Extremophiles 1st sem MSc

2.  Any microbes that exists in extreme
conditions of temperature, pressure,
pH, salinity, nutrient concentrations
are called extremophiles.
 Extremophiles [from Latin] extremus
meaning extreme and [from Greek]
philia meaning love.
 They not only tolerate specific
extreme conditions but usually
requires these for survival and
growth.
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3.  The microbes have been discovered thriving in
most unlikely places 50 years ago.
 Thomas Brock, a biologist at University of
Indiana, in 1965 found mats of microscopic
organisms at Yellowstone National Park in hot
springs.
 With the temperature 175 degree Fahrenheit i.e.,
79.44 degree Celsius.
 RD MacElroy coined the term extremophiles in a
1974 paper – Some comments on the evolution
of extremophiles.
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5.  The limits of growth and
reproduction of microbes are -
12 degree Celsius to more
than 100 degree Celsius, pH 0
to 13 , hydrostatic pressures
up to 1400 atm and salt
concentrations of saturated
brines.
 Extremophiles include
members of all three domains
of life- Bacteria, Archaea and
Eukarya.
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6.  Archaea is the main group to thrive in extreme
environments.
 These are the ancient bacteria discovered fro
Yellowstone National Park.
 They are unicellular, obligate anaerobes which can
tolerate high pressure differents.
 Examples- Thermoproteus tenax, Pyrobolous fumarii .
 Bacteria, the best adapted group to various extreme
conditions is cyanobacteria.
 They often form microbial mats with other bacteria
from Antarctic ice to continental hot springs.
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7.  They can develop in hypersaline and alkaline
lakes.
 They can tolerate xerophilic conditions [ low
availability of water] and can rarely found at pH
lower than 5-6.
 Examples- Oscillatoriales, Pleurocapsales etc
 Among Eukaryotes, fungi [alone or in symbiosis
with cyanobacteria or algae forming lichens] are
more versatile.
 They live in acidic and metal-enriched waters
from mining regions, alkaline conditions, hot and
cold deserts and deep oceans.
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8.  One of the most impressive eukaryotic
polyextremophiles is the Tardigrade.
 They are the larger organisms which survived
days of exposure to the vacuum space, imposing
extreme dehydration, with temperature of -272
degree Celsius[1 degree above absolute zero] to -
151 degree Celsius.
 Can withstand pressure of 6,000 atm as well as
exposure to X-rays and gamma rays.
 Hence, the phylogenetic diversity of
extremophiles is high and complex.
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9. TARDIGRADE
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10.  Extreme environments on Earth has been due to
plate tectonic activity.
 Plate boundaries occur where two tectonic plates
collide and results in mid-ocean ridges,
mountains, deep-ocean trenches, volcanoes and
hydrothermal vents.
 This manifestations produces extreme heat, pH,
salinity, pressure, dissolved gases and metals.
 Extreme conditions may also be due to chemical
and or physical toxics – like soil high in arsenic,
lakes exposed to high incident radiation etc
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11.  These environments provides opportunity for
organisms to evolve.
 Extreme environments many a times involves two or
more extreme conditions.
 There are two types of extermophilic distribution-
organisms present in mere conditions and those
which are metabolically active.
 Is our current knowledge of extremophiles diversity
comprehensive?
 The new ecosystems has to be discovered from great
depths in sub-sea floor and in rock formations.
 A challenge that should not be neglected by
Microbiologist !
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12.  A Niche is the match of species
to a specific environmental
conditions.
 Some of the known ecosystems
of extremophiles are-
 Atacama Desert- located
along western border of South
America.
Driest and oldest deserts on
Earth with high alkaline or
acidic, high pH and
temperature with high pressure
and water stress zone along
with UV radiations.
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13.  Altiplanic Ecosystems- occupies Peruvian,
Bolivian and Chilean territory surrounded by
volcanoes and mountains with 6,700m.
The extreme environments include geothermal
springs and Geysers, some basins, Salars- large
lakes in the north and salt flats in south.
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14.  Patagonia- Regions of South America with low
temperatures, low nutrient concentrations and low
dissolved organic carbon. Cold lakes ranges from
[4 degree Celsius in winter and 20 degree Celsius
in summer].
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15.  Antarctica- displays extreme conditions
below and above the water surface.
This environment is dominated by strong
temperatures[ -10 to -2 degree Celsius],
salinity[ 35-150%] and irradiation[<0-1% to
1-5% UV radiations].
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16.  Extremophiles are classified into different
classes in the basis of their environmental
niche.
