Extremophiles are organisms that thrive in extreme environments that were previously thought to be unable to sustain life, such as high heat, acidity, pressure, and cold. This document discusses several types of extremophiles: Acidophiles thrive in highly acidic environments below pH 5. Alkaliphiles thrive in alkaline environments above pH 9. Thermophiles thrive in hot environments between 45-122°C. Psychrophiles thrive in cold environments between -20°C to 10°C. These organisms have adapted mechanisms to survive in their extreme habitats.

1. Extremophyiles
GROUP 1
ZUNAIRA NAEEM
MEHWISH MAQBOOL
MANAL FATIMA
MUDASSIR BUT T
USWA HUSSAIN

2. EXTRMOPHILES
Ø Extremophiles are organisms that have been discovered on earth that survive in environments
that were once thought not to be able to sustain life.
ØThese extreme environments include intense heat, highly acidic environments, extreme
pressure and extreme cold.
ØDifferent organisms have developed varying ways of adapting to these environments, but most
scientists agree that it is unlikely that life on Earth originated under such extremes.
Ø In general, the Phylogenetic diversity of Extremophiles is high and very complex to study.

3. INTRODUCTION
 An extremophile (from Latin extremus meaning "extreme" and Greek philiā
meaning "love") 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.
 Extremophiles are adapted to their particular extreme environment; it's not
just that they can live there. To thrive, extremophiles must live in their special
environment.

4. ACIDOPHYILES
 Acidophiles or acidophilic organisms are those that thrive under highly acidic
conditions (usually at pH 2.0 or below). These organisms can be found in
different branches of the tree of life, including Archaea, Bacteria, and also
Eukaryotes.
Archaea
 Sulfolobes, an order in the Crenarchaeota branch of Archaea
Thermoplasmatales, an order in the Euryarchaeota branch of Archaea

5.  Acidianus brierleyi, A. infernus, facultatively
anaerobic thermoacidophilic archaebacteria
 Haloarchaeum acidiphilum, acidophilic member
of the Halobacteriacaeae
 Metallosphaera sedula, thermoacidophilic
 Bacteria
 Acidobacterium, a phylum of Bacteria
 Acidithiobacillales, an order of Proteobacteria e.g.
A.ferrooxidans, A. thiooxidans
 Thiobacillus prosperus, T. acidophilus, T.
organovorus, T. cuprinus
 Acetobacter aceti, a bacterium that produces
acetic acid (vinegar) from the oxidation of ethanol.
 Alicyclobacillus, a genus of bacteria that can
contaminate fruit juices.

6. Eukaryotes
Ø Mucor racemosus
Ø Urotricha
Ø Dunaliella acidophila
Ø Philodina roseola
Ø Acidophiles are acid-loving microbes. Most
natural environments on the earth are
essentially neutral, having pH values between
five and nine
Ø Acidophiles thrive in the rare habitats having
a pH below five.

7. Ø Highly acidic environments can result naturally from geochemical activities
(such as the production of sulfurous gases in hydrothermal vents and some
hot springs) and from the metabolic activities of certain acidophiles
themselves.
Ø Acidophiles are also found in the debris left over from coal mining.
Ø Interestingly, acid-loving extremophiles cannot tolerate great acidity inside
their cells, where it would destroy such important molecules as DNA.

8. Ø They survive by keeping the acid out.
Ø But the defensive molecules that
provide this protection, as well as
others that come into contact with
the environment, must be able to
operate in extreme acidity. Indeed,
extremozymes that are able to work
at a pH below one--more acidic than
even vinegar or stomach fluids--have
been isolated from the cell wall and
underlying cell membrane of some
acidophiles.

9. MECHANISM OF ADAPTATION TO ACIDIC
ENVIRONMENT
 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.
 Therefore, intracellular proteins do not need to develop acid
stability through evolution. However, other acidophiles, such as
Acetobacter aceti, have an acidified cytoplasm which forces nearly
all proteins in the genome to evolve ACID stability.

10. Ø For this reason, Acetobacter aceti has become a valuable resource for
understanding the mechanisms by which proteins can attain acid
stability.
Ø Studies of proteins adapted to low pH have revealed a few general
mechanisms by which proteins can achieve acid stability.
Ø In most acid stable proteins (such as pepsin and the soxF protein from
Sulpholobus acidocaldarius), there is an over abundance of acidic
residues which minimizes low pH destabilization induced by a buildup
of positive charge.

11. ALKALIPHYLES
Alkaliphiles are microorganisms that grow
optimally or very well at pH values above 9,
often between 10 and 12, but cannot grow or
grow slowly at the near-neutral pH value of
6.5.
Alkaliphiles are a class of extremophilic
microbes capable of survival in alkaline (pH
roughly 8.5-11) environments, growing
optimally around a pH of 10.

