藏猪肠道菌群及其与高原低氧环境适应性的研究

Selection and adaptation are two basic questions in the field of molecular evolution. Hypoxic adaptation to the high altitude plateau has recently become one of the hottest topics in evolution. However, up to date, most studies have focused on the adaptive evolution of the hosts itself. Little is known about the evolution of the gut bacterial communities (microbiota) in these mammals adaptation to the high altitude environment. In this proposal, we will study the adaptive evolution of the gut microbiota in the Tibetan pigs by comparing the fecal microbiotas of the Tibetan pigs (at high, meduim, and low altitude) and other local pigs in southwest of China. By pyrosequencing of the V4 region of the 16S rDNA gene, we will first characterize the bacterial communities of Tibetan pigs living on the high, medium, and low altitude plateau and identify bacterial taxa that are associated with the high altitude adaptation. Next, we will also perform comparative metagenomics to screen for specific genes or metabolomic pathways related to high altitude adaptation. Finally, we will compare the metabolomics of the gut microbiotas from these pigs to confirm the function of these specific genes and the existence of these metabolomic pathways identified by metagenomics. This is the first study to hypothesize the adaptive evolution of the gut microbiota in mammals living at the high altitude and to test this hypothesis using multi-omics approaches. The structure, diversity and function of the gut microbiota of Tibetan and other pigs characterized in this study will provide invaluable support for future studies focusing on the health and production of Tibetan and other pigs and those interested in the development of probiotics for the application at the high altitude.

选择与适应是分子进化研究的两个基本问题。生活在高原地区的哺乳动物对于高原低氧环境的适应性进化是近期研究的热点之一。然而，迄今为止所有的研究均集中在宿主本身的进化上，而对于这些哺乳动物的肠道微生物的进化还知之甚少。本项目中我们将以高、中、低海拔生活的藏猪及其他低海拔品种猪的新鲜粪便为实验材料，研究高原藏猪肠道微生物的适应性进化问题。首先，我们将利用二代测序技术研究藏猪和其他品种猪的肠道微生物的多样性，并鉴定出适应高原环境的特有菌群。其次，我们将通过宏基因组测序的方法从功能上寻找适应高原环境的基因或者代谢通路。最后，我们将通过代谢组学的研究确定这些基因的功能和代谢通路。本项目提出高原哺乳动物肠道微生物适应性进化的假设，并在藏猪中通过多种组学的方法进行验证，本项目的研究还将为藏猪和其他地方猪种的健康和饲养提供理论基础，并为适应高原生活的微生态制剂的研发提供依据。

目前，对中国高海拔动物的肠道菌群多样性与功能的研究较少，本项目采用16S rDNA高通量测序、肠道菌宏基因组测序和基于GC-MS的宏代谢组研究方法，选择中国高海拔藏猪与藏族人为主要研究对象，加上低海拔多个品种猪与低海拔汉族人为对照，研究高原肠道菌群结构与功能相关科学问题。. 研究发现，高海拔藏猪、藏族人的肠道菌多样性都显著低于低海拔对照组，海拔组间的菌群结构差异显著，主要的高海拔特异肠道菌有Acinetobacter不动杆菌属，Arthrobacter节细菌属，Christensenellaceae克里斯滕森菌科等。高海拔物种与低海拔对照的肠道菌功能基因存在显著差异，其中贡献最大3个功能基因群分别是：异种生物降解和代谢(Xenobiotics biodegradation and metabolism), 能量代谢(Energy metabolism)和其他氨基酸代谢(Metabolism of other amino acids)。高海拔藏猪与低海拔藏猪代谢组存在显著差异，高海拔上调的代谢物主要有D-核糖(D-Ribose)，丙酸(Propanoic acid)，草酸(Ethanedioic acid)，胆甾烷醇(Cholestanol)等。. 本项目研究成果对肠道菌群与高原适应关系科学问题的作出了重要贡献，研究发现的高原特异肠道菌、功能基因群和代谢物，为未来针对高原适应相关理论研究，以及功能性产品开发奠定了重要基础。