Abstract
Me.tha'no.thrix. N.L. neut. n.
methanum
methane; Gr. fem. n.
thrix
, hair; N.L. fem. n.
Methanothrix
, methane (‐producing) hair.
Straight, rod‐shaped cells with flat ends, usually 0.8–1.3 μm wide by 2.0–6.0 μm long enclosed in a tubular sheath. Forms short (∼5–25 μm) to long (>150 μm) flexible chains of cells within the sheath. Nonmotile. Gram‐stain‐negative. Lipids contain
myo
‐inositol, ethanolamine, and galactose as the polar head groups. Oxygen‐tolerant anaerobe. Organotrophic, splitting acetate into methane and CO
2
for energy generation. Some strains split formate into H
2
and CO
2
without producing methane. CO
2
can be reduced to methane in coculture with
Geobacter
spp. via direct interspecies electron transfer (DIET). Growth factors such as vitamins are stimulatory. Yeast extract is required, stimulatory or inhibitory, depending on the strain. NaCl is not required for growth. Optimal temperatures range from 34 to 37°C for mesophilic strains and 55 to 60°C for thermophilic strains; optimal pH range is 7.0–7.8. Gas vacuoles are generally found in thermophilic strains. Occur in both mesophilic and thermophilic anaerobic sludge digesters as well as anaerobic sediments. Synonymous with the genus
Methanosaeta
.
DNA G + C content (mol%)
: 51–61 (genome).
Type species
:
Methanothrix soehngenii
Huser et al. 1982, VL10.
Taxonomic and Nomenclature Notes
According to the List of Prokaryotic names with Standing in Nomenclature (LPSN), the taxonomic status of the genus
Methanothrix
is: correct name (last update, February 2025)
*
.
LPSN classification:
Archaea
/
Methanobacteriati
/
Methanobacteriota
/
Methanosarcinia
/
Methanosarcinales
/
Methanotrichaceae
/
Methanothrix
The genus
Methanothrix
can also be recovered in the Genome Taxonomy Database (GTDB) as
g__Methanothrix
(version v220)
**
.
GTDB classification:
d__Archaea
/
p__Halobacteriota
/
c__Methanosarcinia
/
o__Methanotrichales
/
f__Methanotrichaceae
/
g__Methanothrix
*
Meier‐Kolthoff
et al. (
2022
).
Nucleic Acids Res
,
50
,
D801
–
D807
; DOI:
10.1093/nar/gkab902
**
Parks
et al. (
2022
).
Nucleic Acids Res
,
50
,
D785
–
D794
; DOI:
10.1093/nar/gkab776