Microbiology of extreme environments (Types and Examples)

What are extreme environments?

An extreme environment is a habitat characterized by harsh environmental conditions further than the optimal range for the development of humans or other living organisms.
Extreme environments are characterized by various unfavorable conditions including, high or low temperature, high or low pressure, and acidic or basic pH.
For an area to be considered extreme, certain conditions or aspects of the environment must be considered very hard for different forms of life to survive.
Examples of some extreme environments include the polar region, deserts, volcanic regions, deep ocean trenches, outer space, and every other planet of the Solar System except the Earth.
Some of the common extreme environments include areas that are alkaline, acidic, extremely hot or cold, high salt concentration, without water or oxygen.

Extreme environments are classified into the following groups based on the extreme physicochemical conditions:

Extreme temperature: Two types of extreme environments can be described; cold and hot.

Extremely cold environments are those with environmental temperatures below 5°C. These can be found in deep ocean niches, at the peaks of high mountains, or the Polar Regions.
Extremely hot environments are characterized by environmental temperatures higher than 45°C. These environments are influenced by geothermal activity as geysers and fumaroles of continental volcanic areas or deep-sea vents.

Extreme pH: Extreme environments can also be classified as acidic or alkaline according to their pH.

Extreme acidic environments are natural habitats in which the pH is below 5.
Extreme alkaline environments are those with a pH above 9.

Extreme ionic strength:

Hypersaline environments are environments with an ionic concentration higher than of seawater (greater than 3.5%).

Extreme pressure:

Extreme pressure environments are those environments under extreme hydrostatic or litho pressure, such as aquatic habitats at depths of 2,000 m or more or deep-subsurface ecosystems.

High-radiation environments are those areas that are exposed to abnormally high radiation doses, including ultraviolet or gamma radiation, like deserts and the top of high mountains.

Xeric environments are arid habitats with limited water activity. Cold and hot deserts are some examples of these extreme environments.

What are extremophiles?

Extremophiles are living organisms with the ability to survive and thrive in extreme environments as a result of different physiological and molecular adaptations.
These organisms thrive in extreme niches, ice, and salt solutions, as well as acid and alkaline conditions.
Some might grow in toxic waste, organic solvents, heavy metals, or in several other habitats that are considered inhospitable for life.
Most extremophiles are prokaryotic organisms with few eukaryotes. These extremophiles are defined by the environmental conditions in which they can survive and thrive optimally.
Extremophiles can be divided into two categories: extremophilic organisms that require one or more extreme conditions to survive, and extremotolerant organisms that 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.
Most extremophiles are prokaryotes with a high proportion of belonging to archaea, but some organisms might be eukaryotes such as protists (e.g., algae, fungi, and protozoa) and multicellular organisms.
These are classified according to the conditions in which they grow: thermophiles and hyperthermophiles (organisms growing at high or very high temperatures, respectively), psychrophiles (organisms that grow at low temperatures), acidophiles and alkaliphiles (organisms thriving in habitats with acidic or basic pH values, respectively), barophiles (organisms that grow best under pressure), and halophiles (organisms that grow well in an environment with NaCl).

Characteristics of extremophiles

Extremophiles are characterized by the ability to thrive in extreme environments which results from different forms of physiological and molecular adaptations.
Extremophiles are mostly prokaryotes with the nuclear material in the cytoplasm and unicellular eukaryotes.
Archea is an important group of organisms that tend to be extremophiles due to their ability to adapt to different extreme conditions.
These organisms present a wide and versatile metabolic diversity, along with extraordinary physiological capacities to inhabit extreme environments.
These forms of adaptations are developed through various evolutionary processes over a long period of time.

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Microorganisms in extreme low humidity/water activity (Xerophiles)

Xerophile Definition and Characteristics

Xerophiles are a group of extremophiles that are capable of surviving in environments with low availability of water or low water activity.
Generally, xerophilic organisms are capable of growing at aw values lower than xerotolerant organisms (aw below 0.8).
Two major types of the environment provide habitats for the most xerophilic organisms, namely foods preserved by some form of dehydration or organic solute-promoted lowering of aw and saline lakes, where low aw values are a consequence of inorganic ions.
In environments where little water is available, organisms must take up and maintain sufficient water against extreme concentration gradients to support cellular processes.
Xerophiles are of different types belonging to different groups of living beings. Xerophilic fungi represent a large group of xerophilic organisms.
Eukaryotic organisms like plants capable of surviving at low water condition, called xerophytes are also xerophiles.
Xerophiles are closely related to halophiles as halophilic environments tend to have low water activity.
Even though water is crucial for many biomolecular processes in living beings, xerophiles have intricate means to survive in conditions with low water activity.

Xerophile Mode of adaptation

a. Dormancy

One of the most common responses of prokaryotes to low water conditions is a reversible form of dormancy.
These organisms under a temporary period of dormancy in the form of spores so that they reduce metabolic activity and resume normal metabolism when appropriate conditions are available.
The formation of spores and reduction in metabolic activities provide long periods of survival for many microorganisms as well as larger eukaryotes.

b. Extracellular polysaccharides and biofilm formation

Various xerophilic organisms form biofilms as it allows the survival of organisms in habitats with low moisture content.
These biofilms consist of microbial aggregates and extracellular polysaccharides produced by those organisms.
The extracellular polysaccharides in the biofilms are hydrophilic, which contributes to rapid water absorption rates and restoration of photosynthetic activity.
Biofilm formation also reduces the need for large quantities of water as they occupy less space and have less metabolic activities.

c. Cell membrane

The cell membrane of xerophilic organisms tends to have an increased ratio of fatty acids which creates a tighter lipid packing that preserves the membrane during desiccation.
Increased cyclopropane fatty acid content in the membrane also reduces the membrane permeability to protons which thus, helps in balancing the intracellular pH.
Xerophilic microorganisms adapt to low water activity by increasing the concentration of negatively charged phospholipids that facilitates the preservation of membrane bilayer structural integrity.

d. Proteins

In the case of xerophytes, a range of proteins that counteract the effects of low water activity is produced.
These proteins are rich in glycine and have a highly hydrophobic backbone that transitions into the ordered structure under desiccating conditions, preventing denaturation.
Xerophilic cyanobacteria code for various shock response genes on dehydration that regulate the utilization of water in metabolic processes during desiccation.

Xerophile Examples

Some common examples of xerophiles are Aspergillus penicillioides, Cereus jamacaru, Deinococcus radiodurans, Aphanothece halophytica, Anabaena, Bradyrhizobium japonicum, Saccharomyces bailli, etc.

Microorganisms in extreme salinity (Halophiles)

Halophile Definition and Characteristics

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.
Halophilic microorganisms constitute the natural microbial communities of hypersaline ecosystems, which are widely distributed around the world.
The general features of halophilic microorganisms are low nutritional requirements and resistance to high concentrations of salt with the capacity to balance the osmotic pressure of the environment.
The salt requirement in halophiles is classified into three groups; low (1-3%), moderate (3-15%), and extreme (15-30%).
Salt requirement depends on factors like temperature, pH, and growth medium.
They are physiologically diverse; mostly aerobic and as well anaerobic, heterotrophic, phototrophic, and chemoautotrophic.
Ecologically, the halophilic microorganisms inhabit different ecosystems characterized by a salinity higher than seawater that range from hypersaline soils, springs, salt lakes, sabkhas to marine sediments.
These organisms are found in all three domains of life, i.e., Archaea, Bacteria, and Eukaryota.
Halophilic bacteria are more abundant in specific phylogenetic subgroups, most of which belong to Halomonadaceae, a family of Proteobacteria.

Halophile Mode of adaptation

In order to avoid excessive water loss under high salt conditions, halophiles have employed two distinct strategies to increase the osmotic activity of their cytoplasm with the external environment, either producing compatible organic solutes or accumulating large salt concentrations in their cytoplasm to reach an equilibrium state in which the overall salt concentration within cells correlates that of the environment.

a. High salt-in strategy

The high-salt-in strategy is another adaptation technique that protects halophiles from a saline environment in which they accumulate inorganic ions intracellularly to balance the salt concentration in their environment.
This process involves Cl– pumps that are found only in halophiles that transport Cl– from the environment into the cytoplasm.
Arginines and lysines are positioned at both ends of the channel to facilitate Cl– uptake, and release.
Extreme halophiles maintain their osmotic balance by concentrating the K+ ions inside the cells.
This is achieved by the combined action of the membrane-bound proton-pump bacteriorhodopsin, ATP synthase, and the Na+ antiporter that results in an electrical potential that drives the uptake of K+ into cells.

