FUNCTIONAL GENOMIC AND METABOLIC STUDIES OF THE ADAPTATIONS OF A PROMINENT ADULT HUMAN GUT SYMBIONT, BACTEROIDES THETAIOTAOMICRON, TO THE SUCKLING PERIOD*

摘要: The adult human gut microbiota is dominated by two divisions of Bacteria, the Bacteroidetes and Firmicutes. Assembly this community begins at birth through processes that remain largely undefined. In report, we examine adaptations Bacteroides thetaiotaomicron, a prominent member distal intestinal microbiota, during suckling weaning periods. Germ-free NMRI mice were colonized from their gnotobiotic mothers, who harbored anaerobic Gram-negative saccharolytic bacterium. B. thetaiotaomicron was then harvested ceca these hosts period (postnatal day 17) after 30). Whole genome transcriptional profiles obtained time points using custom GeneChips. Transcriptome-based in silico reconstructions bacterial metabolism gas chromatography-mass spectrometry biochemical assays carbohydrate utilization vivo indicated prefers host-derived polysaccharides, as well mono- oligosaccharides present mother's milk. After weaning, expands its to exploit abundant, plant-derived dietary polysaccharides. bacterium's responses postnatal alterations nutrient landscape involve expression gene clusters encoding environmental sensors, outer membrane proteins involved binding import glycans, glycoside hydrolases. These changes are interpreted light phylogenetic analysis revealed unique expansions related polysaccharide loci three alimentary tract-associated Bacteroidetes, likely reflect evolutionary species different niches.