BACKGROUND Roux-en-Y gastric bypass (RYGB) surgery is a last-resort treatment to induce substantial and sustained weight loss in cases of severe obesity. This anatomical rearrangement affects the intestinal microbiota, but so far, little information is available on how it interferes with microbial functionality and microbial-host interactions independently of weight loss. METHODS A rat model was employed where the RYGB-surgery cohort is compared to sham-operated controls which were kept at a matched body weight by food restriction. We investigated the microbial taxonomy and functional activity using 16S rRNA amplicon gene sequencing, metaproteomics, and metabolomics on samples collected from theileum, the cecum, and the colon, and separately analysed the lumen and mucus-associated microbiota. RESULTS Altered gut architecture in RYGB increased the relative occurrence of Actinobacteria, especially Bifidobacteriaceae and Proteobacteria, while in general, Firmicutes were decreased although Streptococcaceae and Clostridium perfringens were observed at relative higher abundances independent of weight loss. A decrease of conjugated and secondary bile acids was observed in the RYGB-gut lumen. The arginine biosynthesis pathway in the microbiota was altered, as indicated by the changes in the abundance of upstream metabolites and enzymes, resulting in lower levels of arginine and higher levels of aspartate in the colon after RYGB. CONCLUSION The anatomical rearrangement in RYGB affects microbiota composition and functionality as well as changes in amino acid and bile acid metabolism independently of weight loss. The shift in the taxonomic structure of the microbiota after RYGB may be mediated by the resulting change in the composition of the bile acid pool in the gut and by changes in the composition of nutrients in the gut. Video abstract.

中文翻译：

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大鼠模型中的胃绕道手术改变了肠道微生物群的群落结构和功能组成，与体重减轻无关。

背景 Roux-en-Y 胃绕道手术 (RYGB) 手术是严重肥胖病例中诱导显着且持续的体重减轻的最后手段。这种解剖结构的重新排列会影响肠道微生物群，但到目前为止，关于它如何独立于体重减轻而干扰微生物功能和微生物与宿主相互作用的信息很少。方法 采用大鼠模型，将 RYGB 手术组与通过食物限制保持匹配体重的假手术对照组进行比较。我们使用 16S rRNA 扩增子基因测序、宏蛋白质组学和代谢组学对从回肠、盲肠和结肠收集的样本研究了微生物分类和功能活性，并分别分析了管腔和粘液相关微生物群。结果 RYGB 中肠道结构的改变增加了放线菌的相对出现，尤其是双歧杆菌科和变形菌门，而总体而言，厚壁菌门减少，尽管链球菌科和产气荚膜梭菌的丰度相对较高，与体重减轻无关。在 RYGB 肠腔中观察到结合胆汁酸和次级胆汁酸减少。上游代谢物和酶丰度的变化表明，微生物群中的精氨酸生物合成途径发生了改变，导致 RYGB 后结肠中精氨酸水平降低，天冬氨酸水平升高。结论 RYGB 的解剖重排影响微生物群的组成和功能，以及氨基酸和胆汁酸代谢的变化，与体重减轻无关。RYGB 后微生物群分类结构的变化可能是由肠道胆汁酸池组成的变化以及肠道营养成分的变化介导的。视频摘要。