b. Organic salt-in strategy

The high-salt-in strategy might be incompatible for the survival of moderate halophiles that thrive in habitats of fluctuating salinity.
The solute-in strategy includes the evolution of inert, compatible organic solutes (osmolytes) in the halophiles.
These osmolytes protect the microbial proteins from denaturation in the water of low salt concentrations while enhancing their tolerance to drastic fluctuations in the external saline environment.

c. Enzymes

A high-salt environment substantially impacts protein solubility and stability and consequently, its function.
The unfavorable interactions that disrupt internal microbial proteins caused by dehydration may be averted by modulating their net charge.
Proteins and enzymes of halophiles have a larger proportion of glutamate and aspartate on their surfaces that result in a substantial number of protein charges and increased hydrophobicity.
Both of these mechanisms work as a form of molecular halo adaptation of halophilic enzymes.
Halophilic enzymes are more stable than their non-halophilic counterparts owing to their polyextremophilic characteristics.
These enzymes remain active in high-salt environments, thermotolerant, and alkaliphilic.

Halophile Examples

Some common examples of halophilic organisms in terms of their salt requirement are:

Slightly halophilic: Erwinia, Bacillus hunanensis, Halomonas zhaodongensis, Alkalibacterium thalassium, etc.
Moderately halophilic: Spiribacter salinus, Halobacillus sediminis, Halobacillus salicampi, Marinobacter piscensis, Idiomarina aquatica, etc.
Extreme halophile: Halococcus salifodinae, Halobacterium salinarum, Limimonas halophilia, Lentibacillus kimchii, Sporohalobacter salinus, etc.

Microorganisms in extreme sugar concentrations (Osmophiles)

Osmophile Definition and Characteristics

Osmophiles are a group of organisms that are adapted to survive in environments with high osmotic pressures like high sugar concentration.
Osmophilic organisms are similar to halophiles, and xerophiles as all of them have the capacity to survive in environments with low water activity.
Osmophiles are mostly found in food with high sucrose content and environments with high osmolarity.
Fungi are the most common group of organisms that survive as osmophiles. However, organisms of the group Archea and Bacteria are also important osmophiles.
Osmophilic organisms are found in different parts of the world, especially in areas with high sugar content like food sources.
The ability to adapt to fluctuations in external osmotic pressure and the development of specific mechanisms to achieve the adaption is fundamental to the survival of cells.
Most cells maintain an osmotic pressure in the cytoplasm that is higher than that of the surrounding environment, resulting in an outward-directed pressure, turgor, whose maintenance is essential for cell division and growth.
Any changes in environmental osmolarity can trigger the flux of water across the cytoplasmic membrane. Thus, osmophilic organisms develop different mechanisms to overcome the osmotic imbalance.

Osmophile Mode of adaptation

a. Osmoprotectatnts

Osmophiles produce different osmoprotectants like alcohols and amino acids that prevent the change in osmotic pressure inside the cell.
These solutes increase the osmotic pressure inside the cell so as to balance the turgor pressure on the cell from the outside environments.

b. Enzymes

Proteins and enzymes in osmophiles have more protein charges and hydrophobicity that protects them against the change in the solute composition in the cytoplasm.
The unfavorable interactions that disrupt internal microbial proteins caused by dehydration may be averted by modulating their net charge.

Osmophile Examples

Some common examples of osmophiles include Zygosaccharomyces, Torula, Schizosaccharomyces octosprus, etc.

Microorganisms in extreme pressure (Piezophiles/ Barophiles)

Piezophile Definition and Characteristics

Barophiles are defined as organisms that grow and thrive optimally at pressures greater than atmospheric pressure.
The term piezophile is used as a replacement to barophile as piezo means pressure in Greek.
Barophilic bacteria have been isolated from various deep-sea environments throughout the world and have been grown rapidly at low temperatures and high pressures.
Bacteria living in the deep-sea display several unusual features that allow them to thrive in their extreme environment.
Most barophilic organisms tend to be psychrophilic and thus cannot be cultured at a temperature above 20°C.
Similarly, many barophiles tend to be obligate barophiles with few archaea acting as moderately barophilic.
It has been seen that the pressure needed for the maximal rate of reproduction at 2°C may reflect the true habitat depth of an isolate.
High pressure affects the survival of microorganisms, where it influences the membrane structure and functioning of the cell.
High pressure and low temperature in deep-sea environments decrease the fluidity of lipids and even depress the functions of biological membranes.

