In case of flooding, these microscopic animals can inflate themselves into a balloon-like form and float to the surface of the water to get oxygen. They have another strategy which makes them one of the heartiest organisms known. In the case of drought or cold, these little animals can replace most of the water in their bodies with a sugar called trehalose. These sugar solutions do not form damaging ice crystals when frozen, and tardigrades have survived for over a century in museum samples, and many tardigrades survived a 12 day journey into the cold vacuum of space onboard the FOTON M3.
Tardigrades protected by a UV filter almost all survived. Most of the ones without the filter did not. He believed that these hydrocarbons provide the carbon for an underground ecosystem, perhaps completely isolated from our biosphere. Some of these organisms were then tested to see if they could survive in those underground conditions, which would prove that they were not the result of contamination during the drilling process.
Some of these microbes were put into a sealed flask with hot water, carbon dioxide and basalt for a year, and not only did they survive, they thrived under these conditions. Whatever the source of the petroleum may be, and most geologists still believe that it was formed by the remains of plant matter there seem to be at least some forms of life living and thriving in it. The variety of adaptations organisms make - to extreme temperatures and other extremes such as very acidic or very alkaline conditions - are very diverse.
Biologically it is typically easier for organisms to adapt to chemical extremes than to physical extremes like temperature and high pressure. One thing to keep in mind, is that even with life being found in such extreme locations on Earth - under great pressure, at high temperatures, within solid rock - this is not evidence that life could form under these conditions.
Many scientists believe that a more agreeable environment including liquid water, moderate pressure, and temperatures similar to those found on the surface of Earth would be needed for life to arise. The number of uncultured microorganisms at the genus level has been recently estimated to be on average 7.
These uncultivated microorganisms are very likely to include poly extremophiles and will aid in expanding our understanding of the boundary conditions of life.
Several studies have also demonstrated the growth of microorganisms under lab-simulated planetary conditions, including Mars-like Nicholson et al. In this context, defining the boundary limits of life on Earth is a crucial step in identifying the conditions likely to originate or support life on other planetary bodies.
Therefore, studies on the limits of life are important to understand four areas: 1 the potential for panspermia, 2 forward contamination due to human exploration ventures, 3 planetary colonization by humans, and 4 the exploration of extinct and extant life.
Similar to Earth, other planetary bodies might have different environments with varying ranges for each parameter. Since our knowledge of individual niches or habitats is extremely limited for other planetary bodies, we considered the range of each parameter temperature, salinity, pH, and pressure across three planetary layers: 1 atmosphere, 2 surface, and 3 subsurface Table 5.
Many planetary bodies studied thus far have the potential for extinct or extant life, based on our knowledge of life on Earth. Depending on the planetary body, different poly extremophiles could persist. For example, halopsychrophiles might be able to persist on Titan, Ceres, and Europa, which likely have saline subsurface oceans Grindrod et al. These lifeforms would also need to withstand high pressures.
For example, the hydrostatic pressure of the subsurface ocean at Titan ranges from to MPa Sohl et al. Table 5. Boundary conditions for different planetary bodies of astrobiological interest compared to Earth , split into atmosphere, surface, and subsurface layers.
The atmospheres of some planetary bodies could potentially harbor life as well. Other planetary bodies presented in Table 5 have transient or tenuous atmospheres that have extremely low pressures and likely cannot support life. In comparison, on Earth, microorganisms have been observed and cultured from the upper atmosphere, although stresses such as UV-C radiation, low temperatures, and oxidants make it difficult to survive DasSarma and DasSarma, Similar strategies may be needed on other planetary bodies.
The surface of other planetary bodies, such as Ceres, Europa, and Mars, experience high levels of radiation, and thus, may be unsuitable to support life. However, shielding from UV-C radiation increases the chance of survival and includes shielding by atmospheric dust or burial Barbier et al. Shielding is also necessary against charged particle radiation and can be achieved by burial at only centimeter depths below the surface.
However, any subsurface aquifer deeper than a few meters would be protected from damaging radiation. Dartnell et al. At the surface, E. Compared to E. These survival times are, in fact, lower limits in light of recent measurements by the Radiation Assessment Detector onboard the Mars Science Laboratory Hassler et al. Ehresmann et al. In addition to radiation, the surface of other planetary bodies is generally extremely cold.
