Tracing the origin of marine sedimentary hopanoids using compound-specific multi-istope analysis and metagenomics

细菌hopanoids是最具诊断性的脂质生物标志物之一，几乎普遍存在于沉积记录中。它们具有出色但尚未实现的潜力，可以成为微生物过程和生态学研究的丰富信息来源，以及近代和古代系统（与气候变化有关）中环境条件的指标。然而，它们的环境，生理和分类起源仍然难以捉摸，最基本的问题，海洋沉积hopanoids的起源仍然没有答案。目前尚不清楚大多数类Hopanoids是否来自海洋微生物种群或作为陆源有机质通量的一部分输入。同样，它仍然不确定是否大多数hopanoids是细菌的初级生产者的产品或产品的异养社区负责有机物降解，因此，是否其结构和同位素的多样性与hopanoids生产者在环境中的多样性。为了回答这些问题，该项目采用跨学科的方法，结合化合物特异性多同位素分析，辅以宏基因组学，以揭示海洋沉积物中类Hopanoids的起源。该项目的研究结果将有助于对古环境条件和古生态群落状况的关键解释进行评估。进一步了解初级和次级生产力的相对沉积作用以及陆源和海洋碳库之间的相互作用，也将为我们了解全球碳循环提供至关重要的信息。

Bacterial hopanoids are among the most diagnostic lipid biomarkers found almost universally in the sedimentary record. They have an excellent but as yet unfulfilled potential to be a rich source of information in the study of microbial processes and ecology as well as indicators of environmental conditions within recent and ancient systems (linked to climate change). However, their environmental, physiological, and taxonomic origins remain elusive and the most basic questions about the origin of marine sedimentary hopanoids remain unanswered. It is unknown whether most hopanoids derived from the marine microbial population or are imported as part of the terrigenous organic matter flux. Likewise, it remains uncertain whether most hopanoids are the products of bacterial primary producers or products of the heterotrophic community responsible for organic matter degradation and accordingly whether their structural and isotopic diversity is related to the diversity of hopanoid producers in the environment. To answer these questions, this project takes an interdisciplinary approach combining compound-specific multi-isotope analysis complemented by metagenomics to unravel the origins of hopanoids in marine sediments. The results obtained in this project will help to evaluate the critical interpretation of paleoenvironmental conditions and the status of paleoecological communities. An improved understanding of the relative sedimentation of primary and secondary productivity and the interactions between the terrigenous and marine carbon reservoirs also will yield information critical to our understanding of the global carbon cycle.