Pelagibacter ubique
| Pelagibacter ubique | |
|---|---|
| Scientific classification (Candidatus) | |
| Domain: | Bacteria |
| Phylum: | Proteobacteria |
| Class: | Alphaproteobacteria |
| Subclass: | Rickettsidae |
| Order: | Pelagibacterales |
| Family: | "Pelagibacteraceae" |
| Genus: | Pelagibacter |
| Species: | P. ubique |
| Binomial name | |
|
Candidatus Pelagibacter ubique Rappé et al. 2002 |
|
Pelagibacter, with the single species P. ubique, was isolated in 2002 and given a specific name, although it has not yet been validly published according to the bacteriological code. It is an abundant member of the SAR11 clade in the phylum Alphaproteobacteria. SAR11 members are highly dominant organisms found in both salt and fresh water worldwide — possibly the most numerous bacterium in the world, and were originally known only from their rRNA genes, which were first identified in environmental samples from the Sargasso Sea in 1990 by Stephen Giovannoni's laboratory in the Department of Microbiology at Oregon State University and later found in oceans worldwide.P. ubique and its relatives may be the most abundant organisms in the ocean, and quite possibly the most abundant bacteria in the entire world. It can make up about 25% of all microbial plankton cells, and in the summer they may account for approximately half the cells present in temperate ocean surface water. The total abundance of P. ubique and relatives is estimated to be about 2 × 1028 microbes.
It is rod or crescent shaped and one of the smallest self-replicating cells known, with a length of 0.37-0.89 µm and a diameter of only 0.12-0.20 µm. 30% of the cell's volume is taken up by its genome. It is gram negative. It recycles dissolved organic carbon. It undergoes regular seasonal cycles in abundance - in summer reaching ~50% of the cells in the temperate ocean surface waters. Thus it plays a major role in the Earth's carbon cycle.
Its discovery was the subject of "Oceans of Microbes", Episode 5 of "Intimate Strangers: Unseen Life on Earth" by PBS.
Several strains of Pelagibacter ubique have been cultured thanks to improved isolation techniques. The most studied strain is HTCC1062 (high-throughput cultivation collection).
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Wikipedia