Microbial polar membrane lipids in marine sediments and their significance for subsurface life

完整极性膜脂（IPL）是海洋沉积物中普遍存在的痕量化合物，被认为是活微生物细胞的诊断标志物。一组特定的IPL（糖苷古菌二醚和四醚）的优势表明古菌构成微生物生物质的主要部分（Lipp等人，Nature 454，991-994，2008）。一个显着的关系，观察到的浓度之间的IPL和总有机碳。我们认为，这种关系抓住了海洋沉积生物圈的基本属性，并可用于估计生物量。然而，我们目前的数据集仍然强烈偏向于海洋富营养化部分的沉积物。因此，我们建议将我们的环境调查扩大到一个真正具有全球代表性的数据集，其中包括不同的公海环境，并补充现有的和相应的数据集的基础上集中的散装电池。我们希望限制控制海洋沉积物中微生物生物量分布的因素。额外的实验调查将集中在主要IPL类的环境持久性和研究沉积IPL的化石部分的潜在存在。我们还建议研究生长条件和IPL组合物之间的关系，在选定的海洋沉积物中，以了解糖苷醚脂质的优势。我们的研究将提高我们对沉积生物圈的理解，其全球范围和广泛的分类组成，先进的技术用于检测复杂环境样品中的微生物生物量，并发展年轻的研究员朱利叶斯·利普的职业生涯。

Intact polar membrane lipids (IPLs) are ubiquitous trace compounds in marine sediments and are considered diagnostic markers for live microbial cells. The dominance of a particular group of IPLs, glycosidic archaeal di- and tetraethers, suggests that Archaea constitute a major fraction of microbial biomass (Lipp et al., Nature 454, 991-994, 2008). A significant relationship was observed between concentrations of IPLs and total organic carbon. We suggested that this relationship captures a fundamental property of the marine sedimentary biosphere and can be used to estimate quantities of biomass. However, our current data set is still strongly biased towards sediments in eutrophic parts of the ocean. Therefore we propose to extend our environmental survey to a truly globally representative data set that includes diverse open-ocean environments and complements existing and corresponding data sets based on concentrations of bulk cells. We want to constrain the factors that control the distribution of microbial biomass in marine sediments. Additional experimental investigations will focus on the environmental persistence of the major IPL classes and study the potential existence of a fossil fraction of sedimentary IPLs. We also propose to examine the relationship between growth conditions and IPL composition in selected Archaea in order to understand the dominance of glycosidic ether lipids in marine subsurface sediments. Our research will improve our understanding of the sedimentary biosphere, its global extent and broad taxonomic composition, advance technologies for the detection of microbial biomass in complex environmental samples, and develop the career of young investigator Julius Lipp.