Fig. 6: Influence of the flr gene on gut microbial composition under the pressure of flavone apigenin and the abundance of flr-like genes in human gut microbiome.

a Comparison of relative abundance of the WT C. ljungdahlii (WT) and C. ljungdahlii ∆flr (flr deletion) strains in a simplified gut microbiota (containing eight representative human gut bacterial strains without putative flr genes) under the pressure of apigenin. At the beginning of this experiment, the same volume (2 mL) of the cultures of these strains (OD₆₀₀ = 0.8) were mixed; then, 20 mL of the mixture was added aseptically to 200 mL of GMM broth containing 1% mucin and 1 mM apigenin. Therefore, the relative abundance of each strain in this artificial microbial community was considered to be the same at 0 h. The abundance of groEL (marker gene) at different time points relative to that at 0 h was used to indicate the relative abundance of individual strain. CM, simplified core microbiota consisting of eight representative gut bacterial strains. Api, apigenin. The data of two biologically independent samples were presented at each time point. b, c The abundance of the flr homologs across human gut microbiome samples (b) and the prevalence of the flr homologs across human gut metagenomes at different abundance thresholds (c) based on the human microbiota metagenomic data from MetaQuery.