12. Ø These bacteria can be further categorized as obligate alkaliphiles (those that require
high pH to survive), facultative alkaliphiles (those able to survive in high pH, but also
grow under normal conditions) and haloalkaliphiles (those that require high salt
content to survive).
Ø Microbial growth in alkaline conditions presents several complications to normal
biochemical activity and reproduction, as high pH is detrimental to normal cellular
processes.
Ø For example, alkalinity can lead to denaturation of DNA, instability of the plasma
membrane and inactivation of cytosolic enzymes, as well as other unfavorable
physiological changes.

13. Ø Thus, to adequately circumvent these obstacles, alkaliphiles must either possess specific cellular
machinery that works best in the alkaline range, or they must have methods of acidifying the cytosol in
relation to the extracellular environment.
Ø Many different taxa are represented among the alkaliphiles, including prokaryotes (aerobic bacteria
belonging to the genera Bacillus, Micrococcus, Pseudomonas, and Streptomyces;
Ø Anaerobic bacteria from the genera Amphibacillus, Clostridium; Halophilic archaea belonging to the
genera Halorubrum, Natrialba, Natronomonas, and Natronorubrum; Methanogenic archaea from the
genus Methanohalophilus

14. MECHANISM OF CYTOSOLIC
ACIDIFICATION
 Alkaliphiles maintain cytosolic acidification through both passive and active
means.
 In passive acidification, it has been proposed that cell walls contain acidic
polymers composed of residues such as galacturonic acid, gluconic acid,
glutamic acid, aspartic acid, and phosphoric acid.
 Together, these residues form an acidic matrix that helps protect the plasma
membrane from alkaline conditions by preventing the entry of hydroxide ions,
and allowing for the uptake of sodium and hydronium ions.

15. Ø In addition, the peptidoglycan in alkaliphilic B. subtilis has been observed to contain
higher levels of hexosamines and amino acids as compared to its neutrophilic
counterpart.
Ø When alkaliphiles lose these acidic residues in the form of induced mutations, it
has been shown that their ability to grow in alkaline conditions is severely hindered.
Ø To survive alkaliphiles maintain a relatively low alkaline level of about 8 pH inside
their cells by constantly pumping hydrogen ions (H+ ) in the form of hydronium
(H3O) across their cell membranes into their cytoplasm.

16. THERMOPHYLES
 A thermophile is an organism — a type of extremophile — that
thrives at relatively high temperatures, between 45 and 122 °C (113
and 252 °F).
 Many thermophiles are archaea. Thermophilic eubacteria are
suggested to have been among the earliest bacteria.
 "Thermophile" is derived from the Greek: (thermotita), meaning
heat, and Greek: (philia), love

17. Ø Thermophiles are classified into obligate and facultative thermophiles:
Obligate thermophiles (also called extreme thermophiles) require such high
temperatures for growth,
Ø whereas facultative thermophiles (also called moderate thermophiles) can
thrive at high temperatures, but also at lower temperatures (below 50°C)
Ø . Hyperthermophiles are particularly extreme thermophiles for which the
optimal temperatures are above 80°C
Ø Thermophiles, meaning heat-loving, are organisms with an optimum growth
temperature of 50°C or more, a maximum of up to 70°C or more, and a
minimum of about 40°C, but these are only approximate.
Ø Some extreme thermophiles (hyperthermophiles) require a very high
temperature (80°C to 105°C) for growth.

18. Ø Their membranes and proteins are unusually stable at these extremely high
temperatures.
Ø Thus, many important biotechnological processes use thermophilic enzymes because
of their ability to withstand intense heat.
Ø Many of the hyperthermophiles Archea require elemental sulfur for growth.
Ø Some are anaerobes that use the sulfur instead of oxygen as an electron acceptor
during cellular respiration.
Ø Some are lithotrophs that oxidize sulfur to sulfuric acid as an energy source, thus
requiring the microorganism to be adapted to very low pH (i.e., it is an acidophile as
well as thermophile).
Ø These organisms are inhabitants of hot, sulfur-rich environments usually associated
with volcanism, such as hot springs, geysers, and fumarole

19. PSYCHROPHILES
 Psychrophiles or cryophiles are extremophilic organisms that are capable of
growth and reproduction in cold temperatures, ranging from −20°C to +10°C.
 Temperatures as low as −15°C are found in pockets of very salty water (brine)
surrounded by sea ice.
 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, polar ice, glaciers, and snowfields.

