Cable bacteria (Deltaproteobacteria, Desulfobulbaceae) are long filamentous sulfur-oxidizing bacteria that generate long-distance electric currents running through the bacterial filaments. This way, they couple the oxidation of sulfide in deeper sediment layers to the reduction of oxygen or nitrate near the sediment-water interface. Cable bacteria are found in a wide range of aquatic sediments, but an accurate procedure to assess their abundance is lacking. We developed a qPCR approach that quantifies cable bacteria in relation to other bacteria within the family Desulfobulbaceae. Primer sets targeting cable bacteria, Desulfobulbaceae and the total bacterial community were applied in qPCR with DNA extracted from marine sediment incubations. Amplicon sequencing of the 16S rRNA gene V4 region confirmed that cable bacteria were accurately enumerated by qPCR, and suggested novel diversity of cable bacteria. The conjoint quantification of current densities and cell densities revealed that individual filaments carry a mean current of ∼110 pA and have a cell specific oxygen consumption rate of 69 fmol O₂ cell^–1 day^–1. Overall, the qPCR method enables a better quantitative assessment of cable bacteria abundance, providing new metabolic insights at filament and cell level, and improving our understanding of the microbial ecology of electrogenic sediments.

电缆细菌（Deltaproteobacteria， 脱硫茎科）是长丝状的硫氧化细菌，会产生穿过细菌细丝的远距离电流。这样，它们将较深沉积物层中硫化物的氧化与沉积物-水界面附近的氧气或硝酸盐的还原相结合。在各种各样的水生沉积物中都发现了电缆细菌，但是缺乏准确的程序来评估其含量。我们开发了一种qPCR方法，该方法定量了与家庭中其他细菌有关的电缆细菌脱硫茎科。针对电缆细菌的引物组，脱硫茎科并将总细菌群落应用于从海洋沉积物培养中提取的DNA进行qPCR。16S rRNA基因V4区域的扩增子测序证实通过qPCR可以准确地枚举电缆细菌，并表明电缆细菌具有新颖的多样性。电流密度和细胞密度的联合定量分析表明，每根细丝的平均电流为〜110 pA，细胞比氧消耗率为69 fmol O ₂电池^–1天^–1天。总体而言，qPCR方法能够更好地定量评估电缆细菌的丰度，在细丝和细胞水平上提供新的代谢见解，并增进我们对电沉积沉积物微生物生态学的理解。