Piezophile Mode of adaptation

a. Membrane

High pressure might cause the formation of a gel-like membrane which then decreases nutrient uptake and processing.
Barophiles produce increased levels of unsaturated fatty acids in the lipids and increasing the extent of fatty acid unsaturation can maintain the membrane in a functional liquid crystalline state at high pressures, low temperatures, or both.
The reduced fluidity gives a defined structure to the membrane, which supports the normal functioning of the cell.

b. Proteins

The high-pressure condition suitable for barophiles results in conformational changes in the proteins that inhibit their function.
In order to prevent such changes, barophilic proteins usually have lower concentrations of proline residues and a higher concentration of glycine residues.
The proline residues have cyclic side chains that disrupt alpha-helices, whereas the glycine residues have small side chains with high conformational flexibility.
The increased flexibility prevents the disruption of alpha helices and protects the function of such proteins.

Piezophile Examples

Some common examples of barophilic microorganisms are Shewanella benthica, Moritella yayanosii, Shewanella violacea, Photobacterium profundum, Moritella japonica, Sporosarcina spp, etc.

Microorganisms in rocks (Endolith/Hypolith)

Endolith Definition and Characteristics

Endolith is an organism that survives in various inhospitable environments throughout the world, especially inside rocks, animal shells, coral reefs, and sand particles in the soil.
Endoliths occupy habitats beneath and between porous and translucent rocks and minerals.
Rock porosity provides interstitial spaces for microbial colonization and translucence enables photosynthesis to take place.
Despite their limited water availability, cold temperature, strong winds, and large variations in solar radiation input, cold deserts harbor endolithic microorganisms.
Microbial life can thrive, and endolithic microbial communities have been intensively studied in the Antarctic region, which is characterized by extreme climatic conditions, with low humidity and precipitation making it practically an inhospitable environment for living beings.
In terrestrial systems, these microenvironments typically provide protection from intense solar radiation and desiccation, as well as sources of nutrients, moisture, and substrates derived from minerals.
In marine systems, endolithic communities similarly exploit the rocky seafloors, but also dwell into limestone and mineralized skeleton of a broad range of marine animals.
Besides tolerating the desiccating conditions and extreme temperatures, microorganisms inhabiting such arid conditions are subjected to osmotic stress due to the high salt concentrations.
The water content of sandstone colonized by endolithic microorganisms is represented by 0.1–0.2% by weight as a result of little moisture penetrating into the rocks through pores.

Endolith Mode of adaptation

a. Metabolic activities

Endoliths are capable of ‘switching’ their metabolic activities on and off in response to rapid changes in environmental conditions.
In cold areas, the organisms are inactive in a ‘freeze-dried’ state that does not damage cellular structures.
As the temperature increases, the small quantities of water can maintain a level of humidity that is sufficient for metabolic activity.

b. Biofilm formation

Various xerophilic organisms form biofilms as it allows the survival of organisms in habitats with low moisture content.
These biofilms consist of microbial aggregates and extracellular polysaccharides produced by those organisms.
The extracellular polysaccharides in the biofilms are hydrophilic, which contributes to rapid water absorption rates and restoration of photosynthetic activity.

c. Weathering process

Lichen and algae represent the pioneer species in such environments where the release of various enzymes results in the degradation of rock particles.
As the weathering process continues, the organic matter of the area increases so that new groups of living microorganisms can thrive at such a climate.

Endolith Examples

Some examples of endoliths include Leptolyngbya, Helicobacter recurvirostre, Gloeocapsa sanguine, Acaryochloris, Chroococcidiopsis, Anabaena, Spirirestis rafaelensis, etc.

Hypolith Definition and Characteristics

Hypoliths are organisms or communities of organisms that live on the underside of rocks or at the rock–soil interface.
Hypoliths are photosynthetic microorganisms that exist in hot and arid climates, usually at the interface between the rocks and the soil.
The community of microorganisms present in such an area is termed as hypolithon.
Microorganisms that are present underneath the rocks are protected from the harsh radiations of the sun and the wind.
The rocks might even trap moisture which can then be used by these microorganisms.
Different forms of minerals like quartz are found in soil and rocks that also supports different forms of life.
However, there are different stresses, including low water activity and drastic changes in temperature, which limits the biodiversity of such habitats.
The most common habitats for hypoliths include the desert lands and polar regions where the climate change is quite drastic with rapid desiccation and rehydration.

