Extremophiles are organisms primarily prokaryotic (archaea and bacteria), with few examples of eukaryotic. ;Most of the known extremophiles and microbes. Extremophiles are defined by the extreme environmental conditions in which they grow optimally. The term, extremophile was first introduced by Bob McElroy in 1974. In the last decade, studied on extremophiles have progressed to the extent that the first international congress on extremophiles was convened in Portugal and the scientific journal, “Extremophiles” was established in 1997. “ The international Society for Extremophiles (ISE)” was also founded in 2002 for the exchange of information and experience in the rapidly growing field of research on extremophiles. Extreme environments and different extremophiles . An extremophile is and organism, which thrives in or requires ecological niches. These conditions can refer to physical as well as geochemical extremes such as temperature, pressure, radiation, salinity, Ph, presence of toxic compounds and water availability.
The organisms may be described as acideophilic (optimal growth between pH1 and pH5); Alkaliphilic (optimal growth above pH9); Halophilic (optimal growth in environments with high concentrations of salt); thermophilic (optimal growth between 60 and 80C): psychrophilic (Optimal growth at 15c or lower, with a maximum tolerant temperature of 20c and minimal growth at or below 0c); piezophilic, or barophilic (optimal growth at high hydrostatic pressure); oligotrophic (growth in nutritionally limited environments);endolithic(growth with in rock or with in pores of mineral grains|).
Biotechnological Applications
Extremophiles have the potential to produce biomolecules of high relevance for differen biotechnological sectors.
- Bioenzymes :These microorganisms produce extremophilic enzymes and protective organic biomolecules that convey characteristics for srvival in extreme environmental conditions. Owing to their nique enzymatic features and physiological properties, the potential biotechnological applications of whole-cell extremophilic biocatalysts range from the bioremediation of toxic pollutants from water and/or sediments to the productionof biomolecules fo rmedical and industrial purposes.
- Bioremediators: Metalophiles and acidophiles are currently being used fo rbioremediation and biomining due to their adaptation to high concentrations of heavy metals and acidic environment, while radiophiles are suited for application in the management of nuclear waste-plluted environments.
- Biocatalysts: Desert bacterial extemophiles that are able to cope with low water activity conditions can be used to improve the management of water by plants under drought stress in the field of agriculture. In addition to entire microbial cells, extremozymes are enzymes that have developed moleculare mechanisms of adaptation to extreme physicochemical conditions that have relevant applications as biocatalysts in industries. Thermozymes are extremozymes produced by thermophilic microorganisms. These enzymes are also often able to tolerate proteolysis and harsh conditions like the presence of denaturing agents and organice solvents as well as high salinity. The enzymes from thermophiles show high potential in detergent, food,feed , starch, textile, leather, pulp and paper and pharmaceutical industries. Benefits of using thermozymes include reduced risk of contamination, lower viscosity, and higher solubility of substrates.
- Molecular Laboratory : DBA polymerases is the first and foremost example that have been obtained from Thermococuslittoralis, Thermusaquaticus, Thermotoga maritime, pyrococcuswoesiiand P.furiosus for application in polymerase chain reaction (PCR).
- Food and beverage industry: Enzymes produced by psychrophiles have been shown to display high catalytic efficiency in the detergent and food industries and for the production of fine chemicals. Alkaliphiles are good source of Ph stable enzymes like proteases, amylases, cellulases,lipases, xylanases, pullulananses, pectinases and chitinases. The main industrial applications of these enzymes are in processes that are performed at high PH such as in the detergent industry, hide-dehairing, pulp and paper industry, starch-hydrolysis and food processing. Piezophilic microorganisms and their enzymes have considerable potential fo ruse in biotechnology, in particular for food industries, where high pressure is applied for processing and sterilization of food materials.
Xerophiles are considered to be responsible for spoiling of dry foods and stored grains, spices, nuts and oilseeds. Bacterial alkaliphiles are mainly exploited for the production of enzymes that are widely applied in the detergent and laundry industries. Examples of extremolytes include several compounds of polyol derivatives, and various amino acids. Extremolytes have primarily been used in cosmetics and have the potential for application to the pharmaceutical sector.
Source : Aqua International