Inter-individual variation was also evident in the completion ratio of the module for vitamins.
The completion ratio of each KEGG module was compared between humans and human gut microbiomes to illustrate their metabolic linkage.
Similarly, the completion ratio of the KEGG modules (M00135_1 and M00136_1) for γ-aminobutyric acid (GABA) varied among individuals, and Gammaproteobacteria mainly contributed to GABA production.
We have developed a new evaluation method for the potential functionome, based on the completion ratio of Kyoto Encyclopedia of Genes and Genomes (KEGG) functional modules.
These modules are divided into several parts depending on the branching patterns and are redefined as submodules for accurate calculation of the completion ratio.
The completion ratio of all KEGG functional modules in each organism was calculated based on a Boolean algebra-like equation (Additional file 1: Table S6).
In this study, we first calculated the completion ratio of each KEGG module in reference species whose genomic sequences have been completely determined.
Pairwise comparison of the completion ratio of the KEGG module clearly demonstrated the well-recognized functional complementation of the gut microbiome to the human host, which includes essential amino acid and vitamin biosynthesis (Additional file 2: Figure S6).
The completion ratio of each module in the 8 species was calculated based on the Boolean algebra-like equation, and the ratios were compared with each other to differentiate the potential functionome among the 8 species.
The completion ratio of each module by human gut microbiomes from 13 healthy individuals was calculated based on the Boolean algebra-like equation and compared with each other to differentiate the potential functionome between the 13 individuals.
