Thermoacidophile
Encyclopedia
A thermoacidophile is an extreme
archeon
which thrives in acid
ous, sulfur
rich, high temperature environments.
Thermoacidophiles prefer temperatures of 70 - 80 °C and pH
between 2 and 3. They live mostly in hot spring
s and/or within deep ocean vent communities. Classified as an Archaebacteria and an extremophile
, Thermoacidophiles are found in places where most organisims would not survive.
Archaea
.
There are many unique characteristics that make up these prokaryotes. They are specially resistant to high temperatures and high acid concentrations. They have a plasma membrane which contains high amounts of saturated fats, and its enzymes are able to withstand extreme conditions without denaturation
.
sequences of thermoacidophiles, and other Archaebacteria, and complex eukaryote
s provides support to Archae being the progenitor species for the first cellular life on Earth. They were able to thrive on the early, warmer Earth with an atmosphere that lacked oxygen.
Archaeobacteria are prokaryotes, like eubacteria, however, and therefore are most facilely compared to eubacteria (i.e., archaeobacteria represent a monophyletic taxon of bacteria-like things).
Nevertheless, some aspects of archaeobacteria are more eukaryote-like than eubacteria. Most fascinating about archaeobacteria are the often bizarre environments which they inhabit, including water whose temperature exceeds that of hot springs.
This is because the Gram stain is a measure of physical aspects of cell walls that are shared between the eubacteria and the archaeobacteria (though gram-negative archaeobacteria lack outer membranes).
There exist cell-wall less archaeobacteria which live in the high temperature (55 to 59°C) and acidic piles of coal tailings.
Typical structure of eubacteria monoglyceride:
Typical structure of archaeobacteria monoglyceride:
bilayers also contain lipids consisting of ether-linked hydrocarbons stretched between glycerol moieties, linked at both ends (think of two fats joined at the end of their fatty acid chains and you'll get an idea: || where | is glycerol, = are two parallel fatty acids, and |= is a eubacterium diglyceride).
For these linked lipids each glycerol is found in the opposite membrane leaflet, at the hydrophilic-hydrophobic interface.
An archaeobacteria membrane spanning, glycerol-based lipid (only one of expected two spanning hydrocarbon chains shown):
One obvious explanation for the existence of such lipids is that they may make the archaeobacteria membrane sufficiently stable, at least in part, to allow growth and survival in the extreme environments in which many archaeobacteria may be found.
Extremophile
An extremophile is an organism that thrives in physically or geochemically extreme conditions that are detrimental to most life on Earth. In contrast, organisms that live in more moderate environments may be termed mesophiles or neutrophiles...
archeon
Archaea
The Archaea are a group of single-celled microorganisms. A single individual or species from this domain is called an archaeon...
which thrives in acid
Acid
An acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...
ous, sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
rich, high temperature environments.
Thermoacidophiles prefer temperatures of 70 - 80 °C and pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
between 2 and 3. They live mostly in hot spring
Hot spring
A hot spring is a spring that is produced by the emergence of geothermally heated groundwater from the Earth's crust. There are geothermal hot springs in many locations all over the crust of the earth.-Definitions:...
s and/or within deep ocean vent communities. Classified as an Archaebacteria and an extremophile
Extremophile
An extremophile is an organism that thrives in physically or geochemically extreme conditions that are detrimental to most life on Earth. In contrast, organisms that live in more moderate environments may be termed mesophiles or neutrophiles...
, Thermoacidophiles are found in places where most organisims would not survive.
Taxonomy
Thermoacidophiles belong to the Kingdom Archaebacteria, in the DomainDomain (biology)
In biological taxonomy, a domain is the highest taxonomic rank of organisms, higher than a kingdom. According to the three-domain system of Carl Woese, introduced in 1990, the Tree of Life consists of three domains: Archaea, Bacteria and Eukarya...
Archaea
Archaea
The Archaea are a group of single-celled microorganisms. A single individual or species from this domain is called an archaeon...
.
There are many unique characteristics that make up these prokaryotes. They are specially resistant to high temperatures and high acid concentrations. They have a plasma membrane which contains high amounts of saturated fats, and its enzymes are able to withstand extreme conditions without denaturation
Denaturation (biochemistry)
Denaturation is a process in which proteins or nucleic acids lose their tertiary structure and secondary structure by application of some external stress or compound, such as a strong acid or base, a concentrated inorganic salt, an organic solvent , or heat...
.
