Cross-feeding is an important metabolic interaction mechanism of bacterial groups inhabiting the human colon and includes features such as the utilization of acetate by butyrate-producing bacteria as may occur between Bifidobacterium and Faecalibacterium genera. In this study, we assessed the utilization of different carbon sources (glucose, starch, inulin and fructooligosaccharides) by strains of both genera and selected the best suited combinations for evidencing this cross-feeding phenomenon. Co-cultures of Bifidobacterium adolescentis L2-32 with Faecalibacterium prausnitzii S3/L3 with fructooligosaccharides as carbon source, as well as with F. prausnitzii A2-165 in starch, were carried out and the production of short-chain fatty acids was determined. In both co-cultures, acetate levels decreased between 8 and 24 h of incubation and were lower than in the corresponding B. adolescentis monocultures. In contrast, butyrate concentrations were higher in co-cultures as compared to the respective F. prausnitzii monocultures, indicating enhanced formation of butyrate by F. prausnitzii in the presence of the bifidobacteria. Variations in the levels of acetate and butyrate were more pronounced in the co-culture with fructooligosaccharides than with starch. Our results provide a clear demonstration of cross-feeding between B. adolescentis and F. prausnitzii. ; Peer Reviewed