Extended Data Fig. 2: Metatranscriptomic results of a microbial electrolysis cell system.

a. Schematic representation of methane production comparing MEC (poised cathode, −0.5 V vs. SHE) and non-energized (NE) control conditions. Statistical significance was assessed using a two-sided Student’s t-test. p for CH4 (%):3.94 × 10−2⁰; p for CH4 (mL): 9.01 × 10−2⁰. b. Taxonomic composition of dominant methanogenic species detected in biocathode and bulk sludge samples across treatments. c. The expression levels (Transcripts Per Kilobase Million, TPM) of key fpo genes in Methanothrix and Methanosarcina taxa under MEC and NE conditions. d. The expression levels of CO2 reduction genes in Methanothrix and Methanosarcina taxa. e. The expression levels of flaB gene attributed to Methanosarcina and Methanospirillum. f. The expression levels of Mspa (Mthe_1070) gene attributed to Methanothrix. ***: p < 0.001.