Hyperthermophiles: Diversity, Adaptation and Applications

Hyperthermophiles are microorganisms that love to grow optimally in extremely hot environments, with optimum temperatures for growth of 80 °C and above. Most of the hyperthermophiles are represented by archaea; and only a few bacteria, such as Geothermobacterium ferrireducens, and members of the genera Aquifex and Thermotoga have been reported to grow at temperatures closer to 100 °C. Several archaea, on the other hand, such as Methanopyrus kandleri, Geogemma barossii, Pyrolobus fumarii, Pyrococcus kukulkanii, Pyrodictium occultum, etc. isolated from terrestrial hot springs, marine hydrothermal vents, or other hyperthermal environments have been reported to grow optimally even above the boiling point of water. The discovery of this astonishing group of microorganisms has not only provided us with the model systems to study the structural and functional dynamics of the biomolecules, and to understand the molecular mechanisms of their adaptation to such high temperature, not even closer to what can be endured by other life forms, but also have boosted the biotechnological industry to search for new products, particularly enzymes with unique characteristics, from them. This chapter has exhaustively reviewed the different hyperthermal environments on Earth’s surface and the hyperthermophilic microbial diversity in such environments; mechanisms of adaptation of the hyperthermophiles, especially with regard to the adaptations of the membrane structures, maintenance of the structures of the nucleic acids and proteins; and their diverse applications in human welfare.