View source for Carsonella ruddii

{{Taxobox
| name = ''Candidatus'' Carsonella ruddii
| regnum = [[Bacterium|Bacteria]]
| phylum = [[Proteobacteria]]
| classis = [[Gamma Proteobacteria]]
| ordo = unclassified
| genus = ''Candidatus'' Carsonella
| species = ''Ca.'' C. ruddii
| binomial = ''Candidatus'' Carsonella ruddii
| binomial_authority = 
| synonyms = }}
{{italictitle}}
'''''[[Candidatus]]''''' '''Carsonella ruddii''' is an [[Endosymbiosis|endosymbiotic]] [[Gammaproteobacteria|gamma proteobacterium]].<ref>Spaulding A.W. and C.D. von Dohlen. 1998. Phylogenetic characterization and molecular evolution of bacterial endosymbionts in Psyllids (Hemiptera: Sternorrhyncha). ''Molecular Biology and Evolution'' '''15'''(11):1506-1513</ref> It has the smallest known [[genome]] of any bacterium.<ref name = "Science">{{cite journal | author = Nakabachi A | display-authors = etal | title = The 160-kilobase genome of the bacterial endosymbiont Carsonella. | journal = Science | volume = 314 | issue = 5797 | pages = 267 | year = 2006 | pmid = 17038615 | doi = 10.1126/science.1134196| s2cid = 44570539 }}</ref>

The species is an [[endosymbiont]] that is present in all species of [[phloem]] sap-feeding insects known as [[psyllid]]s.<ref>Thao M.L. 2000. Cospeciation of Psyllids and their primary prokaryotic endosymbionts. ''Applied and Environmental Microbiology'' '''66''':2898-2905</ref><ref>Thao M.L. 2001. Phylogenetic analysis of vertically transmitted psyllid endosymbionts (''Candidatus'' Carsonella ruddii) based on atpAGD and rpoC: comparisons with 16S-23S rDNA-derived phylogeny. ''Current Microbiology'' '''42''':419-21 PMID 11381334</ref> The endosymbionts occurs in a specialised structure known as the [[bacteriome]].

In 2006 the genome of one strain of ''Ca.'' C. ruddi was sequenced at [[RIKEN]] in Japan and the [[University of Arizona]]. The genome is a circular chromosome of 159,662 [[base pair]]s and has a high coding density (97%) with many overlapping genes and reduced gene length. The number of predicted [[gene]]s was 182, also the lowest on record ([https://www.ncbi.nlm.nih.gov/sites/entrez?Db=genome&Cmd=ShowDetailView&TermToSearch=20002 NCBI-Genome]). Numerous genes considered essential for life seem to be missing, suggesting that the species may have achieved [[organelle]]-like status.<ref name = "Science"/>

In comparison, ''[[Mycoplasma genitalium]]'', which has the smallest genome of any free-living organism,<ref>'Free-living' in the sense of not being an endosymbiont.</ref> has a genome of 521 genes.

==References ==
{{reflist}}

== Other websites ==
*[https://www.scientificamerican.com/article/tiny-genome-may-reflect-o/ Scientific American] – Tiny genome may reflect organelle in the making

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{{DEFAULTSORT:''Candidatus'' Carsonella ruddii}}
[[Category:Gram-negative bacteria]]