Methane matters: from blue-tinged moos, to boozy roos, and the health of humans too

• Methane emissions from ruminant livestock are proposed to contribute ~10 to 20% of annual global greenhouse gas emissions. • Recent efforts have shown that "low methane emitting" animals can be identified both within and across species, including nondomesticated herbivores. • Methanogens are also present within the human gut and some other body sites, and variations in their diversity and/or abundance has been linked to some functional gastrointestinal disorders and non-communicable chronic diseases. • Recent advances in "-omics" technologies have provided new insights of the roles that methanogens play in both feed digestion and host-microbe interactions. • Although much research and understanding has been derived from the study of the numerically dominant Methanobrevibacter genus, the recent studies outlined above have shown that other, "heterotrophic" methanogens warrant greater attention. • Here, we provide a brief overview of our recent research of the Methanosphaera genus and outline the possible consequences associated with its presence in the gut of livestock, native Australian herbivores, and humans.