Photobacterium phosphoreum

All unapproved Citizendium articles may contain errors of fact, bias, grammar etc. A version of an article is unapproved unless it is marked as citable with a dedicated green template at the top of the page, as in this version of the 'Biology' article. Citable articles are intended to be of reasonably high quality. The participants in the Citizendium project make no representations about the reliability of Citizendium articles or, generally, their suitability for any purpose. This article is currently being developed as part of an Eduzendium student project in the framework of a course entitled Microbiology 201 at Queens College, CUNY. The course homepage can be found at CZ:Biol 201: General Microbiology. For the course duration, the article is closed to outside editing. Of course you can always leave comments on the discussion page. The anticipated date of course completion is May 21, 2009. One month after that date at the latest, this notice shall be removed. Besides, many other Citizendium articles welcome your collaboration!

Photobacterium phosphoreum
Scientific classification
Kingdom: Bacteria Phylum: Proteobacteria Class: Gammaproteobacteria Order: Vibrionales Family: Vibrionaceae Genus: Photobacterium Species: P. phosphoreum
Binomial name
Photobacterium phosphoreum

Description and significance

Photobacterium phosphoreum is a luminescent bacterium. They are gram-negative, straight rod, plump and large (0.8-1.3 um in diameter and 1.8-2.4 um in length). They can be motile or non-motile. Those that are motile have 1-3 unsheathed polar flagella. Their optimum temperature is 18-25˚C [1]. They emit a blue-green light due to the catalytic activity of luciferase. They are oxidase positive because they can use D-glucose as their principle carbon source (Prescott, Harley and Klein 557). They can be cultivated in Long and Hammer Agar (1% NaCl). It is known as a symbiotic bacterium that lives in the light organ of some marine fishes. It can also live freely in seawater, saprophytically and parasitically [2].

Its major significance is its symbiotic relationship with some marine animals like fishes and squids. They have specialized organs that provide P. phosphoreum with a safe place to reside and food; while these animals use the light that the bacteria provide for camouflage and even for attracting mates or escape from predators. Another role that P. phosphoreum has is the ability of signaling the relative toxicity of a substance due to the connection of the light producing process with the cellular metabolism. If the toxins disrupt the cellular metabolism, then the strength of the light produced decreases [3].

Cell structure and metabolism

P. phosphoreum is a chemoorganotroph which is capable of respiratory and fermentative metabolism [4]. It is a facultative anaerobe that can grow in the absence of oxygen when appropriate electron-acceptors are present. It doesn’t denitrify; in other word, it cannot use nitrogen molecules [5].

Ecology

P. phosphoreum is mostly considered a marine bacterium because sodium ions are required for its growth. It lives in the depth of the ocean, seawater, marine sediments, in the guts of marine animals, and on the surface of decomposing fish. Inside of the marine organisms, it can act as a parasite.

References

http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=659

http://www.microbiologyatlas.kvl.dk/biologi/english/showmorf.asp?articleid=44

http://www.disknet.com/indiana_biolab/b203.htm

http://www.biology.pl/bakterie_sw/index_en.html

http://cibt.bio.cornell.edu/programs/archive/0608alum/lumos.pdf

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

http://www.microbelibrary.org/ASMOnly/Details.asp?ID=552