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

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Stevenson, Andrew ^[1] ; Cray, Jonathan A. ^[1] ; Williams, Jim P. ^[1] ; Santos, Ricardo ^{[1, 2]} ; Sahay, Richa ^[3] ; Neuenkirchen, Nils ^[3] ; McClure, Colin D. ^[1] ; Grant, Irene R. ^[1] ; Houghton, Jonathan D. R. ^[1] ; Quinn, John P. ^[1] ; Timson, David J. ^[1] ; Patil, Satish V. ^[4] ; Singhal, Rekha S. ^[5] ; Anton, Josefa ^[6] ; Dijksterhuis, Jan ^[7] ; Hocking, Ailsa D. ^[8] ; Lievens, Bart ^[9] ; Rangel, Drauzio E. N. ^[10] ; Voytek, Mary A. ^[11] ; Gunde-Cimerman, Nina ^[12] ; Oren, Aharon ^[13] ; Timmis, Kenneth N. ^{[3, 14]} ; McGenity, Terry J. ^[3] ; Hallsworth, John E. ^{[3, 1]}

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^[1] Queens Univ Belfast, Sch Biol Sci, MBC, Inst Global Food Secur, Belfast BT9 7BL, Antrim - North Ireland

^[2] Inst Super Tecn, Lab Anal, Lisbon - Portugal

^[3] Univ Essex, Sch Biol Sci, Colchester CO4 3SQ, Essex - England

^[4] North Maharashtra Univ, Sch Life Sci, Jalgaon, Maharashtra - India

^[5] Inst Chem Technol, Dept Food Engn & Technol, Mumbai, Maharashtra - India

^[6] Univ Alicante, Dept Physiol Genet & Microbiol, E-03080 Alicante - Spain

^[7] CBS Fungal Biodivers Ctr, Utrecht - Netherlands

^[8] CSIRO Food & Nutr, N Ryde, NSW - Australia

^[9] Scientia Terrae Res Inst, Microbial Ecol & Biorat Control, St Katelijne Waver - Belgium

^[10] Univ Vale Paraiba, Inst Pesquisa Desenvolvimento, Sao Jose dos Campos, SP - Brazil

^[11] NASA Headquarters, Washington, DC - USA

^[12] Univ Ljubljana, Biotech Fac, Ljubljana - Slovenia

^[13] Hebrew Univ Jerusalem, Alexander Silberman Inst Life Sci, Dept Plant & Environm Sci, Jerusalem - Israel

^[14] Tech Univ Carolo Wilhelmina Braunschweig, Inst Microbiol, D-38106 Braunschweig - Germany

• Tipo de documento: Artigo Científico
• Fonte: ISME Journal; v. 9, n. 6, p. 1333-1351, JUN 2015.
• Citações Web of Science: 76

Resumo

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

• Processo FAPESP: 10/06374-1 - Luz visível durante o crescimento induz aumento de tolerância de conídios a diferentes condições de estresse em fungos
• Beneficiário: Drauzio Eduardo Naretto Rangel
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores