Is there a common water-activity limit for the three domains of life?

  title={Is there a common water-activity limit for the three domains of life?},
  author={Andrew Stevenson and Jonathan A. Cray and Jim P Williams and Ricardo Pires dos Santos and Richa Sahay and Nils Neuenkirchen and Colin D. McClure and Irene R. Grant and Jonathan DR Houghton and John P Quinn and David J. Timson and Satish Vitthalrao Patil and Rekha S. Singhal and Josefa Ant{\'o}n and Jan Dijksterhuis and Ailsa D. Hocking and Bart Lievens and Drauzio E. N. Rangel and Mary A. Voytek and Nina Gunde-Cimerman and Aharon Oren and Kenneth N. Timmis and Terry J. McGenity and John Edward Hallsworth},
  journal={The ISME Journal},
  pages={1333 - 1351}
Archaea and Bacteria constitute a majority of life systems on Earth but have long been considered inferior to Eukarya in terms of solute tolerance. Whereas the most halophilic prokaryotes are known for an ability to multiply at saturated NaCl (water activity (aw) 0.755) some xerophilic fungi can germinate, usually at high-sugar concentrations, at values as low as 0.650–0.605 aw. Here, we present evidence that halophilic prokayotes can grow down to water activities of <0.755 for Halanaerobium… 

Glycerol enhances fungal germination at the water‐activity limit for life

Whether glycerol can enhance xerophile germination under acute water‐activity regimes, using an experimental system which represents the biophysical limit of Earth's biosphere is investigated, and the likely role of Glycerol in expanding the water‐ activity limit for microbial cell function in relation to temporal constraints and location of the microbial cell or habitat is discussed.

Extraordinary solute-stress tolerance contributes to the environmental tenacity of mycobacteria.

Findings challenge the paradigm that bacteria have solute tolerances inferior to those of eukaryotes.

Aspergillus penicillioides differentiation and cell division at 0.585 water activity

This study focused on germination of Aspergillus penicillioides, a xerophile which is also able to grow under low humidity and saline conditions and has an application in understanding the limits to life in extraterrestrial environments.

Water‐, pH‐ and temperature relations of germination for the extreme xerophiles Xeromyces bisporus (FRR 0025), Aspergillus penicillioides (JH06THJ) and Eurotium halophilicum (FRR 2471)

The biophysical capabilities of the most extremely xerophilic organisms known are characterized to characterize the in‐situ ecology of extreme conditions and environments; the study also raises a number of unanswered questions which suggest the need for new lines of experimentation.

Haloadaptative Responses of Aspergillus sydowii to Extreme Water Deprivation: Morphology, Compatible Solutes, and Oxidative Stress at NaCl Saturation

This is the most comprehensive study that investigates the micromorphology and the adaptative cellular response of different non-enzymatic and enzymatic oxidative stress biomarkers in halophilic filamentous fungi.

Physicochemical Salt Solution Parameters Limit the Survival of Planococcus halocryophilus in Martian Cryobrines

Understanding of the limitations of microbial life in saline environments is improved, which provides a basis for better evaluation of the habitability of extraterrestrial environments such as Martian cryobrines.

Water Activities of Acid Brine Lakes Approach the Limit for Life.

Investigating water activity for acid brines from Western Australia and Chile with pH as low as 1.4, salinities as high as 32% total dissolved solids, and complex chemical compositions provides thermodynamic insight into life within end-member natural waters that lie at the very edge of habitable space on Earth.

Beyond Chloride Brines: Variable Metabolomic Responses in the Anaerobic Organism Yersinia intermedia MASE-LG-1 to NaCl and MgSO4 at Identical Water Activity

The global metabolic responses of the anaerobic bacterium Yersinia intermedia MASE-LG-1 to osmotic salt stress induced by either magnesium sulfate (MgSO4) or NaCl at the same water activity are found to be salt-specific, suggesting ion-specific regulation of specific metabolic pathways.



Multiplication of microbes below 0.690 water activity: implications for terrestrial and extraterrestrial life.

Water activity in relation to the limits of Earth's present-day biosphere; the possibility of microbial multiplication by utilizing water from thin, aqueous films or non-liquid sources; whether prokaryotes were the first organisms able to multiply close to the 0.605-aw limit; and whether extraterrestrial aQueous milieux of ≥ 0.605 aw can resemble fertile microbial habitats found on Earth.

Life at low water activity.

  • W. Grant
  • Environmental Science
    Philosophical transactions of the Royal Society of London. Series B, Biological sciences
  • 2004
A restricted range of bacteria and the haloarchaea counterbalance osmotic stress imposed by NaCl by accumulating equivalent amounts of KCl, which helps them to survive and thrive inside halite (NaCl) crystals.

Water and temperature relations of soil Actinobacteria.

This level of solute tolerance is high for non-halophilic bacteria, but is consistent with reported limits for the growth and metabolic activities of soil microbes, and is discussed in relation to planetary protection policy for space exploration and the microbiology of arid soils.

The extreme xerophilic mould Xeromyces bisporus--growth and competition at various water activities.

Limits of life in hostile environments: no barriers to biosphere function?

It is found that some fungi grew optimally under chaotropic conditions, providing evidence for a previously uncharacterized class of extremophilic microbes, and enhanced biotechnological processes, and increased productivity of agricultural and natural ecosystems in arid and semiarid regions.

Sugar metabolism in the extremely halophilic bacterium Salinibacter ruber.

Anaerobic bacteria from hypersaline environments.

Three genera and five species of halophilic methylotrophic methanogens have been reported, and a bloom of phototrophic bacteria in the marine salterns of Salins-de-Giraud, located on the Mediterranean French coast in the Rhone Delta, is also described.

Intracellular ion and organic solute concentrations of the extremely halophilic bacterium Salinibacter ruber

The results presented suggest that the extremely halophilic Bacterium Salinibacter uses a similar mode of haloadaptation to that of the Archaea of the order Halobacteriales, and does not accumulate organic osmotic solutes such as are used by all other known halophile and halotolerant aerobic Bacteria.

Microbial weeds in hypersaline habitats: the enigma of the weed-like Haloferax mediterranei.

The enigma of the less abundant Haloferax mediterranei, an archaeon that grows faster than any other, comparable extreme halophile, is discussed, apparently more qualified as a 'microbial weed' than Haloquadratum and Salinibacter.

Growth Potential of Halophilic Bacteria Isolated from Solar Salt Environments: Carbon Sources and Salt Requirements

  • B. Javor
  • Environmental Science
    Applied and environmental microbiology
  • 1984
Tests of growth potential in natural saltern brines demonstrated that none of the halobacteria grew well in brines which harbor the densest populations of these bacteria in solar salterns, and the high concentrations of Na and Mg found in saltern crystallizer brines limited bacterial growth, but the concentrations of K found in these brines had little effect.