Monday, August 6, 2007

Extremophile... the ETs

Long back I read about these strangecreatures. They are called Extremophiles…

There has been a lot of speculation on whether there are any Extra Terrestrials…
Many skeptics say that the chance of existence of any living being in other planets are slimmest, because of the temperature and pressure and most important the lack of water on these planets…

To solve this problem lets take this analogy…
Just because mr. x is vegetarian he should not assume that his neighbor must also be a vegetarian…..
We have been evolved to suite the conditions on earth, if we were born on some other planet we would have evolved with different need and molecular structure….
May be our extremophile may answer our quest on ET…

The wikipedia classifies extremophiles in the following order.

These are organism which live in high acidic conditions, as high as pH of 2…
To remind you that pH 7 is neutral and it is varies in a logarithmic scale. It means pH 2 is 1000 times more acidic than pH 3.
The acidity of the Ph 2 solution is equal to the acidity of gastric acid or a very strong lemonade… the pH of your cola is 2.5. That I believe is really extreme condition.

They are just opposite to acidophile. These organisms are found in alkalinity of pH 9 to 11. Your soap has alkalinity of 9 and the house hold ammonia has a pH of 11.5.

Barophiles are bacteria which live in high pressure environments. They are generally found on ocean floors, where pressure generally exceeds 380 atm (38 MPa). Some have been found at the bottom of the Pacific Ocean where the maximum pressure is roughly 117 MPa. Now 117 Mpa is equivalent to 11700000 kg of weight distributed equally on one metre squared area or 1170 kg of weight acting on a square area whose sides are 1cm long.
Obligate barophiles cannot survive outside of such environments. For example, the Halomonas species Halomonas salaria requires a pressure of 1000 atm (100 MPa) and a temperature of 3 degrees Celsius. Barotolerant bacteria are able to survive at high pressures, but can exist in less extreme environments as well.
Barophiles grow in darkness, and so are very uv sensitive, they lack many mechanisms of DNA repair.

An endolith or cryptoendolith is an organism (archaea, bacterium, or fungus) that lives inside rock, coral, animal shells, or in the pores between mineral grains. Many are extremophiles; living in places previously thought inhospitable to life. They are of particular interest to astrobiologists, who theorize that endolithic environments on Mars and other planets constitute potential refugia for extraterrestrial microbial communities.

Halophiles are extremophiles that thrive in environments with very high concentrations of salt (at least 2 M, approximately ten times the salt level of ocean water). The name comes from Greek for "salt-loving". Some well-known species give off a red color due to the carotenoid compounds. These species contain the photosynthetic pigment bacteriorhodopsin. Organisms are categorized either slight, moderate or extreme, by the extent of their halotolerance.

A hyperthermophile is an organism that thrives in extremely hot environments — that is, hotter than around 60 °C, with an optimal temperature above 80 °C. The most heat-tolerant hyperthermophile is the recently-discovered Strain 121 which has been able to double its population during 24 hours in an autoclave at 121 °C (hence its name). Many hyperthermophiles are also able to withstand other environmental extremes such as high acidity or radiation levels.
Although no hyperthermophile has yet been discovered living at temperatures above 121 °C, their existence is very possible (Strain 121 survived being heated to 130 °C for 2 hours, but was not able to reproduce until it had been transferred into a fresh growth medium, at a relatively-cooler 103°C). However, it is thought unlikely that microbes could survive at temperatures above 150° C, as the cohesion of DNA and other vital molecules begins to break down at this point.

In Arctic and Antarctic ecology, a hypolith is a photosynthetic organism that lives underneath rocks in climatically extreme deserts such as Cornwallis Island and Devon Island in the Canadian high Arctic. The community itself is the hypolithon.
Hypolithons are protected from harsh ultraviolet radiation and wind scouring by their rock, which can also trap moisture. The rocks are generally translucent to allow for the penetration of light.

A lithoautotroph is a microbe which derives energy from reduced compounds of mineral origin. They may also be referred to as chemolithoautotrophs, a type of lithotrophs, reflecting their autotrophic metabolic pathways. Lithoautotrophs are exclusively microbes; macrofauna do not possess the capability to utilize mineral sources of energy.

