Studies on a new antibiotic M-92 produced by Micromonospora. IV. Bactericidal action of the component VA-2

The action of VA-2, the most active component of antibiotic M-92, against S. aureus is bactericidal but not bacteriolytic. The bactericidal action is markedly affected by incubation temperature, whether bacterial cells are prolific or resting. The bactericidal kinetics of VA-2 is biphasic, since addition of VA-2 caused rapid and straight decrease in viability curve and reached a plateau after several minutes. The bactericidal activity of VA-2 is blocked by 2,4-dinitrophenol. Alike to many membrane-active bacteriocins, VA-2 seems to exert its action through two stages.