Hypolith Mode of adaptation

a. Biofilm

One of the most successful means of survival of microorganisms in rock surfaces is by the production of exopolysaccharides that together microbial aggregates form biofilms.
Biofilms help to retain moisture and also reduce the metabolic activities of these organisms, which help to save energy and nutrients.
Biofilms also protect hypoliths against the harmful radiation and extreme heat conditions of such habitats.

b. Dormant stages

In the case of low water activity, some of the hypoliths modify into dormant stages in the form of spores that help to preserve nutrients and moisture of the surface.
The dormant stages then convert into the active forms as the climate and nutrient content of the environment becomes sufficient.
The formation of spores and reduction in metabolic activities provide long periods of survival for many microorganisms as well as larger eukaryotes.

Hypolith Examples

Some of the common examples of hypoliths include Nostoc, Bryum, Hennediella, Stichococcus mirabilis, Ichthyosporea, etc.

Microorganisms in heavy metals (Metallotolerant)

Metallotolerant Definition and Characteristics

Metallotolearnt microorganisms are the microorganisms that are capable of tolerating and detoxifying high levels of dissolved heavy metals.
Microorganisms utilize metals as structural components of biomolecules, as cofactors in reversible oxidation/reduction reactions, and in electron transfer chains during energy conservation.
However, metals can become toxic if their intracellular concentrations are too high.
Most metallotolerant microorganisms tend to be acidophilic as the physiological activities of such microorganisms enable tolerance against high metal concentrations.
As many metals are more soluble at acidic pH, acidophiles are typically exposed to high metal concentrations and can survive in 1000-fold higher amounts than neutrophilic microorganisms.
Metallotolerant microbes belong to all bacterial groups studied, mostly among aerobic and facultative aerobic chemo-heterotrophic microorganisms.
Polluted soils and waters with untreated industrial and urban wastes and samples of the natural environment with a high concentration of metals are important habitats of metallotolerant microorganisms.
These organisms have different mechanisms that support their survival in very high metal concentrations.

Metallotolerant Mode of adaptation

a. Membranes

The membranes of metallotolerant microorganisms are equipped with various channels that prevent the entry of metals ions into the cytoplasm.
A process termed metal sorption is common in metallotolerant microorganisms where the metal ions are bound to the membrane but cannot enter the cell.
Besides, different transport channels have regulators lie the ferric uptake regulator that regulates the entry of a large number of iron ions into the cell.

b. Mineralization

The process of conversion of organic compounds into inorganic forms so that they can be excreted out of the cell is called mineralization.
The process is common in many metallotolerant, where they have different enzymes that catalyze the mineralization process.
Other metabolic processes that convert toxic forms of metals into less toxic forms via enzymatic oxidation and reduction are also studied in these organisms.

Metallotolerant Examples

Some of the common examples of metallotolerant species include Bacillus subtilis, Bacillus megaterium, Acidithiobacillus ferrooxidans, Acidithiobacillus caldus, Corynebacterium diptheriae, Acidiphilium rubrum, Acidiphilium multivorum, etc.

Microorganisms in extreme Radiation (Radiophiles)

Radiophile Definition and Characteristics

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.
These organisms have low diversity with all organisms belonging to the archaea and bacteria families.
Radiophiles can either be radiation tolerant or radiation-resistant. Radiation tolerant microorganisms can endure harmful radiation for a period of time, whereas radiation-resistant organisms can withstand a longer period of time.
Radiations are harmful to neutrophils as they destroy various important biomolecules like DNA, proteins, and enzymes as a result of ionization.
Non-ionizing radiation, in turn, results in the formation of reactive oxygen species like superoxides which then affects the metabolism of those cells.
The adaptive mechanism utilized by radiophiles might be different for ionizing and non-ionizing radiation.

