CARBON ISOTOPIC SIGNATURES OF MICROBIAL LIPIDS IN GEOTHERMAL DEPOSITS: ELUCIDATING THERMOPHILIC ECOLOGY

地热矿床中微生物脂质的碳同位素特征：阐明嗜热生态学

• 批准号: NE/K006169/1
• 负责人: Richard Pancost
• 金额: $ 11.69万
• 依托单位: University of Bristol
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2013
• 资助国家: 英国
• 起止时间: 2013 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FK006169%2F1
• 关键词: CARBON; ISOTOPIC; SIGNATURES; MICROBIAL; LIPIDS

Understanding the origins and diversification of life represents one of the most challenging scientific endeavours. In such efforts, constraining the limits of life on Earth is vital, as is an understanding of the ecology of those organisms that can survive and even thrive in environments characterised by extremes of temperature, salinity or pH. Of particular interest are geothermal systems, populated by diverse and deeply-branching thermophilic bacteria and Archaea. Recently we have demonstrated that microbial lipids are powerful tools in assessing and reconstructing the microbiology of terrestrial hot springs. In this proposal we focus on elucidating the carbon isotopic signatures of the lipids of geothermal organisms. The use of lipid biomarkers in combination with stable isotope analysis is crucial to understanding microbial ecology, providing a direct link between microbial identity and biochemical processes.Lipids are found in all living organisms, typically serving as energy sources and structural components of cell membranes. Often highly diagnostic, well-preserved in the geological record, and entrained with information on biological diversity, environmental conditions and post-depositional alteration history, these compounds are particularly attractive for early life and astrobiological investigations. Our past studies of biomarkers in geothermal deposits reveal a profound diversity of encapsulated lipids, which can be utilized to profile microbial community composition. However, a potential of microbialite-preserved lipids that was untapped by our previous work is their carbon isotopic composition; strong and highly unusual variations in lipid carbon isotope values were observed in a small subset of our data but lacked crucial contextual data (e.g. the carbon isotopic composition of dissolved inorganic carbon, DIC, in the pools). This remains an untapped source of information on thermophilic physiologies and ecology in the New Zealand Taupo Volcanic Zone and the silica deposits formed there. Such deposits are essential archives of past life and elucidating the controls on organic matter formation in such settings will allow a better interpretation of the OM assemblages preserved in them. We will map the range of carbon isotope values and evaluate their reproducibility in various geothermal sites with differing physicochemical conditions and in different biofacies. By embedding this data in the context of thermal spring DIC carbon isotope values and recent microbiological community profiling based on molecular (DNA and RNA) approaches, we will resolve the origin of the unusual carbon isotopic compositions. This will greatly expand on our capacity to interpret biomarker carbon isotope values preserved in ancient silica sinters, providing crucial information on sources of lipid biomarkers, metabolism and trophic structure. In this work, we will target a range of diagnostic compounds from well-characterized geothermal settings in the Taupo Volcanic Zone in New Zealand and explore the controls on the variation of carbon isotopic signatures, coupling our past biomarker-based interpretations to carbon isotopic analyses in order to achieve a better understanding of the biodiversity of geothermal environments and to unravel biogeochemical and ecological function. This work will advance our interpretation of biosignatures preserved in the rock record, providing insight into the evolution and ecology of the earliest life-forms on Earth and informing the search for life elsewhere in the Solar System.

了解生命的起源和多样化是最具挑战性的科学努力之一。在这些努力中，限制地球上生命的极限至关重要，了解那些能够在极端温度、盐度或 pH 值的环境中生存甚至繁衍生息的生物体的生态也至关重要。特别令人感兴趣的是地热系统，其中充满了多样化且深分支的嗜热细菌和古细菌。最近，我们证明微生物脂质是评估和重建陆地温泉微生物学的有力工具。在本提案中，我们重点阐明地热生物脂质的碳同位素特征。脂质生物标记物与稳定同位素分析相结合的使用对于了解微生物生态学至关重要，它提供了微生物特性和生化过程之间的直接联系。脂质存在于所有活生物体中，通常充当能量来源和细胞膜的结构成分。这些化合物通常具有高度诊断性，在地质记录中保存完好，并夹带有关生物多样性、环境条件和沉积后蚀变历史的信息，对早期生命和天体生物学研究特别有吸引力。我们过去对地热沉积物中生物标志物的研究揭示了封装脂质的深刻多样性，可用于分析微生物群落组成。然而，微生物岩保存的脂质的一个潜力是我们之前的工作尚未开发的，那就是它们的碳同位素组成。在我们的一小部分数据中观察到脂质碳同位素值存在强烈且极不寻常的变化，但缺乏关键的背景数据（例如池中溶解的无机碳 DIC 的碳同位素组成）。这仍然是有关新西兰陶波火山带嗜热生理学和生态学以及那里形成的二氧化硅沉积物的未开发信息来源。这些沉积物是过去生命的重要档案，阐明这些环境中有机物质形成的控制将有助于更好地解释其中保存的有机质组合。我们将绘制碳同位素值的范围，并评估其在具有不同物理化学条件和不同生物相的各种地热地点的再现性。通过将这些数据嵌入到温泉 DIC 碳同位素值和最近基于分子（DNA 和 RNA）方法的微生物群落分析中，我们将解决不寻常碳同位素组成的起源。这将极大地扩展我们解释古代二氧化硅烧结体中保存的生物标志物碳同位素值的能力，提供有关脂质生物标志物来源、代谢和营养结构的重要信息。在这项工作中，我们将针对来自新西兰陶波火山区特征良好的地热环境的一系列诊断化合物，并探索对碳同位素特征变化的控制，将我们过去基于生物标记的解释与碳同位素分析结合起来，以便更好地了解地热环境的生物多样性，并揭示生物地球化学和碳同位素特征的变化。 生态功能。这项工作将推进我们对岩石记录中保存的生物特征的解释，提供对地球上最早生命形式的进化和生态学的深入了解，并为在太阳系其他地方寻找生命提供信息。

项目成果

Bacteriohopanepolyols preserved in silica sinters from Champagne Pool (New Zealand) indicate a declining temperature gradient over the lifetime of the vent

• DOI: 10.1016/j.orggeochem.2014.02.004
• 发表时间: 2014-04-01
• 期刊: ORGANIC GEOCHEMISTRY
• 影响因子: 3
• 作者: Gibson, Robert A.;Sherry, Angela;Talbot, Helen M.
• 通讯作者: Talbot, Helen M.

Temperature and pH control on lipid composition of silica sinters from diverse hot springs in the Taupo Volcanic Zone, New Zealand.

• DOI: 10.1007/s00792-014-0719-9
• 发表时间: 2015-03
• 期刊: EXTREMOPHILES
• 影响因子: 2.9
• 作者: Kaur, Gurpreet;Mountain, Bruce W.;Stott, Matthew B.;Hopmans, Ellen C.;Pancost, Richard D.
• 通讯作者: Pancost, Richard D.