This document discusses barophiles, which are microorganisms that thrive under high hydrostatic pressure, such as in deep ocean environments or subsurface rocks. It classifies barophiles into three groups: barotolerant organisms that can survive higher pressures but grow best at normal atmospheric pressure, barophilic organisms that grow at pressures from 400-500 atm, and extreme barophiles that obligately grow at over 500 atm and do not grow at low pressures. Examples of barophiles found in the deepest parts of the ocean, such as the Mariana Trench, are provided. The document also explains how barophiles are able to regulate membrane fluidity and survive in high pressure environments.

1. BAROPHILES: Classification, High Pressure
Habitat, Life Under Pressure
Presented by: SIRAJ UD DIN WANI
M.Sc Microbiology
2nd sem, CORD
University of Kashmir

2. EXTREMOPHILES
• Term coined by Macelroy in 1974.
• Organisms found living in extreme harsh environments.
• Word originated from Greek : Extremus and Phillia meaning extreme
loving.
• Most members of this group belongs to Archea domain.
Include:
• Thermophiles, Hyperthermophiles, Thermoacidophiles
• Alkaliphiles
• Psychrophiles
• Halophiles
• Barophiles
• Radiation Resistant Bacteria and
• Endoliths

3. BAROPHILES
• Barophile is a term coined by ZoBell and Johnson (1949) to describe
bacteria which grow preferentially or exclusively at moderately high
hydrostatic pressures.(Johnson et al.,1954).
• Barophiles are organisms that need a high-pressure environment in order to
grow.
• Microorganisms that can survive under immense hydrostatic pressure.
• Also known as Piezophiles.
• They have tough cell wall and porins.
High Pressure Habitat:
• An example of a high-pressure habitat is the deep-sea environment, such as
ocean floors and deep lakes where the pressure can exceed 380 atm.
• Some have been found at the bottom of the Pacific Ocean (Mariana Trench-
10500 m) where pressure often exceeds 117 MPa.
• Another is the subsurface rocks with high lithostatic pressures.

4. Where are they generally Found?
• The bottom of the Pacific; Mariana Trench (Xenophyophore).
• Very high pressures.
• Where temperatures are below 10 degrees celsius.
• No UV radiation - they are very sensitive to UV rays.
Where could they be found in the Solar System?
• Europa; vast underwater ocean.
• Jupiter; the surface has extreme pressures up to 200 kPa.
Why such high Pressures?
• They are very UV sensitive, so they require little sunlight exposure.
• Some (Halomonas species, some Xenophyophores) need at least 1000 atm. and a
temperature of 3 degrees celsius.
• Thrive where pressure exceed 380 atm.

5. Examples:
 Photobacterium
 Shewanella
 Colwellia and Motiella.
 Pseudomonas in Mariana Trench.
 Filamentous fungi and actinomycetes, etc.
 Barotolerant Alteromonas sp.
• Some thermophillic archae such as Pyrococcus spp., Methanococcus jannaschii
are barophiles too.(Polyextremophiles).

6. Classification
Barophiles
Barotolerant Barophilic
Extreme
Barophiles

7. Barotolerant
 Able to survive at high temperatures.
 Can also exist in less extreme environments.
 They grow best in environments with standard atmospheric pressure, but can
survive in high pressure environments.
 They grow at pressures from 100 - 400 atm.
 viable microorganisms found in the ocean up to depths of 4 km, nearly 400 atm.
but grow better at 1 atm.

8. Barophilic
 Grow in the pressure of 400-500 atm.
 Can be used to determine things like extraterrestrial life beneath other planets to
determining the properties of organisms that have evolved at certain
temperatures or conditions.

9. Extreme Barophiles (Xenophyophores)
 Organisms that obligately grow at pressures greater than 500 atm. and do not
grow at low pressures.
 Extreme barophile, at least 11,000 feet below sea level.
 Abundant on abyssal plains.
 Feed on amoebas.
 Might be 2000 in 100 square miles.
 Few millimeters to 20 centimeters in size.
 The extreme Barophilic can survive in the Marianas Trench, currently the
deepest area underwater discovered by humans.

10. Life Under Pressure - Barophily
Under pressure:
 Type of extreme environment.
• An extreme environment contains conditions that are hard to survive for
most known life forms.
 Broadly conceived as habitats under extreme hydrostatic pressure i.e. aquat ic
habitats deeper than 2000 meters and enclosed habitats under pressure.
 Includes habitats in oceans and deep lakes.
 Pressure has a substantial effect on the physiology and biochemistry of living
cells. Microorganisms inhabiting the deep-sea and subsurface of Earth have the
ability to survive at hydro-and litho- static pressures greater than 1 atmosphere
(atm). Studies of barotolerant (tolerate high pressure) and barophilic (dependent
on high pressure) cultures of deep-sea bacteria show that both types are present,
and the distribution of these organisms is a function of depth.
How microbes deal with high pressure?
 Barotolerant bacteria under high hydrostatic pressure regulate the fluidity of
membrane phospholipids to compensate for pressure gradients between the
inside of the cell and the environment.

11. Recommendations:
1. Extremophiles by Johri B.N. 2000. Springer V erlag. , New York
2. Microbial Diversity by Colwd , D. 1999, Academic Press.
3. MIcrobial Life in Extreme Environments. Edited by D. J. Kushner. Academic Press.
4. Microbiology of Extreme Environments. Edited by Clive Edward. Open University Press. Milton Keynes.
5. Microbiology of Extreme Environments and its potential for Biotechnology. Edited by M.S. Da Costa, J.C. Duarate,
R.A. D. Williams. Elsiever Applied Science, London.
6. Extreme Environment. Mechanism of Microbial Adaptation. Edited by Milton R. Heinrich. Academic Press.
7. Thermophiles. General, Molecular and Applied Microbiology. Edited by Thomas D. Brock. Wiley Interscience
Publication.
8. Microbiology: Dynamics and Diversity by Perry.
9. Microbial Ecology. Fundamentals and Applications by. Ronald M. Atlas and Richard Bartha. 2nd and 4th Edition.
The Benjamin Cummins Publication Co. Inc.
10. Microbial Ecology. 2nd Edition. by R. Campbell. Blackwell Scientifc Publication.
11. Brocks Biology of Microorganisms. 8th Edition. (International Edition - 1997) by Michael T. Madigan, John M.
Martinko. Jack Parker. Prentice Hall Internation Inc.
12. Advances in Applied Microbiology. Vol. 10. Edited by Wayne W. Umbreit and D. Pearlman. Academic Press.

12. Thank
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