Extremophiles: The Toast of the Industry
Archaebacteria live in extreme environments and, therefore, are sometimes called extremophiles. The three groups of archaebac-teria-methanogens, halophiles, and thermacidophiles-have specific preferences about the precise nature of their environ-ment. Methanogens are strict anaerobes that produce methane (CH4) from carbon dioxide (CO2) and hydrogen (H2).
Halophiles require very high salt concentrations, such as thosefound in the Dead Sea, for growth. Thermacidophiles require high temperatures and acid conditions for growth-typically, 80°C– 90°C and pH 2. These growth requirements may have resulted from adaptations to harsh conditions on the early Earth. Since these organisms can tolerate these conditions, the enzymes they produce must also be stable. Most enzymes isolated from eubacte-ria and eukaryotes are not stable under such conditions. Some of the reactions that are of greatest importance to the biotechnology industry are both enzyme-catalyzed and carried out under condi-tions that cause most enzymes to lose their catalytic ability in a short time. This difficulty can be avoided by using enzymes from extremophiles. An example is the DNA polymerase from Thermusaquaticus (Taq polymerase). Polymerase chain reaction (PCR)technology depends heavily on the properties of this enzyme. Representatives of the biotechnology industry constantly search undersea thermal vents and hot springs for organisms that can provide such enzymes.