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.
AbstractMe.tha'no.thrix. N.L. neut. n.methanummethane; Gr. fem. n.thrix, hair; N.L. fem. n.Methanothrix, methane (‐producing) hair.Halobacterota / Methanosarcinia / Methanotrichales / Methanotrichaceae / MethanothrixStraight, 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 containmyo‐inositol, ethanolamine, and galactose as the polar head groups. Oxygen‐tolerant anaerobe. Organotrophic, splitting acetate into methane and CO2for energy generation. Some strains split formate into H2and CO2without producing methane. CO2can be reduced to methane in coculture withGeobacterspp. 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 genusMethanosaeta.DNA G + C content (mol%): 51–61 (genome).Type species:Methanothrix soehngeniiHuser et al. 1982, VL10.