ABSTRACT
Biotechnological processes and, in general, industrial processes require in many cases the use of catalyzers able to work at extreme conditions in terms of temperature, ionic strength, pressure, and extreme pH values, or even in the presence of toxic or heavy metals. Several approaches have been explored so far involving the use of mesophilic enzymes isolated mainly from bacteria and plants. However, these enzymes are not stable under the extreme conditions previously mentioned, and consequently, they are not active. For these reasons, extremophilic enzymes have been revealed as promising catalyzers to improve several important features sustaining the reactions that are the key processes in biotechnology. Thus, these enzymes are capable of catalyzing their respective reactions in nonaqueous environments, in water–solvent mixtures, at extremely high pressures, at acidic and alkaline pH, at temperatures up to 140°C, or near the freezing point of water. These enzymes, also called extremozymes, are produced by extremophiles, which are microorganisms able to grow and live in environments of extreme temperature (–2°C to 15°C for cold environments, 60°C–120°C in hot environments), ionic strength (2–5 M NaCl), or pH (<4.0 or >9.0). These organisms mainly belong to the Bacteria and Archaea domains. Besides, extremozymes can be enhanced through genetic engineering to obtain biocatalysts more in line with the needs of each moment. This chapter summarizes the current knowledge about extremozymes and their potential uses in biotechnology, paying special attention to those isolated from members of the Archaea domain.
