近些年來科學家們對腸道菌群對人類的有益性進行了大量研究，全球的研究者都在研究揭示腸道微生物如何幫助改善宿主的機體健康以及幫助預防疾病，其中有一種名為鼠李糖乳杆菌（Lactobacillus rhamnosus GG， LGG）的細菌，其是益生菌產品中的重要組成部分；研究者發現該菌可以幫助治療腸道問題、呼吸道感染以及某些皮膚障礙，而且有研究還發現該菌可以幫助減肥。
那麼LGG是否可以真的給人類帶來好處呢？來自馬裏蘭大學醫學院的研究人員就在mBio雜誌上刊登了他們的最新研究成果，他們發現LGG可以扮演一種推進者的角色，來修飾其它腸道細菌的活性；文章中研究者對12名受試者進行了測試，這些參與者連續28天每天攝入兩次LGG，研究者在該療程前和療程後分別分析了參與者的腸道菌群，結果發現，攝入LGG可以增加許多基因的表達，進而促進其它腸道菌群的生長，包括擬杆菌屬、雙歧杆菌屬等菌群，這些菌群都被認為對人類有益處，包括可以促進免疫係統的健康發育等。
研究者Fraser表示，某些益生菌可以通過影響整個腸道的微生態係統來促進機體健康；此前研究中我們趨向於認為LGG和其它益生菌可以直接對宿主產生有益影響，而本文研究則發現並不是如此的。
研究者利用宏基因組分析(metagenomic analysis)的方法對人類腸道中的一係列微生物進行了分析研究，這對於理解腸道微生物促進機體健康的機製提供了新的思路和想法；在接下來的研究中，研究者將還會通過更為深入的研究來揭示腸道微生物和人類疾病的發病關聯，這或許為開發治療人類疾病的特殊靶向療法提供一定的幫助。
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.
