Methanothrix soehngenii is a species of methanogenic archaea. Its cells are non-motile, non-spore-forming, rod-shaped (0.8ÃÂ2 üm) and are normally combined end to end in long filaments, surrounded by a sheath-like structure. It is named in honour of N. L. Söhngen.
Unlike other methanogenic archaea, Methanothrix soehngenii cannot reduce carbon dioxide with hydrogen to produce methane. Its sole source of energy is acetate.
The tRNA<sup>ala</sup> gene of Methanothrix soehngenii differs from those of other archaea in that it encodes a terminal CCA 3â².