Combined effect of the growth temperature and salinity of the medium on the accumulation of compatible solutes by Rhodothermus marinus and Rhodothermus obamensis |
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Authors: | Zélia Silva Nuno Borges Lígia O. Martins Robin Wait Milton S. da Costa H. Santos |
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Affiliation: | (1) Departamento de Bioquímica, Universidade de Coimbra, 3000 Coimbra, Portugal, PT;(2) Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Rua da Quinta Grande 6, Apartado 127, 2780 Oeiras, Portugal Tel. +3-51-1-446-9828; Fax +3-51-1-442-8766 e-mail: santos@itqb.unl.pt, PT;(3) Centre for Applied Microbiology and Research, Porton Down, Salisbury, SP4 0JG, UK, GB |
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Abstract: | In this study we propose revised structures for the two major compatible solutes of Rhodothermus marinus. We have also examined the accumulation of compatible solutes by the type strains of the slightly halophilic and thermophilic species Rhodothermus marinus and Rhodothermus obamensis at several growth temperatures and salinities. The major solutes of R. marinus were identified as α-mannosylglycerate (α-MG) and α-mannosylglyceramide (α-MGA), whereas R. obamensis accumulated only α-mannosylglycerate. The total osmolyte content was higher during the early exponential phase and decreased abruptly as growth continued into the stationary phase. At low growth temperatures, R. marinus responded to water stress by accumulation of α-mannosylglycerate and its amide, in addition to low levels of trehalose, glutamate, and glucose. At the highest growth temperature, α-mannosylglycerate was the major compatible solute and α-mannosylglyceramide was not detected. When both compounds were present, an increase in the salinity of the growth medium favored the accumulation of α-mannosylglyceramide over α-mannosylglycerate. The absence of α-mannosylglyceramide in R. obamensis at all growth temperatures and salinities constituted the most pronounced difference in the profiles of compatible solute accumulation by the two strains. Trehalose was also a prominent solute in this organism. Both organisms accumulated higher levels of α-mannosylglycerate as the temperature was raised. The importance of the two compounds in the mechanisms of thermoadaptation and osmoadaptation is discussed. Received: February 10, 1998 / Accepted: January 11, 1999 |
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Keywords: | Compatible solutes Osmoadaptation Thermoadaptation α -Mannosylglycerate α -Mannosylglyceramide Rhodothermus marinus Rhodothermus obamensis |
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