Vibrio fischeri
1078549
201927215
2008-03-30T00:01:10Z
Gbeebani
3878052
/* Bioluminescence */
{{Taxobox
| color = lightgrey
| name = ''Vibrio fischeri''
| regnum = [[Bacterium|Bacteria]]
| phylum = [[Proteobacteria]]
| classis = [[Gamma Proteobacteria]]
| ordo = [[Vibrionales]]
| familia = [[Vibrionaceae]]
| genus = ''[[Vibrio]]''
| species = '''''V. fischeri'''''
| binomial = ''Vibrio fischeri''
| binomial_authority = (Beijerinck 1889)<br>Lehmann & [[Joseph Henri François Neumann|Neumann]] 1896
}}
'''''Vibrio fischeri''''' is a [[gram-negative]] rod-shaped [[bacterium]] found globally in the [[ocean|marine]] environments. It has [[bioluminescence|bioluminescent]] properties, and is found predominantly in [[symbiosis]] with various marine animals, such as the [[bobtail squid]]. It is [[heterotrophic]] and moves by means of [[flagellum|flagella]]. Free living ''V. fischeri'' survive on decaying [[organic matter]] (see [[saprotroph]]). The bacterium is a key research organism for examination of microbial [[bioluminescence]], [[quorum sensing]], and bacterial-animal symbiosis.
== Ecology ==
{{Unreferencedsection|date=February 2008}}
[[Plankton]]ic ''V. fischeri'' are found in very low quantities (almost undetectable) in almost all [[ocean]]s of the world, preferentially found in [[temperate]] and [[sub-tropical]] waters. These free-living ''V. fischeri'' subsist on organics within the water. They are found in higher concentrations in symbiosis with certain deep sea marine life within special light-organs; or as part of the normal enteral (gut) microbiota of marine animals.
== Symbiotic relationship ==
Symbiotic relationships in [[Pineconefish|monocentrid fish]]es and [[sepiolidae|sepolid squid]] appear to have [[evolution|evolved]] separately. The most prolific of these relationships is with the [[Hawaiian Bobtail Squid|Hawaiian bobtail squid]] (''Euprymna scolopes'').
Free-living ''V. fischeri'' in the ocean waters inoculate the light organs of juvenile [[squid]] and [[fish]]. [[Cilia]]ted cells within the light organs selectively draw in the symbiotic bacteria. These cells promote the growth of the symbionts and actively reject any competitors. The bacteria cause these cells to die off once the light organ is sufficiently colonised.
The light organ of certain squid contain reflective plates that intensify and direct the light produced, due to [[protein]]s known as [[reflectin]]s. They regulate the light to keep the squid from casting a shadow on moonlit nights, for example.
Sepolid squids expel 90% of the symbiotic bacteria in its light organ each morning in process known as "venting". Venting is hypothesised to provide the free-living inoculum source for newly hatched squids.
== Bioluminescence ==
The [[bioluminescence]] of ''V. fischeri'' is caused by [[Transcription (genetics)|transcription]] induced by population-dependent [[quorum sensing]]. The [[luminescence]] is only seen when population density reaches a certain level.
The luminescence appears to follow a [[circadian rhythm]], that is, it is brighter during the nighttime than daytime.
Bioluminescence levels have also been shown to be proportionally related to both protection against [[ultraviolet radiation]] damage to [[gene]]s and the pathogenicity of bioluminescent ''V. fischeri''.
== Genetics of bioluminescence ==
The bacterial [[luciferin]]-[[luciferase]] system is encoded by a set of genes labelled the [[Lux operon]]. In ''V. fischeri'' five such genes (''LuxCDABE'') have been identified as active in the emission of visible light, and two genes (''LuxR'' and ''LuxI'') are involved in regulating the [[operon]]. Several external and intrinsic factors appear to induce and inhibit the transcription of this gene set and produce or suppress [[light emission]]. More research is being done to improve our understanding of these processes.
== List of synonyms ==
*''Achromobacter fischeri'' (Beijerinck 1889) Bergey et al. 1930
*''Bacillus fischeri'' (Beijerinck 1889) Trevisan 1889
*''Bacterium phosphorescens indigenus'' (Eisenberg 1891) Chester 1897
*''Einheimischer Leuchtbacillus'' Fischer 1888
*''Microspira fischeri'''' (Beijerinck 1889) Chester 1901
*''Microspira marina'' (Russell 1892) Migula 1900
*''Photobacterium fischeri'' Beijerinck 1889
*''Vibrio noctiluca'' Weisglass and Skreb 1963
:From [http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi NCBI Taxbrowser]
==References==
* {{cite book | author = Holt JG (editor) | title = Bergey's Manual of Determinative Bacteriology | edition = 9th ed. | publisher = Williams & Wilkins | year = 1994 | id = ISBN 0-683-00603-7 }}
* {{cite book | author = Madigan, Michael; Martinko, John (editors) | title = Brock Biology of Microorganisms | edition = 11th ed. | publisher = Prentice Hall | year = 2005 | id = ISBN 0-13-144329-1 }}
==See also==
*[[Vibrio harveyi]]
*[[Deep sea fish]]
*[[Model organism]]
*[[Marine biology]]
==External links==
*[http://web.uconn.edu/mcbstaff/graf/VfEs/VfEssym.htm The Light-Organ Symbiosis of ''Vibrio fischeri'' and the Hawaiian squid, ''Euprymna scolopes'']
*[http://www.bio.cmu.edu/Courses/03441/TermPapers/97TermPapers/lux/default.html Cell-Cell Communication and the ''lux'' operon in ''Vibrio fischeri'']
[[Category:Vibrionales]]
[[Category:Model organisms]]
[[Category:Bioluminescent organisms]]
[[de:Vibrio fischeri]]