Silva Z, Borges N, Martins L O, Wait R, da Costa M S, Santos H
Departamento de Bioquímica, Universidade de Coimbra, Portugal.
Extremophiles. 1999 May;3(2):163-72. doi: 10.1007/s007920050112.
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 alpha-mannosylglycerate (alpha-MG) and alpha-mannosylglyceramide (alpha-MGA), whereas R. obamensis accumulated only alpha-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 alpha-mannosylglycerate and its amide, in addition to low levels of trehalose, glutamate, and glucose. At the highest growth temperature, alpha-mannosylglycerate was the major compatible solute and alpha-mannosylglyceramide was not detected. When both compounds were present, an increase in the salinity of the growth medium favored the accumulation of alpha-mannosylglyceramide over alpha-mannosylglycerate. The absence of alpha-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 alpha-mannosylglycerate as the temperature was raised. The importance of the two compounds in the mechanisms of thermoadaptation and osmoadaptation is discussed.
在本研究中，我们提出了海栖嗜热放线菌两种主要相容性溶质的修正结构。我们还研究了嗜盐嗜热菌海栖嗜热放线菌和奥巴马海栖嗜热放线菌的模式菌株在几个生长温度和盐度下相容性溶质的积累情况。海栖嗜热放线菌的主要溶质被鉴定为α-甘露糖基甘油酸（α-MG）和α-甘露糖基甘油酰胺（α-MGA），而奥巴马海栖嗜热放线菌仅积累α-甘露糖基甘油酸。总渗透溶质含量在指数生长期早期较高，随着生长进入稳定期而急剧下降。在低生长温度下，除了低水平的海藻糖、谷氨酸和葡萄糖外，海栖嗜热放线菌通过积累α-甘露糖基甘油酸及其酰胺来应对水分胁迫。在最高生长温度下，α-甘露糖基甘油酸是主要的相容性溶质，未检测到α-甘露糖基甘油酰胺。当两种化合物都存在时，生长培养基盐度的增加有利于α-甘露糖基甘油酰胺比α-甘露糖基甘油酸的积累。在所有生长温度和盐度下，奥巴马海栖嗜热放线菌中均不存在α-甘露糖基甘油酰胺，这是两株菌相容性溶质积累概况中最显著的差异。海藻糖也是这种生物中的一种主要溶质。随着温度升高，两种生物都积累了更高水平的α-甘露糖基甘油酸。本文讨论了这两种化合物在热适应和渗透适应机制中的重要性。
