a, P. khanii was grown in liquid culture,
then concentrated culture supernatants tested for inhibition of E.
coli MG1655. P. khanii concentrated supernatant
produced a zone of inhibition on an E. coli lawn, while
unconcentrated supernatant or a colony overlay did not. Paenibacillus
polymyxa produces polymyxin and serves as a positive control.
b, Darobactin structure. c, The BGC consists of
the structural gene darA (colored in blue),
darBCD (transporter encoding genes, in grey) and
darE (encoding a radical SAM enzyme, in orange). In
addition, a relE-like gene (black) ORF can be co-located with
the BGC at different positions. d, Time-dependent killing of
E. coli MG1655 by darobactin. An exponential culture of
E. coli MG1655 was challenged with 16xMIC antibiotics. n=3
biologically independent samples, symbols are mean, error bars are SD.
e, SEM analysis of E. coli MG1655 treated with
16xMIC darobactin (Scale bar, 1 μm).