Environmental Transcription of mmoX by Methane-Oxidizing Proteobacteria in a Subarctic Palsa Peatland

Methane-oxidizing bacteria (MOB) that possess the soluble form of methane monooxygenase (sMMO) are present in various environments, but unlike the prevalent particulate methane monooxygenase (pMMO), the in situ activity of sMMO has not been documented. Here we report on the environmental transcription of a gene (mmoX) for this enzyme, which was attributed mainly to MOB lacking a pMMO. Our study indicates that the sMMO is an active enzyme in acidic peat ecosystems, but its importance for the mitigation of methane releases remains unknown.