Archaea: Ecology, Application, and Conservation

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Archaea are the inhabitants of extreme environments on the earth. They commonly live at extreme acidity, temperature, and alkalinity or in hypersaline water, hot springs, hydrothermal vents, and glaciers and at extreme pressure and radiation. Some of the members live in deep oceans at extreme pressure and temperature above 100 °C. With the advancement of archaeal taxonomy, diversity, and identification of new strains, their functional role has increased in industrial and biotechnological applications in recent years. The extremophilic archaea are well-known sources of extracellular enzymes and biocatalyst and accelerate fermentation process. Some novel antimicrobial compounds and biomolecules have been discovered in certain archaea. Many of archaeal strains have applications in eco-friendly wastewater treatment plants, biodegradation of marshy lands contaminated with organic solvents, and hydrocarbons. In mineralization process, ammonia-oxidizing archaea (AOA) has key role in nitrogen cycle. The long-term preservation of extremely halophilic and thermoacidophilic archaea has been reported successful by L-drying method but it is labile to freeze and freeze-drying. Viability of thermoacidophilic archaea like Thermoplasma sustained at 5 °C for more than 15 years. The halophilic archaea may be preserved in the Petri dishes or in the refrigerator at 4 °C for quite longer periods with proper sealing and in deep freezing at −80 °C with specific media at proper salt concentration in 20% supplemented glycerol. In the case of hyperthermophilic archaea like Pyrococcus furiosus, the glass capillary tube kept over liquid nitrogen with dimethyl sulfoxide is preferred. The lyophilization method of preservation generally results in loss of viability in most of archaea cultures. Likewise, in situ methods of conservation of archaea in their natural habitats become noteworthy since most of archaea are extremophiles in those particular habitats with unique characteristics and specific traits with several applications. Hence, preservation of archaea requires specific preservation techniques for certain groups, and therefore, it is important to be focused on their maintenance, preservation, and conservation. Hence, it is very important for the development of reliable, simple, and durable preservation technique for particular groups of archaea for long-term preservation with stable viability for over the years.