Department of Material Chemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan.
Appl Environ Microbiol. 2011 May;77(9):2877-81. doi: 10.1128/AEM.02867-10. Epub 2011 Mar 4.
The so-called Fe/Mn-oxidizing bacteria have long been recognized for their potential to form extracellular iron hydroxide or manganese oxide structures in aquatic environments. Bacterial species belonging to the genus Gallionella, one type of such bacteria, oxidize iron and produce uniquely twisted extracellular stalks consisting of iron oxide-encrusted inorganic/organic fibers. This paper describes the ultrastructure of Gallionella cells and stalks and the visualized structural and spatial localization of constitutive elements within the stalks. Electron microscopy with energy-dispersive X-ray microanalysis showed the export site of the stalk fibers from the cell and the uniform distribution of iron, silicon, and phosphorous in the stalks. Electron energy-loss spectroscopy revealed that the stalk fibers had a central carbon core of bacterial exopolymers and that aquatic iron interacted with oxygen at the surface of the carbon core, resulting in deposition of iron oxides at the surface. This new knowledge of the structural and spatial associations of iron with oxygen and carbon provides deeper insights into the unique inorganic/organic hybrid structure of the stalks.
所谓的 Fe/Mn- 氧化细菌长期以来一直被认为具有在水生环境中形成细胞外氢氧化铁或氧化锰结构的潜力。属于嘉利翁氏菌属（Gallionella）的细菌种类就是其中的一种，它能氧化铁并产生独特扭曲的细胞外菌柄，由氧化铁包裹的无机/有机纤维组成。本文描述了嘉利翁氏菌细胞和菌柄的超微结构，以及菌柄内组成元素的可视化结构和空间定位。电子显微镜和能量色散 X 射线微分析显示，菌柄纤维从细胞中输出的位置以及菌柄中铁、硅和磷的均匀分布。电子能量损失光谱揭示了菌柄纤维具有细菌胞外聚合物的中央碳核，并且水中的铁与碳核表面的氧相互作用，导致铁氧化物在表面沉积。这种铁与氧和碳的结构和空间关联的新知识为菌柄独特的无机/有机混合结构提供了更深入的了解。
