This document discusses various types of extreme environments and the microorganisms that thrive in them. It defines oligotrophs as microbes that grow in very low nutrient environments. Thermophiles thrive in hot environments and have adaptations like stabilizing proteins and membrane lipids. Psychrophiles love cold environments and produce antifreeze proteins. Barophiles or piezophiles thrive under high pressure, such as the deep sea. Metallophiles and acidophiles resist heavy metals and acid respectively. Halophiles thrive in highly saline environments. The document provides examples of microbes for each type and discusses their adaptations and habitats.

1. -By NOBENDU MUKERJE(Ramakrishna Mission Vivekananda Centenary College)
SWASTIKA MAITRA(Adamas University)

2. 1)Introduction to Extreme Enviornments.
2)Types of extreme enviornments.
3)Occourence, Diversity, Adaptations of the following
a) Oligotrophs
b) Thermophiles
c) Psychrophiles
d) Barophiles
e) Organic solvent & radiation tollerants
f) Metallophiles
g) Acidophiles
h) Halophiles
4)References

3. An extreme environment
contains conditions that are
hard to survive for most known
life forms.

4. • Alkaline
• Acidic
• Extremely cold
• Extremely hot
• Hypersaline
• Under pressure
• Radiation
• Without water
• Without oxygen
• Altered by humans

5. o The word "Oligotroph" Is a combination of the greek
adjective oligos meaning "Few" And the adjective
trophikos meaning "Feeding".
o An oligotroph offers very low levels of nutrients.
o Oligotrophs are characterized by slow growth, low rates
of metabolism.
o Oligotrophs have a large surface area to volume ratio.
o They inherent a resistance to environmental stresses.
o EXAMPLES:
• Sphingomonas sp.
• Cycloclasticus oligotrophicus
• Pelagibacter ubique

6.  Deep oceanic sediments
 Leached soils.
 Caves
 Glacial and polar ice
 Deep subsurface soil
 Aquifers
 Ocean waters

8.  The word “THERMOPHILE" Is a combination of the greek adjective thermos
meaning “heat"And the adjective philes meaning “loving".
 Most thermophiles are anaerobic and chemolithotrophs
 Protein structures are stabilized by more H(hydrogen) and more Proline
 They have Histone like proteins which stabilizes their DNA (Histone like proteins
that bind DNA have been identified in hyperthermophiles, and these may protect
DNA)
 Their cell membrane have ETHER linkage.
 Hyperthermophiles have a reverse gyrase, a type 1 DNA topoisomerase that
causes positive supercoiling and therefore, stabilize the DNA.
 EXAMPLES:
• Pyroccus abyssi • Thermus aquaticus
• Bacillus stearothermophilus • Pyrococcus abyssi
• Pyrolobus fumarii •Thermoplasma acidophilum

9.  Sun-heated soils
 Hot springs
 Submarine hydrothermal vents
 Geothermally heated oil reserves and oil wells.
 Various geothermally heated regions of the earth,
such as hot springs like those in yellow-stone
national park the diversity of bacteria of a hot
spring in bukreshwar (west bengal, india) is also a
home of thermophile.

11.  The word “PSYCHROPHILE" Is a combination of the greek adjective psychros meaning
“cold" And the adjective philes meaning “loving".
 Psychrophilic (also known as cryophiles )are microorganisms that grow in cold
environments
 These organisms are capable to grow and reproduce in low temperatures, ranging from
−20 °C to +10 °C
 They are members in the domain Archaea
 Adaptation:- Psychrophiles are protected from freezing and the expansion of ice by ice-
induced desiccation and vitrification (glass transition), as long as they cool slowly.
 Antifreeze proteins are also synthesized to keep psychrophiles internal space liquid, and
to protect their DNA when temperatures drop below water's freezing point. By doing so,
the protein prevents any ice formation or recrystallization process from occurring.
 Have a high content of short, unsaturated fatty acids. Compared to longer saturated
fatty acids, incorporating this type of fatty acid allows for the lipid cell membrane to have
a lower melting point, which increases the fluidity of the membranes.
 Carotenoids are present in the membrane, which help modulate the fluidity of it.
 EXAMPLES:
• Methanococcoides burtonii • Psychrobacter immobilis

