Abstract
Ni.tro.so.cal.da'les. N.L. masc. n.
Nitrosocaldus
type genus of the order; ‐
ales
ending to denote order; N.L. fem. pl. n.
Nitrosocaldales
the
Nitrosocaldus
order.
Coccoid cells reproduce by binary fission. Thermophilic and neutrophilic. Obligately aerobic. Chemolithoautotrophic growth by ammonia oxidation to nitrite using CO
2
as carbon source. Some members can also use urea as an alternative source of energy for growth. Cell membrane is composed of isoprenoid tetraether lipids, including large amounts of acyclic and cyclized glycerol trialkyl glycerol tetraethers (GTGTs) and crenarchaeol (a unique glycerol dibiphytanyl glycerol tetraether (GDGT) containing one cyclohexane ring and four cyclopentane rings). Fully saturated and monounsaturated menaquinones with six isoprenoid units are present. They are globally distributed in various geothermal environments. Phylogenetic analyses of 16S rRNA and
amoA
gene sequences place the monophyletic order
Ca
. Nitrosocaldales as a basal lineage within the phylum
Thaumarchaeota
. This order can be distinguished from the closest order
Nitrososphaerales
by a lower mol% G + C content, a higher growth temperature (>60°C), and a higher relative abundance of GTGT. The order
Ca
. Nitrosocaldales is currently represented by a single family
Ca
. Nitrosocaldaceae.
Type genus
:
Ca
.
Nitrosocaldus
de la Torre, Walker, Ingalls, Könneke and Stahl 2008, 815.
Taxonomic and Nomenclature Notes
According to the List of Prokaryotic names with Standing in Nomenclature (LPSN), the taxonomic status of the order
Candidatus Nitrosocaldales
is: preferred name (not correct name) (last update, February 2025)
*
.
LPSN classification:
Archaea
/
Thermoproteati
/
Thermoproteota
/
incertae sedis
/
Candidatus Nitrosocaldales
The order
Candidatus Nitrosocaldales
can also be recovered in the Genome Taxonomy Database (GTDB) as
o__Nitrososphaerales
(version v220)
**
.
GTDB classification:
d__Archaea
/
p__Thermoproteota
/
c__Nitrososphaeria
/
o__Nitrososphaerales
*
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