Trichodesmium erythraeum

A Microbial Biorealm page on the genus Trichodesmium erythraeum

Classification

Higher order taxa

Bacteria; Cyanobacteria; Oscillatoriales; Trichodesmium; Trichodesmium erythraeum

Species

NCBI: Taxonomy

Trichodesmium erythraeum

Description and significance

Tricodesmium is a genus of cyanobacteria that is found in tropical and subtropical ocean waters with low nutrient levels. This genus is of great interest because it has been found to contribute over 40% of all nitrogen fixation that occurs in the ocean. In addition, there has been evidence that Trichodesmium blossoms can have a toxic effect on invertebrates and humans. Trichodesmium erythraeum is a species of the Trichodesmium genus and occurs as filaments of 20-200 cells. These filaments often congregate to form larger colonies that can be seen by the naked eye.

Genome structure

Has a circular genome that is 7750108 nucleotides long. This includes 4451 genes and 48 RNA genes.

Cell structure and metabolism

Trichodesumium erythraeum contain gas vesicles which can occupy up to 60-70% of the total cell volume. Within the cell, these gas vacuoles are aligned so that their longitudinal axis is oriented perpendicular to the direction of the filament. These gas vesicles allow T. erythraeum an amount of buoyancy and possibly play a role in protecting the inside of the cell from harmful wavelengths of light. Trichodesumium erythraeum also contain photosynthetic lamellae. While these structures can be seen throughout the cell, they tend to be more populous toward the center of the cell (Van Baalen 1969).

Like other cyanobacteria, Trichodesmium erythraeum are able to derive energy through the process of photosynthesis. Since nitrogenase, enzyme needed for nitrogen fixation, is inactivated in the presence of oxygen, nitrogen fixing bacteria have developed ways to protect the nitrogenase within them from oxygen. Trichodesmium are thought to do this by keeping nitrogenase and oxygen physically separated in a manner not unlike the compartmentalization of oxygen demonstrated by heterocystous cyanobacteria (Bergman 1991). During times of high nitrogen fixation researcher have observed an increase in photosynthetically inactive areas in Trichodesmium colonies. This suggests that in addition to spatial separation, nitrogenase is segregated from oxygen in time by downregulating the amount of photosynthetically derived oxygen when nitrogenase activites are at their highest (Bergman 2001).

Ecology

Trichodesumium erythraeum is found in tropical and subtropical ocean waters. It combines with Trichodesmium thiebautii to form blossoms which have been found to be toxic to various invertebrates as well as humans. Despite it’s toxic effects, this the Trichodesumium genus is important and necessary to the environment because it is a major contributor to nitrogen fixation.

Pathology

Trichodesmium erythraeum is suspected to have toxic effects. While T. erythraeum cells were not found to be toxic to mice, except at high concentrations (500g/kg mouse), they have been linked to the mortality of various marine organisms. Chemical assays of lipophilic T. erythraeum from Australia have not been able to detect common neurotoxins such as tetrodotoxin (Negri 2003).

Application to Biotechnology

Does this organism produce any useful compounds or enzymes? What are they and how are they used?

Current Research

Enter summaries of the most recent research here--at least three required

References

http://expasy.org/sprot/hamap/TRIEI.html

Bergman, B., and E. J. Carpenter. 1991. Nitrogenase confined to randomly distributed trichomes in the marine cyanobacterium Trichodesmium thiebautii. J. Phycol. 27:158-165.

Berman-Frank, I., P. Lundgren, Y.-B. Chen, H. Kupper, Z. Kolber, B. Bergman, and P. Falkowski. 2001. Segregation of nitrogen fixation and oxygenic photosynthesis in the marine cyanobacterium Trichodesmium. Science 294:1534-1537. [

Karl, D., A. Michaels, B. Bergman, D. Capone, E. Carpenter, R. Letelier, F. Lipschultz, H. Paerl, D. Sigman, and L. Stal. 2002. Dinitrogen fixation in the world's oceans. Biogeochemistry 57:-58:47-98.

Van Baalen C, Brown RM Jr. 1969. The ultrastructure of the marine blue green alga, Trichodesmium erythraeum, with special reference to the cell wall, gas vacuoles, and cylindrical bodies. Arch Mikrobiol. 69(1):79-91

Edited by Tara Tsukamoto student of Rachel Larsen and Kit Pogliano