Extreme Environments

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Definition

The word “extreme” comes from the Latin word “extremus,” the superlative of “exter” (= on the outside) (Rothschild and Mancinelli, 2001). Whereas there is no general agreement on how to define an extreme environment, the term is commonly used for any setting that exhibits life conditions detrimental or fatal to higher organisms with respect to its physicochemical properties. Thus, extreme environments differ in one or more aspects from those which humans consider as “normal,” moderate conditions with circumneutral pH, temperatures between 20°C and 35°C, pressures around 0.1 MPA (1 atm), and adequate concentrations of nutrient and saline. It should be considered, however, that such definition represents an anthropocentric view and that what is extreme and what is normal from a microbial perspective remains questionable.

If not completely uninhabitable to life, extreme environments typically harbor specially adapted organisms, the so-called extremophiles. Most extremop ...