The physiological role of Geobacter sulfurreducens extracellular cytochrome filaments is a matter of debate and the development of proposed electronic device applications of cytochrome filaments awaits methods for large-scale cytochrome nanowire production. Functional studies in G. sulfurreducens are stymied by the broad diversity of redox-active proteins on the outer cell surface and the redundancy and plasticity of extracellular electron transport routes. G. sulfurreducens is a poor chassis for producing cytochrome nanowires for electronics because of its slow, low-yield, anaerobic growth. Here we report that filaments of the G. sulfurreducens cytochrome OmcS can be heterologously expressed in Shewanella oneidensis. Multiple lines of evidence demonstrated that a strain of S. oneidensis, expressing the G. sulfurreducens OmcS gene on a plasmid, localized OmcS on the outer cell surface. Atomic force microscopy revealed filaments with the unique morphology of OmcS filaments emanating from cells. Electron transfer to OmcS appeared to require a functional outer-membrane porin-cytochrome conduit. The results suggest that S. oneidensis, which grows rapidly to high culture densities under aerobic conditions, may be suitable for the development of a chassis for producing cytochrome nanowires for electronics applications and may also be a good model microbe for elucidating cytochrome filament function in anaerobic extracellular electron transfer.

中文翻译：

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地杆菌胞外细胞色素 OmcS 丝在希瓦氏菌中的表达


硫还原地杆菌细胞外细胞色素丝的生理作用是一个有争议的问题，细胞色素丝的电子设备应用的开发正在等待大规模细胞色素纳米线生产的方法。 G.sulfurreducens 的功能研究因细胞外表面氧化还原活性蛋白的广泛多样性以及细胞外电子传输路径的冗余性和可塑性而受到阻碍。由于 G.sulfurreducens 生长缓慢、产量低、厌氧，因此不适合生产电子产品细胞色素纳米线。在这里，我们报道 G.硫还原细胞色素 OmcS 的丝可以在 Shewanella oneidensis 中异源表达。多种证据表明，在质粒上表达硫还原杆菌 OmcS 基因的 S. oneidensis 菌株将 OmcS 定位在细胞外表面。原子力显微镜揭示了从细胞中发出的具有 OmcS 细丝独特形态的细丝。电子转移到 OmcS 似乎需要功能性外膜孔蛋白-细胞色素导管。结果表明，S. oneidensis 在有氧条件下快速生长至高培养密度，可能适合开发用于生产电子应用细胞色素纳米线的底盘，也可能是阐明厌氧条件下细胞色素丝功能的良好模型微生物。细胞外电子转移。