Radiophile Mode of adaptation

a. Ionizing radiation

Ionizing radiation is responsible mainly for double-stranded breaks in the genome of organisms.
However, it has also been shown to damage both proteins and lipids and induce persistent oxidative stress.
Therefore, ionizing radioresistant organisms have developed all, or a combination of different strategies like the novel and adaptive DNA repair mechanisms, antioxidant and enzymatic defense systems, and a condensed nucleoid.
Fast and accurate repair of genomes is essential in surviving doses of ionizing radiation which is accomplished in radiophiles through the use of the nucleotide excision repair pathway.
Other forms of oxidative stress prevention and tolerance mechanisms include cell cleaning through the elimination of oxidized macromolecules, selective protection of proteins against oxidative damage, and suppression of reactive oxygen species production.
A condensed nucleoid has also been shown to promote the efficiency and accuracy of DNA repair and to limit the diffusion of radiation-generated DNA fragments.

b. Non-ionizing radiation

UV radiation, unlike gamma radiation, damages DNA in more subtle ways through the formation of cyclobutene pyrimidine dimmers.
To repair these DNA lesions, organisms use a combination of photoreactivation genes, nucleotide excision repair, base excision repair, and homologous recombination.
These organisms have also developed a suite of photoprotection devices to protect themselves from continual exposure to UV radiation.
Products like carotenoids, superoxide dismutases, and hydroperoxides and the gene duplication process via polyploidy work as the photoprotection devices.
The genome composition of the organisms with a reduction in the number of bipyrimidine sequences also provides protection against exposure.

Radiophile Examples

Some common examples of radiophiles are Deinococcus radiodurans, Brevundimonas, Rhodococcus, Halomonas, Herbaspirillum, Hymenobacter, Rhodobacter, etc.

Applications of Extremophiles

Exremophilic enzymes have been model systems to study enzyme evolution, enzyme stability, activity, mechanism, protein structure, function, and biocatalyst under extreme conditions.
Thermophiles have yielded stable α-amylase for starch hydrolysis, oxylonases for paper bleaching, and proteases for brewing and for detergent purposes.
Alkaline active proteases, amylases, cellulases, mannanases, lipases, etc. are used in the formulation of heavy-duty laundry and dishwashing detergents as they are efficient in removing stains and allow effective low-temperature (30–40°C) washing.
Some species of acidophilic microorganisms can be used not only to reduce mine water pollution but also to recover metals from acidic wastewater via selective biomineralization.
Extroenzymes like Taq polymerase from Thermus aquaticus is an ideal for use in a polymerase chain reaction as it reduces the need for adding extra polymerase during the reaction.
Cellulose for various extremophilic organisms has been used for the treatment of juices, color brightening in detergents, and treating cellulose-containing biomass and crops to improve their digestibility and nutritional quality.
Similarly, halophiles are being exploited as a potential source of carotene, compatible solutes, glycerols, and surfactants for pharmaceutical use.
Some extremophilic microorganisms may also comprise a large reservoir of novel therapeutic agents—for example, iron-binding antifungal compound, pyochelin isolated from halophilic species of Pseudomonas.
A thermostable glucokinase from the thermophilic species, Bacillus stereothermphiolus, can be used as a glucose sensor for quick glucose assay.
Alkaline active enzymes have got several notable applications in textile and fiber processing in processes like cotton scoring and blast fiber degumming.
Alkaliphiles and their enzymes have been tried in various synthesis reactions with peptide synthesis being the most important one.
Information on the microbial composition and biogeochemical cycling of extreme ecosystems also helps in understanding the global change, threats, and opportunities for living beings.
Enzymes from extremophiles can also be used in bioremediation processes like toxifying wastewater and air and removing metallic waste from sewages and industries.
Different barophilic enzymes are used for the production and sterilization of items at varied pressure conditions.

Microbiology of extreme environments (Types and Examples)

What are extreme environments?

What are extremophiles?

Characteristics of extremophiles

Microorganisms in extreme temperature (Psychrophile/Thermophile/Hyperthermophile)

Psychrophile Definition and Characteristics

Psychrophile Mode of adaptation

Psychrophile Examples

Thermophile Definition and Characteristics

Thermophile Mode of adaptation

Thermophile Examples

Hyperthermophile Definition and Characteristics

Hyperthermophile Mode of adaptation

Hyperthermophile Examples

Microorganisms in extreme pH (Acidophile/Alkaliphile)

Acidophile Definition and Characteristics

Acidophile Mode of adaptation

Acidophile Examples

Alkaliphile Definition and Characteristics

Alkaliphile Mode of adaptation

Alkaliphile Examples