Project description:This SuperSeries is composed of the following subset Series: GSE25572: Depolymerization of plant cell wall glycans by symbiotic human gut bacteria (Bacteroides thetaiotaomicron) GSE25575: Depolymerization of plant cell wall glycans by symbiotic human gut bacteria (Bacteroides ovatus) Refer to individual Series
Project description:Purpose: Examining the transcriptome of human gut bacteria (Bacteroides xylanisolvens/Bacteroides ovatus) that grow on mucin O-linked glycans as a sole carbon source Methods: Strains were grown on 10 mg/ml mucin O-linked glycans (MOG) or 5 mg/ml glucose as a sole carbon source in vitro. Fold change was calculated as MOG over glucose. Once cells reached an optical density corresponding to mid-log phase growth, RNA was isolated and rRNA depleted. Samples were multiplexed for sequencing on the Illumina HiSeq platform at the University of Michigan Sequencing Core. Data was analyzed using Arraystar software (DNASTAR, Inc.) Genes with significant up- or down-regulation were determined by the following criteria: genes with an average fold-change >10-fold and biological replicates with a normalized expression level >1% of the overall average RPKM expression level. Results: We identified genes activated in response to mucin O-linked glycans from Bacteroides xylanisolvens/Bacteroides ovatus strains
Project description:Bacteroides thetaiotaomicron was grown and transcriptionally profiled on a number of different host mucosal glycans and their component mono- and disaccharides.
Project description:Gene expression profiles of Bacteroides thetaiotaomicron in vitro during growth on host mucosal polysaccharides as sole carbon sources. All substrates in this series are derived from porcine gastric mucin and include mucin O-glycans and glycosaminoglycans.
Project description:Symbiotic bacteria inhabiting the distal human gut have evolved under intense pressure to utilize complex carbohydrates, predominantly plant cell wall glycans abundant in our diets. These substrates are recalcitrant to depolymerization by digestive enzymes encoded in the human genome, but are efficiently targeted by some of the ~103-104 bacterial species that inhabit this niche. These species augment our comparatively narrow carbohydrate digestive capacity by unlocking otherwise unusable sugars and fermenting them into host-absorbable forms, such as short-chain fatty acids. We used phenotype profiling, whole-genome transcriptional analysis and molecular genetic approaches to investigate complex glycan utilization by two fully sequenced and closely related human gut symbionts: Bacteroides thetaiotaomicron and Bacteroides ovatus. Together these species target all of the common glycosidic linkages found in the plant cell wall, as well as host polysaccharides, but each species exhibits a unique ‘glycan niche’: in vitro B. thetaiotaomicron targets plant cell wall pectins in addition to linkages contained in host N- and O-glycans; B. ovatus uniquely targets hemicellulosic polysaccharides along with several pectins, but is deficient in host glycan utilization. Growth of Bacteroides thetaiotaomicron in vitro in minimal medium plus different purified complex glycans. Observation of increased gene expression was used to determine genes that are involved in metabolism of each glycan. Two biological replicates each.
Project description:Symbiotic bacteria inhabiting the distal human gut have evolved under intense pressure to utilize complex carbohydrates, predominantly plant cell wall glycans abundant in our diets. These substrates are recalcitrant to depolymerization by digestive enzymes encoded in the human genome, but are efficiently targeted by some of the ~103-104 bacterial species that inhabit this niche. These species augment our comparatively narrow carbohydrate digestive capacity by unlocking otherwise unusable sugars and fermenting them into host-absorbable forms, such as short-chain fatty acids. We used phenotype profiling, whole-genome transcriptional analysis and molecular genetic approaches to investigate complex glycan utilization by two fully sequenced and closely related human gut symbionts: Bacteroides thetaiotaomicron and Bacteroides ovatus. Together these species target all of the common glycosidic linkages found in the plant cell wall, as well as host polysaccharides, but each species exhibits a unique ‘glycan niche’: in vitro B. thetaiotaomicron targets plant cell wall pectins in addition to linkages contained in host N- and O-glycans; B. ovatus uniquely targets hemicellulosic polysaccharides along with several pectins, but is deficient in host glycan utilization. Bacteroides ovatus bacteria were grown either in vitro on defined complex glycan sources, or in vivo in the intestinal tract of gnotobiotic mice fed variable diets. Increased in vitro gene expression was used to indicate the genes required for metabolism of complex glycans and compared to in vivo transcriptional activity to determine expression in the mouse gut.
Project description:The human gut microbiota is an important metabolic organ, yet little is known about how its individual species interact, establish dominant positions, and respond to changes in environmental factors such as diet. In this study, gnotobiotic mice were colonized with an artificial microbiota comprising 12 sequenced human gut bacterial species and fed oscillating diets of disparate composition. Rapid, reproducible, and reversible changes in the structure of this assemblage were observed. Time-series microbial RNA-Seq analyses revealed staggered functional responses to diet shifts throughout the assemblage that were heavily focused on carbohydrate and amino acid metabolism. High-resolution shotgun metaproteomics confirmed many of these responses at a protein level. One member, Bacteroides cellulosilyticus WH2, proved exceptionally fit regardless of diet. Its genome encoded more carbohydrate active enzymes than any previously sequenced member of the Bacteroidetes. Transcriptional profiling indicated that B. cellulosilyticus WH2 is an adaptive forager that tailors its versatile carbohydrate utilization strategy to available dietary polysaccharides, with a strong emphasis on plant-derived xylans abundant in dietary staples like cereal grains. Two highly expressed, diet-specific polysaccharide utilization loci (PULs) in B. cellulosilyticus WH2 were identified, one with characteristics of xylan utilization systems. Introduction of a B. cellulosilyticus WH2 library comprising >90,000 isogenic transposon mutants into gnotobiotic mice, along with the other artificial community members, confirmed that these loci represent critical diet-specific fitness determinants. Carbohydrates that trigger dramatic increases in expression of these two loci and many of the organism’s 111 other predicted PULs were identified by RNA-Seq during in vitro growth on 31 distinct carbohydrate substrates, allowing us to better interpret in vivo RNA-Seq and proteomics data. These results offer insight into how gut microbes adapt to dietary perturbations at both a community level and from the perspective of a well-adapted symbiont with exceptional saccharolytic capabilities, and illustrate the value of artificial communities.