The Extreme Conditions of Life on the Planet
and Exobiology
10
Jean-Luc Cayol, Bernard Ollivier, Didier Alazard, Ricardo Amils,
Anne Godfroy, Florence Piette, and Daniel Prieur
Abstract
Extreme physicochemical conditions (low and high temperatures, high salinity, low and
high pH, high hydrostatic pressure, etc.) existing on Earth are compatible with the occurrence of microbial life. The diversity and metabolic features of microbial trophic groups
inhabiting extreme environments (cold, hot, saline, acidic, alkaline, and deep marine) are
described. They include hydrothermal vents, acid springs, hypersaline and/or alkaline
lakes, permafrost, and deep-sea environments, etc.
To live or survive under such drastic conditions, prokaryotes (Bacteria or Archaea) have
developed a variety of physiological and metabolic strategies allowing them to adapt to in
situ extreme conditions. Many of these extremophiles are recognized to be of industrial
interest or to be potential candidates for future biotechnological applications.
Clearly, the discovery of extremophiles living in terrestrial, subterrestrial, and deep marine
environments has changed our perception of microbial life. One or a combination of extreme
physicochemical conditions that they have to face may have prevailed in the primitive atmosphere and favored early extremophilic life not only on Earth but perhaps also on other planets.
Keywords
Acidophiles Alkaliphiles Exobiology Extremophiles Halophiles Piezophiles
Psychrophiles Thermophiles/hyperthermophiles
10.1 Introduction
To our knowledge, Earth is the only inhabitable and
inhabited planet in the solar system and even the universe.
All its inhabitants, from the simplest to the most complex,
from the smallest to the biggest are under the control of a
variety of physicochemical parameters within their
environments. According to time and space, the reached
values by these parameters including temperature, salinity,
pH, or pressure vary considerably. Combinations of minimal
and maximal values reached by these parameters within a
particular geographical area define biotopes, or the whole set
of environmental conditions suitable for a given species.
For most of the major parameters listed above, specific
limits beyond which no organism can totally accomplish its
life cycle have been determined. Any environment wherein
one or several parameters show permanently values close to
J.-L. Cayol* (*) B. Ollivier* (*) D. Alazard
Institut Me ´diterrane ´en d’Oce ´anologie (MIO), UM 110, CNRS 7294,
IRD 235, Universite ´ de Toulon, Aix-Marseille Universite ´,
Campus de Luminy, 13288 Marseille Cedex 9, France
e-mail: jean-luc.cayol@univ-amu.fr; bernard.ollivier@univ-amu.fr
R. Amils
Centro de Biologı ´a Molecular Severo Ochoa (CSIC-UAM),
Universidad Auto ´noma de Madrid, Cantoblanco, 28049 Madrid, Spain
Centro de Astrobiologı ´a (CSIC-INTA), 28850 Torrejo ´n de Ardoz,
Madrid, Spain
A. Godfroy D. Prieur
Laboratoire de Microbiologie des Environnements Extre ˆmes,
UMR 6197 (UMR CNRS/IFREMER/Universite ´ de Bretagne
Occidentale), BP70 29280 Plouzane ´, France
F. Piette
Laboratoire de Biochimie, Universite ´ de Lie `ge, 4000 Lie `ge, Belgique
* Chapter Coordinators
J.-C. Bertrand et al. (eds.), Environmental Microbiology: Fundamentals and Applications: Microbial Ecology,
DOI 10.1007/978-94-017-9118-2_10, # Springer Science+Business Media Dordrecht 2015
353
and Exobiology
10
Jean-Luc Cayol, Bernard Ollivier, Didier Alazard, Ricardo Amils,
Anne Godfroy, Florence Piette, and Daniel Prieur
Abstract
Extreme physicochemical conditions (low and high temperatures, high salinity, low and
high pH, high hydrostatic pressure, etc.) existing on Earth are compatible with the occurrence of microbial life. The diversity and metabolic features of microbial trophic groups
inhabiting extreme environments (cold, hot, saline, acidic, alkaline, and deep marine) are
described. They include hydrothermal vents, acid springs, hypersaline and/or alkaline
lakes, permafrost, and deep-sea environments, etc.
To live or survive under such drastic conditions, prokaryotes (Bacteria or Archaea) have
developed a variety of physiological and metabolic strategies allowing them to adapt to in
situ extreme conditions. Many of these extremophiles are recognized to be of industrial
interest or to be potential candidates for future biotechnological applications.
Clearly, the discovery of extremophiles living in terrestrial, subterrestrial, and deep marine
environments has changed our perception of microbial life. One or a combination of extreme
physicochemical conditions that they have to face may have prevailed in the primitive atmosphere and favored early extremophilic life not only on Earth but perhaps also on other planets.
Keywords
Acidophiles Alkaliphiles Exobiology Extremophiles Halophiles Piezophiles
Psychrophiles Thermophiles/hyperthermophiles
10.1 Introduction
To our knowledge, Earth is the only inhabitable and
inhabited planet in the solar system and even the universe.
All its inhabitants, from the simplest to the most complex,
from the smallest to the biggest are under the control of a
variety of physicochemical parameters within their
environments. According to time and space, the reached
values by these parameters including temperature, salinity,
pH, or pressure vary considerably. Combinations of minimal
and maximal values reached by these parameters within a
particular geographical area define biotopes, or the whole set
of environmental conditions suitable for a given species.
For most of the major parameters listed above, specific
limits beyond which no organism can totally accomplish its
life cycle have been determined. Any environment wherein
one or several parameters show permanently values close to
J.-L. Cayol* (*) B. Ollivier* (*) D. Alazard
Institut Me ´diterrane ´en d’Oce ´anologie (MIO), UM 110, CNRS 7294,
IRD 235, Universite ´ de Toulon, Aix-Marseille Universite ´,
Campus de Luminy, 13288 Marseille Cedex 9, France
e-mail: jean-luc.cayol@univ-amu.fr; bernard.ollivier@univ-amu.fr
R. Amils
Centro de Biologı ´a Molecular Severo Ochoa (CSIC-UAM),
Universidad Auto ´noma de Madrid, Cantoblanco, 28049 Madrid, Spain
Centro de Astrobiologı ´a (CSIC-INTA), 28850 Torrejo ´n de Ardoz,
Madrid, Spain
A. Godfroy D. Prieur
Laboratoire de Microbiologie des Environnements Extre ˆmes,
UMR 6197 (UMR CNRS/IFREMER/Universite ´ de Bretagne
Occidentale), BP70 29280 Plouzane ´, France
F. Piette
Laboratoire de Biochimie, Universite ´ de Lie `ge, 4000 Lie `ge, Belgique
* Chapter Coordinators
J.-C. Bertrand et al. (eds.), Environmental Microbiology: Fundamentals and Applications: Microbial Ecology,
DOI 10.1007/978-94-017-9118-2_10, # Springer Science+Business Media Dordrecht 2015
353