Disentangling de-novo synthesis, recycling and transformation of n-alkyl lipids in soils by combination of position-specific 13C labeling with fragment-specific 13C analysis

通过位置特异性 13C 标记与片段特异性 13C 分析相结合，解开土壤中正烷基脂质的从头合成、回收和转化

• 批准号: 278571255
• 负责人: Professorin Dr. Michaela Dippold
• 金额: --
• 依托单位: Arbeitsgruppe Geo-Biosphären Wechselwirkungen
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/278571255?language=en
• 关键词: Disentangling; de; novo; synthesis; recycling

Lipids represent one of the most diverse classes of biomolecules and have various functions: main component of cell membranes, protection layers, storage compounds, etc. High diversity and unique speciation of lipids in plant and microbial taxonomic groups made them to one of the most promising biomarker classes in soils and sediments. They are an important component of soil organic matter (SOM) and contribute to physico-chemical properties like hydrophobicity and C storage. Detailed knowledge on lipid sources exists from studies using lipids as biomarkers, but lipid transformations in soils are nearly unknown. Recycling is assumed to be a highly relevant process in soils as lipids are expensive compounds for de-novo synthesis, but is not proven in-situ, yet. This proposal aims at disentangling microbial transformation of lipid precursors, de-novo synthesis of microbial lipids and recycling of lipids in soil to yield new insights into the network of processes underlying the lipid cycle and to deepen our understanding of SOM transformations. Lipid de-novo synthesis in microbial cells will be investigated by application of 13C glucose, a precursor, which is quickly taken up by microorganisms. Fragment-specific 13C incorporation based on liquid chromatography-mass spectrometry with online fragmentation will enable to separate de-novo synthesis of phospholipid headgroups, backbone and fatty acid alkyl chains. In addition to intracellular de-novo synthesis, lipid recycling from extracellular pools will be investigated. Position-specifically labeled palmitate (13C-1, 13C-2, 13C-16) will be applied to soil and incorporation into microbial phospholipids fatty acids (PLFA) will be analyzed by gas chromatography-mass spectrometry with online fragmentation. Thus, intact incorporation of the added n-alkyl chain into PLFA will reveal recycling of free lipids from soils. The sum of extra- and intracellular transformations of lipids on a medium-term time scale (4 years) will be studied using position-specifically 13C labeled palmitate in an already established field experiment. Recycling and transformations of the n-alkyl chain will be followed into various n-alkyl lipids (n-alkanes, n-alcohols, n-fatty acids, hydroxy fatty acids) of the extractable lipid and hydrolyzable lipid pools. Combining position-specific labeling with fragment-specific 13C incorporation analysis gives us a unique perspective on lipid transformations in soil: Recycling can be unambiguously differentiated from de-novo synthesis in soils in-situ. Distinguishing recycling from stabilization is crucial in understanding the soil C cycle. Such identification of microbial transformations during lipid recycling will strongly improve our interpretation of plant and microbial lipid biomarker fingerprints and deepen our understanding on turnover of one of the major substance classes of SOM.

脂质代表了最多样化的生物分子类别之一，具有各种功能：细胞膜的主要成分，保护层，储存化合物等。植物和微生物分类组中脂质的高度多样性和独特的形态使其成为土壤和沉积物中最有前途的生物标志物类别之一。它们是土壤有机质（SOM）的重要组成部分，并有助于物理化学性质，如疏水性和C储存。关于脂质来源的详细知识存在于使用脂质作为生物标志物的研究中，但土壤中的脂质转化几乎是未知的。循环被认为是土壤中高度相关的过程，因为脂质是从头合成的昂贵化合物，但尚未在原位得到证实。该提案旨在解开微生物转化的脂质前体，从头合成的微生物脂质和循环的脂质在土壤中产生新的见解网络的过程中的脂质循环的基础，并加深我们的理解SOM转换。微生物细胞中的脂质从头合成将通过应用13 C葡萄糖（一种前体）进行研究，该前体可迅速被微生物吸收。基于在线碎片化的液相色谱-质谱法的片段特异性13 C掺入将能够分离磷脂头基、骨架和脂肪酸烷基链的从头合成。除了细胞内从头合成外，还将研究细胞外池的脂质再循环。将位置特异性标记的棕榈酸酯（13 C-1、13 C-2、13 C-16）应用于土壤，并通过气相色谱-质谱联用在线裂解分析微生物磷脂脂肪酸（PLFA）的掺入。因此，完整地将添加的正烷基链并入PLFA将揭示土壤中游离脂质的再循环。在一个已经建立的现场实验中，将使用位置特异性13 C标记的棕榈酸酯研究中期时间尺度（4年）的脂质细胞外和细胞内转化的总和。正烷基链的再循环和转化将随后转化为可浸提脂质和可水解脂质池的各种正烷基脂质（正烷烃、正醇、正脂肪酸、羟基脂肪酸）。结合位置特异性标记与片段特异性13 C掺入分析，为我们提供了一个独特的视角在土壤中的脂质转化：回收可以明确区分从从头合成土壤原位。区分再循环和稳定化对于理解土壤碳循环至关重要。脂质循环过程中微生物转化的这种识别将大大提高我们对植物和微生物脂质生物标志物指纹的解释，并加深我们对SOM的主要物质类别之一的营业额的理解。

项目成果

Food for microorganisms: Position-specific 13 C labeling and 13 C-PLFA analysis reveals preferences for sorbed or necromass C

• DOI: 10.1016/j.geoderma.2017.09.042
• 发表时间: 2018-02
• 期刊: Geoderma
• 影响因子: 6.1
• 作者: C. Apostel;J. Herschbach;Ezekiel K. Bore;S. Spielvogel;Y. Kuzyakov;M. Dippold

Structural and physiological adaptations of soil microorganisms to freezing revealed by position-specific labeling and compound-specific 13C analysis

• DOI: 10.1007/s10533-019-00558-5
• 发表时间: 2019-03-01
• 期刊: BIOGEOCHEMISTRY
• 影响因子: 4
• 作者: Bore, Ezekiel K.;Halicki, Sara;Dippold, Michaela A.
• 通讯作者: Dippold, Michaela A.