Halobacterium

The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN)[2] and National Center for Biotechnology Information (NCBI).

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

Though the cytoplasm retains an osmotic equilibrium with the hypersaline environment, the cell maintains a high potassium concentration using many active transporters.

Halobacterium can be identified in bodies of water by the light-detecting pigment bacteriorhodopsin, which not only provides the archaeon with chemical energy, but adds to its reddish hue as well.

In addition, Halobacterium makes pigments called bacterioruberins that are thought to protect cells from damage by ultraviolet light.

The obstacle they need to overcome is being able to grow at a low temperature during a presumably short time when a pool of water could be liquid.

Halophiles also produce degradative enzymes such as lipases, amylases, proteases, and xylanases that are used in various food processing methods.

Notable applications of these enzymes include enhancing the fermentation process of salty foods, improving dough quality for the baking of breads, and contributing to the production of coffee.

[12] It has been shown in knockout studies, that the absence of bacterioruberin increases the sensitivity of the bacterium to oxidative DNA-damaging agents.

Hydrogen peroxide, for example, reacts with bacteroruberin which prevents the production of reactive oxygen species, and thus protects the bacterium by reducing the oxidative capacity of the DNA-damaging agent.

[13] H. salinarum also exhibits high intracellular concentrations of potassium chloride which has also been shown to confer radiation resistance.

For instance, genomic sequencing of the Halobacterium species NRC-1 revealed their use of eukaryotic-like RNA polymerase II and translational machinery that are related to Escherichia coli and other Gram-negative bacteria.

In addition, they possess genes for DNA replication, repair, and recombination that are similar to those present in bacteriophages, yeasts, and bacteria.

Additionally, the gas vesicles demonstrate the ability to function as natural adjuvants to help evoke stronger immune responses.

Because of the requirement of Halobacteria for a high-salt environment, the preparation of these gas vesicles is inexpensive and efficient, needing only tap water for their isolation.

Halobacterium salinarum NRC-1
Size bar = 270 nm