[2] They are sulfate-reducing archaea, coupling the reduction of sulfate to sulfide with the oxidation of many different organic carbon sources, including complex polymers.

The function of these genes in A. fulgidus remains unknown, while the lack of the enzyme methyl-CoM reductase does not allow for methanogenesis to occur by a mechanism similar to that found in other methanogens.

They can produce biofilm when subjected to environmental stresses such as extreme pH or temperature, high concentrations of metal, or the addition of antibiotics, xenobiotics, or oxygen.

This suggests metabolic differentiation specifically with respect to the decomposing and recycling carbon pathways through scavenged fatty acids.

However, the possibility that the shared presence of these signature proteins in these archaeal lineages is due to lateral gene transfer cannot be excluded.

[2] The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN)[5] and National Center for Biotechnology Information (NCBI).