부산대학교 도서관

Extremophiles not only tolerate the extreme harsh conditions, but also require those conditions for their survival. The name extremophile describes how much the extremophiles love to adapt and have been evolved to grow under optimal conditions such as thriving in acidic conditions (acidophiles), extreme high temperature (thermophiles) above pH 9 (alkaliphiles), below 15 °C (psychrophiles), above 80 °C (hyperthermophiles), and at high hydrostatic pressure (barophiles). When these organisms evolved to adapt in more than one extremity at once, they are then known as Polyextremophiles, for example, surviving in high salt concentration in alkaline condition (haloalkaliphile) with tolerance against high UV radiation of sun, in warm, hot acidic springs (thermoacidophiles), and in extreme temperatures from −272 to 151 °C. These fascinating life-forms adapt to such harsh conditions by either having DNA, membrane, or enzyme modifications, by forming cyst spores, changing cellular membrane expression or having malleable membrane, by altering expression of repair enzymes for damage and synthesizing molecules for relieving stress, or by processing remarkable adaptive mechanisms producing unique but useful enzymes called extremozymes. In these ways, by maintenance of fluidity and stability of their membrane under harsh and extreme environments and protecting their genetical structure and system, they help us understand the limits of habitability on other worlds, their ecological importance and importantly their significances in industrial uses and for human welfare by their applications in medical sciences. In this article, we will focus onto the evolutionary significances of these organisms that will help us find out how life evolved on the Earth, type of prevailing extremities, and exploration of some unexplored habitats on the Earth.