Iron oxyhydroxide mineralization on microbial extracellular polysaccharides
Iron oxyhydroxide mineralization on microbial extracellular polysaccharides
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DOI：
10.1016/j.gca.2009.02.036
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发表时间：
2009-07-01
影响因子：
5
通讯作者：
Banfield, Jillian F.
中科院分区：
文献类型：
--
作者：
Chan, Clara S.;Fakra, Sirine C.;Banfield, Jillian F.
铁生物矿物可以在中性pH微需氧环境中形成，其中微生物既催化铁氧化又产生使矿物沉淀局部化的聚合物。为了对影响FeOOH矿物学的微生物聚合物进行分类，我们使用扫描透射X射线显微镜（STXM），微X射线荧光（mu XRF）显微镜和高分辨率透射电子显微镜（HRTEM）研究了生物矿物的有机和矿物成分。我们重点研究了来自小溪和废弃矿井的铁微生物垫样本;这些样本以氢氧化铁涂层结构为主，具有鞘、茎和细丝形态。此外，我们的特点是铁氧化，茎形成细菌培养物从矿山分离的矿化产物。在自然和培养的样品中，微生物聚合物被发现是具有羧基官能团的酸性多糖，与羟基氧化铁分布模式在空间上密切相关。有机纤维收集FeOOH并控制其重结晶，在某些情况下导致具有高纵横比的定向晶体。随着材料的老化，聚合物的影响尤其明显。模拟生物矿化过程的合成实验表明，多糖羧基强烈地结合溶解的铁，但随着矿化的进行而释放。我们的研究结果表明，羧基的酸性多糖由不同的微生物产生，以创建一个广泛的羟基氧化铁生物矿物结构。这种密切的和潜在的长期关联控制着自然体系中羟基氧化铁纳米颗粒的晶体生长、相态和反应性。(C)2009爱思唯尔有限公司版权所有。
Iron biominerals can form in neutral pH microaerophilic environments where microbes both catalyze iron oxidation and create polymers that localize mineral precipitation. In order to classify the microbial polymers that influence FeOOH mineralogy, we studied the organic and mineral components of biominerals using scanning transmission X-ray microscopy (STXM), micro X-ray fluorescence (mu XRF) microscopy, and high-resolution transmission electron microscopy (HRTEM). We focused on iron microbial mat samples from a creek and abandoned mine; these samples are dominated by iron oxyhydroxide-coated structures with sheath, stalk, and filament morphologies. In addition, we characterized the mineralized products of an iron-oxidizing, stalk-forming bacterial culture isolated from the mine. In both natural and cultured samples, microbial polymers were found to be acidic polysaccharides with carboxyl functional groups, strongly spatially correlated with iron oxyhydroxide distribution patterns. Organic fibrils collect FeOOH and control its recrystallization, in some cases resulting in oriented crystals with high aspect ratios. The impact of polymers is particularly pronounced as the materials age. Synthesis experiments designed to mimic the biomineralization processes show that the polysaccharide carboxyl groups bind dissolved iron strongly but release it as mineralization proceeds. Our results suggest that carboxyl groups of acidic polysaccharides are produced by different microorganisms to create a wide range of iron oxyhydroxide biomineral structures. The intimate and potentially long-term association controls the crystal growth, phase, and reactivity of iron oxyhydroxide nano-particles in natural systems. (C) 2009 Elsevier Ltd. All rights reserved.