a) Functional selection of metagenomic libraries with 12 AMPs (red bars) resulted in
fewer distinct resistance-conferring DNA contigs than with 11 conventional
small-molecule antibiotics (ABs, blue bars). p=0.002 from
two-sided negative binomial regression, n=34 (AMP resistance
contigs), n=119 (AB resistance contigs). Red asterisks indicate
zero values and ** indicates a significant difference between AMPs and
antibiotics. b) Phylum-level distribution (%) of the AMP- (red
bars) and antibiotic-resistance contigs (blue bars). In the case of AMPs,
significantly more resistance contigs are originating from the Proteobacteria
phylum (p=0.015, two-tailed Fisher's exact test,
n=110), while contigs originating from the Firmicutes
phylum are underrepresented (p=0.033, two-tailed
Fisher's exact test, n=110). *Significant difference
between AMPs and antibiotics for a given phylum.