Suboxic Deposition of Ferric Iron by Bacteria in Opposing Gradients of Fe(II) and Oxygen at Circumneutral pH
Suboxic Deposition of Ferric Iron by Bacteria in Opposing Gradients of Fe(II) and Oxygen at Circumneutral pH
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DOI：
10.1128/aem.67.3.1328-1334.2001
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发表时间：
2001-03
影响因子：
4.4
通讯作者：
D. Sobolev;E. Roden
中科院分区：
文献类型：
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作者：
D. Sobolev;E. Roden
利用O2微电极和铁扩散微探针，在亚毫米分辨率下研究了富营养化Fe（II）氧化细菌对Fe（II）和O2相反梯度下氧化铁沉积模式的影响。在接种了富营养化铁（II）氧化细菌的培养物中，大多数铁（III）沉积发生在氧渗透深度以下。相反，在非生物对照培养中，铁（III）沉积完全发生在好氧区。扩散微探针揭示了铁（II）生物氧化过程中可溶或胶体铁（III）化合物的形成。通过在缺氧水中洗涤探针，验证了活培养物中扩散探针中移动铁（III）的存在，这从活培养物中去除了探针中约70%的铁（III）含量，但没有改变非生物对照中探针的铁（III）含量。与探针相比，在培养基中沉积的铁（III）氧化物的量的测量表明，在活培养物中沉积的铁（III）中约有90%是生物形成的。我们的研究结果表明，细菌铁（II）氧化可能会产生活性铁（III）化合物，这些化合物可以立即用作厌氧呼吸的电子受体，并且生物铁（II）氧化可能因此促进好氧-厌氧界面上快速的微尺度铁氧化还原循环。
ABSTRACT The influence of lithotrophic Fe(II)-oxidizing bacteria on patterns of ferric oxide deposition in opposing gradients of Fe(II) and O2 was examined at submillimeter resolution by use of an O2 microelectrode and diffusion microprobes for iron. In cultures inoculated with lithotrophic Fe(II)-oxidizing bacteria, the majority of Fe(III) deposition occurred below the depth of O2 penetration. In contrast, Fe(III) deposition in abiotic control cultures occurred entirely within the aerobic zone. The diffusion microprobes revealed the formation of soluble or colloidal Fe(III) compounds during biological Fe(II) oxidation. The presence of mobile Fe(III) in diffusion probes from live cultures was verified by washing the probes in anoxic water, which removed ca. 70% of the Fe(III) content of probes from live cultures but did not alter the Fe(III) content of probes from abiotic controls. Measurements of the amount of Fe(III) oxide deposited in the medium versus the probes indicated that ca. 90% of the Fe(III) deposited in live cultures was formed biologically. Our findings show that bacterial Fe(II) oxidation is likely to generate reactive Fe(III) compounds that can be immediately available for use as electron acceptors for anaerobic respiration and that biological Fe(II) oxidation may thereby promote rapid microscale Fe redox cycling at aerobic-anaerobic interfaces.