Department of Plant and Environmental Sciences, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel.
Extremophiles. 2013 May;17(3):445-51. doi: 10.1007/s00792-013-0522-z. Epub 2013 Mar 16.
We have examined the organic osmotic solutes content within the stratified microbial communities in an evaporitic gypsum crust found in an evaporation pond (~194 g/l total dissolved salts) of the salterns of the Israel Salt Company, Eilat. We extracted intracellular solutes from the upper three pigmented layers of the crust: a yellow-orange layer dominated by unicellular cyanobacteria, a green layer with filamentous cyanobacteria, and a layer colored red-purple by purple sulfur bacteria; dense communities of heterotrophic bacteria were present in all layers. The solutes were analyzed by Raman spectroscopy, (1)H and (13)C nuclear magnetic resonance, and HPLC. All layers contained glycine betaine as the only detectable osmotic solute; ectoine and other solutes known to be produced by many halophilic and halotolerant prokaryotes were not found. In this first attempt to assess the osmotic solute content within complex natural communities of halophilic microorganisms, the predominant role of glycine betaine as an osmolyte was established. Most heterotrophic bacteria cannot produce glycine betaine but preferentially use it when it is supplied. Presence of glycine betaine produced by the photoautotrophic members of the community, therefore, may relieve the heterotrophs from the need to synthesize other compounds at a high-energy cost.
我们研究了位于以色列盐业公司埃拉特盐田蒸发池蒸发石膏壳分层微生物群落中的有机渗透溶质含量（~194 g/l 总溶解盐）。我们从壳的上三层色素层中提取了细胞内溶质：一层由单细胞蓝细菌主导的黄橙色层，一层有丝状蓝细菌的绿色层，和一层由紫色硫细菌染成红紫色的层；所有层都存在密集的异养细菌群落。溶质通过拉曼光谱、（1）H 和（13）C 核磁共振和 HPLC 进行分析。所有层都含有甘氨酸甜菜碱作为唯一可检测的渗透溶质；未发现其他已知由许多嗜盐和耐盐原核生物产生的海藻糖和其他溶质。在首次尝试评估嗜盐微生物复杂自然群落中的渗透溶质含量时，确立了甘氨酸甜菜碱作为渗透调节剂的主要作用。大多数异养细菌不能产生甘氨酸甜菜碱，但当它被供应时，它们会优先使用它。因此，群落中光自养成员产生的甘氨酸甜菜碱的存在可能使异养生物免于以高能量成本合成其他化合物的需要。
