The Invader
This is an interesting microbe. Bdellovibrio bacteriovorus is a gram negative curved rod. The name Bdellovibrio bacteriovorus comes from the Latin "curved leach." B. bacteriovorus is approximately 0.2-0.5um x 0.5-1.4um. B. bacteriovorus are found in a variety of environments including marine or fresh water environments. They are obligate aerobes, which grow optimally at 28-300C. Some of the marine strains can grow in 60C or as high at 370C.
The organism to be classified as a B. bacteriovorus must meet the following criteria: "The organism must grow in the periplasmic space of the prey cell. The organism must also have an ensheathed polar flagella."
Bdellovibrios have a biphasic life cycle. One phase is called a non-growing motile predatory phase. In this phase the cells are very lively and chemotactic. The bacteria are looking for ionic conditions, which are favored by their prey cells. These cells have a single ensheathed polar flagellum. This flagellum enables the bacteria to move at incredible speeds. It can move up to 100 cell lengths per second. That is a meter in less than 2 hours. B. bacteriovorus, when its starts it attacks, propel the microbe forward at maximum speed. They bore through the prey that happens to be at the right place at the wrong time.
The second part of the life cycle is the reproductive phase of the bacteria’s life cycle. Once the B. bacteriovorus has attached to a prey cell, which is usually a Gram-Negative cell, it looses its flagellum. The B. bacteriovorus penetrates the outer membrane and peptidoglycan layer. It will then reside in the periplasmic space of the invaded cell. Once infected the prey cell loses its rigidity. When the host bacterium dies it bloats into a spherical shape called a bdelloplast. The invading B. bacteriovorus elongates until is has increased it’s length by 20 times. Sometimes the cell invaded limits this elongation. B. bacteriovorus now replicates. Once the invaded cell is "full" the cell is lysed and the progeny are released to become predators.
A mild ocean breeze plays over the water surface, dispelling any notion that danger lurks in the murky depths. However, a gruesome event is about to occur as a silent attacker speeds forth toward an unsuspecting victim. In a furious collision, the savage meets its target and whittles its way into the body of the innocent prey. Once inside, the transformation begins - the predator ceases its frenzy and prepares to multiply. The host is reduced to a protective cocoon, supplying food and shelter for the growing parasite. Within hours, the nourishment is drained and the ghost-like shell of the host bursts open to release a new generation of deadly predators. And all the while, the waters remain still... This description was produced by Laurel Crosby. http://commtechlab.msu.edu/sites/dlc-me/curious/caOc96LC.hmtl
Below is a picture of the life cycle of B. bacteriovorus curtesy of http://lsvl.la.asu.edu/mic494/html/bdellovibrio.html.
In order for the B. bacteriovorus to be able to invade other bacteria they must contain some enzymes to aid in penetration. Although the shear impact is a great aid. They contain Lipopolysacharidase, glycanase, deacetylase, and peptidase.
Sewage pollution can result in prey densities high enough to support B. bacteriovorus populations. It has a unique way to adhere to surfaces in aquatic environments which aids in predidation.
This bacterium has some modern uses. It is used to fight food borne pathogens such as Escherichia coli. In fact, it will lower an E.coli colony by 90% in one hour.
So friend or foe? B. bacteriovorus, the invader, getting a little back for those bacteria not liking humans!!
References
*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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