Figure 5: A workflow for the discovery of interactions between metabolites and gut microbiota.

Pathways analysis and association analysis among plasma, urine potential biomarkers and gut microbiota were implemented in the workflow. First, plasma and urine potential biomarkers could be obtained in the previous metabolomics studies, the information of gut flora ECs, KOs and species could be attained in the metagenomics study. They could be applied for the metabolic and metagenomics pathways constructions. Second, we could find the metabolites corresponded ECs by analysing the metabolic and metagenomics pathways and get the corresponded KOs by tracing the ECs data, further we could obtain the corresponded species by tracing the KOs data. Third, association analysis would be performed between KOs and metabolites, species and metabolites. Significant correlations would be obtained on the condition of correlation q.value < 0.05. Lastly, in these significant correlations, we further strictly screened these correlations on the conditions that the correlated KOs and species should be significant in the metagenomics data (p.value < 0.05), and the correlated species should contain these significantly correlated KOs. By integrating these metabolomics and metagenomics data, Clostridium sp. HGF2 was found to significantly correlate with GlcNAc-6-P. Clostridium sp. HGF2, Streptococcus sp. M143, Streptococcus sp. M334 were found to significantly associate with mannitol.