程中形成的中间产物来加速这些速率。利用氧化锰芽孢杆菌进行了实验研究。菌株SG-1表明，与非生物和生物产生的锰氧化物相比，该细菌能够加速铬(III)的氧化。生物源氧化物氧化铬(III)的初始速率约为等量合成β-MnO2氧化铬(III)的7倍，含Mn(II)的SG-1孢子的氧化速率约为SG-1的25倍。SG-1对铬(III)的氧化不是直接的；需要锰，但量很少，表明它是循环利用的。在5µM以上溶解的Mn(II)对Cr(III)的氧化有抑制作用，而对Mn(II)的氧化则没有抑制作用，表明这两个过程受不同的机理控制。这些结果表明，在预测铬(III)氧化潜力时，需要考虑细菌活性和锰的浓度。
Manganese oxides are the only known oxidants of Cr(III) in the environment, and predictions of the fate of Cr(III) have been based on Cr(III) oxidation rates with well-characterized Mn(III,IV) oxide minerals. Our research, however, indicates that the presence of Mn(II)-oxidizing bacteria may accelerate these rates through the production of very reactive Mn oxides or intermediates formed in the oxidation process. Experiments with the Mn(II)-oxidizing Bacillus sp. strain SG-1 show that this bacterium can accelerate Cr(III) oxidation compared to both abiotic and biologically produced Mn oxides. Initial rates of Cr(III) oxidation by biogenic oxides were approximately 7 times faster than Cr(III) oxidation rates by equivalent amounts of synthetic delta-MnO2 and 25 times faster by SG-1 spores with Mn(II). Cr(III) oxidation by SG-1 is not direct; Mn is required, but only in small amounts, indicating that it is recycled. Cr(III) oxidation is inhibited above 5 mu M dissolved Mn(II), while Mn(II) oxidation is not, suggesting that the processes are controlled by different mechanisms. These results illustrate the need to consider bacterial activity and the concentration of Mn when predicting the potential for Cr(III) oxidation.