Ligand Effects on Biotic and Abiotic Fe(II) Oxidation by the Microaerophile Sideroxydans lithotrophicus
Ligand Effects on Biotic and Abiotic Fe(II) Oxidation by the Microaerophile Sideroxydans lithotrophicus
复制标题
微需氧微生物氧化铁盐对生物和非生物 Fe(II) 氧化的配体效应
DOI：
10.1021/acs.est.1c00497
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发表时间：
2021
影响因子：
11.4
通讯作者：
Chan, Clara S.
中科院分区：
文献类型：
--
作者：
Zhou, Nanqing;Luther, George W.;Chan, Clara S.
有机配体分布广泛，可以影响微生物驱动的铁生物地球化学循环，但对微生物铁氧化的影响尚未得到很好的量化。我们的研究使用了一种模型嗜微氧铁氧化细菌sideroxydans lithotrophicusES-1来量化有机配体存在下的生物铁（II）氧化速率，条件为0.02 atm o2和pH 6.0。我们使用了两种不同结合强度的常见铁螯合剂：柠檬酸盐（logKFe(II)-柠檬酸= 3.20）和硝基三乙酸（NTA） （logKFe(II)-NTA= 8.09）和两种标准腐植酸物质，Pahokee泥炭腐植酸（PPHA）和Suwannee河黄腐酸（SRFA）。我们的研究结果提供了不同配体浓度下生物和非生物铁（II）氧化的速率常数，并进一步证明了不同的模型和天然铁结合配体对非生物和生物铁（II）氧化速率有不同的影响。我们表明NTA加速非生物氧化和柠檬酸盐的影响可以忽略不计，使其成为一个更好的实验室螯合剂。腐殖质仅通过螯合作用和电子转移作用影响生物Fe（II）氧化。PPHA加速生物Fe（II）氧化，而SRFA根据浓度减慢或加速氧化速率。有机-铁微生物相互作用的特定性质可能在环境铁（II）氧化中发挥关键作用，这对与铁氧化物矿物相关的营养物质和污染物的循环具有级联影响。
Organic ligands are widely distributed and can affect microbially driven Fe biogeochemical cycles, but effects on microbial iron oxidation have not been well quantified. Our work used a model microaerophilic Fe(II)-oxidizing bacteriumSideroxydans lithotrophicusES-1 to quantify biotic Fe(II) oxidation rates in the presence of organic ligands at 0.02 atm O2and pH 6.0. We used two common Fe chelators with different binding strengths: citrate (logKFe(II)-citrate= 3.20) and nitrilotriacetic acid (NTA) (logKFe(II)-NTA= 8.09) and two standard humic substances, Pahokee peat humic acid (PPHA) and Suwannee River fulvic acid (SRFA). Our results provide rate constants for biotic and abiotic Fe(II) oxidation over different ligand concentrations and furthermore demonstrate that various models and natural iron-binding ligands each have distinct effects on abiotic versus biotic Fe(II) oxidation rates. We show that NTA accelerates abiotic oxidation and citrate has negligible effects, making it a better laboratory chelator. The humic substances only affect biotic Fe(II) oxidation, via a combination of chelation and electron transfer. PPHA accelerates biotic Fe(II) oxidation, while SRFA decelerates or accelerates the rate depending on concentration. The specific nature of organic-Fe microbe interactions may play key roles in environmental Fe(II) oxidation, which have cascading influences on cycling of nutrients and contaminants that associate with Fe oxide minerals.