Extremophiles can be divided into two categories
Here we are going to study some Types of Extremophiles…
- Extremophilic organisms that require one or more extreme conditions to survive.
- Extremotolerant organisms can tolerate extreme conditions of one or more physical parameters even though they grow optimally at neutral conditions. Extremophiles include members of all three domains of life; bacteria, archaea, and eukarya.
These are classified according to the conditions in which they grow –
Thermophiles – Organisms growing at high temperatures.
Hyperthermophiles – Organisms growing at very high temperatures.
Psychrophiles – Organisms that grow at low temperatures.
Acidophiles – Organisms thriving in habitats with an acidic PH.
Alkaliphiles – Organisms thriving in habitats with basic PH.
Halophiles – Organisms that grow well in an environment with NaCl.
Radoduric – Organisms that grow well in the presence of high radiation.
Barophiles – Organisms that grow best under pressure.
Types of Extremophiles
- Psychrophiles, literally meaning cold-loving.
- They are organisms adapted to growth at low temperatures.
- Having an optimum growth temperature of greater than 15°C and a maximum growth temperature of greater than 20°C and a minimum of 0°C.
- Thermophiles (lovers of true heat) are organisms that grow at temperatures higher than those (25-40 ° C) that support many species.
- Typically, a thermophile shows maximum growth rates at temperatures above 45°C.
- Hyperthermophiles are organisms that can survive and grow at extremely high temperatures (above 80°C).
- Hypothermophiles are a type of thermophiles that can endure even higher temperatures than other thermophiles.
- The optimum temperature of growth for hyperthermophiles is 80°C, but they can survive at temperatures higher than 100°C.
- Acidophiles are organisms that can survive and thrive in highly acidic conditions (usually at pH 2.0).
- Acidophilic microorganisms thrive in very low pH and man-made natural environments such as acidic lakes, other hydrothermal systems, acid sulfate soils, sulfidic regoliths, ores, and areas affected by iron and coal mines.
- Alkaliphiles are a group of extremophiles that can live and thrive in environments with extremely high pH values (9-13) with the optimal pH being 10.
- Alkaliphiles are of two types; obligate alkaliphiles growing only in environments with pH higher than 9 and facultative alkaliphiles that can live both at neutral pH and alkaline conditions.
- Halophiles are a group of extremophiles that require high salt concentrations for their survival and growth.
- Halophiles are of two types; obligate halophiles that require NaCl concentration of 3% or more and halotolerant that survive at both average salt concentrations and higher.
- Metallotolearnt microorganisms are microorganisms that are capable of tolerating and detoxifying high levels of dissolved heavy metals.
- Most metallotolerant microorganisms tend to be acidophilic as the physiological activities of such microorganisms enable tolerance against high metal concentrations.
- Radiophiles are a group of extremophiles that are capable of surviving extreme forms of radiations like ionizing radiant (gamma rays) and UV radiation.
- Studies on radiophiles are quite limited as they are to be isolated from extreme environments like outer space of other planets.