Filamentous cable bacteria, belonging to the family Desulfobulbaceae, are widely distributed in marine and freshwater sediments and can glide along vertical redox gradients at the sediment–water interface. They possess long-distance electron transport (LDET) capabilities, connecting sulfide-oxidizing zones with oxygen- or nitrate-reducing zones over centimeter scales, which distinguishes them from other electroactive bacteria that only perform short-range electron transfer. In this study, by observing the behavior of live filamentous cable bacteria, the researchers aim to reveal how they achieve LDET in environments where connections between distant electron donors and acceptors are lost. Understanding these strategies provides new insights into the energy flow between spatially separated electron donors and acceptors in sedimentary environments.
The research found that when cable bacteria lose direct connections between spatially separated electron donors and acceptors, they engage in brief mutual contacts. These contacts always occur end-to-end and are frequently repeated. Observations further revealed that cable bacteria exhibit noticeable sliding along extracellular polymeric substance (EPS) trails during contact, suggesting that EPS may play a key role in guiding precise alignment and contact between individual filaments. In situ Raman microscopy captured significant redox changes in c-type cytochromes during these contacts, providing strong evidence for active electron transfer between cable bacteria.
This study reveals a novel filament-to-filament interaction in microbiology, where cable bacteria can form end-to-end connections through highly precise physical contact. This unique interaction may allow LDET to overcome the limitations of individual cable bacteria. Such cooperative behavior not only enhances the efficiency of electron transfer but also reduces reliance on energy-intensive motility, enabling cable bacteria to better conserve energy, sustain survival, and maintain their ecological functions.
Read the full journal article titled End-to-end contact enables long-distance electron transport between filaments in cable bacteria in The ISME Journal. This article has been selected as Editor’s Choice for the month of August 2025.
Authors
- Rong Tang, Guangdong University of Technology, China
- Xiaoxue Zhang, Guangdong University of Technology, China
- Linyan Huang, Guangdong University of Technology, China
- Guoping Ren, Fujian Agriculture and Forestry University, China
- Yin Ye, Fujian Agriculture and Forestry University, China
- Yong Yuan, Guangdong University of Technology, China
- Shungui Zhou, Fujian Agriculture and Forestry University, China