Department of Marine Organic Biogeochemistry, NIOZ Royal Netherlands Institute for Sea Research, Den Burg, The Netherlands.
ISME J. 2010 Apr;4(4):542-52. doi: 10.1038/ismej.2009.138. Epub 2009 Dec 24.
Analyses of archaeal membrane lipids are increasingly being included in ecological studies as a comparatively unbiased complement to gene-based microbiological approaches. For example, crenarchaeol, a glycerol dialkyl glycerol tetraether (GDGT) with a unique cyclohexane moiety, has been postulated as biomarker for ammonia-oxidizing Archaea (AOA). Crenarchaeol has been detected in Nitrosopumilus maritimus and 'Candidatus Nitrosocaldus yellowstonii' representing two of the three lineages within the Crenarchaeota containing described AOA. In this paper we present the membrane GDGT composition of 'Candidatus Nitrososphaera gargensis', a moderately thermophilic AOA, and the only cultivated Group I.1b Crenarchaeon. At a cultivation temperature of 46 degrees C, GDGTs of this organism consisted primarily of crenarchaeol, its regioisomer, and a novel GDGT. Intriguingly, 'Ca. N. gargensis' is the first cultivated archaeon to synthesize substantial amounts of the crenarchaeol regioisomer, a compound found in large relative abundances in tropical ocean water and some soils, and an important component of the TEX(86) paleothermometer. Intact polar lipid (IPL) analysis revealed that 'Ca. N. gargensis' synthesizes IPLs similar to those reported for the Goup I.1a AOA, Nitrosopumilus maritimus SCMI, in addition to IPLs containing uncharacterized headgroups. Overall, the unique GDGT composition of 'Ca. N. gargensis' extends the known taxonomic distribution of crenarchaeol synthesis to the Group I.1b Crenarchaeota, implicating this clade as a potentially important source of crenarchaeol in soils and moderately high temperature environments. Moreover, this work supports the hypothesis that crenarchaeol is specific to all AOA and highlights specific lipids, which may prove useful as biomarkers for 'Ca. N. gargensis'-like AOA.
古菌膜脂分析越来越多地被纳入生态研究中，作为对基于基因的微生物方法的一种相对无偏的补充。例如，具有独特环己烷部分的甘油二烷基甘油四醚（GDGT）crenarchaeol 被假定为氨氧化古菌（AOA）的生物标志物。Nitrosopumilus maritimus 和 'Candidatus Nitrosocaldus yellowstonii' 中均检测到了 crenarchaeol，它们分别代表含有描述性 AOA 的三个 Crenarchaeota 谱系中的两个。在本文中，我们介绍了中度嗜热 AOA 和唯一培养的 Group I.1b Crenarchaeon 'Candidatus Nitrososphaera gargensis' 的膜 GDGT 组成。在 46°C 的培养温度下，该生物的 GDGT 主要由 crenarchaeol、其区域异构体和一种新型 GDGT 组成。有趣的是，'Ca. N. gargensis' 是第一个合成大量 crenarchaeol 区域异构体的培养古菌，该化合物在热带海洋水和一些土壤中大量存在，是 TEX(86)古温度计的重要组成部分。完整极性脂（IPL）分析表明，'Ca. N. gargensis' 合成的 IPL 与 Group I.1a AOA Nitrosopumilus maritimus SCMI 报道的类似，除了含有未鉴定的头基的 IPL 之外。总体而言，'Ca. N. gargensis' 独特的 GDGT 组成将 crenarchaeol 合成的已知分类分布扩展到 Group I.1b Crenarchaeota，表明该分支可能是土壤和中高温环境中 crenarchaeol 的重要来源。此外，这项工作支持了 crenarchaeol 是所有 AOA 特异性的假设，并强调了特定的脂类，这些脂类可能被证明对类似 'Ca. N. gargensis' 的 AOA 有用作生物标志物。
