Laboratory of Microbial Ecology and Technology (LabMET), Ghent University, Ghent, Belgium.
FEMS Microbiol Ecol. 2010 Dec;74(3):601-11. doi: 10.1111/j.1574-6941.2010.00974.x. Epub 2010 Oct 14.
Significant amounts of glycerol reach the colon microbiota daily through the diet and/or by in situ microbial production or release from desquamated epithelial cells. Some gut microorganisms may anaerobically reduce glycerol to 1,3-propanediol (1,3-PDO), with 3-hydroxypropanal as an intermediate. Accumulation of the latter intermediate may result in the formation of reuterin, which is known for its biological activity (e.g. antimicrobial properties). To date, glycerol metabolism in mixed cultures from the human colon has received little attention. Using in vitro batch incubations of faeces from 10 human individuals, we demonstrated that glycerol addition (140 mM) significantly affects the metabolism and composition of the microbial community. About a third of the samples exhibited rapid glycerol conversion, yielding proportionally higher levels of acetate and 1,3-PDO. In contrast, a slower glycerol metabolism resulted in higher levels of propionate. Furthermore, rapid glycerol metabolism correlated with significant shifts in the Lactobacillus-Enterococcus community, which were not observed in slower glycerol-metabolizing samples. As the conversion of glycerol to 1,3-PDO is a highly reducing process, we infer that the glycerol metabolism may act as an effective hydrogen sink. Given the importance of hydrogen-consuming processes in the gut, this work suggests that glycerol may have potential as a tool for modulating fermentation kinetics and profiles in the gastrointestinal tract.
大量的甘油通过饮食或原位微生物生产或从脱落的上皮细胞中释放进入结肠微生物群。一些肠道微生物可能会将甘油厌氧还原为 1,3-丙二醇（1,3-PDO），其中 3-羟基丙醛为中间产物。后者中间产物的积累可能导致雷普汀的形成，雷普汀以其生物活性（如抗菌特性）而闻名。迄今为止，人类结肠混合培养物中的甘油代谢尚未得到广泛关注。通过对 10 个人的粪便进行体外批量孵育实验，我们证明了甘油的添加（140mM）会显著影响微生物群落的代谢和组成。约三分之一的样本表现出快速的甘油转化，产生比例更高的乙酸盐和 1,3-PDO。相比之下，较慢的甘油代谢会导致丙酸盐水平升高。此外，快速的甘油代谢与乳杆菌-肠球菌群落的显著变化相关，而在较慢的甘油代谢样本中未观察到这种变化。由于甘油转化为 1,3-PDO 是一个高度还原的过程，我们推断甘油代谢可能充当有效的氢汇。鉴于氢消耗过程在肠道中的重要性，这项工作表明甘油可能有潜力作为调节胃肠道发酵动力学和特征的工具。
