Aerobic Methanotrophy in Extreme Environments

Abstract Methanotrophy is the ability of a few prokaryotes to grow on methane as a sole energy source. Aerobic methanotrophic bacteria that couple methane oxidation to O 2 reduction are active in environments with pH values ranging from 1 to 11, temperatures ranging from 0 to 72°C, and salinities up to 30% w/v. Several extremophilic species of aerobic methanotrophs have been isolated and studied in pure culture, including thermophiles, psychrophiles, acidophiles, alkaliphiles and halophiles. Many of these isolates have multiple extremophilic phenotypes. The knowledge of aerobic methanotrophs in extreme environments, with particular focus on those studied in pure culture, is summarized here. Key Concepts Methane is oxidized by prokaryotes in diverse environments, including some with extreme temperatures, pH values and salinities. The ecology of extremophilic methanotrophs has been studied using cultivation‐independent molecular methods. Extremophilic methanotrophs have been isolated and studied in pure culture. Some aerobic methanotrophs combine multiple extremophilic phenotypes.