Bacterial Fluorescent-dextran Diffusion Assay

Abstract

Antimicrobial peptides are known to disrupt bacterial membranes allowing solutes to flow across the membrane in an unregulated manner resulting in death of the organism. Disrupting the bacterial membrane would thus perturb the cells osmotic balance resulting in an initial influx of the external aqueous buffer. We have designed an assay to investigate how antimicrobial peptide concentration affects the ability of fluorescently labelled dextran moieties of differing molecular weight and hydrodynamic radii to cross membranes of viable bacteria. This assay was used to show that diffusion of low and high molecular weight dextrans into bacteria was a function of antimicrobial peptide concentration (Sani et al., 2013).