Electromethanogenesis refers to the bioelectrochemical synthesis of methane from CO₂ by biocathodes. In an electromethanogenic system using thermophilic microorganisms, metagenomic analysis along with quantitative real-time polymerase chain reaction and fluorescence in situ hybridization revealed that the biocathode microbiota was dominated by the methanogen Methanothermobacter sp. strain EMTCatA1 and the actinobacterium Coriobacteriaceae sp. strain EMTCatB1. RNA sequencing was used to compare the transcriptome profiles of each strain at the methane-producing biocathodes with those in an open circuit and with the methanogenesis inhibitor 2-bromoethanesulfonate (BrES). For the methanogen, genes related to hydrogenotrophic methanogenesis were highly expressed in a manner similar to those observed under H₂-limited conditions. For the actinobacterium, the expression profiles of genes encoding multiheme c-type cytochromes and membrane-bound oxidoreductases suggested that the actinobacterium directly takes up electrons from the electrode. In both strains, various stress-related genes were commonly induced in the open-circuit biocathodes and biocathodes with BrES. This study provides a molecular inventory of the dominant species of an electromethanogenic biocathode with functional insights and therefore represents the first multiomics characterization of an electromethanogenic biocathode.

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产甲烷菌和放线菌在产甲烷生物阴极的嗜热微生物群落中占主导地位的分析

产甲烷是指通过生物阴极从CO ₂生物电化学合成甲烷。在使用嗜热微生物的产甲烷系统中，宏基因组分析以及定量实时聚合酶链反应和荧光原位杂交显示生物阴极微生物群由产甲烷菌Methanothermobacter sp.主导。菌株 EMTCatA1 和放线杆菌Coriobacteriaceaesp. 菌株 EMTCatB1。RNA测序用于比较产甲烷生物阴极中每个菌株与开路和产甲烷抑制剂2-溴乙磺酸盐（BrES）的转录组谱。对于产甲烷菌，与氢营养产甲烷相关的基因以类似于在 H ₂下观察到的方式高表达- 条件有限。对于放线菌，编码多血红素 c 型细胞色素和膜结合氧化还原酶的基因的表达谱表明放线菌直接从电极吸收电子。在这两种菌株中，通常在开路生物阴极和带有 BrES 的生物阴极中诱导各种应激相关基因。该研究提供了具有功能洞察力的电甲烷生物阴极的主要物种的分子清单，因此代表了电甲烷生物阴极的第一个多组学表征。