title: Bacteroides fragilis metabolises exopolysaccharides produced by bifidobacteria.
abstract: Bacteroides fragilis is the most frequent species at the human intestinal mucosal surface, it contributes to the maturation of the immune system although is also considered as an opportunistic pathogen. Some Bifidobacterium strains produce exopolysaccharides (EPS), complex carbohydrate polymers that promote changes in the metabolism of B. fragilis when this microorganism grows in their presence. To demonstrate that B. fragilis can use EPS from bifidobacteria as fermentable substrates, purified EPS fractions from two strains, Bifidobacterium longum E44 and Bifidobacterium animalis subsp. lactis R1, were added as the sole carbon source in cultures of B. fragilis DSMZ 2151 in a minimal medium. Bacterial counts were determined during incubation and the evolution of organic acids, short chain fatty acids (SCFA) and evolution of EPS fractions was analysed by chromatography.
  
  
  
  Growth of B. fragilis at early stages of incubation was slower in EPS than with glucose, microbial levels remaining higher in EPS at prolonged incubation times. A shift in metabolite production by B. fragilis occurred from early to late stages of growth, leading to the increase in the production of propionate and acetate whereas decrease lactate formation. The amount of the two peaks with different molar mass of the EPS E44 clearly decreased along incubation whereas a consumption of the polymer R1 was not so evident.
  
  
  
  This report demonstrates that B. fragilis can consume some EPS from bifidobacteria, with a concomitant release of SCFA and organic acids, suggesting a role for these biopolymers in bacteria-bacteria cross-talk within the intestine.
authors.affiliation: Probiotics and Prebiotics Group, Department of Microbiology and Biochemistry of Dairy Products, Instituto de Productos Lácteos de Asturias, Consejo Superior de Investigaciones Científicas (IPLA-CSIC), Villaviciosa, Asturias, Spain. drioscovian@ipla.csic.es.
authors.forename: David
authors.initials: D
authors.lastname: Rios-Covian
authors.affiliation: Scientific and Technical Facilities, Instituto de Productos Lácteos de Asturias, Consejo Superior de Investigaciones Científicas (IPLA-CSIC), Villaviciosa, Asturias, Spain.
authors.forename: Isabel
authors.initials: I
authors.lastname: Cuesta
authors.affiliation: Scientific and Technical Facilities, Instituto de Productos Lácteos de Asturias, Consejo Superior de Investigaciones Científicas (IPLA-CSIC), Villaviciosa, Asturias, Spain.
authors.forename: Jorge R
authors.initials: JR
authors.lastname: Alvarez-Buylla
authors.affiliation: Probiotics and Prebiotics Group, Department of Microbiology and Biochemistry of Dairy Products, Instituto de Productos Lácteos de Asturias, Consejo Superior de Investigaciones Científicas (IPLA-CSIC), Villaviciosa, Asturias, Spain.
authors.forename: Patricia
authors.initials: P
authors.lastname: Ruas-Madiedo
authors.affiliation: Probiotics and Prebiotics Group, Department of Microbiology and Biochemistry of Dairy Products, Instituto de Productos Lácteos de Asturias, Consejo Superior de Investigaciones Científicas (IPLA-CSIC), Villaviciosa, Asturias, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Gueimonde
authors.affiliation: Probiotics and Prebiotics Group, Department of Microbiology and Biochemistry of Dairy Products, Instituto de Productos Lácteos de Asturias, Consejo Superior de Investigaciones Científicas (IPLA-CSIC), Villaviciosa, Asturias, Spain.
authors.forename: Clara G
authors.initials: CG
authors.lastname: de Los Reyes-Gavilán
mesh_terms: D000085:Acetates / Q000378:metabolism; D000328:Adult; D058491:Bacterial Load; D001441:Bacteroides fragilis / Q000254:growth & development / Q000378:metabolism*; D001644:Bifidobacterium / Q000254:growth & development / Q000378:metabolism*; D050260:Carbohydrate Metabolism; D002244:Carbon / Q000378:metabolism; D005232:Fatty Acids, Volatile / Q000378:metabolism; D006801:Humans; D007413:Intestinal Mucosa / Q000382:microbiology; D007422:Intestines / Q000382:microbiology; D019344:Lactic Acid / Q000378:metabolism; D056265:Microbial Interactions; D011135:Polysaccharides, Bacterial / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D011422:Propionates / Q000378:metabolism
chemical_list: D000085:Acetates; D005232:Fatty Acids, Volatile; D011135:Polysaccharides, Bacterial; D011422:Propionates; D019344:Lactic Acid; D002244:Carbon
keywords: Bacteroides fragilis; Bifidobacterium; Exopolysaccharides; Heteropolysaccharides; MALLS