Which microorganism is the most common archaeal member of the human gut microbiome?

Methanobrevibacter smithii is the most common archaeal member of the human gut microbiome.

This anaerobic methanogen consumes hydrogen and carbon dioxide produced by other gut microbes, releasing methane. By removing hydrogen, it can influence fermentation and the flow of energy through microbial communities in the colon.

Unlike bacteria, archaea have distinctive cell membranes and molecular machinery. Their presence in people is usually studied through methane production, breath testing, stool samples, or genetic surveys rather than ordinary bacterial culture methods.

The species is associated with the human digestive tract, but its abundance varies among individuals and populations. It is not a disease-causing bacterium, and methane production does not by itself diagnose a digestive disorder. Its role is best understood as part of a complex microbial ecosystem in which many organisms exchange metabolic products.