Editorial: The microbiology of the biogas process.

The world is facing unprecedent challenges, related with energy crisis and climate change. 35 Intensification of renewable energy production, with special focus on sustainable biogas and 36 biomethane, is one of the front-line topics today. Biogas/biomethane will play a role in the transition 37 towards climate-neutral and secure energy system. Ensuring that biomethane is produced from 38 organic waste/wastewater is essential to support circularity and sustainability. Scaling up biomethane 39 production and assuring its economic competitiveness are current key challenges. 40 Biogas generation occurs in natural and engineered environments, such as anaerobic bioreactors, and 41 involves a cascade of reactions catalyzed by complex microbial communities. In summary, this Research Topic explores both applied and fundamental aspects of anaerobic 107 microbial communities thriving in biogas processes, highlighting the importance of key microbial 108 players and crucial microbial interactions on the performance and stability of these systems. We hope 109 that this collection will inspire future works pursuing the goals of sustainable waste-based high-110 performance bioenergy-producing AD systems. 111 112