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Classification

Higher order taxa

Bacteria; Cyanobacteria; Prochlorales; Prochlorococcacae; Prochlorococcus

Species

NCBI: Taxonomy [1]

Prochlorococcus

Description and significance

Describe the appearance, habitat, etc. of the organism, and why you think it is important.

Genome structure

Because of its small size, Prochlorococcus usually has a small genome1. It actually maintains the smallest genome of all cyanobacteria, with only 1.7 Mb1. This may be considered an adaptation because in the ocean (environment of this organism) there is not an excess nitrogen or phosphorus, which are essential in the production of nucleotides1. There are generally two strains of this bacteria found in the ocean. The low-light adapted and high- light adapted strains are a result of the difference of light levels at different depths in the ocean1. The low- light adapted strains have extra genes for the antenna complex protein, which is where the chlorophyll gets its energy from light1. These low-light adapted strains genetically produce chlorophyll b as opposed to chlorophyll a (high-light adapted strain) because chlorophyll b can be more helpful at a with a wider spectrum of light, which is essential when light is scarce1. By having genes for more chlorophyll b and antenna protein complex, these bacteria are able to thrive even at depths of up to 200m1. These low-light adapted strains have a lot more variation when it comes to there genome, probably as an adaptation for the tougher environment that the deeper ocean poses1. The ocean is a very stable environment, thus these microbes have seen a decrease in the amount of stress- related and housekeeping genes, as compared to the genome of other cyanobacteria1. The genes for antenna protein however are much increased, as we discussed their characteristics that are essential to this bacteria1. The genome of these bacteria are essential in the studying of photosynthetic bacteria, and their response to changing environments because of their unique and decreased genome1.

References

1. Unknown Authors. "One of the Smallest Photosynthetic Organisms Known." Site Du Genoscope. Genoscope, 16 Jan. 2008. Web. 02 Feb. 2012. <http://www.cns.fr/spip/Prochlorococcus-marinus-smallest.html>.