Lusk Bradley G, Morgan Sheba, Mulvaney Shawn P, Blue Brandon, LaGasse Sam W, Cress Cory D, Bjerg Jesper T, Lee Woo K, Eddie Brian J, Robinson Jeremy T
Science the Earth, Mesa, AZ 85201.
National Research Council Research Associateships Program Postdoctoral Fellow Residing in the Chemistry Division, United States Naval Research Laboratory, Washington, DC 20375.
Proc Natl Acad Sci U S A. 2025 Jan 28;122(4):e2416008122. doi: 10.1073/pnas.2416008122. Epub 2025 Jan 13.
This study presents the direct measurement of proton transport along filamentous , or cable bacteria. Cable bacteria are filamentous multicellular microorganisms that have garnered much interest due to their ability to serve as electrical conduits, transferring electrons over several millimeters. Our results indicate that cable bacteria can also function as protonic conduits because they contain proton wires that transport protons at distances >100 µm. We find that protonic conductivity (σ) along cable bacteria varies between samples and is measured as high as 114 ± 28 µS cm at 25 °C and 70% relative humidity (RH). For cable bacteria, the protonic conductance (G) and σ are dependent upon the RH, increasing by as much as 26-fold between 60% and 80% RH. This observation implies that proton transport occurs via the Grotthuss mechanism along water associated with cable bacteria, forming proton wires. In order to determine σ and G along cable bacteria, we implemented a protocol using a modified transfer-printing technique to deposit either palladium interdigitated protodes (IDP), palladium transfer length method (TLM) protodes, or gold interdigitated electrodes (IDE) on top of cable bacteria. Due to the relatively mild nature of the transfer-printing technique, this method should be applicable to a broad array of biological samples and curved materials. The observation of protonic conductivity in cable bacteria presents possibilities for investigating the importance of long-distance proton transport in microbial ecosystems and to potentially build biotic or biomimetic scaffolds to interface with materials via proton-mediated gateways or channels.
本研究展示了对沿丝状或索状细菌的质子传输的直接测量。索状细菌是丝状多细胞微生物，因其能够作为电导体，在数毫米的距离上转移电子而备受关注。我们的结果表明，索状细菌也可以作为质子导体，因为它们含有能在大于100 µm的距离上传输质子的质子线。我们发现，沿索状细菌的质子传导率（σ）在不同样本间有所变化，在25°C和70%相对湿度（RH）下测量高达114±28 µS cm。对于索状细菌，质子电导（G）和σ取决于相对湿度，在60%至80% RH之间增加多达26倍。这一观察结果意味着质子传输通过Grotthuss机制沿着与索状细菌相关的水发生，形成质子线。为了确定沿索状细菌的σ和G，我们实施了一种方案，使用改良的转移印刷技术在索状细菌顶部沉积钯叉指电极（IDP）、钯转移长度法（TLM）电极或金叉指电极（IDE）。由于转移印刷技术性质相对温和，该方法应适用于广泛的生物样本和弯曲材料。在索状细菌中观察到质子传导率为研究微生物生态系统中长距离质子传输的重要性以及潜在构建生物或仿生支架以通过质子介导的网关或通道与材料接口提供了可能性。
