Geyser - Biology of Geysers

Biology of Geysers

Further information: Thermophile and Hyperthermophile

The specific colours of geysers derive from the fact that despite the apparently harsh conditions, life is often found in them (and also in other hot habitats) in the form of thermophilic prokaryotes. No known eukaryote can survive over 60 °C (140 °F).

In the 1960s, when the research of biology of geysers first appeared, scientists were generally convinced that no life can survive above around 73 °C maximum (163 °F)—the upper limit for the survival of cyanobacteria, as the structure of key cellular proteins and deoxyribonucleic acid (DNA) would be destroyed. The optimal temperature for thermophilic bacteria was placed even lower, around 55 °C average (131 °F).

However, the observations proved that it is actually possible for life to exist at high temperatures and that some bacteria even prefer temperatures higher than the boiling point of water. Dozens of such bacteria are known. Thermophiles prefer temperatures from 50 to 70 °C (122 to 158 °F), whilst hyperthermophiles grow better at temperatures as high as 80 to 110 °C (176 to 230 °F). As they have heat-stable enzymes that retain their activity even at high temperatures, they have been used as a source of thermostable tools, that are important in medicine and biotechnology, for example in manufacturing antibiotics, plastics, detergents (by the use of heat-stable enzymes lipases, pullulanases and proteases), and fermentation products (for example ethanol is produced). Among these, the first discovered and the most important for biotechnology is Thermus aquaticus. The fact that such bacteria exist also stretches our imagination about life on other celestial bodies, both within and beyond the solar system.