Electron Spin Resonance Study of Chromium(V) Formation and Decomposition by Basalt-Inhabiting Bacteria

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• 作者：Tamaz L. Kalabegishvili ; Nelly Y. Tsibakhashvili ; and Hoi-Ying N. Holman
• 刊名：Environmental Science & Technology
• 出版年：2003
• 出版时间：October 15, 2003
• 年：2003
• 卷：37
• 期：20
• 页码：4678 - 4684
• 全文大小：131K
• 年卷期：v.37,no.20(October 15, 2003)
• ISSN：1520-5851

文摘

Bacterial reduction of Cr(VI) to Cr(III) compounds mayproduce reactive intermediates Cr(V) and Cr(IV), which canaffect the mobility and toxicity of chromium in environments.To address this important subject, we conducted anelectron spin resonance (ESR) study to understand thekinetics of the formation and decomposition of Cr(V) duringCr(VI) reduction by different Gram-positive Cr(VI)-tolerantbacteria, which were isolated from polluted basalts from theUnited States of America and the Republic of Georgia.Results from our batch experiments show that during Cr(VI)reduction, the macromolecules at the cell wall of thesebacteria could act as an electron donor to Cr(VI) to forma stable square-pyramidal Cr(V) complexes, whichwere reduced further probably via a one-electron transferpathway to form Cr(IV) and Cr(III) compounds. The Cr(V)peak at the ESR spectrum possessed superhyperfine splittingcharacteristic of the Cr(V) complexes with diol-containingmolecules. It appears that the kinetics of Cr(V) formationand decomposition depended on the bacterial growth phaseand on the species. Both formation and decompositionof Cr(V) occurred more quickly when Cr(VI) was added atthe exponential phase. In comparison with other Gram-positive bacteria from the republic of Georgia, the formationand decomposition of Cr(V) in Arthrobacter species fromthe Unites States was significantly slower.