Chinese yam (Dioscorea oppositifolia L.) extract is a product which concentrates many active ingredients. In this study, the effects of Chinese yam extract on the intestinal microbiota, digestive enzymes, and the immune response of rainbow trout (Oncorhynchus mykiss) were investigated. Fish were fed a basic diet (Con) and 0.1% (O1), 0.2% (O2) and 0.4% (O3) yam extract diet, respectively, for 8 weeks. After the feeding experiment, Actinobacteria, Firmicutes and Patescibacteria abundances at the phylum level in intestinal were significantly differential under the effect of yam respectively. Actinobacteria and Firmicutes phylum were significantly decreased in O1 group compared with control, while Patescibacteria was significantly increased in O3 group. Anaeroplasma, Candidatus_Saccharimonas, Ruminococcaceae_ UCG‐014, Lactobacillus, Rikenella, Lachnospiraceae_NK4A136_group, [Eubacterium]_ coprostanoligenes_group, Bifidobacterium, Marvinbryantia and Uncultured abundances at the genus level were significantly differential under the effect of yam respectively. Bifidobacterium, Marvinbryantia and Candidatus_ Saccharimonas were significantly enriched in O3 group. KEGG and COG functional prediction on intestinal microflora revealed that yam has beneficial effects on metabolism, antibacterial and defence function. Serum immune factors and intestinal immune genes were significantly regulated in yam groups. In addition, yam also increased gastrointestinal digestive enzyme activities of rainbow trout. The results showed that yam could enhance gastrointestinal function, stimulate immunomodulatory effects, and induce intestinal microbiota changes, rendering beneficial effects to rainbow trout.

中文翻译：

---

补充山药饮食对虹鳟肠道菌群，消化酶活性和免疫力的影响

山药（Dioscorea oppositifolia L。）提取物是一种浓缩许多活性成分的产品。在这项研究中，研究了山药提取物对虹鳟（Oncorhynchus mykiss）肠道菌群，消化酶和免疫反应的影响。分别给鱼类喂食基础饮食（Con）和0.1％（O1），0.2％（O2）和0.4％（O3）的山药提取物饮食，持续8周。饲喂试验后，在山药作用下，肠道门菌水平的放线菌，硬毛和杆菌的丰度分别有显着差异。放线菌和菌丝体与对照组相比，O1组的门静脉显着减少，而O3组的杆菌属显着增加。Anaeroplasma，Candidatus_Saccharimonas，Ruminococcaceae _ UCG-014 ，乳杆菌属，Rikenella，Lachnospiraceae_ NK4A136_group，[真杆菌] _ coprostanoligenes_group，双歧杆菌，Marvinbryantia并在属水平未培养丰度分别为山药分别作用下显著差。双歧杆菌，Marvinbryantia和Candidatus_ SaccharimonasO3组明显富集。KEGG和COG对肠道菌群的功能预测表明，山药对代谢，抗菌和防御功能具有有益作用。在山药组中，血清免疫因子和肠道免疫基因受到显着调节。此外，山药还增加了虹鳟的胃肠道消化酶活性。结果表明，山药可以增强肠胃功能，刺激免疫调节作用，并诱导肠道菌群变化，对虹鳟鱼具有有益作用。