Methanobacteriales is an order of archaeans in the class Methanobacteria.[1] Species within this order differ from other methanogens in that they can use fewer catabolic substrates and have distinct morphological characteristics, lipid compositions, and RNA sequences.[2] Their cell walls are composed of pseudomurein. Most species are Gram-positive with rod-shaped bodies and some can form long filaments. Most of them use formate to reduce carbon dioxide, but those of the genus Methanosphaera use hydrogen to reduce methanol to methane.[2]
Murray, RGE (1984). "The higher taxa, or, a place for everything...". In NR Krieg; JG Holt (eds.). Bergey's Manual of Systematic Bacteriology. Vol. 1 (1st ed.). Baltimore: The Williams & Wilkins Co. pp. 31–34.