Department of Biology, University of New Mexico, Albuquerque, New Mexico, USA.
School of Earth and Space Exploration, Arizona State University, Tempe, Arizona, USA.
Ecol Lett. 2023 Aug;26(8):1359-1369. doi: 10.1111/ele.14246. Epub 2023 Jun 8.
Herbivory is a dominant feeding strategy among animals, yet herbivores are often protein limited. The gut microbiome is hypothesized to help maintain host protein balance by provisioning essential macromolecules, but this has never been tested in wild consumers. Using amino acid carbon (δ C) and nitrogen (δ N) isotope analysis, we estimated the proportional contributions of essential amino acids (AA ) synthesized by gut microbes to five co-occurring desert rodents representing herbivorous, omnivorous and insectivorous functional groups. We found that herbivorous rodents occupying lower trophic positions (Dipodomys spp.) routed a substantial proportion (40%-50%) of their AA from gut microbes, while higher trophic level omnivores (Peromyscus spp.) and insectivores (Onychomys arenicola) obtained most of their AA (58%) from plant-based energy channels but still received ~20% of their AA from gut microbes. These findings empirically demonstrate that gut microbes play a key functional role in host protein metabolism in wild animals.
食草是动物中占主导地位的觅食策略，但食草动物往往蛋白质有限。肠道微生物群被假设通过提供必需的大分子来帮助维持宿主的蛋白质平衡，但这在野生消费者中从未得到过验证。本研究使用氨基酸碳（δ¹³C）和氮（δ¹⁵N）同位素分析，我们估计了共生的五种沙漠啮齿动物（代表草食性、杂食性和食虫性功能群）中由肠道微生物合成的必需氨基酸（AA）的比例贡献。我们发现，处于较低营养级（跳鼠属）的草食性啮齿动物从肠道微生物中获得了相当大比例（40%-50%）的 AA，而处于较高营养级的杂食性啮齿动物（沙漠棉鼠属）和食虫性啮齿动物（沙漠囊鼠）从植物源能量通道获得了大部分 AA（58%），但仍从肠道微生物中获得了约 20%的 AA。这些发现从经验上证明了肠道微生物在野生动物的宿主蛋白质代谢中发挥着关键的功能作用。
