Table 1 Classification of extremophiles and examples of their habitats.
From: Biotechnological applications of archaeal enzymes from extreme environments
Type | Growth characteristics | Habitat |
|---|---|---|
Acidophiles | Low pH (< 2) | Hot sulfur springs, waste treatment plants, and mine drainage |
Alkaliphiles | High pH (> 10) | Soda lakes, alkaline hot springs, deserts, and mine waste |
Halophiles | High concentration of salt (2–5 M NaCl) | Salt lakes, coastal lagoons, and saline soils |
Metallophiles | High concentration of heavy metals (Cu, Cd, As, Zn) | Deep-sea or terrestrial hydrothermal sources and metal-processing factories |
Piezophiles or barophiles | High hydrostatic pressure (40–130 MPa) | Ocean floor and deep-sea hot vents |
Psychrophiles | Low temperature (< 15 °C) | Arctic and Antarctic soils and waters, alpine soils, deep ocean water, and glaciers |
Radiophiles | High levels of ionizing radiation (> 25 kGy); 5 Gy is lethal for humans | Terrestrial surfaces, upper layers of the sea, and nuclear waste |
Thermophiles | High temperature Thermophiles (60–80 °C) Hyperthermophiles (> 80 °C) | Deep-sea or shallow hydrothermal vents, hot springs, geysers, volcanoes, coal refuse piles, and industrial hot water systems |
Xerophiles | Low water activity (aw ≤ 0.8) | Deserts and salt beds |