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

• DOI: 10.1038/ismej.2014.219
• Publication Date: 2014-12-12T14:57:03Z
• Authors: Andrew Stevenson; Jonathan A Cray; Jim P Williams; Ricardo Santos; Richa Sahay; Nils Neuenkirchen; Colin D McClure; Irene R Grant; Jonathan D R Houg...; John P Quinn; David J Timson; Satish V Patil; Rekha S Singhal; Josefa Antón; Jan Dijksterhuis; Ailsa D Hocking; Bart Lievens; Drauzio E N Rangel; Mary A Voytek; Nina Gunde-Cimerman; Aharon Oren; Kenneth N Timmis; Terry J McGenity; John E Hallsworth
• Keywords: Halobacterium; Extremophile; Water activity; Sarcina; Extreme environment

Abstract Archaea and Bacteria constitute a majority of life systems on Earth but have long been considered inferior to Eukarya in terms solute tolerance. Whereas the most halophilic prokaryotes are known for an ability multiply at saturated NaCl (water activity (aw) 0.755) some xerophilic fungi can germinate, usually high-sugar concentrations, values as low 0.650–0.605 aw. Here, we present evidence that prokayotes grow down water activities <0.755 Halanaerobium lacusrosei (0.748), Halobacterium strain 004.1 (0.728), sp. NRC-1 Halococcus morrhuae (0.717), Haloquadratum walsbyi (0.709), salifodinae (0.693), noricense (0.687), Natrinema pallidum (0.681) haloarchaeal strains GN-2 GN-5 (0.635 aw). Furthermore, extrapolation growth curves (prone giving conservative estimates) indicated theoretical minima 0.611 aw extreme, obligately Bacteria. These were compared with solute-tolerant (or other non-saline) media (Mycobacterium spp., Tetragenococcus halophilus, Saccharibacter floricola, Staphylococcus aureus so on) eukaryotic microbes saline (Wallemia Basipetospora halophila, Dunaliella spp. substrates (for example, Xeromyces bisporus, Zygosaccharomyces rouxii, Aspergillus Eurotium spp.). We also manipulated balance chaotropic kosmotropic stressors penicilloides X. bisporus and, via this approach, their established water-activity limits mycelial (∼0.65) reduced 0.640. extrapolations 0.632 0.636 A. respectively. Collectively, these findings suggest there is common limit determined by physicochemical constraints three domains life.