海洋沉积物古菌膜脂超声萃取前处理中溶剂比对古环境反演指标的影响

Influence of solvent ratio on paleoenvironmental inversion indexes in ultrasonic extraction of marine sediment archaea membrane lipids

中文关键词:  甘油二烷基甘油四醚 （GDGTs）  脂类生物标志物  脂质组学  萃取  古环境指标

英文关键词:Glycerol dialkyl glycerol tetraethers (GDGTs)  lipid biomarkers  lipidomics  extraction  paleoenvironmental index

中文摘要:

      古菌膜脂广泛存在于海洋沉积物中，并且作为生物标志物被广泛应用于古环境重建。超声辅助萃取（UAE） 是一种普遍运用于海洋沉积物中古菌膜脂萃取的技术，在萃取过程中，不同比例的超声溶剂可以影响目标物质在溶剂中的溶解度和分散程度，从而影响萃取效率。本研究采用不同比例超声法试剂萃取了位于东海的沉积物柱状样中广泛存在的甘油二烷基甘油四醚 （glycerol dialkyl glycerol tetraethers，GDGTs），计算分析了TEX86、MI以及ACE等指标。研究结果表明，DCM/MeOH比值为5∶1 （V /V） 的超声萃取法对GDGTs萃取效率最高，而DCM/MeOH比值为3∶1（V /V）的萃取法更适用于Archaeol的萃取。此外，除DCM/MeOH（1∶1，V /V）溶剂比外，其余四种不同梯度溶剂比得到的TEX86、RI、MI和ACE指数基本相同。因此，在未来的研究中，我们建议使用5∶1的DCM/MeOH混合有机溶剂作为溶剂萃取膜脂的优选方案。本研究旨在为利用UAE技术对海洋环境样品进行靶向脂质组学分析及指标应用提供方法参考。

英文摘要:

      Archaeal membrane lipids exist widely in marine sediments and are extensively used as biomarkers for reconstructing the paleoenvironment. Ultrasonic-assisted extraction (UAE) is a widely used technology for extracting these membrane lipids from marine sediments. In this process, different proportions of ultrasonic solvents are found to have impacts on the solubility and dispersion of the target substances in the solvent, hence influencing the extraction efficiency. In this study, we primarily extracted glycerol dialkyl glycerol tetraethers (GDGTs) found in a gravity core located in the East China Sea, using ultrasonic reagents at different ratios. The TEX86, MI, and ACE indexes were further determined and analyzed. The results of this study showed that the absolute content of GDGTs extracted by DCM/MeOH (5∶1, V/V) was the highest, while the ratio of DCM/MeOH (3∶1, V/V) was more suitable for extracting Archaeol. Except for the DCM/MeOH (1∶1, V/V) solvent ratio, the TEX86, RI index, MI index, and ACE index obtained with the other four different gradient solvents were essentially the same. Therefore, in future studies the use of a 5∶1 DCM/MeOH mixed organic solvent is recommended as the preferred scheme for solvent extraction of environmental core lipids. This study provides a reference method for targeted lipidomics analysis of marine environmental samples using the UAE technique and addresses application deviations of the indicators.