Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame , 156 Fitzpatrick Hall, Notre Dame, Indiana, United States.
Environ Sci Technol. 2014 Jan 21;48(2):1015-22. doi: 10.1021/es404186v. Epub 2013 Dec 31.
Microorganisms in aerobic, circum-neutral environments are challenged to acquire sufficient nutrient Fe due to low solubilities of Fe oxides. To overcome this challenge, many aerobic microbes produce low molecular weight (MW) organic ligands, or siderophores, with extremely high Fe-binding affinities. This research expands the existing understanding of siderophore-mediated Fe acquisition from minerals by examining the effects of the siderophore desferrioxamine B (DFOB) on Fe removal from aquatic humic substances (XAD-8-isolated) and other organic matter (OM) isolates (reverse osmosis, RO; and "transphilic", XAD-4) from several rivers including the Suwannee River (GA, USA). Analysis of samples by asymmetrical flow field-flow fractionation (AsFlFFF) with in-line ICP-MS and UV-vis detectors showed that Fe was naturally abundant and primarily associated with intermediate to high MW OM. An excess of DFOB (relative to naturally present Fe) removed ∼ 75% of Fe and shifted the OM MW distribution to lower MWs, perhaps due to removal of "bridging" Fe, although additional mechanistic study of MW shifts is needed. Removal of other OM-associated metals (e.g., Al, Cu, Zn) by DFOB was minimal for all but a few samples. Fe bound to humic substances and other more "transphilic" organic components therefore should be considered readily bioavailable to aerobic, siderophore-producing microorganisms.
在有氧、近中性环境中，由于氧化铁的溶解度较低，微生物获取足够的营养铁是一项挑战。为了克服这一挑战，许多好氧微生物会产生具有极高铁结合亲和力的低相对分子质量（MW）有机配体，即铁载体。本研究通过考察铁载体去铁胺 B（DFOB）对从包括苏万尼河（美国佐治亚州）在内的几条河流中的 XAD-8 分离的水生腐殖质（XAD-8-分离）和其他有机物（RO 和“顺磁”，XAD-4）中矿物质介导的铁获取的影响，扩展了对铁载体介导的铁获取的现有理解。通过使用带有在线 ICP-MS 和 UV-vis 检测器的不对称流场流分离（AsFlFFF）对样品进行分析表明，铁自然丰富，主要与中等到高分子量的 OM 相关。DFOB 的过量（相对于天然存在的铁）去除了约 75%的铁，并将 OM 的 MW 分布转移到较低的 MW，这可能是由于去除了“桥接”铁，尽管需要进一步研究 MW 变化的机制。除了少数几个样品外，DFOB 对其他与 OM 相关的金属（例如 Al、Cu、Zn）的去除作用微不足道。因此，与腐殖质和其他更“顺磁”有机成分结合的铁应被视为好氧、产生铁载体的微生物容易获得的铁。
