Figure 5.

Distribution of different pathways for propionate and butyrate formation in dominant human gut bacteria, based on genome searches of corresponding genes (Table 2; note that no sequence information is currently available for C. lactatifermentans), metagenomic mining (Figures 3 and 4) and validation of degenerate primers (Supplementary Table S1). C. lactatifermentans and M elsdenii originate from animal hosts (chicken and sheep, respectively). They are included as closely related bacteria are carriers of the acrylate pathway based on human metagenome mining (Figure 3). 16S rRNA sequences were obtained from the Ribosomal Database Project (Cole et al., 2009). Phylogenetic assignment—Lach.: Lachnospiraceae, Rum.: Ruminococcaceae, Neg.: Negativicutes, Ver.: Verrucomicrobia, Bact.: Bacteroidetes. P1–P3, B1–B2: Propionate and butyrate pathways as per Table 2. Question marks indicate the presence of genes with ⩾50% sequence identity (Table 2). As M. elsdenii is known to produce butyrate and A. munciniphila propionate, this has been taken into consideration for the assignment of pathways.