DIET-based Simplified Lignocellulose-to-Methane Consortia (DIETsimp)

Two simplified methanogenic consortia (DIETsimp) constructed by top-down selection from cow manure combined with paddy soil or marine sediment inocula for high-efficiency conversion of lignocellulose to methane via direct interspecies electron transfer (DIET). Metagenomic analysis identified Methanosarcina mazei, capable of accepting electrons via DIET, as the dominant archaeon, and the electroactive bacteria Sphaerochaeta globosa and Clostridium aceticum as the dominant bacteria. The proposed DIET-based methanogenic pathway has S. globosa and C. aceticum metabolizing intermediates (xylose, glucose, pyruvate, acetate) and transferring electrons to M. mazei for reduction of CO2 to methane. Both consortia shortened methanogenesis periods and increased methane production rates relative to conventional anaerobic digestion.