Oxidation of Fe(II)-Organic Matter Complexes in the Presence of the Mixotrophic Nitrate-Reducing Fe(II)-Oxidizing Bacterium Acidovorax sp. BoFeN1.
Oxidation of Fe(II)-Organic Matter Complexes in the Presence of the Mixotrophic Nitrate-Reducing Fe(II)-Oxidizing Bacterium Acidovorax sp. BoFeN1.
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DOI：
10.1021/acs.est.8b00953
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发表时间：
2018-04
影响因子：
11.4
通讯作者：
Chao Peng;Anneli Sundman;C. Bryce;Charlotte Catrouillet;T. Borch;A. Kappler
中科院分区：
文献类型：
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作者：
Chao Peng;Anneli Sundman;C. Bryce;Charlotte Catrouillet;T. Borch;A. Kappler
Fe(II)-有机物 (Fe(II)-OM) 配合物在环境中含量丰富，可能对 Fe 和污染物的行为发挥关键作用。混合营养型硝酸盐还原 Fe(II) 氧化细菌 (NRFeOx) 还原硝酸盐并伴随有机化合物和 Fe(II) 的氧化。 Fe(II) 氧化可以通过酶促或非生物方式与异养反硝化过程中形成的亚硝酸盐反应发生。然而，Fe(II)-OM 配合物是否可以被 NRFeOx 氧化尚不清楚。我们使用混合营养硝酸盐还原 Fe(II) 氧化细菌 Acidovorax sp 进行细胞悬浮实验。菌株 BoFeN1 揭示了非有机结合的 Fe(II)（Fe(II) 水溶液）和亚硝酸盐对 Fe(II)-OM 复合物（Fe(II)-柠檬酸盐、Fe(II)-EDTA、Fe(II)-腐植酸和 Fe(II)-黄腐酸）氧化速率和程度的作用。我们发现 Fe(II)-OM 络合抑制了微生物硝酸盐还原 Fe(II) 的氧化；大胶体和带负电的复合物显示出比 Fe(II) 水溶液更低的氧化速率。亚硝酸盐的积累和 Fe(II)-OM 复合物的快速非生物氧化仅发生在水性 Fe(II) 存在的情况下，Fe(II) 可能与周质中的（亚硝酸盐还原）酶相互作用，导致亚硝酸盐在周质和细胞外积累，而 Fe(II)-OM 复合物可能无法进入周质并导致亚硝酸盐积累。这些结果表明，环境中混合营养型硝酸盐还原剂对 Fe(II) 的氧化取决于 Fe(II) 的形态，并且水性 Fe(II) 可能在调节微生物反硝化过程中发挥关键作用。
Fe(II)-organic matter (Fe(II)-OM) complexes are abundant in the environment and may play a key role for the behavior of Fe and pollutants. Mixotrophic nitrate-reducing Fe(II)-oxidizing bacteria (NRFeOx) reduce nitrate coupled to the oxidation of organic compounds and Fe(II). Fe(II) oxidation may occur enzymatically or abiotically by reaction with nitrite that forms during heterotrophic denitrification. However, it is unknown whether Fe(II)-OM complexes can be oxidized by NRFeOx. We used cell-suspension experiments with the mixotrophic nitrate-reducing Fe(II)-oxidizing bacterium Acidovorax sp. strain BoFeN1 to reveal the role of nonorganically bound Fe(II) (aqueous Fe(II)) and nitrite for the rates and extent of oxidation of Fe(II)-OM complexes (Fe(II)-citrate, Fe(II)-EDTA, Fe(II)-humic acid, and Fe(II)-fulvic acid). We found that Fe(II)-OM complexation inhibited microbial nitrate-reducing Fe(II) oxidation; large colloidal and negatively charged complexes showed lower oxidation rates than aqueous Fe(II). Accumulation of nitrite and fast abiotic oxidation of Fe(II)-OM complexes only happened in the presence of aqueous Fe(II) that probably interacted with (nitrite-reducing) enzymes in the periplasm causing nitrite accumulation in the periplasm and outside of the cells, whereas Fe(II)-OM complexes probably could not enter the periplasm and cause nitrite accumulation. These results suggest that Fe(II) oxidation by mixotrophic nitrate reducers in the environment depends on Fe(II) speciation, and that aqueous Fe(II) potentially plays a critical role in regulating microbial denitrification processes.