''Blattabacterium'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

obligate {{wiktionary, obligate As an adjective, obligate means "by necessity" (antonym ''facultative'') and is used mainly in biology in phrases such as: * Obligate aerobe, an organism that cannot survive without oxygen * Obligate anaerobe, an organism that ...

mutualistic

endosymbiont An ''endosymbiont'' or ''endobiont'' is any organism that lives within the body or cells of another organism most often, though not always, in a mutualistic relationship. (The term endosymbiosis is from the Greek: ἔνδον ''endon'' "within" ...

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

that are believed to inhabit all species of

cockroach Cockroaches (or roaches) are a paraphyletic group of insects belonging to Blattodea, containing all members of the group except termites. About 30 cockroach species out of 4,600 are associated with human habitats. Some species are well-known as ...

studied to date, with the exception of the genus ''

Nocticola ''Nocticola'' is a genus of cockroaches in the family Nocticolidae distributed in Africa, south-east Asia and Australia. Nocticola are different from every other cockroach in that they are not infected with '' Blattabacterium cuenoti''. This make ...

''. The genus' presence in the termite ''

Mastotermes darwiniensis ''Mastotermes darwiniensis'', common names giant northern termite and Darwin termite, is a termite species found only in northern Australia. It is the most primitive extant termite species. Evolutionary significance This species shows uncanny s ...

'' led to speculation, later confirmed, that termites and cockroaches are evolutionarily linked.

Diversity

''B. cuenoti'' was traditionally considered the only species in the genus ''Blattabacterium'', which is in turn the only genus in the family Blattabacteriaceae. However, three new species have been described hosted by different species of cockroaches in the genus ''

Cryptocercus ''Cryptocercus'' is a genus of Dictyoptera (cockroaches and allies) and the sole member of its own family Cryptocercidae. Species are known as wood roaches or brown-hooded cockroaches. These roaches are subsocial, their young requiring considera ...

'': * ''Blattabacterium relictus'' in ''

Cryptocercus relictus ''Cryptocercus'' is a genus of Dictyoptera (cockroaches and allies) and the sole member of its own family Cryptocercidae. Species are known as wood roaches or brown-hooded cockroaches. These roaches are subsocial, their young requiring consider ...

'' * ''B. clevelandi'' in '' C. clevelandi'', and * ''B. punctulatus'' in '' C. darwini'', '' C. garciai'', '' C. punctulatus'' and '' C. wrighti''. The ancient (~150 My) genus retains throughout a core set of metabolic genes. According to the GTDB, the many strains of the genus have nevertheless diverged enough at the sequence level to define around 40 "species" out of ''B. cuenoti'' alone. In addition, newer genera have been found sufficiently closely related to the genus to warrant assignment to the same family by

GTDB The Genome Taxonomy Database (GTDB) is an online database that maintains information on a proposed nomenclature of prokaryotes, following a phylogenomic approach based on a set of conserved single-copy proteins. In addition to breaking up parap ...

: Ca. "

Karelsulcia "''Candidatus'' Karelsulcia muelleri" is an aerobic, gram-negative, bacillus bacterium that is a part of the phylum Bacteroidota. "''Ca.'' K. muelleri" is an obligate and mutualistic symbiotic microbe commonly found occupying specialized cell ...

", Ca. " Uzinura", Ca. " Walczuchella", all symbionts of insects.

Function

Blattabacterium lives inside the fat cells of the

fat bodies Adipose tissue, body fat, or simply fat is a loose connective tissue composed mostly of adipocytes. In addition to adipocytes, adipose tissue contains the stromal vascular fraction (SVF) of cells including preadipocytes, fibroblasts, vascular ...

(tissues in the abdominal cavity that store fat) of its insect hosts. It serves a vital role in nitrogen recycling, which is important in insects that mainly live on plant material such as wood, which are poor in nitrogen. In insects, uric acid is a waste product of protein metabolism. After breakdown of uric acid by the host (and its other microbial flora, such as gut bacteria and fungi) into urea and/or ammonia, blattabacterium recycles nitrogen by converting these products into glutamate, and using other raw materials from the host, is able to synthesize all of the essential amino acids and several vitamins. It appears to be transmitted to succeeding generations of the host by infection of the mother's eggs prior to their fertilization.

Diversity

Function

References

Further reading