Photochemical cycling of iron in the surface ocean mediated by microbial iron(III)-binding ligands
Photochemical cycling of iron in the surface ocean mediated by microbial iron(III)-binding ligands
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DOI：
10.1038/35096545
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发表时间：
2001-09-27
期刊：
影响因子：
64.8
通讯作者：
Butler, A
中科院分区：
文献类型：
--
作者：
Barbeau, K;Rue, EL;Butler, A
铁是海洋大片区域初级生产的一种限制性营养物质（1 - 4）。海洋上层溶解的铁（III）几乎完全以与强有机配体形成的复合物形式存在（5 - 7），这些配体被认为是生物源的（8，9）。尽管有机配体对水体铁循环的重要性日益明确，但它们参与这一过程的机制仍不确定。在此我们报道了涉及与铁载体结合的铁（III）的光化学反应的观测结果——铁载体是细菌产生的高亲和力铁（III）配体，用于促进铁的获取（10 - 12）。我们表明，铁（III） - 铁载体复合物的光解会导致低亲和力铁（III）配体的形成以及铁（III）的还原，增加了与铁载体结合的铁可供浮游生物群落摄取的可能性。这些光化学反应是由α - 羟基酸部分介导的，这是一个通常被发现存在于已被鉴定的海洋铁载体中的基团（13 - 15）。我们认为，铁（III）结合配体能够增强透光层中活性铁物种的光解产生，从而影响水生系统中铁的可利用性。
Iron is a limiting nutrient for primary production in large areas of the oceans(1-4). Dissolved iron(III) in the upper oceans occurs almost entirely in the form of complexes with strong organic ligands(5-7) presumed to be of biological origin(8,9). Although the importance of organic ligands to aquatic iron cycling is becoming clear, the mechanism by which they are involved in this process remains uncertain. Here we report observations of photochemical reactions involving Fe(III) bound to siderophores-high-affinity iron(III) ligands produced by bacteria to facilitate iron acquisition(10-12). We show that photolysis of Fe(III)-siderophore complexes leads to the formation of lower-affinity Fe(III) ligands and the reduction of Fe(III), increasing the availability of siderophore-bound iron for uptake by planktonic assemblages. These photochemical reactions are mediated by the alpha -hydroxy acid moiety, a group which has generally been found to be present in the marine siderophores that have been characterized(13-15). We suggest that Fe(III)-binding ligands can enhance the photolytic production of reactive iron species in the euphotic zone and so influence iron availability in aquatic systems.