Summary
Organisms thriving in extremes of heat, acidity, salt or pressure, with specialised enzymes.
In depth
Thermophiles (above 45 °C) and hyperthermophiles (up to 122 °C), psychrophiles (cold), acidophiles, alkaliphiles, halophiles and piezophiles (pressure). Adaptations include stable proteins, special lipids and DNA-protecting proteins.
Extremophile enzymes (extremozymes) are used in industry. Thermophiles' proteins have extra salt bridges. Halophiles accumulate salt or compatible solutes.
Key idea: life exists in nearly all conditions on Earth.
Extreme conditions: Pyrolobus fumarii grows at 113 degrees, Picrophilus lives at pH 0, Halobacterium thrives in saturated salt, Deinococcus radiodurans survives radiation doses thousands of times those lethal to humans, and microbes live more than a kilometre below the surface or in the Mariana Trench. Adaptations include heat-stable proteins, ether lipids, compatible solutes, efficient DNA repair and antifreeze proteins.
Extremophiles inform astrobiology by showing possible limits for life elsewhere, and provide enzymes (extremozymes) for industry. Tardigrades are extremotolerant animals, not extremophiles in the strict sense.
Example: Thermus aquaticus from Yellowstone gave the heat-stable Taq polymerase.
Frequently asked questions
What is Extremophiles?
Organisms thriving in extremes of heat, acidity, salt or pressure, with specialised enzymes.
Which area of biology covers Extremophiles, and how advanced is it?
Extremophiles is one of the 54 topics in Microbiology. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Thermophilic Enzymes, Archaea, Microorganisms.
Can you give an example of Extremophiles?
Deinococcus radiodurans withstands thousands of grays of radiation.
What should I learn before Extremophiles?
Work through the Beginner topics in Microbiology first, such as Microorganisms, Bacteria, Archaea, then return to Extremophiles. Advanced topics assume the Intermediate vocabulary.
What topics are related to Extremophiles?
The closest topics to Extremophiles are Thermophilic Enzymes, Archaea, Microorganisms, Endospores. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Extremophiles?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Extremophiles. To practise the whole of Microbiology, use the Microbiology quiz.
How is Extremophiles different from Thermophilic Enzymes?
Extremophiles: Organisms thriving in extremes of heat, acidity, salt or pressure, with specialised enzymes. Thermophilic Enzymes: Heat-stable enzymes such as Taq polymerase from Thermus aquaticus enable PCR. Read both side by side and note what each one explains.
How should I study Extremophiles step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Thermophilic Enzymes and explain the difference aloud. Finally, take the Microbiology quiz and come back to this page for any question you miss.