Methanothrix soehngenii is a species of methanogenic archaea.
Its cells are non-motile, non-spore-forming, rod-shaped (0.8×2 μm) and are normally combined end to end in long filaments, surrounded by a sheath-like structure.
[1] Unlike other methanogenic archaea, Methanothrix soehngenii cannot reduce carbon dioxide with hydrogen to produce methane.
Its sole source of energy is acetate.
[2] The tRNAala gene of Methanothrix soehngenii differs from those of other archaea in that it encodes a terminal CCA 3′.