Institute of Arctic Biology and Department of Biology and Wildlife, University of Alaska, Fairbanks, Alaska 99775-7000, USA.
Ecology. 2009 Dec;90(12):3526-35. doi: 10.1890/08-1695.1.
Amino acids play an important role in ecology as essential nutrients for animals and as currencies in symbiotic associations. Here we present a new approach to tracing the origins of amino acids by identifying unique patterns of carbon isotope signatures generated by amino acid synthesis in plants, fungi, and bacteria ("13C fingerprints"). We measured amino acid delta 13C from 10 C3 plants, 13 fungi, and 10 bacteria collected and isolated from a boreal forest in interior Alaska, USA, using gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). Microorganisms were cultured under amino-acid-free conditions and identified based on DNA sequences. Bacteria, fungi, and plants generated consistent, unique 13C fingerprints based on the more complex amino acids (five or more biosynthetic steps) that are classified as essential for animals. Linear discriminant analysis classified all samples correctly with >99% certainty and correctly classified nearly all insect samples from a previous study by diet. Our results suggest that 13C fingerprints of amino acids could provide a powerful in situ assay of the biosynthetic sources of amino acids and a potential new tool for understanding nutritional linkages in food webs.
氨基酸在生态学中起着重要作用，是动物的必需营养素，也是共生关系中的货币。在这里，我们提出了一种新的方法来追踪氨基酸的起源，通过识别植物、真菌和细菌中氨基酸合成产生的独特碳同位素特征模式（“13C 指纹”）。我们使用气相色谱-燃烧-同位素比质谱法（GC-C-IRMS）测量了来自美国阿拉斯加内陆一个北方森林的 10 种 C3 植物、13 种真菌和 10 种细菌的氨基酸 delta 13C。微生物在无氨基酸条件下培养，并根据 DNA 序列进行鉴定。细菌、真菌和植物根据被归类为动物必需的更复杂的氨基酸（五个或更多生物合成步骤）产生一致的、独特的 13C 指纹。线性判别分析以>99%的确定性正确分类所有样本，并正确分类了之前一项关于饮食的昆虫样本研究中的几乎所有昆虫样本。我们的研究结果表明，氨基酸的 13C 指纹可能为氨基酸生物合成来源提供一种强大的原位检测方法，并且可能成为理解食物网营养联系的新工具。
