title: Understanding methane bioelectrosynthesis from carbon dioxide in a two-chamber microbial electrolysis cells (MECs) containing a carbon biocathode.
abstract: To better understand the underlying mechanisms for methane bioelectrosynthesis, a two-chamber MECs containing a carbon biocathode was developed and studied. Methane production substantially increased with increasing cathode potential. Considerable methane yield was achieved at a poised potential of -0.9 V (vs. Ag/AgCl), reaching 2.30±0.34 mL after 5 h of operation with a faradaic efficiency of 24.2±4.7%. Confirmatory tests done at 0.9 V by switching the type of flushed substrates (CO2/N2) or the electrical exposure modes (ON/OFF) demonstrated that cathode serving as an electron donor was the vital driving force for methanogenesis occurring at microbe-electrode surface. Fluorescence in situ hybridization reveled Methanobacteriaceae (particularly Methanobacterium) was the predominant methanogens, supporting the mechanisms of direct electron transfer between cell-electrode. Additionally, the analysis of scanning electron microscope confirmed that the multiple pathways of electron transfer, including direct cathode-to-cell, interspecies exchange and semi-conductive conduits all together ensured the successful electromethanogenesis process.
authors: Center for Material Cycles and Waste Management Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan. Electronic address: zhenguangyin@163.com.
authors: Guangyin
authors: G
authors: Zhen
authors: Center for Material Cycles and Waste Management Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan.
authors: Takuro
authors: T
authors: Kobayashi
authors: Department of Civil and Environmental Engineering, Graduate School of Engineering, Tohoku University, Sendai, Miyagi 980-8579, Japan.
authors: Xueqin
authors: X
authors: Lu
authors: Center for Material Cycles and Waste Management Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan. Electronic address: joexu@nies.go.jp.
authors: Kaiqin
authors: K
authors: Xu
mesh_terms: D001674:Bioelectric Energy Sources / Q000382:microbiology*; D002244:Carbon / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism*; D004560:Electricity; D004563:Electrochemistry / Q000379:methods; D004566:Electrodes / Q000382:microbiology*; D004572:Electrolysis / Q000379:methods; D008697:Methane / Q000096:biosynthesis* / Q000378:metabolism*; D017014:Methanobacterium / Q000378:metabolism*
chemical_list: D002245:Carbon Dioxide; D002244:Carbon; D008697:Methane
keywords: CO(2) reduction; Electromethanogenesis; Electron transfer; Methane production; Microbial electrolysis cells