Single-cell, time-resolved study of the effects of the antimicrobial peptide alamethicin on Bacillus subtilis.

ABSTRACT: Alamethicin is a well-studied antimicrobial peptide (AMP) that kills Gram-positive bacteria. It forms narrow, barrel-stave pores in planar lipid bilayers. We present a detailed, time-resolved microscopy study of the sequence of events during the attack of alamethicin on individual, live Bacillus subtilis cells expressing GFP in the cytoplasm. At the minimum inhibitory concentration (MIC), the first observed symptom is the halting of growth, as judged by the plateau in measured cell length vs time. The data strongly suggest that this growth-halting event occurs prior to membrane permeabilization. Gradual degradation of the proton-motive force, inferred from a decrease in pH-dependent GFP fluorescence intensity, evidently begins minutes later and continues over about 5 min. There follows an

SUBMITTER: Barns KJ 

PROVIDER: S-EPMC4779711 | biostudies-literature | 2016 Apr

REPOSITORIES: biostudies-literature