This indicates the physiology of radiation-tolerant psychrophiles is important for understanding the potential of life on the surface of other planetary bodies, such as the production of a fibril network, cell aggregation, and cold shock proteins Reid et al.
This suggests the subsurface is one of the most important locations in the search for extinct and extant extraterrestrial life Jones et al. The subsurface of other planetary bodies is potentially warmer than the surface and atmosphere Table 5 , influenced by geothermal processes [e. Several planetary bodies Enceladus, Titan, Ceres, and Europa likely have subsurface oceans, and Mars could potentially have a limited supply of groundwater Clifford et al.
Potential communities in these extraterrestrial subsurface environments are unlikely to be supported by surface exports of organic carbon like on our planet Kallmeyer et al. The abiotic production of H 2 can occur through a variety of mechanisms, including the radiolysis of water Lin et al. Thus, serpentinization may have played a role in the origins of life on Earth Russell et al.
Several planetary bodies could have ongoing serpentinization in a subsurface ocean, including Enceladus, Titan, Ceres, and Europa Table 5 , and serpentinization reactions could be widespread in the cosmos Holm et al.
Mars might also have serpentinization occurring in the subsurface or had serpentinization occurring millions of years ago, as indicated by the observation of hydrated minerals, such as serpentine phases, on the surface of Mars Ehlmann et al. Serpentinite-hosted sites on planetary bodies could likely support chemoautotrophic life, such as methanogens McCollom, For example, the piezotolerant thermophile Methanothermococcus okinawensis was capable of growing under Enceladus-like conditions up to 5 MPa Taubner et al.
In contrast to serpentinization, radiolysis consists of radionuclides decay, such as uranium, thorium, and radioactive potassium, decomposing water molecules into oxidizing radicals that then react with oxidizable substrates, such as pyrite, generating the necessary chemical energy for life to survive. It is possible that radiolysis could support such life on other planetary bodies, including the Europan ocean Altair et al. It is important to note that the presence of liquid water or other liquid solvent is the main indicator to consider the possibility of extinct or extant life on a planetary body.
In places with low water activity, desiccation-tolerance could become an important factor in determining the survivability of organisms, coupled with the transient availability of water over time either by precipitation, moisture, fog, or atmospheric humidity.
For example, desiccation tolerant organisms may be able to survive under Mars-like surface conditions Johnson et al. Given the limited understanding of the processes that have led to life on our planet, discussions regarding the conditions under which life might originate on other planets remains rather speculative McKay, An additional point to keep in mind while discussing the origin—and long-term persistence—of life on a planetary body is the necessity of elemental cycling on planetary scales Jelen et al.
Extremophiles have pushed our understanding of the boundaries of life in all directions since they were first discovered. As already highlighted by Harrison et al. Despite this, there is a fundamental lack of studies addressing the tolerance of microorganisms to multiple extremes Rothschild and Mancinelli, ; Harrison et al. In the past 50 years of extremophile research it has become apparent that the limit of life varies when organisms face co-occurring multiple extremes.
Future research will need to focus more on the interaction factor between multiple parameters. While considering the basic requirements of life discussed in the introduction namely, energy, solvent, and building blocks , it is possible that the true limits of life are actually controlled by practical implications of these requirements. For example, the current theoretical limits of life regarding temperature, pressure, and salinity are directly linked to the water activity or the stability of biological molecules under such conditions Price and Sowers, Despite ongoing scientific investigations of our planet for most of recorded human history, we still find life in unexpected places, and given the number of Earth ecosystems that still need to be explored in detail, we expect the current boundary of life to be pushed even further.
Taken together, these observations suggest that the true shape of the terrestrial biosphere remains undefined. Moreover, the astonishing diversity of planetary bodies and exoplanets Seager, will most likely expand the combinatorial space of environmental conditions, allowing us to speculate wildly about possible extraterrestrial lifeforms.
While considering the possibility for life to originate and exist on other planetary bodies, it is important to consider the variability of Earth local conditions when compared to the planetary mean Tables 2 , 5. The majority of parameters considered in this review are unlikely to be extreme over an entire planet, and local or transient conditions might still support life.
