energy derivation by oxidation of organic compounds
   |__cellular respiration
       |__anaerobic respiration
           |__anaerobic electron transport chain
           |__anaerobic respiration, using ammonium as electron donor
           |__dissimilatory sulfate reduction
           |__methanogenesis
               |__methane biosynthetic process from 3-(methylthio)propionic acid(+)
               |__methane biosynthetic process from carbon monoxide(+)
               |__methane biosynthetic process from dimethyl sulfide(+)
               |__methane biosynthetic process from dimethylamine(+)
               |__methane biosynthetic process from formic acid(+)
               |__methane biosynthetic process from methanethiol(+)
               |__methane biosynthetic process from methylamine(+)
               |__methane biosynthetic process from trimethylamine(+)
               |__methanogenesis, from acetate
               |__methanogenesis, from carbon dioxide
               |__methanogenesis, from methanol(+)