''Polynucleobacter'' is a genus of

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 ...

, originally established by Heckmann and Schmidt (1987) to exclusively harbor obligate

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" ...

s of

ciliate The ciliates are a group of alveolates characterized by the presence of hair-like organelles called cilia, which are identical in structure to flagellum, eukaryotic flagella, but are in general shorter and present in much larger numbers, with a ...

s belonging to the genus ''

Euplotes ''Euplotes'' is a genus of ciliates in the subclass Euplotia. Species are widely distributed in marine and freshwater environments, as well as soil and moss. Most members of the genus are free-living, but two species have been recorded as commens ...

''. Recently, several new ''Polynucleobacter'' species were described, which all represent free-living (i.e. not host-associated)

plankton Plankton are the diverse collection of organisms found in Hydrosphere, water (or atmosphere, air) that are unable to propel themselves against a Ocean current, current (or wind). The individual organisms constituting plankton are called plankt ...

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...

bacteria. Thus, the genus ''Polynucleobacter'' currently includes one species containing obligate endosymbionts of ciliates and nine species representing free-living planktonic strains. The

type strain The International Code of Nomenclature of Prokaryotes (ICNP) formerly the International Code of Nomenclature of Bacteria (ICNB) or Bacteriological Code (BC) governs the scientific names for Bacteria and Archaea.P. H. A. Sneath, 2003. A short histor ...

s of the planktonic species were isolated from freshwater systems located in

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, and the

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. Currently, the genus harbors 31 species. Free-living ''Poynucleobacter'' bacteria represent important members of bacterioplankton in freshwater systems such as lakes, ponds, and streams.

Genomics

Two

genome In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding ge ...

projects are finished on ''P. necessarius'' strains: one project on an obligately freeliving strain isolated from an acidic freshwater pond, and one project on an obligate endosymbiont of the ciliate ''Euplotes aediculatus''.GOLD CARD: Gc00757
Genome project: ''Polynucleobacter necessarius'' subsp. ''necessarius'' STIR1, GOLD - Genomes OnLine Database

Analyses of the genome sequences resulted in the discovery of a conserved RNA motif.

References

External links

Genus: ''Polynucleobacter''
- LPSN, List of Prokaryotic names with Standing in Nomenclature
''Polynucleobacter''
– NCBI Taxonomy Browser {{Taxonbar, from=Q7226655 Burkholderiaceae Bacteria genera