12.  Cold deserts (antarctica) dryness and drastic variation in temperature (-55 to 15°c)
water availability is a problem, high uv irradiation.
 Endolithic communities: Algae, pigmented bacteria micrococcus, deinococcus,
yeast cryptococcus and cyanobacteria desiccation resistant, wind dispersion.
 Sea ice :-major habitat for microorganisms in artic and antarctic marine
ecosystems (-35°c to -2°c).
 Sea ice microbial community (simco), ice algae (diatoms) proteobacteria,
flavobacteria/cytophaga/bacteroides gram positive: Planococcus, arthrobacter
archaea psychromonas ingrahamii can grow at –12°c with a generation time of
240h.
 Permafrost sediments (permanently frozen sediments)
 Cold cave sediments
 Sediments of glaciers
 Deep sea (1.5 to 11 km mariana trench) in Siberia
 Man-made environments :-Industrialized production of food, refrigeration

14.  Also known PIEZOPHILES.
 The word “PIEZOPHILES" Is a combination of the greek adjective piezo meaning
“pressure" And the adjective philes meaning “loving".
 Barophile is a bacterium which prefers to grow or exclusively grows at
moderately high hydrostatic pressures.
 Barophiles are a type of an extremophile. An example of a high-pressure habitat is
the deep-sea environment.
 Enzymes produced by barophilic bacteria can function at high pressure.
 Barophiles are extremely sensitive to uv light and therefore, require dark or light-
reduced environment, as prevails in the deep sea, for growth.
 The high pressure decreases the ability of the subunits of multimeric proteins to
interact.
 EXAMPLES:
•Thermococcus piezophilus •Alteromonas sp. •Methanopyrus
kandleri
• Geobacillus sp. • Shewanella sp.

15.  Deep-sea environment i.e ocean floors
 Dee lakes where the pressure can exceed 380 atm
 Pseudomonas found in MarianaTrench
 Lives in bottom part of sea as it lives in dark due to
U.V sensitive

17.  Organic-solvent-tolerant bacteria are a relatively novel group of
extremophilic microorganisms.
 Organic-solvent-tolerant bacteria are a relatively novel group of
extremophilic microorganisms.
 They overcome the toxic and destructive effects of organic solvents due to
the presence of various adaptive mechanisms. Extensive studies done on
the Toluene tolerance of certain Pseudomonas strains have led to an
understanding of the mechanisms of organic solvent tolerance involving
novel adaptations such as the toluene efflux pumps, cis-
trans isomerisation of membrane fatty acids, rapid membrane repair
mechanisms, etc.
 Organic solvent tolerant mutants of Escherichia coli have been constructed
and genes enhancing such tolerance characterised.

19.  Metallophiles are a group of extremophiles
which are resistant to high concentration of
metals.
 Metallophiles are able to resist high
concentrations of heavy metals such as
cadmium, cobalt, copper, lead, mercury,
nickel, zinc.

21.  The word “ACIDOPHILES" Is a combination of the greek
adjective acido meaning “acid" And the adjective philes
meaning “loving".
 Acidophiles or acidophilic organisms are those that thrive
under highly acidic conditions (usually at pH 2.0 or below).
 Most acidophile organisms have evolved extremely efficient
mechanisms to pump protons out of the intracellular space
in order to keep the cytoplasm at or near neutral pH.
 However, other acidophiles, such as Acetobacter aceti, have
an acidified cytoplasm which forces nearly all proteins in the
genome to evolve acid stability.
 In a specialized case of acid stability, the NAPase protein
from Nocardiopsis alba was shown to have relocated acid-
sensitive salt bridges away from regions that play an
important role in the unfolding process.

22.  Volcanic areas (Yellowstone)
 Hydrothermal sources
 Deep-sea vents
 Metal mining activities (Iron Mountain, Río
Tinto)
 In the stomachs of animals.

24.  The halophiles, named after the Greek word for "salt-loving", are
extremophiles that thrive in high salt concentrations.
 Halophiles can be found in water bodies with salt concentration more than
five times greater than that of the ocean.
 To survive the high salinities, halophiles employ two differing strategies to
prevent dessication through osmotic movement of water out of their
cytoplasm.
 Both strategies work by increasing the internal osmolarity of the cell.
 Halophiles use a variety of energy sources and can be aerobic or
anaerobic; anaerobic halophiles include phototrophic, fermentative, sulfate-
reducing, homo-acetogenic & methanogenic species.
 EXAMPLES:
•Salinibacter ruber •Hortaea werneckii
• Halobacterium halobium •Chromohalobacter beijerinckii
•Tetragenococcus halophilus

25.  Such as the Great Salt Lake in Utah, Owens
Lake in California.
 The Dead Sea and in evaporation ponds.

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 Psychrophilic Bacteria-Molecular Adaptations of Membrane Lipids (Nicholas J. Russell MICROBIOLOGY)
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 The international sociaty of extremophiles.
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