Table 1.

Examples of common methanogens reportedly present in full-scale anaerobic digesters of wastewater treatment plants and some genus-specific information.

Class	Genus	Temperature optimum	Gram stain	pH growth	Motility	Genome size (Mb)a	Genesa	Substrate usage / Notes	References
Methanobacteria	Methanobrevibacter	Mesophiles	+	5.0–10	NM	1.7–2.9	1,700–2,020	Hydrogen, carbon dioxide	A, B
Methanobacteria	Methanothermobacter	Thermophiles	+	5.0–9.0	NM	1.6–1.8	1,750–1,860	Hydrogen, carbon dioxide	A, B
Methanobacteria	Methanobacterium	Mesophiles	+, −	5.5–9.9	NM	2.4–2.6	2,411–2,584	Hydrogen, carbon dioxide, formate, alcohols or carbon monoxide / filamentous growth	B, C
Thermococci	Candidatus Methanofastidiosum	Mesophiles	NA	NA	NA	1.5–1.99	NA	Methylated thiol	A, H
Methanomicrobia	Methanolinea	Mesophiles	−	6.7–8.0	NM	~2.0	~2,108	Hydrogen, carbon dioxide, formate / filamentous growth	D, B
Methanomicrobia	Methanospirillum	Mesophiles	−	6.5–10	M, NM	~3.5	~3,294	Hydrogen, carbon dioxide, formate, 2-probanol, 2-butanol	A, B
Methanomicrobia	Methanoculleus	Mesophiles	−	5.0–8.5	M, NM	2.15–2.9	NA	Hydrogen, carbon dioxide, formate / associated with high ammonium levels	A, B, E, F, G
Methanomicrobia	Methanoregula	Mesophiles	−	4.5–5.5	NM	~2.6	~2,517	Hydrogen, carbon dioxide / acidophilic	B, C
Methanomicrobia	Methanothrix b	Mesophiles	−	5.5–8.4	NM	~2.8	~3,008	Acetate / filamentous; often the most abundant genus	A, B, I
Methanosarcinia	Methanosarcina	Mesophiles & Thermophiles	+, −	5.0–8.9	NM	3.4–5.8	3,434–4,721	Acetate, hydrogen, carbon dioxide, methanol / abundant	A, B

^abased on referenced type strains or metagenome assembled genomes.

^bSynonym = Methanosaeta, illegitimate name.

References: A (Kirkegaard et al., 2017); B (DeLong et al., 2014); C (Tonanzi et al., 2021); D (Imachi et al., 2008), E (Manzoor et al., 2016), F (Anderson et al., 2009), G (Kougias et al., 2017); H (Nobu et al., 2016); I (Garrity et al., 2011); NM, non-motile; M, motile, Mb, Megabases, NA; not available.