Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089, USA.
Proc Natl Acad Sci U S A. 2010 Oct 19;107(42):18127-31. doi: 10.1073/pnas.1004880107. Epub 2010 Oct 11.
Bacterial nanowires are extracellular appendages that have been suggested as pathways for electron transport in phylogenetically diverse microorganisms, including dissimilatory metal-reducing bacteria and photosynthetic cyanobacteria. However, there has been no evidence presented to demonstrate electron transport along the length of bacterial nanowires. Here we report electron transport measurements along individually addressed bacterial nanowires derived from electron-acceptor-limited cultures of the dissimilatory metal-reducing bacterium Shewanella oneidensis MR-1. Transport along the bacterial nanowires was independently evaluated by two techniques: (i) nanofabricated electrodes patterned on top of individual nanowires, and (ii) conducting probe atomic force microscopy at various points along a single nanowire bridging a metallic electrode and the conductive atomic force microscopy tip. The S. oneidensis MR-1 nanowires were found to be electrically conductive along micrometer-length scales with electron transport rates up to 10(9)/s at 100 mV of applied bias and a measured resistivity on the order of 1 Ω·cm. Mutants deficient in genes for c-type decaheme cytochromes MtrC and OmcA produce appendages that are morphologically consistent with bacterial nanowires, but were found to be nonconductive. The measurements reported here allow for bacterial nanowires to serve as a viable microbial strategy for extracellular electron transport.
细菌纳米线是一种细胞外的附属物，被认为是在包括异化金属还原菌和光合蓝藻在内的具有不同进化关系的微生物中进行电子传递的途径。然而，目前还没有证据表明电子可以沿着细菌纳米线进行传递。在这里，我们报告了来自异化金属还原菌 Shewanella oneidensis MR-1 的电子受体限制培养物中得到的单个细菌纳米线的电子传输测量结果。通过两种技术独立评估了纳米线中的传输：（i）在单个纳米线上的纳米制造电极图案化，以及（ii）在横跨金属电极和导电原子力显微镜尖端的单个纳米线上的各个点进行的导电探针原子力显微镜。发现 S. oneidensis MR-1 纳米线在微米长度范围内具有导电性，在 100 mV 的外加偏压下，电子传输速率高达 10(9)/s，测量的电阻率约为 1 Ω·cm。在 c 型 decaheme 细胞色素 MtrC 和 OmcA 基因缺失的突变体中产生的形态上与细菌纳米线一致的附属物，但被发现是不导电的。这里报告的测量结果表明，细菌纳米线可以作为一种可行的微生物策略，用于细胞外电子传递。
