3‐D analysis of bacterial cell‐(iron)mineral aggregates formed during Fe(II) oxidation by the nitrate‐reducing Acidovorax sp. strain BoFeN1 using complementary microscopy tomography approaches
3‐D analysis of bacterial cell‐(iron)mineral aggregates formed during Fe(II) oxidation by the nitrate‐reducing Acidovorax sp. strain BoFeN1 using complementary microscopy tomography approaches
复制标题
DOI：
10.1111/gbi.12088
复制
发表时间：
2014-07
期刊：
影响因子：
3.7
通讯作者：
Gregor Schmid;Fabian Zeitvogel;Likai Hao;Pablo Ingino;Matthias Floetenmeyer;Y. Stierhof;Birgit Schroeppel
中科院分区：
文献类型：
--
作者：
Gregor Schmid;Fabian Zeitvogel;Likai Hao;Pablo Ingino;Matthias Floetenmeyer;Y. Stierhof;Birgit Schroeppel
细菌铁氧化形成细胞-(铁)矿物团聚体是一种广泛存在于环境中的过程，对污染物和营养物质的吸附和共沉淀等过程有许多影响。虽然这种聚集体的整体外观很容易使用2-D显微镜技术获得，但3-D和内部结构仍然模糊不清。在这项研究中，我们研究了还原硝酸盐的Acidovorax sp.在Fe(II)氧化过程中形成的细胞(铁)矿物聚集体的三维结构。使用先进的3-D显微镜技术相结合的方法获得了BoFeN1菌株。我们在高空间分辨率(4-200 nm，取决于方法)下获得了关于不同细胞结皮模式的三维结构和化学信息：更具体地说，(1)不含铁矿物的细胞，(2)充满铁矿物的周质，(3)尖状或片状的铁矿物结构，(4)细胞表面的粗大结构，(5)细胞外的铁矿物外壳结构，(6)充满铁矿物的细胞质，以及(7)细胞外球状结构的聚集。除了结构信息，化学纳米断层扫描还表明，细胞外聚合物(EPS)在控制细胞-(铁)矿物聚集体的形成方面发挥了主导作用。此外，水合状态的样品在原始条件下显示细胞-(铁)矿物聚集体，没有制备(即干燥/脱水)人工制品。所有这些结果都是使用三维显微镜技术获得的，如聚焦离子束(FIB)/扫描电子显微镜(SEM)层析、透射电子显微镜(TEM)层析、扫描透射式(STXM)层析和激光共聚焦扫描显微镜(CLSM)。结果表明，由于不同方法的不同对比机制，以及所需的样品制备步骤，只有这些技术的结合才能全面了解各种铁沉淀物的结构和组成及其与细菌细胞和EPS的关系。
The formation of cell‐(iron)mineral aggregates as a consequence of bacterial iron oxidation is an environmentally widespread process with a number of implications for processes such as sorption and coprecipitation of contaminants and nutrients. Whereas the overall appearance of such aggregates is easily accessible using 2‐D microscopy techniques, the 3‐D and internal structure remain obscure. In this study, we examined the 3‐D structure of cell‐(iron)mineral aggregates formed during Fe(II) oxidation by the nitrate‐reducing Acidovorax sp. strain BoFeN1 using a combination of advanced 3‐D microscopy techniques. We obtained 3‐D structural and chemical information on different cellular encrustation patterns at high spatial resolution (4–200 nm, depending on the method): more specifically, (1) cells free of iron minerals, (2) periplasm filled with iron minerals, (3) spike‐ or platelet‐shaped iron mineral structures, (4) bulky structures on the cell surface, (5) extracellular iron mineral shell structures, (6) cells with iron mineral filled cytoplasm, and (7) agglomerations of extracellular globular structures. In addition to structural information, chemical nanotomography suggests a dominant role of extracellular polymeric substances (EPS) in controlling the formation of cell‐(iron)mineral aggregates. Furthermore, samples in their hydrated state showed cell‐(iron)mineral aggregates in pristine conditions free of preparation (i.e., drying/dehydration) artifacts. All these results were obtained using 3‐D microscopy techniques such as focused ion beam (FIB)/scanning electron microscopy (SEM) tomography, transmission electron microscopy (TEM) tomography, scanning transmission (soft) X‐ray microscopy (STXM) tomography, and confocal laser scanning microscopy (CLSM). It turned out that, due to the various different contrast mechanisms of the individual approaches, and due to the required sample preparation steps, only the combination of these techniques was able to provide a comprehensive understanding of structure and composition of the various Fe‐precipitates and their association with bacterial cells and EPS.