Biological electron transport is classically thought to occur over nanometre distances, yet recent studies suggest that electrical currents can run along centimetre-long cable bacteria. The phenomenon remains elusive, however, as currents have not been directly measured, nor have the conductive structures been identified. Here we demonstrate that cable bacteria conduct electrons over centimetre distances via highly conductive fibres embedded in the cell envelope. Direct electrode measurements reveal nanoampere currents in intact filaments up to 10.1 mm long (>2000 adjacent cells). A network of parallel periplasmic fibres displays a high conductivity (up to 79 S cm−1), explaining currents measured through intact filaments. Conductance rapidly declines upon exposure to air, but remains stable under vacuum, demonstrating that charge transfer is electronic rather than ionic. Our finding of a biological structure that efficiently guides electrical currents over long distances greatly expands the paradigm of biological charge transport and could enable new bio-electronic applications.
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机译：传统上认为生物电子传输发生在纳米距离上，但是最近的研究表明电流可以沿厘米长的电缆细菌传播。然而，这种现象仍然难以捉摸，因为尚未直接测量电流，也没有识别出导电结构。在这里，我们证明电缆细菌通过嵌入细胞膜中的高导电纤维在厘米范围内传导电子。直接电极测量揭示了完整长丝中的纳安电流，最长可达10.1毫米，（> 2000个相邻电池）。平行的周质纤维网络显示出高电导率（高达79 S cm -1 ），解释了通过完整细丝测得的电流。暴露于空气中后电导迅速下降，但在真空下保持稳定，这表明电荷转移是电子的，而不是离子的。我们发现的一种能有效地引导远距离电流的生物结构大大扩展了生物电荷传输的范式，并有可能实现新的生物电子应用。
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