Na.no.clep'ta. Gr. masc. n.
a dwarf; Gr. masc. n.
a thief; N.L. masc. n.
a small thief, a small organism that steals from its host.
Nanoarchaeota / Nanobdellia / Nanobdellales / Nanobdellaceae / Candidatus
Nanoclepta currently comprises a single species,
Nanoclepta minutus Ncl‐1, an anaerobic hyperthermophile (optimal growth observed from 80 to 85°C) cultivated from a New Zealand hot spring. Cells are ultra‐small cocci (∼200 nm) with archaeal flagella and are cultivated in near‐neutral pH conditions (pH ∼6.0). Like several other
. N. minutus cells are epibionts on the surface of a host from the
. Although this symbiosis is obligate for
. N. minutus, the relationship is not required for the host,
, which can survive as a free‐living organism.
. N. minutus has a highly reduced genome (∼0.58 Mb) with minimal biosynthetic potential and no detected ATP synthase genes, and
. Nanoclepta cells likely rely on their host for many metabolic precursors.
DNA G + C content (mol%)
32.2 (genome analysis).
Candidatus Nanoclepta minutus
St. John et al. 2019a.
Na.no.pu.sil'lus. Gr. masc. n.
a dwarf; L. masc. adj.
very small; N.L. masc. n.
a very small member of the
Nanoarchaeota / Nanobdellia / Nanobdellales / Nanobdellaceae /
Nanopusillus is comprised of small coccoid cells (∼100–400 nm) that live epibiotically on the surface of archaeal hosts. The first described species,
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.
. Nanopusillus acidilobi cells associate with the
sp. 7A. Archaeal flagella (archaella) have been predicted from the genome sequence and shown to be expressed in the proteome. A second putative species,
Nanopusillus massiliensis, was recently reported from human dental plaque and associates with the methanogen
. The genome consists of a single scaffold which is highly fragmented by spans of ambiguous nucleotides, with 16S rRNA gene fragments from
. 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).
Wurch et al. 2016.
AbstractTrace metals have been an important ingredient for life throughout Earth’s history. Here, we describe the genome-guided cultivation of a member of the elusive archaeal lineage Caldarchaeales (syn. Aigarchaeota), Wolframiiraptor gerlachensis, and its growth dependence on tungsten. A metagenome-assembled genome (MAG) of W. gerlachensis encodes putative tungsten membrane transport systems, as well as pathways for anaerobic oxidation of sugars probably mediated by tungsten-dependent ferredoxin oxidoreductases that are expressed during growth. Catalyzed reporter deposition-fluorescence in-situ hybridization (CARD-FISH) and nanoscale secondary ion mass spectrometry (nanoSIMS) show that W. gerlachensis preferentially assimilates xylose. Phylogenetic analyses of 78 high-quality Wolframiiraptoraceae MAGs from terrestrial and marine hydrothermal systems suggest that tungsten-associated enzymes were present in the last common ancestor of extant Wolframiiraptoraceae. Our observations imply a crucial role for tungsten-dependent metabolism in the origin and evolution of this lineage, and hint at a relic metabolic dependence on this trace metal in early anaerobic thermophiles.