The genus ''Methanimicrococcus'' was described based on the strain PA (ATCC BAA-276; DSM 13328), isolated from the hindgut of a

cockroach Cockroaches (or roaches) are insects belonging to the Order (biology), order Blattodea (Blattaria). About 30 cockroach species out of 4,600 are associated with human habitats. Some species are well-known Pest (organism), pests. Modern cockro ...

, ''

Periplaneta americana The American cockroach (''Periplaneta americana'') is the largest species of common cockroach, and often considered a pest. In certain regions of the U.S. it is colloquially known as the waterbug, though it is not a true waterbug since it is not ...

''. The species was initially named ''Methanomicrococcus blatticola''; however, the name was later corrected to ''Methanimicrococcus blatticola'', making it the only genus of

methanogens Methanogens are anaerobic archaea that produce methane as a byproduct of their energy metabolism, i.e., catabolism. Methane production, or methanogenesis, is the only biochemical pathway for ATP generation in methanogens. All known methanogens b ...

that has -i as a connecting vowel rather than -o in the name. The cells are irregular

cocci Bacterial cellular morphologies are the shapes that are characteristic of various types of bacteria and often key to their identification. Their direct examination under a light microscope enables the classification of these bacteria (and archaea ...

with a diameter of 0.7 – 1 μm, occurring singly or in clusters. ''M. blatticola'' can only use methylated compounds, such as

methanol Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical compound and the simplest aliphatic Alcohol (chemistry), alcohol, with the chemical formula (a methyl group linked to a hydroxyl group, often ab ...

or methylamines, in combination with H₂ to produce

methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The abundance of methane on Earth makes ...

, which is in sharp contrast to other methanogens from the ''

Methanosarcinales Methanosarcinales is an order of Archaea in the class '' Methanomicrobia'', phylum '' Methanobacteriota''. The order ''Methanosarcinales'' contains both methanogenic and methanotrophic lineages, although the latter have so far no pure culture r ...

'' order. Later studies showed a lack of activity for enzymes involved in the Wood-Ljungdahl pathway that reduce CO₂ to the methyl group. Genome analysis demonstrated that the highly reduced genome of ''M. blatticola'' lacks the upper part of the Wood-Ljungdahl pathway, restricting this methanogen to methylated compounds and H₂. ''Methanimicrococcus'' could be very abundant among

cockroaches Cockroaches (or roaches) are insects belonging to the Order (biology), order Blattodea (Blattaria). About 30 cockroach species out of 4,600 are associated with human habitats. Some species are well-known Pest (organism), pests. Modern cockro ...

, representing up to 97% of the archaeal community in some species. It is also present in some species of

termites Termites are a group of detritophagous eusocial cockroaches which consume a variety of decaying plant material, generally in the form of wood, leaf litter, and soil humus. They are distinguished by their moniliform antennae and the sof ...

and

scarab beetle The family Scarabaeidae, as currently defined, consists of over 35,000 species of beetles worldwide; they are often called scarabs or scarab beetles. The classification of this family has undergone significant change. Several groups formerly tre ...

larvae. One of the reasons for such success is the very low H₂ and methanol threshold attributed to H₂-dependent methyl-reducing methanogenesis. Additionally, it is suggested that ''Methanimicrococcus'' can withstand O₂ fluxes in the microoxic environment of the arthropod gut wall, a feature that is rarely observed among methanogens. However, the molecular mechanism of such resistance is still not deciphered. Recently, more species from the ''Methanimicrococcus'' genus were described. Three were described based on cultures and were also isolated from cockroaches - ''M. hacksteinii'', ''M. hongohii'', and ''M. stummii''. Two other species were described solely based on genomes obtained from termite gut metagenomes - ''Candidatus'' M. labiotermitis and ''Ca''. M. odontotermitis.

Phylogeny

The currently accepted taxonomy is based on the

List of Prokaryotic names with Standing in Nomenclature List of Prokaryotic names with Standing in Nomenclature (LPSN) is an online database that maintains information on the naming and taxonomy of prokaryotes, following the taxonomy requirements and rulings of the International Code of Nomenclatu ...

(LPSN) and

National Center for Biotechnology Information The National Center for Biotechnology Information (NCBI) is part of the National Library of Medicine (NLM), a branch of the National Institutes of Health (NIH). It is approved and funded by the government of the United States. The NCBI is lo ...

(NCBI).

References

External links

Archaea genera Euryarchaeota {{Euryarchaeota-stub

Phylogeny

See also

References

Further reading

External links