Gas chromatography/mass spectrometry based metabolomic study in a murine model of irritable bowel syndrome

AIM To study the role of microbial metabolites in the modulation of biochemical and physiological processes in irritable bowel syndrome(IBS).METHODS In the current study, using a metabolomic approach, we analyzed the key metabolites differentially excreted in the feces of control mice and mice with IBS, with or without Clostridium butyricum(C. butyricum) treatment. C57 BL/6 mice were divided into control, IBS, and IBS + C. butyricum groups. In the IBS and IBS + C. butyricum groups, the mice were subjected to water avoidance stress(WAS) for 1 h/d for ten days. Gas chromatography/mass spectrometry(GC-MS) together with multivariate analysis was employed to compare the fecal samples between groups. RESULTS WAS exposure established an appropriate model of IBS in mice, with symptoms of visceral hyperalgesia and diarrhea. The differences in the metabolite profiles between the control group and IBS group significantly changed with the progression of IBS(days 0, 5, 10, and 17). A total of 14 differentially excreted metabolites were identified between the control and IBS groups, and phenylethylamine was a major metabolite induced by stress. In addition, phenylalanine metabolism was found to be the most relevant metabolic pathway. Between the IBS group and IBS + C. butyricum group, 10 differentially excreted metabolites were identified. Among these, pantothenate and coenzyme A(Co A) biosynthesis metabolites, as well as steroid hormone biosynthesis metabolites were identified as significantly relevant metabolic pathways.CONCLUSION The metabolic profile of IBS mice is significantly altered compared to control mice. Supplementation with C. butyricum to IBS mice may provide a considerable benefit by modulating host metabolism.

艰难梭菌荚膜多糖单糖组成的气相色谱分析

本文对两株艰难梭菌（ＣｄＡ３１８和ＣｄＣＤＣ２７９）荚膜多糖进一步分析，结果证实纯化的艰难梭菌荚膜多糖为单一均匀的物质；经气相色谱分析表明，其单糖组分主要由Ｄ－葡萄糖、Ｄ－甘露糖和Ｄ－半乳糖组成，不同菌株的荚膜多糖可能有微小差异。

应用气相色谱法鉴定艰难梭菌

应用国产气相色谱仪，选用不锈钢色谱柱，在色谱柱柱温１４０℃、检测室温度１９０℃下采用１５％改性聚乙二醇固定液（ＦＦＡＰ），以氮气作载体，将从临床肿瘤病人粪便中分离的５株艰难梭菌（Ｃｌｏｓｔｒｉｄｉｕｍｄｉｆｆｉｃｉｌｅ）菌株与１株参考株的脂肪酸代谢产物气相色谱图进行了对比分析，发现分离株与参考株的色谱图非常相似：均出现乙酸、异丁酸、丁酸、异戊酸、异己酸、丙酸、戊酸峰。其中乙酸、丁酸、异己酸峰较高；其次为异丁酸及异戊酸峰；而丙酸及戊酸峰则较低。此外，在１４ｍｉｎ时尚可见出现１个低平峰，此峰与国外Ｂｅｒｇ等报道的ｐ－甲（苯）酚峰相似。实验结果表明气相色谱法是一种简单、快速鉴定艰难梭菌的方法。

基于超高效液相色谱质谱联用的艰难梭菌腹泻患者粪便代谢组学研究

目的 探索艰难梭菌腹泻患者粪便代谢谱特点,为揭示其发病机制、建立新的诊断方法提供参考。方法 收集2013年7月-2014年2月入住医院重症监护室患者的腹泻粪便41份,其中艰难梭菌组21份,艰难梭菌阴性组20份,另收集健康对照者粪便23份,使用超高效液相色谱质谱联用检测其代谢谱,采用多元统计分析进行数据分析。结果 三组在无监督的主成分分析得分图上有分离的趋势,而在有监督的正交偏最小二乘法判别分析得分图上清晰有序排列,三组两两比较时,在各得分图中区分度更好。正交偏最小二乘法判别分析对于艰难梭菌组和腹泻组样本判断的准确率、灵敏度和特异性均为100%,受试者工作曲线下面积为1.000。艰难梭菌组患者粪便中的甘氨熊脱氧胆酸(Glycoursodeoxycholic acid,GUDCA)、甘氨鹅脱氧胆酸(Glycochenodeoxycholic acid,GCDCA)、溶血卵磷脂18∶0、溶血卵磷脂18∶1、亚油酸、油酸的相对丰度较高,卵磷脂18∶0/18∶1的相对丰度较低。结论 艰难梭菌感染者有着独特的粪便代谢谱,可用代谢组学模型来诊断。