| Candidatus Carsonella ruddii | |
|---|---|
| Scientific classification | |
| Kingdom: | Bacteria |
| Phylum: | Proteobacteria |
| Class: | Gamma Proteobacteria |
| Order: | unclassified |
| Genus: | Candidatus Carsonella |
| Species: | Ca. C. ruddii |
| Binomial name | |
| Candidatus Carsonella ruddii |
|
Candidatus Carsonella ruddii is an obligate endosymbiotic Gamma Proteobacterium[1]; it has the smallest genome of any characterised bacteria.[2]
The species is an endosymbiont that is present in all species of phloem sap-feeding insects known as psyllids.[3][4] The endosymbionts occurs in a specialised structure known as the bacteriome.
In 2006 the genome of Ca. C. ruddii strain Pv (Carsonella-Pv) of the hackberry petiole gall psyllid, Pachypsylla venusta, was sequenced at RIKEN in Japan and the University of Arizona. It was shown that the genome consists of a circular chromosome of 159,662 base pairs and that it has a high coding density (97%) with many overlapping genes and reduced gene length. The number of predicted genes was 182, also the lowest on record (NCBI-Genome). In comparison, Mycoplasma genitalium, which has the smallest genome of any free-living organism, has a genome of 521 genes. Numerous genes considered essential for life seem to be missing, suggesting that the species may have achieved organelle-like status.[2]