Vibrio harveyi
Tom Whithaus

Vibrio harveyi is a bioluminescent marine bacterium, meaning that it generates light in salty water. This light produced depends on the density of the microorganism in a certain area and follows a circadian rhythm, meaning it is extremely more visible during the night than the day.

This phenomenon of illuminated salt water has been around for centuries. Scientists at the time did not know what was causing this light, in which many myths of mermaids and other mystical sea creatures surfaced. It was finally identified as a microbe in 1936 by Johnson and Shunk. Though no data on the name origin was found, it is believed that the name “harveyi” is some sort of significance towards a scientist around the time. Many feel that V. harveyi is unlike any other type of “vibrio” genus and will sometimes be referred to as Beneckea harveyi.

V. harveyi can be found all throughout the water column, on the exterior of many marine organisms, and is found to be pathogenic in shrimp, causing a disease called luminous vibriosis. Unlike its relative, Vibrio fischeri, V. harveyi does not form any symbiotic relationships with any other marine organisms. It communicates via autoinducers, by exchanging chemical signal molecules in a process called quorum sensing. This allows the bacteria to control its population density, in which they act as individuals when density is low but act as a large group at high density, much like school of fish or a flock of seagulls. V. harveyi possesses a multi-channel quorum signal transduction pathway, which is a way to monitor the population density along with the entire community within its habitat.

The source of its bioluminescence is from the luciferin-luciferase system which is encoded by genes called the lux operon. Bioluminescent levels produced have been shown to protect the bacteria from ultraviolet radiation.
The microbe can move with its flagella freely in the water, not needing a larger marine organism to latch onto. V. harveyi is heterotrophic, aerobic, grows reasonably at 30°C, and is Gram negative when stained.

References

http://genome.wustl.edu/genome.cgi?GENOME=Vibrio+harveyi&GROUP=3

http://www.chem.uwec.edu/Webpapers_F98/quiles/Pages/vharveypage.html

http://www.aapqis.org/main/path/viewpath_infect.asp?PathID=209&sec=infect&action

http://www.thelabrat.com/restriction/sources/Vibrioharveyi.shtml

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

http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=242072
*Disclaimer - This report was written by a student participaring in a microbiology course at the Missouri University of Science and Technology. The accuracy of the contents of this report is not guaranteed and it is recommended that you seek additional sources of information to verify the contents.

 

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