Production of long-chain n-alkyl lipids by heterotrophic microbes: New evidence from Antarctic lakes
Production of long-chain n-alkyl lipids by heterotrophic microbes: New evidence from Antarctic lakes
复制标题
异养微生物生产长链正烷基脂质：来自南极湖泊的新证据
DOI：
10.1016/j.orggeochem.2019.103909
复制
发表时间：
2019-12-01
影响因子：
3
通讯作者：
Huang, Yongsong
中科院分区：
文献类型：
--
作者：
Chen, Xin;Liu, Xiaodong;Huang, Yongsong
长链正烷基脂质传统上归因于来自陆生维管植物，因为这些化合物是高等植物叶蜡的主要成分。在过去的半个世纪里，许多研究利用这些沉积生物标志物及其同位素比值来重建各种时间尺度上的古环境和古气候变化。然而，由于高等植物在地球仪的大多数环境中的普遍存在，确定这些化合物是否也可以来自微生物是不确定的，并且非常困难。在这里，我们首次从天然沉积物样品中发现，长链N-烷基脂质主要来源于三个高纬度（南纬69度）南极湖泊的水生微生物来源，周围的陆地上没有维管植物。这些长链正烷基脂质的碳同位素值很高（高达千分之12），排除了这些化合物是由风从邻近植被覆盖的陆地上传播过来的可能性。相反，这些同位素值与水生微生物垫产生的脂质相似，平均体积Δ C-13值为-14.2 +/-1.7/1000，表明异养微生物可能是这些长链正烷基脂质的来源。为了比较，我们还表明，即使是少量的维管植物和苔藓存在于研究区域，例如在长湖，（与南纬62度相似）在南极半岛，沉积长链正烷基脂类的碳同位素值急剧下降，这表明在湖泊沉积物中，叶蜡源对总长链N-烷基脂质库存的相对贡献迅速成比例增加。(C)2019爱思唯尔有限公司发布
Long-chain n-alkyl lipids are traditionally ascribed to an origin from terrestrial vascular plants because these compounds are major constituents of higher plant leaf waxes. Over the past half century, numerous studies have taken advantage of these sedimentary biomarkers and their isotopic ratios to reconstruct paleo-environmental and paleo-climatological changes at a variety of time scales. However, it is uncertain and extremely difficult to determine if these compounds can also derive from microbes because of the prevalence of higher plants in most environments around the globe. Here we show, for the first time from natural sediment samples, that long-chain n-alkyl lipids can predominantly originate from aquatic microbial sources at three high-latitude (>69 degrees S latitude) Antarctic lakes, where no vascular plants are present in the surrounding land mass. The high carbon isotopic values (up to -12 parts per thousand) of these long-chain n-alkyl lipids exclude the possibility that these compounds are transported by wind from adjacent vegetated land masses. Instead, these isotope values are similar to lipids produced by aquatic microbial mats with an average bulk delta C-13 value of -14.2 +/- 1.7 parts per thousand, indicating heterotrophic microbes are the likely source of these long-chain n-alkyl lipids. For comparison, we also show that when even small amount of vascular plants and mosses are present in the study region, for instance at Long Lake (similar to 62 degrees S latitude) in the Antarctic Peninsula, the carbon isotopic values of sedimentary long-chain n-alkyl lipids decline dramatically, suggesting a rapid proportional increase in the relative contribution of leaf wax sources to total long-chain n-alkyl lipid inventory in lake sediments. (C) 2019 Published by Elsevier Ltd.