Archaebacteria - Halobacterium salinarum

Taxonomy:
Domain - Archaea
Kingdom - Archaebacteria
Phylum - Euryarchaeota
Class - Halobacteria
Order - Halobacteriales
Family - Halobacteriaceae
Genus - Halobacterium
Species - Halobacterium salinarum




Characteristics:

1. Halobacterium species are rod shaped and enveloped by a single lipid bilayer membrane surrounded by an S-layer made from the cell-surface glycoprotein.

2. H. salinarum is an obligate aerobe.

3. It reproduces by binary fission.

4. Does not form spores.

5. Most are not motile.

6. Approx. 0.5–1.0 µm (microns)





Habitat:

Halobacteria can be found in highly saline lakes such as the Great Salt Lake, the Dead Sea, and Lake Magadi. Halobacterium can be identified in bodies of water by the light-detecting pigment bacteriorhodopsin, which not only provides the archaeon with chemical energy, but gives it a reddish hue as well. An optimal temperature for growth has been observed at 37oC. To survive in extremely salty environments, this archaeon -- as with other halophilic Archaean species -- utilizes compatible solutes (in particular potassium chloride) that acts as a sort of antifreeze/coolant to keep the cell metabolism functioning.





Predators:

Filter feeders such as brine shrimp


Prey:

Decomposers, halobacteria feed on dead matter and wastes.



Anatomy:

Archaebacteria have a cell type that is described as prokaryotic . Prokaryotic cells have a cell membrane, like all cells do, but there is no internal compartmentalization of function. In other words, prokaryotes do not have internal organelles, such as mitochondria or a nucleus. The DNA in a prokaryotic cell is a loop-like molecule suspended in the cytoplasm (it appears as the bright red squiggle in the diagram, left).




Historical information:

Biologists have discovered fossils of these organisms preserved in rocks over 3 billion years old, making these incredible creatures the oldest known lifeforms on Earth.



Interesting notes:

1. Despite its name, this microorganisms is not a bacterium, but rather a member of the Domain Archaea.

2. Halobacteria are a candidate for a life form present on Mars!!! Archaebacteria emerged at least 3.5 billion years ago and live in environments that resemble conditions existing when the earth was young.

3.H. salinarum has also been found in high-salt food such as salted pork, marine fish, and sausages!!!

4. Bright red pigment in cells. Halobacteria can survive in dry conditions for years. Food preserved in salt from brine ponds will spoil, because the halobacteria decompose it.

5. Halobacteria can survive in extremely high salinity, 25–35%. Normal seawater is 3.5% saline.