Arabinoxylo-oligosaccharides (AXOS) are non-digestible dietary fibers that potentially confer a health benefit by stimulating beneficial bacteria in the gut. Still, a detailed overview of the diversity of gut bacteria and their specificity to utilize structurally different AXOS has not been provided to date and was aimed for in this study. Moreover, we assessed the genetic information of summarized bacteria, and we extracted genes expected to encode for enzymes that are involved in AXOS hydrolysis (based on the CAZy database). The taxa involved in AXOS fermentation in the gut display a large variety of AXOS-active enzymes in their genome and consequently utilize AXOS to a highly different extent. Clostridia and Bacteroidales are generalists that consume many structurally diverse AXOS, whereas Bifidobacterium are specialists that specifically consume AXOS with a low degree of polymerization. Further complexity is evident from the fact that the exact bacterial species, and in some cases even the bacterial strains (e.g. in Bifidobacterium longum) that are stimulated, highly depend on the specific AXOS molecular structure. Furthermore, certain species in Bifidobacterium and Lactobacillaceae are active as cross-feeders and consume monosaccharides and unbranched short xylo-oligosaccharides released from AXOS. Our review highlights the possibility that (enzymatic) fine-tuning of specific AXOS structures leads to improved precision in targeting growth of specific beneficial bacterial species and strains in the gut.

中文翻译：

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阿拉伯木低聚糖 （AXOS） 对肠道细菌的结构依赖性刺激：综述。


阿拉伯木低聚糖 （AXOS） 是不易消化的膳食纤维，通过刺激肠道中的有益细菌，可能带来健康益处。尽管如此，迄今为止尚未提供肠道细菌多样性及其利用结构不同的 AXOS 的特异性的详细概述，这是本研究的目标。此外，我们评估了汇总细菌的遗传信息，并提取了预期编码参与 AXOS 水解的酶的基因（基于 CAZy 数据库）。参与肠道中 AXOS 发酵的分类群在其基因组中显示出多种 AXOS 活性酶，因此以高度不同的程度利用 AXOS。梭状芽胞杆菌和拟杆菌属是消耗许多结构多样的 AXOS 的多面手，而双歧杆菌是专门消耗聚合度低的 AXOS 的专家。从以下事实中可以明显看出，确切的细菌种类，甚至在某些情况下受到刺激的细菌菌株（例如在长双歧杆菌中）都高度依赖于特定的 AXOS 分子结构。此外，双歧杆菌和乳酸菌科中的某些物种作为交叉摄食者活跃，并消耗 AXOS 释放的单糖和未支链的短木寡糖。我们的综述强调了特定 AXOS 结构的（酶促）微调导致提高肠道中特定有益细菌种类和菌株生长的精度的可能性。