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Abstract：
\"Candidatus Nitrosotenuis uzonensis\" is the only cultured moderately thermophilic member of the thaumarchaeotal order Nitrosopumilales (NP) that contains many mesophilic marine strains. We examined its membrane lipid composition at different growth temperatures (37°C, 46°C, and 50°C). Its lipids were all membrane-spanning glycerol dialkyl glycerol tetraethers (GDGTs), with 0 to 4 cyclopentane moieties. Crenarchaeol (cren), the characteristic thaumarchaeotal GDGT, and its isomer (cren\') were present in high abundance (30 to 70%). The GDGT polar headgroups were mono-, di-, and trihexoses and hexose/phosphohexose. The ratio of glycolipid to phospholipid GDGTs was highest in the cultures grown at 50°C. With increasing growth temperatures, the relative contributions of cren and cren\' increased, while those of GDGT-0 to GDGT-4 (including isomers) decreased. TEX86 (tetraether index of tetraethers consisting of 86 carbons)-derived temperatures were much lower than the actual growth temperatures, further demonstrating that TEX86 does not accurately reflect the membrane lipid adaptation of thermophilic Thaumarchaeota As the temperature increased, specific GDGTs changed relative to their isomers, possibly representing temperature adaption-induced changes in cyclopentane ring stereochemistry. Comparison of a wide range of thaumarchaeotal core lipid compositions revealed that the \"Ca Nitrosotenuis uzonensis\" cultures clustered separately from other members of the NP order and the Nitrososphaerales (NS) order. While phylogeny generally seems to have a strong influence on GDGT distribution, our analysis of \"Ca Nitrosotenuis uzonensis\" demonstrates that its terrestrial, higher-temperature niche has led to a lipid composition that clearly differentiates it from other NP members and that this difference is mostly driven by its high cren\' content.IMPORTANCE For Thaumarchaeota, the ratio of their glycerol dialkyl glycerol tetraether (GDGT) lipids depends on growth temperature, a premise that forms the basis of the widely applied TEX86 paleotemperature proxy. A thorough understanding of which GDGTs are produced by which Thaumarchaeota and what the effect of temperature is on their GDGT composition is essential for constraining the TEX86 proxy. \"Ca Nitrosotenuis uzonensis\" is a moderately thermophilic thaumarchaeote enriched from a thermal spring, setting it apart in its environmental niche from the other marine mesophilic members of its order. Indeed, we found that the GDGT composition of \"Ca Nitrosotenuis uzonensis\" cultures was distinct from those of other members of its order and was more similar to those of other thermophilic, terrestrial Thaumarchaeota This suggests that while phylogeny has a strong influence on GDGT distribution, the environmental niche that a thaumarchaeote inhabits also shapes its GDGT composition.
摘要：
“念珠菌Nitrosotenuisuzonensis”是唯一培养的中等嗜热成员，该成员包含许多嗜温海洋菌株。我们检查了其在不同生长温度（37°C，46°C,和50°C)。它的脂质都是跨膜甘油二烷基甘油四醚（GDGT），具有0至4个环戊烷部分。Crenarcheol(cren),特征的古细菌GDGT，及其异构体（cren\'）的含量很高（30％至70％）。GDGT极性头部基团是单-，di-,和三己糖和己糖/磷酸己糖。在50°C下生长的培养物中，糖脂与磷脂GDGTs的比率最高。随着生长温度的升高,克伦和克伦的相对贡献增加了，而GDGT-0至GDGT-4(包括异构体)的含量下降。TEX86（由86个碳组成的四醚的四醚指数）得出的温度远低于实际生长温度，进一步证明TEX86不能准确反映嗜热Thaumarchareota的膜脂适应随着温度的升高，特定的GDGT相对于它们的异构体发生了变化，可能代表温度适应引起的环戊烷环立体化学变化。广泛的古细菌核心脂质组成的比较表明，“Nitrosotenuisuzonensis”培养物与NP顺序和Nitrososphaerales（NS）顺序的其他成员分开聚集。虽然系统发育似乎对GDGT分布有很大影响，我们对“UzonensisNitrosotenuisCa”的分析表明，它的陆地，较高温度的生态位导致脂质成分明显区别于其他NP成员，并且这种差异主要是由其高cren\'含量驱动的。对Thaumarcheota的重要性,它们的甘油二烷基甘油四醚（GDGT）脂质的比例取决于生长温度，一个前提，构成了广泛应用的TEX86古温度代理的基础。彻底了解哪些GDGT是由哪些Thaumarcheoota产生的，以及温度对其GDGT组成的影响对于限制TEX86代理至关重要。“Nitrosotenuisuzonensis钙”是一种从温泉中富集的中度嗜热苏木古菌，将其在环境生态位与其他海洋中温成员区分开来。的确,我们发现，“亚硝基uzonensis”培养物的GDGT组成与其顺序的其他成员不同，并且与其他嗜热者更相似，陆生Thaumarcheota这表明，虽然系统发育对GDGT分布有很大影响，古菌栖息的环境生态位也塑造了其GDGT组成。
