''Polynucleobacter'' is a genus of

bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...

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

endosymbiont An endosymbiont or endobiont is an organism that lives within the body or cells of another organism. Typically the two organisms are in a mutualism (biology), mutualistic relationship. Examples are nitrogen-fixing bacteria (called rhizobia), whi ...

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 that drift in Hydrosphere, water (or atmosphere, air) but are unable to actively propel themselves against ocean current, currents (or wind). The individual organisms constituting plankton are ca ...

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

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) or Prokaryotic Code, 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 ...

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 Bacterioplankton refers to the bacterial component of the plankton that drifts in the water column. The name comes from the Ancient Greek word (), meaning "wandering" or "drifting", and , a Latin term coined in the 19th century by Christian Got ...

in freshwater systems such as lakes, ponds, and streams.

Genomics

Two

genome 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 genes, other functional regions of the genome such as ...

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