Bacteroides xylanisolvens Y-11 and Bifidobacterium longum y37 isolated from human gut were found to inhibit each other's growth after co-culturing in previous studies. To further reveal the potential mechanism of mutual inhibition between them, ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used to investigate the metabolic changes of the strains after monoculture and co-culture, and the key differential metabolites were subject to the validation. The results showed that the types and amounts of metabolites were significantly changed during co-culture, with hydrocarbons and their derivatives, organic acids and esters being the main differential metabolites, which posed a greater influence on the metabolism of B. xylanisolvens Y-11 than on B. longumy y37. Further studies suggest that cycloserine and succinic acid may be the main metabolites that inhibit the growth of both strains, and the decrease of pH may be the main reason for succinic acid to inhibit the growth of the two strains. Moreover, B. longum y37 played a dominant role in the co-culture and its metabolites influenced the growth of B. xylanisolvens Y-11 to a greater extent. This study provides a new perspective for further understanding of the interaction between intestinal microbes and the influence of intestinal microecology on the occurrence and development of diseases.
