Contribution of Microaerophilic Iron(II)-Oxidizers to Iron(III) Mineral Formation
Contribution of Microaerophilic Iron(II)-Oxidizers to Iron(III) Mineral Formation
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DOI：
10.1021/acs.est.9b01531
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发表时间：
2019-07-16
影响因子：
11.4
通讯作者：
Schmidt, Caroline
中科院分区：
文献类型：
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作者：
Maisch, Markus;Lueder, Ulf;Schmidt, Caroline
嗜中性微生物好氧氧化亚铁（Fe（II））被限制在pH值的环中性环境中，其特征在于低氧，其中微好氧Fe（II）氧化微生物成功地与非生物Fe（II）氧化竞争。然而，铁（生物）矿物的积累增加了竞争，刺激非生物表面催化的异质Fe（II）氧化。在这里，我们提出了一种实验方法，允许量化的微生物和非生物的贡献，铁（II）氧化的存在或初始不存在的铁（生物）矿物。我们发现，在20 μ M O-2和初始缺乏Fe（III）矿物质，铁（II）氧化富集培养（99.6%的相似性Sideroxydans spp.）在约26 h内，对总Fe（II）氧化的贡献为40%，氧化高达3.6 x 10（-15）mol Fe（II）电池（-1）h（-1）。酶促Fe（II）氧化可与非生物Fe（II）氧化竞争的最佳O-2浓度范围为5至20 μ M。较低的O-2水平限制生物Fe（II）氧化，而在较高的O-2水平非生物Fe（II）氧化占主导地位。铁（生物）矿物的存在下诱导的表面催化非生物的非生物Fe（II）氧化和减少的微生物的贡献，Fe（II）的氧化从40%到10%，在10 μ M O-2。所获得的结果将有助于更好地评估微需氧Fe（II）氧化对在各种环境中的自然和人为设置的地球化学铁循环的影响。
Neutrophilic microbial aerobic oxidation of ferrous iron (Fe(II)) is restricted to pH-circumneutral environments characterized by low oxygen where microaerophilic Fe(II)-oxidizing microorganisms successfully compete with abiotic Fe(II) oxidation. However, accumulation of ferric (bio)minerals increases competition by stimulating abiotic surface-catalyzed heterogeneous Fe(II) oxidation. Here, we present an experimental approach that allows quantification of microbial and abiotic contribution to Fe(II) oxidation in the presence or initial absence of ferric (bio)minerals. We found that at 20 mu M O-2 and the initial absence of Fe(III) minerals, an iron(II)-oxidizing enrichment culture (99.6% similarity to Sideroxydans spp.) contributed 40% to the overall Fe(II) oxidation within approximately 26 h and oxidized up to 3.6 x 10(-15) mol Fe(II) cell(-1) h(-1). Optimum O-2 concentrations at which enzymatic Fe(II) oxidation can compete with abiotic Fe(II) oxidation ranged from 5 to 20 mu M. Lower O-2 levels limited biotic Fe(II) oxidation, while at higher O-2 levels abiotic Fe(II) oxidation dominated. The presence of ferric (bio)minerals induced surface-catalytic heterogeneous abiotic Fe(II) oxidation and reduced the microbial contribution to Fe(II) oxidation from 40% to 10% at 10 mu M O-2. The obtained results will help to better assess the impact of microaerophilic Fe(II) oxidation on the biogeochemical iron cycle in a variety of environmental natural and anthropogenic settings.