Department of Biological Sciences, California State University, Chico, Chico, California, USA
Bigelow Laboratory for Ocean Sciences, East Boothbay, Maine, USA.
Appl Environ Microbiol. 2018 Apr 16;84(9). doi: 10.1128/AEM.02239-17. Print 2018 May 1.
is known for producing large volumes of iron oxyhydroxide sheaths that alter wetland biogeochemistry. For over a century, these delicate structures have fascinated microbiologists and geoscientists. Because still resists long-term culture, the debate regarding its metabolic classification dates back to 1885. We developed a novel culturing technique for using natural waters and coupled this with single-cell genomics and nanoscale secondary-ion mass spectrophotometry (nanoSIMS) to probe 's physiology. In microslide cultures doubled every 5.7 h and had an absolute growth requirement for ferrous iron, the genomic capacity for iron oxidation, and a branched electron transport chain with cytochromes putatively involved in lithotrophic iron oxidation. Additionally, its genome encoded several electron transport chain proteins, including a molybdopterin alternative complex III (ACIII), a cytochrome oxidase reductase, and several terminal oxidase genes. contained two key autotrophic proteins in the Calvin-Benson-Bassham cycle, a form II ribulose bisphosphate carboxylase, and a phosphoribulose kinase. also assimilated bicarbonate, although calculations suggest that bicarbonate assimilation is a small fraction of its total carbon assimilation. Finally, 's fundamental physiology is a hybrid of those of the chemolithotrophic type iron-oxidizing bacteria and the sheathed, heterotrophic filamentous metal-oxidizing bacteria of the genera. This allows to inhabit a unique niche within the neutrophilic iron seeps. was one of three groups of organisms that Sergei Winogradsky used in the 1880s to develop his hypothesis on chemolithotrophy. continues to resist cultivation and appears to have an absolute requirement for organic-rich waters, suggesting that its true physiology remains unknown. Further, is an ecological engineer; a few cells can generate prodigious volumes of iron oxyhydroxides, changing the ecosystem's geochemistry and ecology. Therefore, to determine 's basic physiology, we employed new single-cell techniques to demonstrate that oxidizes iron to generate energy and, despite having predicted genes for autotrophic growth, assimilates a fraction of the total CO that autotrophs do. Although not a true chemolithoautotroph, 's physiological strategy allows it to be flexible and to extensively colonize iron-rich wetlands.
它以产生大量改变湿地生物地球化学的铁氧氢氧化物鞘而闻名。一个多世纪以来，这些脆弱的结构一直吸引着微生物学家和地球科学家的注意。由于 仍然难以长期培养，关于其代谢分类的争论可以追溯到 1885 年。我们开发了一种用于 的新型培养技术，使用天然水，并将其与单细胞基因组学和纳米级二次离子质谱法 (nanoSIMS) 相结合，以探究 的生理学。在微载玻片培养中， 每 5.7 小时倍增一次，绝对需要亚铁铁、氧化铁的基因组能力以及具有细胞色素的分支电子传递链，这些细胞色素可能参与了自养铁氧化作用。此外，其基因组编码了几种电子传递链蛋白，包括钼喋呤替代复合物 III（ACIII）、细胞色素 氧化还原酶和几种末端氧化酶基因。 含有卡尔文-本森-巴斯汉姆循环中的两个关键自养蛋白，一种形式 II 核酮糖 1,5-二磷酸羧化酶和磷酸核糖激酶。 还同化了碳酸氢盐，尽管计算表明碳酸氢盐同化作用只是其总碳同化作用的一小部分。最后， 的基本生理学是化学自养型铁氧化细菌和鞘状异养丝状金属氧化细菌的混合体。这使得 能够在中性铁渗出物中占据独特的生态位。 是谢尔盖·温纳戈斯基 (Sergei Winogradsky) 在 19 世纪 80 年代用来发展他的化学自养假说的三种生物体之一。 仍然难以培养，似乎绝对需要富含有机物的水，这表明其真正的生理学仍然未知。此外， 是生态工程师；几个 细胞可以产生大量的铁氧氢氧化物，改变生态系统的地球化学和生态学。因此，为了确定 的基本生理学，我们采用了新的单细胞技术来证明 氧化铁以产生能量，尽管有预测的自养生长基因，但只同化了自养生物总 CO 的一部分。尽管不是真正的化学自养生物，但 的生理策略使其具有灵活性，并能广泛地在富含铁的湿地中定殖。
