Data from: Antimicrobial peptide LL37 is potent against non-growing Escherichia coli cells despite a slower action rate

Antimicrobial peptides (AMPs) have long been considered as potential
agents against non-growing, dormant cells due to their membrane-targeted
action, which is largely independent of the cell’s growth state. However,
the relationship between the action of AMPs and the physiological state of
their target cells has been unclear, with recent reports offering
conflicting views on the efficacy of AMPs against bacteria in a stationary
phase. In this study, we employ single-cell approaches combined with
population-level experiments to examine the action of human LL37 peptides
against Escherichia coli cells in different growth phases. Time-lapse,
single-cell data from our experiments reveal that LL37 peptides act faster
on large, dividing cells than on small, newborn cells. We extend this
investigation to non-growing E. coli cells in a stationary phase, where we
observe that the action of LL37 peptides is slower on non-growing cells
compared to exponentially growing cells. This slower action rate is,
however, not mirrored in the minimum bactericidal concentration (MBC)
measurements. Notably, we find that the MBC for non-growing cells is lower
than for exponentially growing cells, indicating that, given sufficient
time, LL37 peptides exhibit strong potency against non-growing cells. We
propose that the enhanced potency of LL37 peptides against non-growing
cells, despite their slower action, can be attributed to a continuous
absorption of AMPs on the cell membrane over time.