Bifidobacteria are common and frequently dominant members of the gut microbiota of many animals, including mammals and insects. Carbohydrates are considered key carbon sources for the gut microbiota, imposing strong selective pressure on the complex microbial consortium of the gut. Despite its importance, the genetic traits that facilitate carbohydrate utilization by gut microbiota members are still poorly characterized. Here, genome analyses of 47 representative Bifidobacterium (sub)species revealed the genes predicted to be required for the degradation and internalization of a wide range of carbohydrates, outnumbering those found in many other gut microbiota members. The glycan-degrading abilities of bifidobacteria are believed to reflect available carbon sources in the mammalian gut. Furthermore, transcriptome profiling of bifidobacterial genomes supported the involvement of various chromosomal loci in glycan metabolism. The widespread occurrence of bifidobacterial saccharolytic features is in line with metagenomic and metatranscriptomic datasets obtained from human adult/infant faecal samples, thereby supporting the notion that bifidobacteria expand the human glycobiome. This study also underscores the hypothesis of saccharidic resource sharing among bifidobacteria through species-specific metabolic specialization and cross feeding, thereby forging trophic relationships between members of the gut microbiota. ; We thank GenProbio srl for financial support of the Laboratory of Probiogenomics. This work was financially supported by a FEMS Jensen Award to FT, and by a Ph.D. fellowship (Spinner 2013, Regione Emilia Romagna) to S.D. DvS and FT are members of The APC Microbiome Institute, while DvS is also a member of the Alimentary Glycoscience Research Cluster, both funded by Science Foundation Ireland (SFI), through the Irish Government’s National Development Plan (Grant numbers SFI/12/RC/2273 and 08/SRC/B1393, respectively). This work was also partially supported by Fondazione Caritro, by the EU FP7 (PCIG13- GA-2013-618833), and by MIUR “Futuro in Ricerca” E68C13000500001 to NS. Furthermore, this project has been funded in part with funds from the National Institute of Allergy and Infectious Diseases, National Institutes of Health, Department of Health and Human Services, under Contract No. HHSN272200900018C. ; Peer Reviewed