Diversity of Life
Prochlorococcus marinus. Image from Claire S. Ting, Department of Biology, Williams College.
Prochlorococcus marinus. Image from Claire S. Ting, Department of Biology, Williams College.

Kingdom: Eubacteria

Prochlorococcus marinus

Contents
  1. Taxonomy
  2. Introduction
  3. Morphological Features
  4. Anatomical/Physiological Features
  5. Range of Habitat
  6. Interesting Facts
  7. References

Taxonomy



Kingdom
Eubacteria
Phylum
Cyanobacteria
Class
Prochlorophytes
Order
Prochlorococcaceae
Family
Prochlorococcus
Genus
Prochlorococcus
Species
marinus
Cyanobacteria is a phylum catergorized in the kingdom Eubacteria, and is crucial to the survival of millions of other species. Also known as "blue-green algae", cyanobacteria's importance is due to that it can perform photosynthesis to obtain its energy through sunlight energy, producing oxygen as a byproduct.
Prochlorococcus marinus comes in two main forms; one which lives close to the surface of water so it can aborb sunlight, whereas the other lives in deeper waters which less sunlight can get to.

Introduction



Prochlorococcus marinus is a unicellular cyanobacterium and the most photosynthetic abundant organism on the planet, numbered by trillions of trillions. They are autotrophs, being able to produce their own glucose through the process of photosynthesis. They account for an enormous part of the Earth's oxygen due to their huge numbers, around 30~80% of the total photosynthesis in the oligotrophic oceans, though they were unnoticed until the end of the 1980's. The genus was Synechococcus discovered first due to its strong fluoresence glow, where in contrast, the genus Prochlorococcus has a very weak fluorescence signal, its late discovery being the result.

Morphological Features


Prochlorococcus marinus are coccus-shaped bacteria with a diameter between 0.5~0.7 micrometers long. This amazingly tiny size makes Prochlorococcus the smallest oxygen-evolving autotroph known to humans so far. The colour of the organism is green with a bluish tint, mainly due to the chlorophyll inside the organism that enables it to undergo photosynthesis.
Prochlorococcus with a 0.1 micrometer scale. As we can see, the diameter of the organism is roughly around 0.6 micrometers long. Image from Structural Biology Labs, Biomedical Cebtre, Uppsala, Sweden.
Prochlorococcus with a 0.1 micrometer scale. As we can see, the diameter of the organism is roughly around 0.6 micrometers long. Image from Structural Biology Labs, Biomedical Cebtre, Uppsala, Sweden.


Anatomical/Physiological Features


Inside the organism, Prochlorococcus marinus contains divinyl parts of chlorophyll a and chlorophyll b, a photosynthetic feature which is unique to the genus Prochlorococcus that is located inside the cell and can contribute to the cell's process of photosynthesis. Chlorophyll a is the primary photosynthetic pigment, while chlorophyll b is the secondary photosynthetic pigment that passes on the collected energy to chlorophyll a. The molecular structure of the two chlorophylls are shown below. While Prochlorococcus numerically dominates the phytoplankton in tropical and temperate oceans alongside with species under the genus of Synechococcus, Synechococcus organisms mainly collect solar energy though complexes called phycobilisomes, whereas phycobilisomes are usually nowhere to be seen in Procholococcus.

Molecular structure of Chlorophyll B. Image from Mathews/van Holde/Ahern 3rd Edition.
Molecular structure of Chlorophyll B. Image from Mathews/van Holde/Ahern 3rd Edition.

Molecular structure of Chlorophyll A. Image from Mathews/van Holde/Ahern 3rd Edition.
Molecular structure of Chlorophyll A. Image from Mathews/van Holde/Ahern 3rd Edition.

Also, the energy produced through photosynthesis (glucose) in Prochlorococcus marinus largely contributes to the ecosystem of the ocean. Being at the base of the oceanic food chain and so numerous, Prochlorococcus marinus serves as the main source of energy in the chain, providing the energy that is needed to maintain the diverse ecosystem in the ocean. ll the oceans between 40 degrees north latitude and 40 degrees south. In these oligotrophic waters, they represent 40 to 50% of the phytoplankton biomass. Moreover, they are present down to 200 meters under the surface, a depth at which light energy is a thousand times weaker than at the surface.



Range of Habitat



Prochlorococcus marinus has a very wide range in its habitat, being the most abundant photosynthetic organism in the oceans. They can be found mainly in the central zones of all oceans between 40 degrees north latitude and 40 degrees south latitude. They are usually present down to 200 meters under the water surface, where light is about one thousand times weaker than at the surface of the water.
Range of Prochlorococcus marinus. Green, white and purple indicates a location that is dominated by Prochlorococcus marinus. Image by Proceedings of the National Academy of Sciences of the United States of America.
Range of Prochlorococcus marinus. Green, white and purple indicates a location that is dominated by Prochlorococcus marinus. Image by Proceedings of the National Academy of Sciences of the United States of America.


Interesting Facts




  • Prochlorococcus marinus accounts for up to 40~50% of the phytoplankton biomass in some oceans.
  • Prochlorococcus marinus represents approximately 50 % of the total chlorophyll in the subtropical Pacific.


References


  1. "Prochlorococcus Marinus MIT 9313 - Home." JGI Genome Portal - Home. Web. 15 Nov. 2010. <http://genome.jgi-psf.org/prom9/prom9.home.html>.
  2. "The Most Important Microbe You've Never Heard Of : NPR." NPR : National Public Radio : News & Analysis, World, US, Music & Arts : NPR. Web. 15 Nov. 2010. <http://www.npr.org/templates/story/story.php?storyId=91448837>.
  3. "Mathews/van Holde/Ahern 3rd Edition." Web. 15 Nov. 2010. <http://www.aw-bc.com/mathews/ch17/chloroph.htm>.
  4. "One of the Smallest Photosynthetic Organisms Known." Site Du Genoscope. Web. 15 Nov. 2010. <http://www.genoscope.cns.fr/spip/Prochlorococcus-marinus-smallest.html>.
  5. "Prochlorococcus." MicrobeWiki. Web. 15 Nov. 2010. <http://microbewiki.kenyon.edu/index.php/Prochlorococcus>.
  6. "Prochlorococcus_marinus | 2can Support Portal | EBI." European Bioinformatics Institute | Homepage | EBI. Web. 15 Nov. 2010. <http://www.ebi.ac.uk/2can/genomes/bacteria/Prochlorococcus_marinus.html>.