The diether core membrane lipid sesterterpanyl-phytanyl-glycerol (so-called extended archaeol and often abbreviated C₂₀-C₂₅) is considered as a hallmark of Haloarchaea, a clade of archaea thriving under extreme high salinities. We here report about extended archaeol occurrence in different saline aquatic settings with salinity ranging from ca. 50 psu (5 % NaCl w/v) to saturation (ca. 350 psu). This demonstrates that this lipid is not restricted to extreme saline environments but suggests a minimum salinity threshold of ca. 50 psu above which C₂₀-C₂₅ is most commonly produced. The proportion of C₂₀-C₂₅ relative to that of archaeol (C₂₀-C₂₀) did not appear linearly dependent on the salinity of the site and was potentially also influenced by pH and temperature, preventing its direct use as a quantitative salinity proxy based on the present data set. An extensive literature review of archaeal membrane lipid compositions further highlighted that taxonomy also contributes to the distribution of this lipid in the environment and identifies Natrialbales (one of the three orders of Haloarchaea) as the main source. Statistical analysis showed that, among Haloarchaea, C₂₀-C₂₅ producers display pH and salinity growth optima slightly higher than non-producers and are distributed within two distinct groups, one composed mostly of neutrophiles and one of alkaliphiles. In contrast, the presence of C₂₀-C₂₅ was not correlated to the optimal growth temperature of the strains. This suggests that two confounding parameters, i.e., taxonomy and adaptation to changes in salinity and/or pH, contribute to the distribution of C₂₀-C₂₅ within Haloarchaea.

二醚核心膜脂质 sesterterpanyl-phytanyl-glycerol（所谓的扩展古菌，通常缩写为 C ₂₀ -C ₂₅）被认为是盐古菌的标志，盐古菌是在极高盐度下蓬勃发展的古菌进化枝。我们在这里报告了在不同盐度水生环境中扩展的古菌发生，盐度范围从约 。50 psu（5 % NaCl w/v）至饱和（约 350 psu）。这表明这种脂质不限于极端盐度环境，但表明最低盐度阈值为约。50 psu 以上最常产生C ₂₀ -C ₂₅。C ₂₀ -C ₂₅相对于古菌(C ₂₀ -C ₂₀) 似乎与该地点的盐度呈线性关系，并且还可能受到 pH 值和温度的影响，因此无法直接将其用作基于当前数据集的定量盐度代理。对古菌膜脂质成分的广泛文献综述进一步强调，分类学也有助于这种脂质在环境中的分布，并将 Natrialbales（Haloarchaea 的三个目之一）确定为主要来源。统计分析表明，在 Haloarchaea 中，C ₂₀ -C ₂₅生产者的 pH 和盐度生长最佳值略高于非生产者，并且分布在两个不同的群体中，一个主要由中性粒细胞组成，一个由嗜碱生物组成。相比之下，C ₂₀ -C₂₅与菌株的最佳生长温度无关。这表明两个混杂的参数，即分类学和对盐度和/或pH 变化的适应，有助于Haloarchaea中C ₂₀ -C ₂₅的分布。