An outstanding example are communities present in microbialites in the Atacama Desert, where seasonal water deliquescence on salt grains was sufficient to sustain a productive and diverse community Davila et al. Therefore, it is unlikely that time-limited, coarse-grained observation of any extraterrestrial environment will be enough to definitely rule out the existence of life or conditions within the boundary space of Earth life, at least transiently.
NM conducted literature search, created figures, and wrote the manuscript. DG devised the topic, supervised manuscript structure and data collection, conducted literature search, created figures, and wrote the manuscript. The opinions expressed in this publication are those of the authors and do not necessarily reflect the views of the John Templeton Foundation.
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. We thank Karla Abuyen for insightful discussions on the limitations of life. We thank Patricia Barcala Dominguez for assistance with figure illustration. Airey, M. The distribution of volcanism in the Beta-Atla-Themis region of Venus: its relationship to rifting and implications for global tectonic regimes.
Planets , — Aislabie, J. Soil Biol. Alazard, D. Desulfovibrio hydrothermalis sp. Alcaide, M. Pressure adaptation is linked to thermal adaptation in salt-saturated marine habitats. Altair, T. Microbial habitability of Europa sustained by radioactive sources.
Amato, P. FEMS Microbiol. Amend, J. Energetics of overall metabolic reaction of thermophilic and hyperthermophylic Archaea and Bacteria. Anitori, R. Extremophiles: Microbiology and Biotechnology. Poole: Caister Academic Press. Google Scholar. Arney, G. Astrobiology 16, — Aston, J. Response of Halomonas campisalis to saline stress: changes in growth kinetics, compatible solute production and membrane phospholipid fatty acid composition. Babu, P. Extremophiles and Their Applications in Medical Processes.
Berlin: Springer. Baker, B. Microbial communities in acid mine drainage. Baker-Austin, C. Life in acid: pH homeostasis in acidophiles. Trends Microbiol. Baland, R. Icarus , 29— Barbier, B. Photochemical processing of amino acids in Earth orbit.
Space Sci. Bartlett, D. Charles and G. Basilevsky, A. The surface of Venus. Becker, K. Hyndman, M. Salisbury et al. Washington, DC: U. Printing Office , — Bertaux, J. Nature , — Bertrand, J. Bertrand, P. Caumette, P. Lebaron, R. Matheron, P.
Normand, and T. Sime Ngando Dordrecht: Springer , 25— Blum, J. Astrobiology 17, 8— Brock, T. Thermus aquaticus gen. Byrne, R. Evolution of extreme resistance to ionizing radiation via genetic adaptation of DNA repair. Caldwell, M. The changing solar ultraviolet climate and the ecological consequences for higher plants. Trends Ecol. Capece, M. Seckbach, A. Oren, and H. Stan-Lotter Dordrecht: Springer. Cassidy, T. Magnetospheric ion sputtering and water ice grain size at Europa.
Castillo-Rogez, J. Chan, C. Effects of physiochemical factors on prokaryotic Biodiversity in Malaysian circumneutral hot springs. Chivian, D. Environmental genomics reveals a single-species ecosystem deep within earth. Science , — Chopra, A. The case for a Gaian bottleneck: the biology of habitability.
Astrobiology 16, 7— Chyba, C. Possible ecosystems and the search for life on Europa. Clarke, A. A low temperature limit for life on earth. PLoS One 8:e Clifford, S. Depth of the Martian cryosphere: revised estimates and implications for the existence and detection of subpermafrost groundwater. Cnossen, I. Cockell, C. Life on Venus. Impact-induced microbial endolithic habitats. Ozone and life on the Archaean Earth.
A Math. Effects of a simulated martian uv flux on the cyanobacterium, Chroococcidiopsis. Astrobiology 5, — Coker, J. Extremophiles and biotechnology: current uses and prospects. Cole, J. Sediment microbial communities in Great Boiling Spring are controlled by temperature and distinct from water communities.
