methanogens

https://doi.org/10.1351/goldbook.M03879
Strictly @A00316@ archaebacteria, able to use only a very limited substrate spectrum (e.g. molecular hydrogen, formate, methanol, methylamine, carbon monoxide or acetate) as electron donors for the reduction of carbon dioxide to methane.
Source:
PAC, 1992, 64, 143. (Glossary for chemists of terms used in biotechnology (IUPAC Recommendations 1992)) on page 160 [Terms] [Paper]