An oligotroph is an organism that can live in a very low carbon concentration, less than one part per million. They may be contrasted with copiotrophs, which prefer environments rich in carbon. Most oligotrophs are bacteria, though archaean oligotrophs also exist. Oligotrophs are characterized by slow growth, low rates of metabolism, and generally low population density. Low-carbon environments are ubiquitous; oligotrophs may be found a wide range of environments including in deep oceanic sediments, caves, glacial and polar ice, deep subsurface soil, aquifers, and ocean water.

Osmophillic organisms are extremophiles that are able to grow in environments with a high sugar concentration. Osmophiles are similar to halophillic (salt-loving) organisms because a critical aspect of both types of environment is their low water activity.

A piezophile is an organism which thrives at high pressures, such as deep sea bacteria or archaea.
The high pressures experienced by organisms in deep-sea trenches, for example, can cause the normally fluid cell membrane of these organisms to become waxy and relatively impermeable to nutrients. Evolution has forced these organisms to adapt in novel ways to become tolerant of these pressures in order to colonize deep sea habitats.

A polyextremophile (to like several extremes in more-or-less Greek) is an organism which combines several extremophilic features. For example, a polyextremophile living at the summit of a mountain in the Atacama Desert might be a radioresistant xerophiler, a psychrophile, and an oligotroph.

Psychrophiles or Cryophiles (adj. cryophilic) are extremophilic organisms that are capable of growth and reproduction in cold temperatures. They can be contrasted with thermophiles, which thrive at unusually hot temperatures. The environments they inhabit are ubiquitous on Earth, as a large fraction of our planetary surface experiences temperatures lower than 15°C. They are present in alpine and arctic soils, high-latitude and deep ocean waters, arctic ice, glaciers, and snowfields. They are of particular interest to astrobiology, the field dedicated to the formulation of theory about the possibility of extraterrestrial life.

Radioresistance is the property of organisms which are capable of living in environments with very high levels of ionizing radiation.
Radioresistance is surprisingly high in many organisms, in contrast to previously held views. For example, the study of environment, animals and plants around the Chernobyl accident area has revealed an unexpected survival of many species, despite the high radiation levels. A Brazilian study in a hill in the state of Minas Gerais which has high natural radiation levels from uranium deposits, has also shown many radioresistant insects, worms and plants. To have a comparison, if a human can survive 5 units of radiation, these extremophiles can survive 15000 units of radiation.
Radiation can also help some plants to become more adapted to their environment by increasing the growth rate of the seeds. This helps them germinate faster.

A thermophile is an organism – a type of extremophile – which thrives at relatively high temperatures, above 45 °C. Many thermophiles are archaea.

Xerophiles are extremophilic organisms that can grow and reproduce in conditions with a low availability of water, also known as water activity. Water activity (aw) is a measure of the amount of water within a substrate that an organism can use to support growth. Xerophiles are often said to be "xerotolerant", meaning tolerant of dry conditions. They can survive in environments with water activity below 0.8. Endoliths and halophiles are often xerotolerant.

So the next time you boil water, think again if the water is sterilised or there are still some strain121 there reproducing….

I know this post is really long but, you have to put with rain to see the rainbow…

Take care
Blessed be.


Jon said...

OK, we've got a hypothesis that extremophile bacteria are of extraterrestrial origin. How could we test that hypothesis?

Well, if these bacteria were of different origin they would not share a common ancestor with non-extremophile bacteria and the rest of life on earth. In this case they are highly unlikely to have genetic similarity to the rest of life on earth. Many genes in some of these extremophiles have been sequenced (see, for example, Helicobacter pylori which can give you stomach ulcers). What do you think happens when we compare gene sequences of extremophiles and other life on earth?

Don't take my word for it. Look it up yourself.

mystic said...

sorry, havent been online these days.

kind of busy, will see to it soon and possibly come back with an answer.
thanx for the suggestion, this surely is a point to think about.

however i dint mean that extremophiles are extraterrestrial in origin, but if at all there is ant extraterrestrial life, it would be much like these Extremophiles and not some short green men.

rexacrouch said...

I found a good primer paper on Extremophiles at:

Pankaj kumar yadav said...

@ Rexacrouch

Thanks for the link.

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