经常有广告吹嘘益生菌酸奶的好处,但吃这种酸奶对肠道中居住的微生物的影响以及对一般健康有何影响则仍然不清楚。
在一组人类双胞胎和小鼠中进行的一项新的研究显示,每日食用酸奶不会显著地改变肠道的细菌组成,但它确实会诱导细菌代谢碳水化合物方式的变化。在该试验中,JeffreyGordon及其同事对在一段为期4个月的时间中食用某一特别品牌酸奶的7组人类双胞胎和小鼠的肠道微生物进行了较为仔细的观察。这些小鼠为无菌小鼠,它们的饲养情况使得它们只含有典型的人类肠道菌群中的15种细菌。
研究人员分析了在食用酸奶之前、当中及之后的肠道细菌的组成和人及动物的肠道菌群的特殊基因表达模式。
该研究团队发现,在人和小鼠中,食用酸奶不会改变其肠道菌群的种类和基因含量。然而,对小鼠肠道细菌的基因表达及其尿液中的代谢物的进一步分析披露,食用酸奶在许多代谢通路中都引起了明显的变化,尤其是那些与碳水化合物的处理有关的代谢通路。
尽管人们对每日食用一瓶酸奶医生远离哉这一说法是否正确仍不清楚,但这些结果显示,益生菌食品可能会以微妙、复杂的方式改变我们肠道的微生物组,这值得我们对其做进一步的调查。(生物谷 Bioon.com)
doi:10.1126/scitranslmed.3002701
PMC:
PMID:
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.