Fig. 3

Bacteriocin gene abundance distributions in the gut metagenomes. In the leftmost panel, the total fraction of reads in each metagenome aligning to some bacteriocin is shown for the metagenomes in the infant group (pink), the child group (orange), the adolescent group (purple), the adult group (blue) and the elderly group (yellow). The median value of the infant group is 2.5 × 10^–5 and the median value of the adult group is 8.3 × 10^–6. Note that the y-axis is log-transformed, making differences appear smaller. The other panels are also showing the fraction of reads in each metagenome aligning to some bacteriocin, but limited to bacteriocins of class I, II or III, respectively. The difference in bacteriocin gene abundance between the infant group and each of the other age groups was significant in all cases, both when considering all matching reads and when considering reads matching bacteriocins from each of the three bacteriocin classes (p < 0.01)