Thiomargarita namibiensis

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Description and significance

Thiomargarita namibiensis is the largest known bacterium and was discovered in 1997. It is also referred to as the “Sulfur pearl of Namibia” because it looks like a large pearl made out of white globules of sulfur and was found off the coast of Namibia. The cell is generally 0.1 - 0.3 mm wide, although some become as large as 1.0 mm, and is approximately 3 million times the volume of a normal bacterium cell.

Genome structure

Once discovered scientist were able to place Thiomargarita Namibiensis in to the phylogenetic tree were they concluded that Thiomargarita Namibiensis is closing related to the bacterial genera Triploca and Beggiatoa because of the high sulfur enivorment it is able to survive in. Thiomargarita Namibiensis is from the family of bacteria known as Thiotrichaceae.

Cell structure and metabolism

Thiomargarita Namibiensis is a chemolithotroph, which means that it obtains its electrons required for the electron transport chain from nitrates rather then organic molecules. The sulfur granules found in the cytoplasm of this organism is due to the oxidation of Hydrogen Sulfide in to sulfur. Thiomargarita Namibiensis is a non-motile organism, due to this it must wait for its nitrate supply and store it for long periods of time. The cytoplasm of Thiomargarita Namibiensis lines the cell membrane, giving the bacterium the flexibility to diffuse the nitrate from its surroundings.Thiomargarita Namibiensis contains a large vacuole which is 80% of its size in its cytoplasm for the shortage of nitrates and can survive three months at a time if nitrate supply is low in its environment.

References

http://www.accessexcellence.org/WN/SUA12/marg499.php

http://web.mst.edu/~microbio/BIO221_2005/T_namibiensis.htm

http://www.scienceagogo.com/news/19990318191806data_trunc_sys.shtml

http://www.whoi.edu/oceanus/viewImage.do?id=5667&aid=2497

http://www.madsci.org/posts/archives/2006-06/1151465295.Mi.r.html

http://en.wikipedia.org/wiki/Thiomargarita_namibiensis