Enhancing anaerobic digestion of complex organic waste with carbon-based conductive materials

[Display omitted] •Conductive materials stimulated methanogenesis in reactors treating food wastes.•Conductive materials promoted faster recovery of soured reactors.•Fermentative Sporanaerobacter and Enterococcus were enriched on carbon cloth.•Methanosarcina was also specifically enriched on carbon cloth.•The results suggest fermenter-methanogen DIET aided metabolism of complex waste. The aim of this work was to study the methanogenic metabolism of dog food, a food waste surrogate, in laboratory-scale reactors with different carbon-based conductive materials. Carbon cloth, carbon felt, and granular activated carbon all permitted higher organic loading rates and promoted faster recovery of soured reactors than the control reactors. Microbial community analysis revealed that specific and substantial enrichments of Sporanaerobacter and Methanosarcina were present on the carbon cloth surface. These results, and the known ability of Sporanaerobacter species to transfer electrons to elemental sulfur, suggest that Sporanaerobacter species can participate in direct interspecies electron transfer with Methanosarcina species when carbon cloth is available as an electron transfer mediator.