20. Ø They are of particular interest to astrobiology, the field dedicated to the
formulation of theory about the possibility of extraterrestrial life, and to
geomicrobiology, the study of microbes active in geochemical processes.
Ø Psychrophiles use a wide variety of metabolic pathways, including
photosynthesis, chemoautotrophy (also sometimes known as lithotrophy), and
heterotrophy, and form robust, diverse communities.
Ø Most psychrophiles are bacteria or archaea, and psychrophily is present in
widely diverse microbial lineages within those broad groups.
Ø Additionally, recent research has discovered novel groups of psychrophilic
fungi living in oxygen-poor areas under alpine snowfields.

21. Ø A further group of eukaryotic cold-adapted organisms are snow algae, which
can cause watermelon snow.
Ø Psychrophiles are characterized by lipid cell membranes chemically resistant
to the stiffening caused by extreme cold, and often create protein
'antifreezes' to keep their internal space liquid and protect their DNA even in
temperatures below water's freezing point.
Ø Examples are Arthrobacter sp., Psychrobacter sp. and members of the
genera Halomonas, Pseudomonas, Hyphomonas, and Sphingomonas.

22. OSMOPHILE
 Osmophilic organisms are microorganisms adapted to environments with high osmotic
pressures, such as high sugar concentrations.
 Osmophiles are similar to halophillic (salt-loving) organisms because a critical aspect
of both types of environment is their low water activity, aW.
 Generally microorganisms capable of growing at water activity values 0.85 or less are
classiffied in this category
 High sugar concentrations represent a growth-limiting factor for many
microorganisms, yet osmophiles protect themselves against this high osmotic pressure
by the synthesis of osmoprotectants such as alcohols and amino acids.

23. Ø Osmoprotectants are small molecules (Compatible solutes) that act as osmolytes
and help organism to survive extreme osmotic pressure.
Ø Examples of Compatible solutes include betaines, amino acids, and the sugar
trehalose.
Ø These molecules accumulate in cells and balance the osmotic difference
between the cell’s surroundings and the cytosol.
Ø Bacteria respond to osmotic stress by rapidly accumulating electrolytes or small
organic solutes via transporters whose activities are stimulated by increases
omolarity.
Ø The bacteria may also turn on genes encoding transporters of osmolytes and
enzymes that synthesize osmoprtectants.
Ø Many osmophilic microorganisms are from the yeast lineage of fungi, however a
variety of bacteria are also osmophilic.

24.  Osmophile yeasts are important
because they cause spoilage in the
sugar and sweet goods industry, with
products such as fruit juices, fruit juice
concentrates, liquid sugars (such as
golden syrup), honey and in some
cases marzipan. Among the most
osmophillic are: Organism Minimum
aW
 Saccharomyces rouxii 0.62
 Saccharomyces bailii 0.80
 Debaryomyces 0.83
 Wallemia sebi 0.87
 Saccharomyces cerevisiae 0.90

25.  Osmophiles with possible
pathogenesis are
Aspergillus, Saccharomyces,
Enterobacter aerogenes and
Micrococcus.​
 However, none of them are highly
pathogenic, and only cause
opportunistic infections, i.e.
infections in people with weakened
immune system.​
 They are rather a cause of general
food spoiling than causing any food
poisoning in humans.​

26. BAROPHILE
 A piezophile (also called a barophile) is an organism which thrives at high
pressures, such as deep sea bacteria or archaea.
 They are generally found on ocean floors, where pressure often exceeds
380 atm (38 MPa).
 Barophile is a bacterium which prefers to grow or exclusively grows at
moderately high hydrostatic pressure such as challenger deep in the Marianas
Trench which has a depth of 10,994m.
 Some have been found at the bottom of the Pacific Ocean where the
maximum pressure is roughly 117 MPa.

27. Ø The high pressures experienced by these organisms can cause the
normally fluid cell membrane to become waxy and relatively
impermeable to nutrients.
Ø These organisms have adapted in novel ways to become tolerant of these
pressures in order to colonize deep sea habitats.
Ø Enzymes produced by barophilic bacteria can function at high pressure,
hence these enzymes may be useful in high pressure bioreactors, toxic
clean-up in deep sea and high pressure food processors.
Ø One example, xenophyophores, have been found in the deepest ocean
trench, 6.6 miles (10,541 meters) below the surface.

28. Ø Barotolerant bacteria are able to survive at high pressures, but can exist
in less extreme environments as well.
Ø Obligate barophiles cannot survive outside such environments. For
example, the Halomonas species Halomonas salaria requires a pressure
of 1000 atm (100 MPa) and a temperature of 3 degrees Celsius.
Ø Most piezophiles grow in darkness and are usually very UV-sensitive;
they lack many mechanisms of DNA repair.