Abstract
Na.no.pu.sil'lus. Gr. masc. n.
nânos,
a dwarf; L. masc. adj.
pusillus,
very small; N.L. masc. n.
Nanopusillus,
a very small member of the
Nanoarchaeota
.
The genus
Candidatus
Nanopusillus is comprised of small coccoid cells (∼100–400 nm) that live epibiotically on the surface of archaeal hosts. The first described species,
Candidatus
Nanopusillus acidilobi, is an anaerobic, hyperthermophilic acidophile whose best growth is observed at 82°C, pH 3.6, cultivated from a hot spring in Yellowstone National Park.
Ca
. Nanopusillus acidilobi cells associate with the
Crenarchaeota
host organism
Acidilobus
sp. 7A. Archaeal flagella (archaella) have been predicted from the genome sequence and shown to be expressed in the proteome. A second putative species,
Candidatus
Nanopusillus massiliensis, was recently reported from human dental plaque and associates with the methanogen
Methanobrevibacter oralis
. The genome consists of a single scaffold which is highly fragmented by spans of ambiguous nucleotides, with 16S rRNA gene fragments from
Bacteria
. Both species have small genomes (∼0.6 Mb) encoding few biosynthetic genes and no apparent ATP synthase complex genes, suggesting that the nanoarchaeotes rely on their host for the production of major cellular precursors.
DNA G + C content (mol%)
: 24 (genome analysis).
Type species
:
Candidatus
Nanopusillus acidilobi
Wurch et al. 2016.
Taxonomic and Nomenclature Notes
According to the List of Prokaryotic names with Standing in Nomenclature (LPSN), the taxonomic status of the genus
Candidatus Nanopusillus
is: preferred name (not correct name) (last update, February 2025)
*
.
LPSN classification:
Archaea
/
Nanobdellati
/
Nanobdellota
/
Nanobdellia
/
Nanobdellales
/
Nanobdellaceae
/
Candidatus Nanopusillus
The genus
Candidatus Nanopusillus
can also be recovered in the Genome Taxonomy Database (GTDB) as
g__Nanopusillus
(version v220)
**
.
GTDB classification:
d__Archaea
/
p__Nanoarchaeota
/
c__Nanoarchaeia
/
o__Nanoarchaeales
/
f__Nanopusillaceae
/
g__Nanopusillus
*
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