Translational Research Center for Gastrointestinal Disorders and Leuven Food Science and Nutrition Research Center, University Hospital Gasthuisberg, Katholieke Universiteit Leuven, Leuven, Belgium.
Am J Physiol Gastrointest Liver Physiol. 2012 Jan 1;302(1):G1-9. doi: 10.1152/ajpgi.00048.2011. Epub 2011 Oct 20.
With the use of molecular techniques, numerous studies have evaluated the composition of the intestinal microbiota in health and disease. However, it is of major interest to supplement this with a functional analysis of the microbiota. In this review, the different approaches that have been used to characterize microbial metabolites, yielding information on the functional end products of microbial metabolism, have been summarized. To analyze colonic microbial metabolites, the most conventional way is by application of a hypothesis-driven targeted approach, through quantification of selected metabolites from carbohydrate (e.g., short-chain fatty acids) and protein fermentation (e.g., p-cresol, phenol, ammonia, or H(2)S), secondary bile acids, or colonic enzymes. The application of stable isotope-labeled substrates can provide an elegant solution to study these metabolic pathways in vivo. On the other hand, a top-down approach can be followed by applying metabolite fingerprinting techniques based on (1)H-NMR or mass spectrometric analysis. Quantification of known metabolites and characterization of metabolite patterns in urine, breath, plasma, and fecal samples can reveal new pathways and give insight into physiological regulatory processes of the colonic microbiota. In addition, specific metabolic profiles can function as a diagnostic tool for the identification of several gastrointestinal diseases, such as ulcerative colitis and Crohn's disease. Nevertheless, future research will have to evaluate the relevance of associations between metabolites and different disease states.
利用分子技术，许多研究已经评估了健康和疾病状态下肠道微生物组的组成。然而，补充对微生物组的功能分析是非常重要的。在这篇综述中，总结了用于描述微生物代谢产物的不同方法，这些方法提供了微生物代谢的功能终产物的信息。为了分析结肠微生物代谢物，最传统的方法是应用基于假设的靶向方法，通过定量分析碳水化合物（例如短链脂肪酸）和蛋白质发酵（例如 p- Cresol、苯酚、氨或 H 2 S）、次级胆汁酸或结肠酶的选定代谢物。稳定同位素标记底物的应用可以为体内研究这些代谢途径提供一个优雅的解决方案。另一方面，可以采用基于（1）H-NMR 或质谱分析的代谢物指纹图谱技术进行自上而下的方法。定量已知代谢物和鉴定尿液、呼吸、血浆和粪便样本中的代谢物模式可以揭示新的途径，并深入了解结肠微生物组的生理调节过程。此外，特定的代谢谱可以作为识别几种胃肠道疾病（如溃疡性结肠炎和克罗恩病）的诊断工具。然而，未来的研究将不得不评估代谢物与不同疾病状态之间的关联的相关性。
