Editing Geyser (section)

== Biology ==
{{Further|Thermophile|Hyperthermophile}}
[[File:Aerial image of Grand Prismatic Spring (view from the south).jpg|alt=A large blue pool surround by orange border on a purple ground|thumb|upright=1.15|Hyperthermophiles produce some of the bright colours of [[Grand Prismatic Spring]], Yellowstone National Park]]

Some geysers have specific colours, because despite the harsh conditions, life is often found in them (and also in other hot [[habitat (ecology)|habitats]]) in the form of [[thermophiles|thermophilic]] [[prokaryote]]s. No known [[eukaryote]] can survive over {{convert|60|°C|°F|0|lk=on}}.<ref name="bot">{{cite journal |first1=LE |last1=Morrison |first2=FW |last2=Tanner |title=Studies on Thermophilic Bacteria |journal=Botanical Gazette |volume=77 |number=2 |year=1924 |pages=171–185 |doi=10.1086/333297}}</ref>

In the 1960s, when the research of the biology of geysers first appeared, scientists were generally convinced that no life can survive above around {{convert|73|°C|°F|adj=mid|maximum}}—the upper limit for the survival of [[cyanobacteria]], as the structure of key cellular [[protein]]s and [[DNA|deoxyribonucleic acid]] (DNA) would be destroyed. The optimal temperature for thermophilic bacteria was placed even lower, around {{convert|55|°C|°F|adj=mid|average|0}}.<ref name="bot" />

However, the observations proved that can exist at high temperatures and that some bacteria even prefer temperatures higher than the boiling point of water. Dozens of such bacteria are known.<ref>{{cite web |first1=MT |last1=Madigan |first2=BL |last2=Marrs |url=http://atropos.as.arizona.edu/aiz/teaching/a204/extremophile.pdf |title=Extremophiles |archive-url=https://web.archive.org/web/20080409071712/http://atropos.as.arizona.edu/aiz/teaching/a204/extremophile.pdf |archive-date=9 April 2008 |publisher=University of Arizona |access-date=1 April 2008}}</ref>
[[Thermophile]]s prefer temperatures from {{convert|50|to|70|°C|°F|0}}, while [[hyperthermophile]]s grow better at temperatures as high as {{convert|80|to|110|°C|°F|0}}. As they have heat-stable enzymes that retain their activity even at high temperatures, they have been used as a source of thermostable [[tool]]s, which are important in [[medicine]] and [[biotechnology]],<ref>{{cite journal |last1=Vielle |first1=C |last2=Zeikus |first2=GJ |title=Hyperthermophilic Enzymes: Sources, Uses, and Molecular Mechanisms for Thermostability |journal=Microbiology and Molecular Biology Reviews |year=2001 |volume=65 |issue=1 |pages=1–34 |doi=10.1128/MMBR.65.1.1-43.2001 |pmid=11238984 |pmc=99017}}</ref> for example in manufacturing [[antibiotic]]s, [[plastic]]s, [[detergent]]s (by the use of heat-stable enzymes [[lipase]]s, [[pullulanase]]s and [[protease]]s), and fermentation products (for example [[ethanol]] is produced). Among these, the first discovered and the most important for biotechnology is ''[[Thermus aquaticus]]''.<ref>{{cite web |url=http://www.udel.edu/chem/bahnson/chem645/websites/Heaton/ |title=Industrial Uses of Thermophilic Cellulase |publisher=[[University of Delaware]] |access-date=29 March 2008 |archive-url=https://web.archive.org/web/20071010114505/http://www.udel.edu/chem/bahnson/chem645/websites/Heaton/ |archive-date=10 October 2007}}</ref>