Supplementary Material for: Monosodium L-Glutamate and Dietary Fat Differently Modify the Composition of the Intestinal Microbiota in Growing Pigs

<b><i>Background: </i></b>The Chinese have been undergone rapid transition to a high-fat diet-consuming lifestyle, while monosodium L-glutamate (MSG) is widely used as a daily food additive. It has been reported that fat alters the composition of intestinal microbiota. However, little information is available on the effects of oral MSG on intestinal microbiota, and no study was done focusing on the interaction effect of fat and MSG with respect to intestinal microbiota. The present study thus aimed to determine the effects of MSG and/or fat on intestinal microbiota, and also to identify possible interactions between these two nutrients. <b><i>Methods: </i></b>Four iso-nitrogenous and iso-caloric diets were provided to growing pigs. The microbiota from jejunum, ileum, cecum, and colon were analyzed. <b><i>Results: </i></b>Our results show that both MSG and fat clearly increased the intestinal microbiota diversity. MSG and fat modified the composition of intestinal microbiota, particularly in the colon. Both MSG and fat promoted the colonization of microbes related to energy extraction in gastrointestinal tract via different ways. MSG promoted the colonization of <i>Faecalibacterium prausnitzii </i>and <i>Roseburia</i>, while fat increased the percentage of <i>Prevotella</i> in colon and other intestinal segments. <b><i>Conclusion: </i></b>Our results will help to understand how individual or combined dietary changes modify the microbiota composition to prevent obesity.

背景：中国居民正快速向高脂饮食的生活方式转型，而L-谷氨酸钠（monosodium L-glutamate，MSG）作为日常食品添加剂被广泛使用。已有研究表明，脂肪可改变肠道菌群组成。然而，目前关于口服MSG对肠道菌群影响的相关研究较少，且尚无针对脂肪与MSG对肠道菌群交互作用的研究。因此本研究旨在探究MSG与（或）脂肪对肠道菌群的影响，并明确这两种营养素之间可能存在的交互作用。方法：本研究给生长猪饲喂四种等氮等热量日粮，分别对空肠、回肠、盲肠和结肠的菌群进行分析。结果：本研究结果显示，MSG与脂肪均可显著提升肠道菌群的多样性。MSG与脂肪均可改变肠道菌群组成，其中结肠部位的改变尤为显著。二者均可通过不同途径促进胃肠道内与能量提取相关的微生物定植：MSG可促进普拉梭菌（Faecalibacterium prausnitzii）和罗斯氏菌属（Roseburia）的定植，而脂肪则可提升结肠及其他肠道节段中普雷沃氏菌属（Prevotella）的占比。结论：本研究结果有助于阐明单一或联合膳食改变如何调节菌群组成，从而为肥胖防控提供理论依据。