經(jīng)常有廣告吹噓益生菌酸奶的好處，但吃這種酸奶對腸道中居住的微生物的影響以及對一般健康有何影響則仍然不清楚,。
在一組人類雙胞胎和小鼠中進行的一項新的研究顯示,，每日食用酸奶不會顯著地改變腸道的細菌組成，但它確實會誘導細菌代謝碳水化合物方式的變化,。在該試驗中,，JeffreyGordon及其同事對在一段為期4個月的時間中食用某一特別品牌酸奶的7組人類雙胞胎和小鼠的腸道微生物進行了較為仔細的觀察,。這些小鼠為無菌小鼠，它們的飼養(yǎng)情況使得它們只含有典型的人類腸道菌群中的15種細菌,。
研究人員分析了在食用酸奶之前,、當中及之后的腸道細菌的組成和人及動物的腸道菌群的特殊基因表達模式。
該研究團隊發(fā)現(xiàn),，在人和小鼠中,，食用酸奶不會改變其腸道菌群的種類和基因含量,。然而,，對小鼠腸道細菌的基因表達及其尿液中的代謝物的進一步分析披露,，食用酸奶在許多代謝通路中都引起了明顯的變化,，尤其是那些與碳水化合物的處理有關(guān)的代謝通路。
盡管人們對每日食用一瓶酸奶醫(yī)生遠離哉這一說法是否正確仍不清楚,，但這些結(jié)果顯示,，益生菌食品可能會以微妙,、復雜的方式改變我們腸道的微生物組,，這值得我們對其做進一步的調(diào)查,。（生物谷 Bioon.com）
doi:10.1126/scitranslmed.3002701
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The Impact of a Consortium of Fermented Milk Strains on the Gut Microbiome of Gnotobiotic Mice and Monozygotic Twins
Nathan P. McNulty, Tanya Yatsunenko, Ansel Hsiao, Jeremiah J. Faith, Brian D. Muegge, Andrew L. Goodman, Bernard Henrissat, Raish Oozeer, Stéphanie Cools-Portier, Guillaume Gobert, Christian Chervaux, Dan Knights, Catherine A. Lozupone, Rob Knight, Alexis E. Duncan, James R. Bain, Michael J. Muehlbauer, Christopher B. Newgard, Andrew C. Heath and Jeffrey I. Gordon
Understanding how the human gut microbiota and host are affected by probiotic bacterial strains requires carefully controlled studies in humans and in mouse models of the gut ecosystem where potentially confounding variables that are difficult to control in humans can be constrained. Therefore, we characterized the fecal microbiomes and metatranscriptomes of adult female monozygotic twin pairs through repeated sampling 4 weeks before, 7 weeks during, and 4 weeks after consumption of a commercially available fermented milk product (FMP) containing a consortium of Bifidobacterium animalis subsp. lactis, two strains of Lactobacillus delbrueckii subsp. bulgaricus, Lactococcus lactis subsp. cremoris, and Streptococcus thermophilus. In addition, gnotobiotic mice harboring a 15-species model human gut microbiota whose genomes contain 58,399 known or predicted protein-coding genes were studied before and after gavage with all five sequenced FMP strains. No significant changes in bacterial species composition or in the proportional representation of genes encoding known enzymes were observed in the feces of humans consuming the FMP. Only minimal changes in microbiota configuration were noted in mice after single or repeated gavage with the FMP consortium. However, RNA-Seq analysis of fecal samples and follow-up mass spectrometry of urinary metabolites disclosed that introducing the FMP strains into mice results in significant changes in expression of microbiome-encoded enzymes involved in numerous metabolic pathways, most prominently those related to carbohydrate metabolism. B. animalis subsp. lactis, the dominant persistent member of the FMP consortium in gnotobiotic mice, up-regulates a locus in vivo that is involved in the catabolism of xylooligosaccharides, a class of glycans widely distributed in fruits, vegetables, and other foods, underscoring the importance of these sugars to this bacterial species. The human fecal metatranscriptome exhibited significant changes, confined to the period of FMP consumption, that mirror changes in gnotobiotic mice, including those related to plant polysaccharide metabolism. These experiments illustrate a translational research pipeline for characterizing the effects of FMPs on the human gut microbiome.
