What is "methanomicrobiales"

In the taxonomy of microorganisms, the Methanomicrobiales are an order of the Methanomicrobia. Methanomicrobiales are strictly carbon dioxide reducing methanogens, using hydrogen or formate as the reducing agent. As seen from the phylogenetic tree based on the 'The All-Species Living Tree' Project the family Methanomicrobiaceae is highly polyphyletic within the Methanomicrobiales.