Uncovering novel metabolism, microbial interactions and environmental roles of electroactive ANaerobic MEthanotrophic archaea

Anaerobic methanotrophic (ANME) archaea are ecologically critical microorganisms that remove methane from natural environments, thereby reducing emissions of this potent greenhouse gas. However, their physiology and ecology remain vastly unexplored due to the lack of axenic (single species) cultures of ANME archaea, their slow doubling times (in the order of weeks or months) and their complex nutritional requirements and interactions with other organisms. Recently, we achieved a breakthrough in ANME archaea cultivation, developing bioelectrochemical systems with highly enriched (>95% pure) and rapidly growing (doubling time ~4.5 days) cultures of Ca. Methanoperedens, a representative freshwater ANME archaeon. Now, in electroANME, we propose to leverage our expertise in growing and characterizing ANME archaea and our unique access to these near-axenic cultures to address urgent scientific questions related to microbial methane removal. In Aim 1, we will elucidate the molecular mechanisms involved in methane oxidation, particularly by elucidating how ANME archaea perform extracellular electron transfer to electron acceptors. In Aim 2, we will identify bacterial partners of ANME archaea and delineate the mechanisms involved in direct interspecies electron transfer between ANME archaea and bacteria. In Aim 3, we will explore the metabolic diversity of ANME archaea, including in the absence of external electron acceptors, and probe the environmental relevance of these metabolic processes. The findings from this project will not only provide novel insights into the physiology and ecology of ANME archaea but also have the potential to improve climate models and inform future biotechnological applications exploring the capacity of these microbes to oxidize methane, thereby helping to address the pressing societal problem of climate change.