Microbial Symbiosis: A Network towards Biomethanation.

Biomethanation through anaerobic digestion (AD) is the most reliable energy harvesting process to achieve waste-to-energy. Microbial communities, including hydrolytic and fermentative bacteria, syntrophic bacteria, and methanogenic archaea, and their interspecies symbioses allow complex metabolisms for the volumetric reduction of organic waste in AD. However, heterogeneity in organic waste induces community shifts in conventional anaerobic digesters treating sewage sludge at wastewater treatment plants globally. Assessing the metabolic roles of individual microbial species in syntrophic communities remains a challenge, but such information has important implications for microbially enhanced energy recovery. This review focuses on the alterations in digester microbiome and intricate interspecies networks during substrate variation, symbiosis among the populations, and their implications for biomethanation to aid stable operation in real-scale digesters.