人体肠道微生物组主要通过使用粪便样本进行研究，这种做法已经得到了关于胃肠道微生物群落的组成和功能的重要知识。然而，这种对粪便材料的依赖限制了对胃肠道其他位置（原位）微生物动力学的研究，并且粪便样本不能随时获得，这也阻碍了在更精细的时间尺度（如小时）下进行分析。在我们的研究中，我们利用结肠途径经内镜肠内导管（一种最初为粪便微生物群移植开发的技术）每天两次对回盲部微生物组进行采样；然后对这些样品进行宏基因组和宏转录组学分析。从5 名健康志愿者身上共收集了43 份回盲部样本及28 份尿液和粪便样本。在5 名志愿者中分析的回盲部和粪便微生物组被发现在宏基因组分析中相似，但它们的活性基因（宏转录组）被发现高度不同。两种微生物组在泻药暴露后都受到干扰；随着时间的推移，它们表现出与治疗前状态的差异减少，从而证明了作为肠道微生物组的先天特性——恢复力，尽管它们在我们的观察时间窗口内没有完全恢复。白天和夜间对回盲部微生物组的采样显示，在一系列细菌种类和功能途径中存在昼夜节律，特别是与短链脂肪酸产生相关的细菌，如痤疮丙酸杆菌和辅酶A生物合成II。自相关分析和波动分解进一步表明了昼夜振荡的显著周期性。粪便和尿液样本中的代谢组学分析反映出了肠道微生物组的扰动和恢复，表明肠道微生物组对参与宿主健康的诸多关键代谢物的重要贡献。这项研究为人体肠道微生物组及其内在恢复力和昼夜节律以及这些对宿主的潜在后果提供了新的见解。

The human gut microbiome has primarily been studied through the use of fecal samples, a practice that has generated vital knowledge on the composition and functional capacities of gastrointestinal microbial communities. However, this reliance on fecal materials limits the investigation of microbial dynamics in other locations along the gastrointestinal tract (in situ), and the infrequent availability of fecal samples prevents analysis at finer temporal scales (e.g., hours). In our study, we utilized colonic transendoscopic enteral tubing, a technology originally developed for fecal microbiota transplantation, to sample the ileocecal microbiome twice daily; metagenomic and metatranscriptomic analyses were then conducted on these samples. A total of 43 ileocecal and 28 urine and fecal samples were collected from five healthy volunteers. The ileocecal and fecal microbiomes, as profiled in the five volunteers, were found to be similar in metagenomic profiling, yet their active genes (metatranscriptome) were found to be highly distinct. Both microbiomes were perturbed after laxative exposure; over time, they exhibited reduced dissimilarity to their pre-treatment state, thereby demonstrating resilience as an innate property of the gut microbiome, although they did not fully recover within our observation time window. Sampling of the ileocecal microbiome during the day and at night revealed the existence of diurnal rhythms in a series of bacterial species and functional pathways, particularly those related to short-chain fatty acid production, such as Propionibacterium acnes and coenzyme A biosynthesis II. Autocorrelation analysis and fluctuations decomposition further indicated the significant periodicity of the diurnal oscillations. Metabolomic profiling in the fecal and urine samples mirrored the perturbance and recovery in the gut microbiome, indicating the crucial contribution of the gut microbiome to many key metabolites involved in host health. This study provides novel insights into the human gut microbiome and its inner resilience and diurnal rhythms, as well as the potential consequences of these to the host.