2-Methylhopanoids as biomarkers for cyanobacterial oxygenic photosynthesis
2-Methylhopanoids as biomarkers for cyanobacterial oxygenic photosynthesis
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DOI：
10.1038/23005
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发表时间：
1999-08-05
期刊：
影响因子：
64.8
通讯作者：
Logan, GA
中科院分区：
文献类型：
--
作者：
Summons, RE;Jahnke, LL;Logan, GA
含氧光合作用被广泛认为是地球表面环境中最重要的生物能量过程（1）。它被认为是在蓝藻谱系中进化的，但很难确定它是何时开始的。基于层膜的出现和外观（2）和微体化石的证据表明，光养作用早在34.65亿年前就已经发生了，尽管从这些物体中还不能做出明确的生理学推论。碳同位素和其他地质现象（4，5）提供了线索，但也是模棱两可的，生物标志物是潜在的有用的，因为现存生命的三个领域-细菌，古生物和真核生物-有标志性的膜脂与反柠檬酸碳骨架。这些脂类在沉积物中转化为碳氢化合物，并且可以在任何记录保存完好的地方找到。在这里，我们表明，2-甲基bacteriophopane多元醇出现在一个高比例的培养蓝藻和蓝藻垫，其2-甲基hopane烃衍生物丰富的有机物丰富的沉积物，作为2,500万年前。这些生物标志物可能有助于限制最古老的蓝藻的年龄和产氧光合作用的出现。它们也可以用来量化蓝藻在地质时期的生态重要性。
Oxygenic photosynthesis is widely accepted as the most important bioenergetic process happening in Earth's surface environment(1). It is thought to have evolved within the cyanobacterial lineage, but it has been difficult to determine when it began. Evidence based on the occurrence and appearance of stromatolites(2) and microfossils' indicates that phototrophy occurred as long ago as 3,465 Myr although no definite physiological inferences can be he made from these objects. Carbon isotopes and other geological phenomena(4,5) provide clues but are also equivocal, Biomarkers are potentially useful because the three domains of extant life-Bacteria, Archaea and Eukarya-have signature membrane lipids with recalcitrant carbon skeletons. These lipids turn into hydrocarbons in sediments and can be found wherever the record is sufficiently well preserved. Here we show that 2-methylbacteriohopanepolyols occur in a high proportion of cultured cyanobacteria and cyanobacterial mats, Their 2-methylhopane hydrocarbon derivatives are abundant in organic-rich sediments as old as 2,500 Myr. These biomarkers may help constrain the age of the oldest cyanobacteria and the advent of oxygenic photosynthesis. They could also be used to quantify the ecological importance of cyanobacteria through geological time.