Laboratory of Microbial Ecology and Technology, Ghent University, Coupure Links 653, 9000 Ghent, Belgium.
Environ Microbiol. 2011 Oct;13(10):2667-80. doi: 10.1111/j.1462-2920.2011.02533.x. Epub 2011 Aug 30.
The endogenous gut microbiota affects the host in many ways. Prebiotics should favour beneficial intestinal microbes and thus improve host health. In this study, we investigated how a novel class of potential prebiotic long-chain arabinoxylans (LC-AX) and the well-established prebiotic inulin (IN) modulate the gut microbiota of humanized rats. Six weeks after axenic rats were inoculated with a human faecal microbiota, their colonic microbiota was similar to this inoculum (∼ 70%), whereas their caecal microbiota was enriched with Verrucomicrobia and Firmicutes concomitant with lower abundance of Bacteroidetes. Moreover, different Bifidobacterium species colonized the lumen (B. adolescentis) and mucus (B. longum and B. bifidum). Both LC-AX and IN increased SCFA levels and induced a shift from acetate towards health-promoting propionate and butyrate respectively. By applying a high-resolution phylogenetic micro-array (HITChip) at the site of fermentation (caecum), IN and LC-AX were shown to stimulate bacterial groups with known butyrate-producers (Roseburia intestinalis, Eubacterium rectale, Anaerostipes caccae) and bifidobacteria (B. longum) respectively. Prebiotic administration also resulted in lower caecal abundances of the mucin-degrading Akkermansia muciniphila and potentially more mucin production by the host. Both factors might explain the increased caecal mucin levels for LC-AX (threefold) and IN (sixfold). These mucins were degraded along the colon, resulting in high faecal abundances of Akkermansia muciniphila for LC-AX and especially IN-treated rats. Finally, the microbial changes caused an adaptation period for the host with less weight gain, after which the host fine-tuned the interaction with this altered microbiota. Our results demonstrate that next to IN, LC-AX are promising prebiotic compounds by stimulating production of health-promoting metabolites by specific microbes in the proximal regions. Further, prebiotic supplementation shifted mucin degradation to distal regions, where mucin-degraders may produce beneficial metabolites (e.g. propionate by Akkermansia muciniphila), so that prebiotics may potentially improve gut health along the entire length of the intestine.
内源性肠道微生物群通过多种方式影响宿主。益生元应该有利于有益的肠道微生物，从而改善宿主健康。在这项研究中，我们研究了一类新型潜在的益生元长链阿拉伯木聚糖 (LC-AX) 和成熟的益生元菊粉 (IN) 如何调节人源化大鼠的肠道微生物群。无菌大鼠接种人体粪便微生物群 6 周后，其结肠微生物群与该接种物相似（~70%），而其盲肠微生物群富含厚壁菌门和Firmicutes，同时拟杆菌门丰度降低。此外，不同的双歧杆菌物种定植在腔（B. adolescentis）和黏液（B. longum 和 B. bifidum）中。LC-AX 和 IN 均增加了 SCFA 水平，并分别诱导从乙酸向促进健康的丙酸和丁酸的转变。通过在发酵部位（盲肠）应用高分辨率的系统发育微阵列（HITChip），发现 IN 和 LC-AX 分别刺激了具有已知丁酸产生菌（Roseburia intestinalis、Eubacterium rectale、Anaerostipes caccae）和双歧杆菌（B. longum）的细菌群。益生元的给药还导致盲肠中粘蛋白降解菌 Akkermansia muciniphila 的丰度降低，以及宿主产生更多的粘蛋白。这两个因素可能解释了 LC-AX（三倍）和 IN（六倍）盲肠粘蛋白水平的增加。这些粘蛋白沿着结肠降解，导致 LC-AX 和尤其是 IN 处理大鼠的粪便 Akkermansia muciniphila 丰度很高。最后，微生物的变化导致宿主经历了一段适应期，体重增加减少，之后宿主对这种改变的微生物群进行了微调。我们的结果表明，除了 IN 之外，LC-AX 是有前途的益生元化合物，因为它们刺激了近端特定微生物产生有益的代谢物。此外，益生元的补充将粘蛋白的降解转移到远端，在那里粘蛋白降解菌可能产生有益的代谢物（例如 Akkermansia muciniphila 产生的丙酸），因此益生元可能有潜力沿着整个肠道改善肠道健康。
