近些年来科学家们对肠道菌群对人类的有益性进行了大量研究，全球的研究者都在研究揭示肠道微生物如何帮助改善宿主的机体健康以及帮助预防疾病，其中有一种名为鼠李糖乳杆菌（Lactobacillus rhamnosus GG， LGG）的细菌，其是益生菌产品中的重要组成部分；研究者发现该菌可以帮助治疗肠道问题、呼吸道感染以及某些皮肤障碍，而且有研究还发现该菌可以帮助减肥。

　　那么LGG是否可以真的给人类带来好处呢？来自马里兰大学医学院的研究人员就在mBio杂志上刊登了他们的最新研究成果，他们发现LGG可以扮演一种推进者的角色，来修饰其它肠道细菌的活性；文章中研究者对12名受试者进行了测试，这些参与者连续28天每天摄入两次LGG，研究者在该疗程前和疗程后分别分析了参与者的肠道菌群，结果发现，摄入LGG可以增加许多基因的表达，进而促进其它肠道菌群的生长，包括拟杆菌属、双歧杆菌属等菌群，这些菌群都被认为对人类有益处，包括可以促进免疫系统的健康发育等。

　　研究者Fraser表示，某些益生菌可以通过影响整个肠道的微生态系统来促进机体健康；此前研究中我们趋向于认为LGG和其它益生菌可以直接对宿主产生有益影响，而本文研究则发现并不是如此的。

　　研究者利用宏基因组分析(metagenomic analysis)的方法对人类肠道中的一系列微生物进行了分析研究，这对于理解肠道微生物促进机体健康的机制提供了新的思路和想法；在接下来的研究中，研究者将还会通过更为深入的研究来揭示肠道微生物和人类疾病的发病关联，这或许为开发治疗人类疾病的特殊靶向疗法提供一定的帮助。

　　doi:10.1128/mBio.00231-15

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　　Functional Dynamics of the Gut Microbiome in Elderly People during Probiotic Consumption

　　Emiley A. Eloe-Fadrosha, Arthur Bradya, Jonathan Crabtreea, Elliott F. Drabeka, Bing Maa, Anup Mahurkara, Jacques Ravela, Miriam Haverkampb, Anne-Maria Fiorinob, Christine Botelhob, Irina Andreyevab, Patricia L. Hibberdb, Claire M. Frasera,c

　　A mechanistic understanding of the purported health benefits conferred by consumption of probiotic bacteria has been limited by our knowledge of the resident gut microbiota and its interaction with the host. Here, we detail the impact of a single-organism probiotic, Lactobacillus rhamnosus GG ATCC 53103 (LGG), on the structure and functional dynamics (gene expression) of the gut microbiota in a study of 12 healthy individuals, 65 to 80 years old. The analysis revealed that while the overall community composition was stable as assessed by 16S rRNA profiling, the transcriptional response of the gut microbiota was modulated by probiotic treatment. Comparison of transcriptional profiles based on taxonomic composition yielded three distinct transcriptome groups that displayed considerable differences in functional dynamics. The transcriptional profile of LGG in vivo was remarkably concordant across study subjects despite the considerable interindividual nature of the gut microbiota. However, we identified genes involved in flagellar motility, chemotaxis, and adhesion from Bifidobacterium and the dominant butyrate producers Roseburia and Eubacterium whose expression was increased during probiotic consumption, suggesting that LGG may promote interactions between key constituents of the microbiota and the host epithelium. These results provide evidence for the discrete functional effects imparted by a specific single-organism probiotic and challenge the prevailing notion that probiotics substantially modify the resident microbiota within nondiseased individuals in an appreciable fashion.