Extremophiles

A very interesting research area in biology and biotechnology is the topic of extremophiles. Life on Earth has adapted over the course of evolution, even to extreme habitats (although there is evidence that organisms had to adapt to ever cooler conditions on Earth over the course of early evolution). Extreme habitats encompass the range of conditions as described  

The isothermal and isobaric conditions in a habitat require adaptation as a strategy at unusual pressures and temperatures. Extremophilic microorganisms are adapted to survive in ecological niches, and they produce unique biocatalysts that function under extreme conditions comparable to those prevailing in various industrial processes. 

Even extremophilic organisms and their proteins contain the same 20 amino acids with bonds similar to those in mesophiles. As the difference in free enthalpy between folded and unfolded states of globular proteins AG N G is only about 45 15 kj mol-1 the sequence and structure of extremophilic proteins should differ from those of ordinary species. However, the main question, namely which properties cause the increase in denaturation temperature of thermostable proteins, is still debated (Rehaber, 1992). Theoretical and experimental analyses have shown that thermal stability is largely achieved by small but relevant changes at different locations in the structure involving electrostatic interactions and hydro-phobic effects (Karshikoff, 2001). There is no evidence for a common determinant or for just one effect causing thermostability. 

Recent structural comparisons between enzymes from mesophiles and thermo-philes have validated numerous protein-stablizing effects, including hydrophobic interactions, packing efficiency, salt bridges, hydrogen bonds, loop stabilization 

Nr number of salt bridges statistically expected for that protein structure. Source Karshikoff (2001). 

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Enzymes for Extreme Conditions. The possibihty of using enzymes from extremophiles, which thrive in oil wells, hot temperatures, freezing conditions, etc, is being explored for the removal of environmental contaminants and survival at extreme temperatures (see Wastes, HAZARDOUS WASTE TREATlffiNT BlORETffiDIATION (SuPPLET NT)). 

Could it be the case that microorganisms, like the suspected fossils in the Mars meteorite ALH 84001, exist in the Martian soil This question leads to the counterquestion as to whether it has previously been possible to detect and study life (primitive life forms) under highly extreme conditions. Are there such conditions on Earth We now know quite a lot about extremophiles such as the thermophilic, halophilic and hyperthermophilic microorganisms. 

Extreme Biocatalyst Culture Collection (EBCC), Extremophile Culture Collection. 

Unique Extremophilic Microorganisms, Collection of Unique Microbial Cultures, Russian Academy of Sciences (UNIQEM). 

These activities are supported by specialist s know-how and a portfolio of intellectual property. Proteus proprietary elements include a unique collection of extremophilic microorganisms, novel patented technologies for high-throughput functional biodiversity screening (Phenomics ) and for protein engineering (L-Shuffling ), novel chemistry... 

Archaea are usually extremophiles, living at extremes of salt, of temperature or of pH. (At high temperatures (80°C), they often obtain energy from H2, CO, CH4 and H2S... 

Archaea Special membrane lipids, coenzymes and uses of nickel (several specialist types see under bacteria) Extremophiles of various kinds. Use of sulfate and limited use of light and 02... 

The fairly recent discovery of bacteria living in obscure environments (Table 9.2) has led to a new classification of bacteria the extremophile bacteria, with a diverse array of likes and dislikes. A useful working definition for extremophile is ... 

Extremophile an organism that is isolated from an extreme environment and often requires the extreme condition for growth. 

Many types of extremophile bacteria have been identified, described by some of the following definitions ... 

Astrobiology The search for exotic environments in which life has evolved. Drawing inspiration from the extremophile bacteria from the Earth s biota, knowing where to look on another planet is not an easy question... 

Extremophile A bacterium that has adapted to life in an extreme environment perhaps of temperature, pressure, salinity, etc. 

Setter K. O. (1999). Extremophiles and their adaptation to hot environments. FEBS Letters 452 22-25... 

Christner, B.C., Kvitko, B.H., II Reeve, J.N. 2003. Molecular identification of bacteria and eukarya inhabiting an Antarctic cryoconite hole. Extremophiles, 7, 177-183. 

One of the most important of these extremophiles is a bacterium (Thermus acquaticus) discovered in 1965 in a Yellowstone National Park hot spring where the temperature is a constant 73 °C (Centigrade or Celsius) or 163 °F (Fahrenheit). About twenty years... 

To overcome this shortcoming, biologists turned to an enzyme that could survive the PCR hot cycle. They replaced the original heat-sensitive enzyme with DNA-polymerase from Thermus acqua-ticus, the Yellowstone extremophile. The new enzyme is unscathed... 

Beyond their practical value, extremophile enzymes present scientists with a fundamental puzzle. Fike all molecular characteristics, their exceptional stability must originate in their chemical structures. However, it is not yet certain what structural features determine these properties. What is known is that in their active folded form, cold-resistant enzymes appear to have relatively fewer structure-stabilizing interactions between different parts of the amino acid chain. As a result, they remain more flexible at a lower temperature than ordinary enzymes but unfold and lose their activity more quickly as the temperature is raised. Conversely, heat-resistant enzymes seem to have a larger number of... 

The structural integrity of enzymes in aqueous solution is often compromised by the addition of small quantities of water-miscible organic solvents. However, there are numerous examples, particularly using extremophiles, where enzymes have been successfully employed in organic solvent-aqueous mixtures.A good example is the savinase-catalysed kinetic resolution of an activated racemic lactam precursor to abacavir in 1 1 THF/water (Scheme 1.39). The organic solvent is beneficial as it retards the rate of the unselective background hydrolysis. 

Butler, L.G., Enzymes in non-aqueous solvents. Enzyme Microb. Technol., 1979,1, 253-259. Gerard A. Sellek, G.A. and Chaudhuri, J.B., Biocatalysis in organic media using enzymes from extremophiles. Enzyme Microb. Technol., 1999, 25, 471-482. 

Bacteria-like microbes found in extreme environments ( extremophiles ) were sometimes presumed to belong exclusively to the specialized domain known as Archaea. However, it has transpired that the arrangement of microbes in ecological niches was not as simple as this - many Archaea have been found in temperate zones and in ecosystems similar to those occupied by bacteria, and some conventional microbes occupy extreme environments. 

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