Abstract Freshwater wetlands harbour diverse archaeal communities and associated membrane lipid assemblages, but the effect of environmental factors (e.g. pH and temperature) on the distribution of these lipids is relatively poorly constrained. Here we explore the effects of temperature and pH on archaeal core-lipid and intact polar lipid (IPL) derived core lipid distributions in a range of wetlands. We focus, not only on the commonly studied isoprenoidal glycerol dialkyl glycerol tetraethers (isoGDGTs), but also widen our analyses to include more recently identified, but relatively widespread, archaeal lipids such as isoGDGT isomers, methylated isoGDGTs (Me-GDGTs), and butanetriol and pentanetriol tetraethers (BDGTs and PDGTs). Based on multivariate analysis and a globally distributed set of wetlands, we find that the degree of isoGDGT cyclisation does increase along with temperature and pH in wetlands. However, and unlike in some other settings, this relationship is obscured in simple scatterplots due to the incorporation of isoGDGTs from highly diverse archaeal sources with multiple ring-temperature or ring-pH relationships. We further show that the relative abundance of early eluting to later eluting isoGDGT isomers increases with pH, representing a previously unknown and seemingly widespread archaeal membrane homeostasis mechanism or taxonomic signal. The distribution and abundance of crenarchaeol, a marker for Thaumarchaeota, demonstrates that in wetlands these Archaea, likely involved in ammonia oxidation, are restricted primarily to the generally drier soil/sediment surface and typically are more abundant in circumneutral pH settings. We identify Me-GDGTs and Me-isoGMGTs (homologs of isoGDGTs and isoGMGTs, but with additional methylation on the biphytanyl chain) as ubiquitous in wetlands, but variation in their abundance and distribution suggests changing source communities and/or membrane adaptation. The high relative abundance of BDGTs and PDGTs in the perennially anoxic part of the peat profile (catotelm), as well as their elevated abundance in a circumneutral pH wetland, is consistent with an important input from their only known culture source, belonging to the methanogenic Methanomassiliicoccales. Our results underline the diversity of archaeal membrane lipids preserved in wetlands and provide a baseline for the use of archaeal lipid distributions in wetlands as tracers of recent or ancient climate and biogeochemistry.

中文翻译：

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温度和pH值对淡水湿地古菌膜脂分布的影响

摘要淡水湿地拥有不同的古菌群落和相关的膜脂组合，但环境因素（如 pH 值和温度）对这些脂类分布的影响相对较少。在这里，我们探讨了温度和 pH 值对一系列湿地中古菌核心脂质和完整极性脂质 (IPL) 衍生的核心脂质分布的影响。我们不仅专注于普遍研究的类异戊二烯甘油二烷基甘油四醚 (isoGDGT)，而且还扩大了我们的分析范围，以包括最近发现但相对广泛的古菌脂质，如 isoGDGT 异构体、甲基化 isoGDGT (Me-GDGT) 和丁三醇和戊三醇四醚（BDGT 和 PDGT）。基于多变量分析和全球分布的湿地集，我们发现isoGDGT环化程度确实随着湿地温度和pH值的增加而增加。然而，与其他一些设置不同的是，这种关系在简单的散点图中被掩盖了，因为结合了来自具有多种环温度或环 pH 关系的高度多样化古菌来源的 isoGDGT。我们进一步表明，早期洗脱到后期洗脱的 isoGDGT 异构体的相对丰度随着 pH 值而增加，代表了以前未知且看似广泛的古菌膜稳态机制或分类信号。奇古菌属的标志物 crenarchaeol 的分布和丰度表明，在湿地中，这些可能参与氨氧化的古菌主要限于通常较干燥的土壤/沉积物表面，并且通常在中性 pH 值环境中更为丰富。我们确定 Me-GDGTs 和 Me-isoGMGTs（isoGDGTs 和 isoGMGTs 的同源物，但在联植烷基链上有额外的甲基化）在湿地中普遍存在，但它们的丰度和分布的变化表明源群落和/或膜适应的变化。BDGTs 和 PDGTs 在泥炭剖面 (catotelm) 的常年缺氧部分的相对丰度高，以及它们在中性 pH 值周围湿地中的丰度升高，与它们唯一已知的培养源的重要输入一致，属于产甲烷菌。甲烷球菌属。我们的结果强调了湿地中保存的古菌膜脂质的多样性，并为使用湿地中的古菌脂质分布作为近期或古代气候和生物地球化学的示踪剂提供了基线。