Possibly the progenitor of cellular life
The similarities between DNADNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
sequences of thermoacidophiles, and other Archaebacteria, and complex eukaryote
Eukaryote
A eukaryote is an organism whose cells contain complex structures enclosed within membranes. Eukaryotes may more formally be referred to as the taxon Eukarya or Eukaryota. The defining membrane-bound structure that sets eukaryotic cells apart from prokaryotic cells is the nucleus, or nuclear...
s provides support to Archae being the progenitor species for the first cellular life on Earth. They were able to thrive on the early, warmer Earth with an atmosphere that lacked oxygen.
Comparisons to Eukaryotes and Eubacteria
Archaeobacteria constitute the third domain of living organisms, one distinct from that represented by the eubacteria and the eukaryotes.Archaeobacteria are prokaryotes, like eubacteria, however, and therefore are most facilely compared to eubacteria (i.e., archaeobacteria represent a monophyletic taxon of bacteria-like things).
Nevertheless, some aspects of archaeobacteria are more eukaryote-like than eubacteria. Most fascinating about archaeobacteria are the often bizarre environments which they inhabit, including water whose temperature exceeds that of hot springs.
Identification
Archaeobacteria nevertheless often may be differentiated in terms of Gram staining.This is because the Gram stain is a measure of physical aspects of cell walls that are shared between the eubacteria and the archaeobacteria (though gram-negative archaeobacteria lack outer membranes).
There exist cell-wall less archaeobacteria which live in the high temperature (55 to 59°C) and acidic piles of coal tailings.
Physical Characteristics
The following is quoted from Prescott et al., 1996 (p. 478):
As a group the archaeobacteria [Greek archaios, ancient, and bakterion, a small rod] are quite diverse, both in morphology and physiologically.
They can stain either gram positive or gram negative and may be spherical, rod-shaped, spiral, lobed, plate-shaped, irregularly shaped, or pleomorphic.
Some are single cells, whereas others form filaments or aggregates.
They range in diameter from 0.1 to over 15 µm, and some filaments can grow up to 200 µm in length.
Multiplication may be by binary fission, budding, fragmentation, or other mechanisms.
Archaeobacteria are just as diverse physiologically. They can be aerobic, facultatively anaerobic, or strictly anaerobic.
Nutritionally they range from chemolithoautotrophs to organotrophs.
Some are mesophiles; others are hyperthermophiles that can grow above 100°C.
Archaeobacteria usually prefer restricted or extreme aquatic and terrestrial habitats.
They are often present in anaerobic, hypersaline, or high-temperature environments.
Recently archaeobacteria have been discovered in cold environments. It appears that they constitute up to 34% of the procaryotic biomass in coastal Antarctic surface waters.
A few are symbionts in animal digestive systems.
Cell wall
The archaeobacteria cell wall differs chemically from that of the eubacteria cell wall. Specifically, they lack in peptidoglycan.Branched chain hydrocarbons
Archaeobacteria lipid bilayers consist of branched chain hydrocarbons linked by ether (as opposed to ester) linkages to glycerol.Typical structure of eubacteria monoglyceride:
H
H-C-OH O
| ||H H H H H H H
H-C -O- C-C-C-C-C-C-C-C-H
| H H H H H H H
H-C-OH
H
Typical structure of archaeobacteria monoglyceride:
H H H
H-C-OH H-C-H H-C-H
| H H | H H H | H
H-C -O- C-C-C-C-C-C-C-C-H
| H H H H H H H H
H-C-OH
H
Membrane-spanning lipids
Archaeobacteria lipidLipid
Lipids constitute a broad group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins , monoglycerides, diglycerides, triglycerides, phospholipids, and others...
bilayers also contain lipids consisting of ether-linked hydrocarbons stretched between glycerol moieties, linked at both ends (think of two fats joined at the end of their fatty acid chains and you'll get an idea: || where | is glycerol, = are two parallel fatty acids, and |= is a eubacterium diglyceride).
For these linked lipids each glycerol is found in the opposite membrane leaflet, at the hydrophilic-hydrophobic interface.
An archaeobacteria membrane spanning, glycerol-based lipid (only one of expected two spanning hydrocarbon chains shown):
H H H H H
H-C-OH H-C-H H-C-H H-C-H H-C-H
| H H | H H H | H H H | H H H H | H H
H-C-O-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-O-C-H
| H H H H H H H H H H H H H H H H H |
H-C-OH H-C-OH
H |
H-C-OH
H
One obvious explanation for the existence of such lipids is that they may make the archaeobacteria membrane sufficiently stable, at least in part, to allow growth and survival in the extreme environments in which many archaeobacteria may be found.