 Accordingly they are classified as
thermophiles, methanogens, alkalophiles,
acidophiles, halophiles and barophiles.
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18.  These organisms can thrive at temperature
between 60 to 80 degree Celsius.
 Either they live in geothermal habitats or they live
in environments that produces heat themselves.
 In 1965, Thomas Brock discovered Thermus
aquaticus, in thermal vents of Yellowstone
National Park.
 He also discovered large amount of Pink
filamentous bacteria at 82 to 88 degree Celsius.
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19.  In 1966 T.aquaticus was
first to be developed as
source of Taq Polymerase
which is now routinely used
in molecular biology.
 They are economically
important due to their ability
to produce thermostable
extracellular enzymes which
have important
biotechnological and
industrial applications [ Ex-
Protease enzyme].
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20.  These are large group of archaebacteria with
unique metabolism.
 They convert fermentation products formed by
other anaerobic microbes such as CO2, H2,
acetate, formate, methylamine and methanol to
either methane [CH4] or methane and CO2.
 Strict anaerobes.
 Hence produce methane in Oxygen- free as well
as low redox potential [ less thann-333v].
 Some examples- Methanobacterium,
Mathanococuus, Methanomicrobium etc
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21.  Used in production of biogas-
conversion of CO2 into methane
 Methane can be used as storable
energy carrier as fuel for
vehicles, for production of
electricity or as base chemical for
synthesis.
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22.  In 1956, Koki Horikoshi first encountered with
alkaliphilic bacteria- Bacillus circulans.
 They lives in alkaline environments like soda lakes
or alkaline lakes.
 The pH ranges from 9-11
 The organisms does not keep an alkaline level
inside the cell but lives in environment with high
alkaline level.
 Some examples belonging to genera- Bacillus,
Micrococcus, Pseudomonas, Clostridium etc
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23.  The enzymes produced by them
have greater industrial use due to
the enzyme activity at higher pH.
 The additional capabilities of these
microbes, example- some microbes
are active with high pH are also
active at high temperature.
 Alkaliphile enzymes also include
alkaline proteases used as detergent
additives.
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24.  These organisms survive at acidic pH.
 The pH level is at or below 3.
 They survive in acid habitat because its cell pump
out poisonous hydrogen ions fast enough as not to
damage the DNA inside the nucleus.
 They have 2 types of mechanisms- active[
requires energy] and passive [ doesn’t require
energy]
 Some examples are Thiobacillus acidophilus
[bacteria], Vorticella [ eukaryote]
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25.  Many enzymes produced by
these microbes have industrial
application.
 The property of
thermoacidophiles – show
activity at low pH and high
temperature is applied in fields
such as- Baking industry, Starch
industry, Animal feed,
Pharmaceutical industry etc.
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26.  These organisms require atleast 0.2 Molar
concentrations of salt [NaCl] for growth.
 They are aerobic microbes living in high saline
conditions.
 The salinity is 10 times more than normal
conditions.
 Some environments that halophiles live in are the
Greek Salt Lake in Utah, Owens Lake in
California and the Dead sea.
 Example are Halobacteriaceae is a family
including a large part of halophilic archaea.
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27.  A vast variety of halophiles are
used in unique commercial
applications such as food coloring
pigments in food industry, stress
protectant metabolites, additives
in cosmetic industry etc
 They favor biodegradation of
certain hazardous organic and
inorganic compounds in both
aerobic and anaerobic conditions.
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28.  These are the microorganisms that survive under
great pressure.
 They live deep under the surfaces of the earth or
water.
 They are of 3 kinds-
Barotolerant [ can survive upto 400 atm], Barophilic
[ best at higher pressures up to 500-600 atm] and
Extreme Barophiles [ best at 700 atm pressure].
Examples- Halomonas salaria
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29.  Used in microbially
enhanced oil recovery
process.
 The proteins from barophiles
are used for the production
and sterilization of food items
at varied pressure
conditions.
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30.  Brock TD, Freeze H (1969) Thermus aquaticus
gen. n. and sp. n., a nonsporulating extreme
thermophile. J Bacteriol 98:289–297
 Goswami, Shreerup & Das, Madhumita. (2016).
EXTREMOPHILES- A CLUE TO ORIGIN OF
LIFE AND BIOLOGY OF OTHER PLANETS.
Everyman's Science. LI. 17-25.
 https://www.frontiersin.org/articles/10.3389/fbioe
.2015.00075/full
 Kirby, Bronwyn & Barnard, Desiré & Tuffin,
Marla & Cowan, Donald. (2011). Extremophiles
Handbook. 10.1007/978-4-431-53898-1_41.
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