Cable bacteria are filamentous, multicellular microorganisms that display an exceptional form of biological electron transport across centimeter-scale distances. Currents are guided through a network of nickel-containing protein fibers within the cell envelope. Still, the mechanism of long-range conduction remains unresolved. Here, we characterize the conductance of the fiber network under dry and wet, physiologically relevant, conditions. Our data reveal that the fiber conductivity is high (median value: 27 S cm; range: 2 to 564 S cm), does not show any redox signature, has a low thermal activation energy ( = 69 ± 23 meV), and is not affected by humidity or the presence of ions. These features set the nickel-based conduction mechanism in cable bacteria apart from other known forms of biological electron transport. As such, conduction resembles that of an organic semi-metal with a high charge carrier density. Our observation that biochemistry can synthesize an organo-metal-like structure opens the way for novel bio-based electronic technologies.

中文翻译：

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电缆细菌长程传导的类有机金属性质

电缆细菌是丝状多细胞微生物，具有跨厘米级距离的生物电子传输的特殊形式。电流被引导通过细胞膜内的含镍蛋白质纤维网络。尽管如此，长程传导的机制仍未解决。在这里，我们表征了纤维网络在干燥和潮湿、生理相关条件下的电导率。我们的数据表明，纤维电导率较高（中值：27 S cm；范围：2 至 564 S cm），不显示任何氧化还原特征，具有较低的热活化能 (= 69 ± 23 meV)，并且不具有任何氧化还原特征。受湿度或离子存在的影响。这些特征使电缆细菌中的镍基传导机制有别于其他已知形式的生物电子传输。因此，导电类似于具有高载流子密度的有机半金属。我们观察到生物化学可以合成类似有机金属的结构，为新型生物基电子技术开辟了道路。