Rettedal Elizabeth A, Altermann Eric, Roy Nicole C, Dalziel Julie E
Food Nutrition & Health Team, AgResearch (Grasslands Research Centre), Palmerston North, New Zealand.
Riddet Institute, Massey University, Palmerston North, New Zealand.
Front Microbiol. 2019 Mar 6;10:458. doi: 10.3389/fmicb.2019.00458. eCollection 2019.
A variety of fermented foods have been linked to improved human health, but their impacts on the gut microbiome have not been well characterized. Dairy products are one of the most popular fermented foods and are commonly consumed worldwide. One area we currently lack data on is how the process of fermentation changes the gut microbiota upon digestion. What is even less well characterized are the possible differences between cow and other mammals' milks. Our aim was to compare the impact of unfermented skim milk and fermented skim milk products (milk/yogurt) originating from two species (cow/sheep) on the gut microbiome using a rat model. Male Sprague-Dawley rats were fed a dairy-free diet supplemented with one of four treatment dairy drinks (cow milk, cow yogurt, sheep milk, sheep yogurt) for 2 weeks. The viable starter culture bacteria in the yogurts were depleted in this study to reduce their potential influence on gut bacterial communities. At the end of the study, cecal samples were collected and the bacterial community profiles determined via 16S rRNA high-throughput sequencing. Fermentation status drove the composition of the bacterial communities to a greater extent than their animal origin. While overall community alpha diversity did not change among treatment groups, the abundance of a number of taxa differed. The cow milk supplemented treatment group was distinct, with a higher intragroup variability and a distinctive taxonomic composition. was of particularly high abundance (9%) for this group. Taxa such as Firmicutes and were found in higher abundance in communities of rats fed with milk, while Proteobacteria, Bacteroidetes, and were higher in yogurt fed rats. was also found to be of higher abundance in both milk (vs. yogurt) and cows (vs. sheep). This research provides new insight into the effects of unfermented vs. fermented milk (yogurt) and animal origin on gut microbial composition in a healthy host. A number of differences in taxonomic abundance between treatment groups were observed. Most were associated with the effects of fermentation, but others the origin species, or in the case of cow milk, unique to the treatment group. Future studies focusing on understanding microbial metabolism and interactions, should help unravel what drives these differences.
多种发酵食品都与人类健康改善有关，但其对肠道微生物群的影响尚未得到充分描述。乳制品是最受欢迎的发酵食品之一，在全球范围内广泛消费。我们目前缺乏数据的一个领域是发酵过程如何在消化时改变肠道微生物群。牛和其他哺乳动物的乳汁之间可能存在的差异更是鲜为人知。我们的目的是使用大鼠模型比较来自两个物种（牛/羊）的未发酵脱脂牛奶和发酵脱脂牛奶产品（牛奶/酸奶）对肠道微生物群的影响。雄性Sprague-Dawley大鼠喂食不含乳制品的饮食，并补充四种处理乳制品饮料（牛奶、酸奶、羊奶、羊酸奶）之一，持续2周。本研究中酸奶中的活性发酵剂培养细菌被消耗掉，以降低它们对肠道细菌群落的潜在影响。在研究结束时，收集盲肠样本，并通过16S rRNA高通量测序确定细菌群落谱。发酵状态比动物来源在更大程度上驱动细菌群落的组成。虽然各处理组之间总体群落α多样性没有变化，但一些分类群的丰度有所不同。补充牛奶的处理组与众不同，组内变异性更高，分类组成独特。该组中 的丰度特别高（达9%）。在喂食牛奶的大鼠群落中，厚壁菌门等分类群的丰度较高，而在喂食酸奶的大鼠中，变形菌门、拟杆菌门和 的丰度较高。在牛奶（与酸奶相比）和牛（与羊相比）中也发现 的丰度较高。这项研究为未发酵与发酵牛奶（酸奶）以及动物来源对健康宿主肠道微生物组成的影响提供了新的见解。观察到各处理组之间在分类丰度上存在许多差异。大多数与发酵作用有关，但其他差异与来源物种有关，或者就牛奶而言，是该处理组所特有的。未来专注于理解微生物代谢和相互作用的研究，应有助于揭示造成这些差异的原因。
