The aim of this work was to study the effect of antimicrobial peptides: divergicin M35 and nisin A on Listeria monocytogenes LSD 530 potassium (K+) channels: ATP-sensitive (K-ATP), calcium-activated (BKCa), and depolarization-activated (K-v) types. Increase on K+ efflux and inhibition of cellular growth were observed after adding K+ channel activators pinacidil, NS1619, and cromakalim to divergicin M35. Increase in K+ efflux from log-phase cells was about 18 +/- 1.1, 11 +/-0.63, and nmol mg(-1) of cell dry weight (CDW) for pinacidil and NS1619, respectively, over the efflux obtained with divergicin M35 alone. Increases in K+ efflux obtained by adding the same K+ channel activators to nisin A fit a completely different profile. Divergicin M35 activates K+ channels, particularly of the K-v and BKCa types and to a lesser extent the K-ATP type, causing K+ efflux and consequently cell death.