ISME J. Colman, D. Geobiological feedbacks and the evolution of thermoacidophiles. Confalonieri, F. Bacterial and archaeal resistance to ionizing radiation. Cordier, D. Czop, M. Water Air Soil Pollut. Dalmasso, C. Thermococcus piezophilus sp. Daly, M. Accumulation of Mn II in Deinococcus radiodurans facilitates gamma-radiation resistance. Danovaro, R. Deep-Sea Biodiversity in the Mediterranean Sea: the known, the unknown, and the unknowable.
PLoS One 5:e Dartnell, L. Modelling the surface and subsurface Martian radiation environment: implications for astrobiology. DasSarma, P. DasSarma, S. Davila, A. Facilitation of endolithic microbial survival in the hyperarid core of the Atacam Desert by mineral deliquescence. Icarus , — De Vera, J. Delmelle, P. Geochemistry, mineralogy, and chemical modeling of the acid crater lake of Kawah Ijen Volcano, Indonesia.
Acta 58, — Delort, A. A short overview of the microbial population in clouds: potential roles in atmospheric chemistry and nucleation processes. Deming, J. Gerday, and N. DeVeaux, L. Extremely radiation-resistant mutants of a halophilic archaeon with increased single-stranded DNA-binding protein RPA gene expression. Dickson, J. Dion, P. Microbiology of Extreme Soils. Dose, K. Survival of microorganisms under the extreme conditions of the Atacama desert. Life Evol. Dundas, C. Granular flows at recurring slope lineae on Mars indicate a limited role for liquid water.
Durvasula, R. Dzaugis, M. Radiolytic H2 production in martian environments. Astrobiology 18, — Radiolytic hydrogen production in the subseafloor basaltic aquifer. Edwards, K. An Archaeal iron-oxidizing extreme acidophile important in acid mine drainage. The team decided to borrow a technique used in polymerase chain reaction machines, to warm the cultures from the top as well as the bottom. Halophiles, too, are tricky to work with under the microscope.
They lack the rigid cell walls found in bacteria, and survive by maintaining the same osmotic pressure as their environment, giving them all the rigidity of a limp balloon. Ye-Jin Eun encountered this problem during a postdoc at Harvard University in Cambridge, Massachusetts, while investigating how the salt-loving archaeon Halobacterium salinarum controls its size. The organisms, which are shaped like rods in liquid cultures, deformed into bizarre polygonal shapes or amorphous blobs when she used a soft agar pad to hold the cells in place for microscopy.
She finally succeeded by fabricating tiny agarose chambers to confine the cells gently. At last, Eun could see that the archaeon maintains its size in much the same way as bacteria do, with each newborn cell adding a consistent length to its rod before dividing again 6. For example, an international team faced a challenge with a halophile called Haloferax volcanii , found in the Dead Sea, because it makes a pigment that naturally fluoresces.
That made it tricky to use fluorescent protein tags for tracking single molecules, the group reported in a preprint in July 7. So, first, the team deleted a gene involved in synthesizing that pigment, creating colourless but otherwise normal microbes. The search for microbial dark matter. Then, the researchers tackled the genetic milieu of H.
Like many halophiles, H. Furthermore, genes that use the same codons will be expressed at higher levels. Versions of the crimson-coloured protein mCherry and the green-to-red photoswitchable tag Dendra2 were especially useful for single-molecule tracking. Indeed, with perseverance, scientists interested in extremophiles can make impossible-seeming experiments work.
Tighe, S. PubMed Article Google Scholar. Flusberg, B. Nature Methods 7 , — Riley, L. The topics in the issue include but are not limited to: diversity and microbial ecology, physiology, genetic systems, microbe-environment interactions, adaptation and evolution, element cycling and biotechnological applications of microbes in changing and extreme ecosystems. In near future these incredible creatures are going to play a very crucial role in maintaining the environmental sustainability.
You can also search for this author in PubMed Google Scholar. Correspondence to Naveen Kumar Arora. Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Reprints and Permissions. Arora, N. Extremophiles: applications and roles in environmental sustainability. Environmental Sustainability 2, — Download citation.
Published : 31 July Issue Date : 01 September Anyone you share the following link with will be able to read this content:. Sorry, a shareable link is not currently available for this article.
Provided by the Springer Nature SharedIt content-sharing initiative. Skip to main content.
0コメント