Isotopologue Ratios Identify 13C-Depleted Biomarkers in Environmental Samples Impacted by Methane Turnover

IF 1.7 3区化学 Q4 BIOCHEMICAL RESEARCH METHODS

Rapid Communications in Mass Spectrometry Pub Date : 2025-08-05 DOI:10.1002/rcm.10118

Janina Groninga, Julius Lipp, Min Song, Kai-Uwe Hinrichs

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引用次数: 0

Abstract

Rationale

The stable carbon isotopic composition (δ¹³C) of individual lipids is of great value in studying carbon cycling. Among those, microbial lipids in sediments impacted by high methane turnover stand out due to their uniquely depleted isotopic fingerprint. However, gas chromatography/isotope ratio mass spectrometry (GC/irMS) is limited to volatile compounds, whereas intact polar lipids require extensive preprocessing, which results in the loss of chemotaxonomic information. Expanding compound-specific isotopic information to intact polar lipids would enhance insights into the microbial turnover of methane.

Methods

We performed ultra-high-performance liquid chromatography/electrospray ionization/high-resolution mass spectrometry (UHPLC/ESI/HRMS) to analyze standards of archaeol and lipid extracts from a diverse set of sediment samples of a hydrothermal methane seep system. Using the ratio of the M1 isotopologue over the monoisotopic isotopologue M0, we calculated the δ¹³C values of archaeol and various polar, non-GC-amenable lipids. The δ¹³C values of archaeol obtained via ratios were compared to those measured via GC/irMS.

Results

δ¹³C values of archaeol determined in natural samples via GC/irMS and the UHPLC/HRMS approach were strongly correlated (R² = 0.94; N = 76–82) across a wide range of δ¹³C values (GC-irMS = −119‰ to −34‰). Biomarkers associated with methane turnover consistently yielded δ¹³C values below −60‰, whereas the δ¹³C values of compounds presumably associated with the photosynthesis-based food web remained above −45‰. UHPLC/HRMS measurements of archaeol standard further indicated that δ¹³C values can be reliably determined across an M0 signal-intensity range of approximately one order of magnitude.

Conclusions

Our results highlight that the M1/M0 ratio from UHPLC/HRMS measurements can be utilized to evaluate the carbon isotopic fingerprint of non-GC-amenable lipids and to reliably detect lipid biomarkers putatively associated with microbial methane turnover carrying extremely depleted isotopic signatures. This paves the way for a comprehensive exploration of intact lipids associated with microbial methane turnover in environmental samples.

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甲烷循环影响下环境样品中13c贫化生物标志物的同位素鉴定

理论基础单个脂类的稳定碳同位素组成（δ13C）对研究碳循环具有重要价值。其中，受高甲烷周转量影响的沉积物中的微生物脂质因其独特的耗尽同位素指纹而脱颖而出。然而，气相色谱/同位素比值质谱（GC/irMS）仅限于挥发性化合物，而完整的极性脂质需要大量的预处理，这会导致化学分类信息的丢失。将化合物特定的同位素信息扩展到完整的极性脂质将加强对甲烷微生物周转的了解。方法采用超高效液相色谱/电喷雾电离/高分辨率质谱（UHPLC/ESI/HRMS）对热液甲烷渗漏系统中不同沉积物样品的古醇和脂质提取物进行标准分析。利用M1同位素与M0单同位素的比值，计算了古醇和各种极性非气相色谱脂质的δ13C值。将比值法测定的古醇和GC/irMS测定的δ13C值进行了比较。结果GC/irMS法与UHPLC/HRMS法测定天然样品中古酚的δ13C值呈强相关(R2 = 0.94；N = 76 ~ 82)， δ13C值范围宽（GC-irMS = - 119‰~ - 34‰）。与甲烷周转有关的生物标志物的δ13C值始终低于- 60‰，而可能与光合作用食物网有关的化合物的δ13C值保持在- 45‰以上。UHPLC/HRMS对古酚标准品的测量进一步表明，δ13C值可以在大约一个数量级的M0信号强度范围内可靠地测定。我们的研究结果表明，UHPLC/HRMS测量的M1/M0比值可用于评估非气相色谱可适应的脂质碳同位素指纹图谱，并可靠地检测与微生物甲烷转换相关的脂质生物标志物，这些生物标志物携带极贫的同位素特征。这为全面探索与环境样品中微生物甲烷周转相关的完整脂质铺平了道路。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Rapid Communications in Mass Spectrometry 化学-分析化学

CiteScore

4.10

自引率

5.00%

发文量

219

审稿时长

2.6 months

期刊介绍： Rapid Communications in Mass Spectrometry is a journal whose aim is the rapid publication of original research results and ideas on all aspects of the science of gas-phase ions; it covers all the associated scientific disciplines. There is no formal limit on paper length ("rapid" is not synonymous with "brief"), but papers should be of a length that is commensurate with the importance and complexity of the results being reported. Contributions may be theoretical or practical in nature; they may deal with methods, techniques and applications, or with the interpretation of results; they may cover any area in science that depends directly on measurements made upon gaseous ions or that is associated with such measurements.