Prochlorococcus | |
---|---|
Scientific classification | |
Kingdom: | Bacteria |
Phylum: | Cyanobacteria |
Order: | Synechococcales |
Family: | Prochloraceae |
Genus: |
Prochlorococcus Chisholm et al., 1992 |
Species | |
Prochlorococcus is a genus of very small (0.6 µm) marine cyanobacteria with an unusual pigmentation (chlorophyll b). These bacteria belong to the photosynthetic picoplankton and are probably the most abundant photosynthetic organism on Earth. Microbes of the genus Prochlorococcus are among the major primary producers in the ocean, responsible for a large percentage of the photosynthetic production of oxygen. Analysis of the genome sequences of 12 Prochlorococcus strains show that 1100 genes are common to all strains, and the average genome size is about 2000 genes. In contrast, eukaryotic algae have over 10,000 genes.
Although there had been several earlier records of very small chlorophyll-b-containing cyanobacteria in the ocean,Prochlorococcus was discovered in 1986 by Sallie W. (Penny) Chisholm of the Massachusetts Institute of Technology, Robert J. Olson of the Woods Hole Oceanographic Institution, and other collaborators in the Sargasso Sea using flow cytometry. The first culture of Prochlorococcus was isolated in the Sargasso Sea in 1988 (strain SS120) and shortly another strain was obtained from the Mediterranean Sea (strain MED). The name Prochlorococcus originated from the fact it was originally assumed that Prochlorococcus was related to Prochloron and other chlorophyll-b-containing bacteria, called prochlorophytes, but it is now known that prochlorophytes form several separate phylogenetic groups within the cyanobacteria subgroup of the bacteria domain.