Metabolic Flexibility of Microbial Methane Oxidation

Methane is the second most important greenhouse gas after carbon dioxide and contributes up to 20% to current global warming. Microbial methane oxidation plays a significant role in mitigating methane emission to the atmosphere and therefore is a crucial process to understand in the battle against climate change, where methane mitigation has highest priority as recently reported by the IPCC. Methanotrophs have long been believed to be exclusively dependent on methane for carbon and energy. However, research in the past two decades has demonstrated a much higher metabolic versatility of these environmentally highly relevant microbes. Methanotrophs have been shown to utilize multicarbon compounds in addition to methane, presumably deriving a competitive advantage from this metabolic versatility. They also can oxidize ammonia, fix nitrogen and catalyze denitrification, hydrogen metabolism and glycolysis under environmental stress such as nitrate, hydrogen and low oxygen concentrations. Additionally, it has been shown that microbial methane oxidation can be coupled to denitrification, sulfate reduction and metal reduction such as iron and manganese under anoxic conditions. These novel insights into the metabolic versatility of methanotrophs also has implication for the interaction with other organisms in the environment. Methanotrophs have been demonstrated to provide methane-derived carbon to food chains in terrestrial and aquatic ecosystems designated them as “primary producers”.

There is a high demand toward elucidating the role of methanotrophs in global climate models, reducing uncertainty in global methane emissions therein, as well as developing methanotrophs as biotechnological platforms for production of methane-based building blocks for industry. Hence, both from the viewpoint of climate change mitigation as well as sustainability, synthesis and deepening of the current knowledge on metabolic potential of these intriguing microbes is necessary.

Research themes on “Metabolic flexibility of microbial methane oxidation” represent a collective focus on ecology, physiology, genomics, metabolomics and proteomics of key methane oxidizers in various natural and man-made ecosystems. New organisms, novel metabolic pathways, and new biogeochemical processes will be the key to calculate methane flux and reduce the uncertainty of predictive climate change models from various ecosystems, and to develop biotechnologies of methanotrophs in methane mitigation for the production of valuable bioproducts enabling a bio-based and circular economy.

This Research Topic aims to present original research articles and reviews in order to provide solid new findings with regard to the metabolic flexibility of microbial methane oxidation under aerobic and anaerobic conditions. Topics to be covered include, but are not limited to, review and original research in: (1) genomics, metabolomics and proteomics of methanotrophs utilizing methane and other compounds; (2) community structure and metabolic characteristics of methanotrophs and their associated archaea under anoxic conditions; (3) interaction between methanotrophs and non-methanotrophs in various habits; and (4) emerging tools and approaches to study methanotrophs and their function. The present topic is hosted in Frontiers in Terrestrial Microbiology, Frontiers in Aquatic Microbiology and Frontiers in Evolutionary and Genomic Microbiology to ensure a wide range of contributions.