Saline formations appearing on Dead Sea shore on Palestinian side.
The Dead Sea was so named because of the absence of life forms in it due to its salinity of more than 30%, which is ten times the concentration of salt in the seas and oceans. But a group of salt-loving bacteria colonize and reproduce in the Dead Sea through their miraculous ability to withstand the enormous osmotic pressure of its salt water.
Halobacterium halobium is known to be one of the first isolated bacteria from the Dead Sea, and has recently been renamed Halobacterium salinarum.
Salt-loving bacteria
This are a group of microorganisms that grow and thrive in environments with high concentrations of salts, including sodium chloride, magnesium chloride, calcium chloride, potassium chloride, magnesium bromide, etc.
These environments include multiple areas, such as the Great Salt Lake in Utah in the United States, the Dead Sea in Palestine and Jordan, and Antarctica's Deep Lake. More recently, the distinctive pink color of a lake in Australia has been associated with salt-loving bacteria.
How do they live in a very salty environment?
A mechanism for salt-loving bacteria to resist high concentration of salts is the construction of small molecules known as compatible solutes whose principle is to balance internal and external osmotic pressure. This is by far the most common method.
Another less common method is to control potassium levels (K+) by pumping large amounts of potassium ions into the cytoplasm.
Salt-loving bacteria on human tables
Salt-loving bacteria play a key role in fermenting some foods with high amounts of salt. Far Eastern countries are famous for this type of food, such as Thai fish sauce, fermented seafood in Korea, some fermented Japanese food made from fish, Indonesian sweet soy sauce, and pickles.
In addition to fermentation products, salt-loving bacteria are used to produce dietary supplements, such as long-chains unsaturated fatty acids necessary for human nutrition, and they were traditionally added to food in the form of fish oil.
Industrial applications
Salt-loving bacteria produce some biopolymers such as surfactants that can reduce surface tension in liquids, thus increasing the movement of water-damaging hydrocarbons, and have been used in the biological treatment of soil and water contaminated with oil.
Salinity products produce a number of stable enzymes, including many degradable enzymes capable of operating under high concentrations of salt, which usually lead to the deposition or deformation of most proteins. This means that these enzymes are stable and operating in harsh conditions, which qualifies them for use in many industries such as food coloring and glycerine production.
Environmental applications of salt-loving bacteria
- Biological analysis of heavy oils: "TM-1" was isolated from salt-loving bacteria from the Xingli oil field in East China. This strain of Gram positive bacteria is spherical and immobile, able to live at temperatures up to 58, and salt concentrations of up to 18% of sodium chloride salt, and was found to be able to analyze crude oils, i.e. they can be used in the disposal of oil stains resulting from leakage of oil tankers.
- Removal of colors from the azo dyes: Of the 27 strains of salt-tolerant bacteria isolated from liquids of textile industries, three strains of the genus Halomanus showed clear ability to remove color from widely-used azo dyes.
- Biological treatment of residues: These bacteria can be used in the biological treatment of residues because they have a number of advantages compared to the use of traditional methods of treatment, including their ability to work in high concentration areas and the tolerability of heavy metals, as well as their ability to destroy a wide range of organic compounds.