A review of interspecies electron transfer in anaerobic digestion

Anaerobic digestion (AD) is an effective way to recover energy from organic waste. About 70% of the methane emitted into the atmosphere is derived from the degradation of organic matter by microorganisms under anaerobic conditions. Interspecies electron transfer (IET) is the key link of syntrophic methanogenesis, an in-depth understanding of IET during AD contributes to the rational use of energy. IET mainly includes three modes, namely, interspecies hydrogen transfer (IHT), interspecies formate transfer (IFT) and interspecies direct electron transfer (DIET). This review summarized and analyzed the IET patterns in the AD process, and related metabolic mechanisms and existing studies were explained.