Harnessing Microbial Diversity and Genetic Variability for Unraveling the Potential of CO2 Methanation

The growing ecological crisis, driven by fossil fuel consumption, has propelled the urgent search for sustainable energy alternatives. Transitioning to renewable sources must be coupled with the development of new technologies to manage hard-to-abate emissions. Carbon Capture, Utilization, and Storage (CCUS) is a promising strategy, capturing carbon dioxide (CO2) from industrial sources for storage or reprocessing. Biological methanation offers a promising approach for integrating CO2 into a circular economy framework. This process utilizes hydrogenotrophic archaea in a mixed community as catalysts to convert CO2 to methane (CH₄) using hydrogen (H₂) as electron acceptor. This thesis examines the potential of CO2 methanation using a hybrid approach: DNA-stable isotope probing (DNA-SIP) and compiling a comprehensive list of microorganisms and their functions involved in CO2 methanation processes. The identification of populations associated in the consumption of CO2 provides competitive dynamics within this system. Concurrently, a metagenomic analysis is performed, using shotgun sequencing data from various CO2 biomethanation experiments. This combined approach allows the exploration of the global microbial diversity associated with this process, through the identification of the community structure, functional roles, and potential interactions. By unraveling these complexities, this research maximizes the potential of CO2 methanation for sustainable energy production and greenhouse gas reduction.