Vibrio fischeri: Difference between revisions

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==Description and significance==
==Description and significance==
      ''Vibrio fischeri'', a species of bioluminescent bacterium, is frequently found in symbiotic relationships with marine animals like the bobtail squid.  One of its most distinguishing characteristics, bioluminescence, is controlled by a small set of genes known as the ''lux'' operon.
 
''Vibrio fischeri'', a species of bioluminescent bacterium, is frequently found in symbiotic relationships with marine animals like the bobtail squid.  One of its most distinguishing characteristics, bioluminescence, is controlled by a small set of genes known as the ''lux'' operon.
Luminescence is a chemical reaction in which the enzyme, luciferase, oxidizes organic compounds so as to release energy in the form of blue-green light at 490nm.  The reaction that occurs in Vibrio fischeri is as follows:
Luminescence is a chemical reaction in which the enzyme, luciferase, oxidizes organic compounds so as to release energy in the form of blue-green light at 490nm.  The reaction that occurs in Vibrio fischeri is as follows:
FMNH2 + RCHO + O2  FMN + RCOOH + H2O + hv (490nm)  
FMNH2 + RCHO + O2  FMN + RCOOH + H2O + hv (490nm)  

Revision as of 21:33, 27 April 2007

A Microbial Biorealm page on the genus Vibrio fischeri

Classification

Higher order taxa

Bacteria; Proteobacteria; Gammaproteobacteria; Vibrionales; Vibrionaceae; Vibrio; Vibrio fischeri

Species

Vibrio fischeri

Description and significance

Vibrio fischeri, a species of bioluminescent bacterium, is frequently found in symbiotic relationships with marine animals like the bobtail squid. One of its most distinguishing characteristics, bioluminescence, is controlled by a small set of genes known as the lux operon. Luminescence is a chemical reaction in which the enzyme, luciferase, oxidizes organic compounds so as to release energy in the form of blue-green light at 490nm. The reaction that occurs in Vibrio fischeri is as follows: FMNH2 + RCHO + O2  FMN + RCOOH + H2O + hv (490nm) The lux operon is a 9 kb fragment that consists of genes that code for the subunits of luciferase (luxAB) and for enzymes (luxCDE) that convert compounds to oxidizable substrates. This 9 kb fragment includes all that is necessary to carry out the functions of luminescence in other organisms such as E. Coli. It has been found that expression of luminescence is dependent on cell density and thus light is not seen unless the bacteria are in high concentration, like in light emitting organs of fish and squid. This phenomenon is known as quorum sensing. The rationale behind quorum sensing has to do with the proteins encoded on the lux operon. The lux operon is actually set up like two differently transcribed operons. As mentioned before, luxA and luxB code for the subunits of the enzyme luciferase. LuxCDE codes for enzymes that convert fatty acids into aldehydes which are needed for the reaction to proceed. These genes, in addition to luxI and luxG, make up one operon. LuxI is at the head of this first operon and is responsible for the production of the auto inducer protein. This is the molecule that is involved in sensing the concentration of bacterium in a space. This protein can easily diffuse out of the cell, and if Vibrio fischeri were found floating freely in the ocean, as is sometimes seen, this auto inducer would diffuse out of the cell and float away. However, when in a restricted space, it is forced to react with the protein produced from the second operon, the regulator, luxR. This results in increasing the affinity of RNA polymerase to the promoter region of the first operon and eventually producing luminescence.

Genome structure

Describe the size and content of the genome. How many chromosomes? Circular or linear? Other interesting features? What is known about its sequence? Does it have any plasmids? Are they important to the organism's lifestyle?

Cell structure and metabolism

Describe any interesting features and/or cell structures; how it gains energy; what important molecules it produces.

Ecology

Describe any interactions with other organisms (included eukaryotes), contributions to the environment, effect on environment, etc.

Pathology

How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.

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

Ruby, E.G., Urbanowski, M., Campbell, J., Dunn, A., Faini, M., Gunsalus, R., Lostroh, P., Lupp, C., McCann, J., Millikan, D., chaefer, A., Stabb, E., Stevens, A., Visick, K., Whistler, C., and Greenberg, E.P. "Complete genome sequence of Vibrio fischeri: A symbiotic bacterium with pathogenic congeners." Proc. Natl. Acad. Sci. USA. In press (2005), published online 9 February 2005.

Edited by student of Rachel Larsen