Bacterial Dye Release Measures in Response to Antimicrobial Peptides.

Assessment of bacterial dye release following exposure to antimicrobial peptides (AMPs) provides a detailed understanding regarding their interaction with the inner and outer membrane of bacteria, and the leak of bacterial intracellular materials. This underpins the overall antimicrobial mechanism of these membrane-active peptides. DiSC3(5) is a membrane potential sensitive dye and can characterize the changes in bacterial membrane potential following exposure to AMPs (see Note 1). SYTOX Green is a nucleic acid stain that enters the cell upon loss of membrane integrity after exposure to AMPs and binds to DNA. SYTO9 is another nucleic acid stain, whereas propidium iodide (PI) is a fluorescent intercalating agent that can be used to stain cells and nucleic acids. Both of these stains are widely used to monitor the viability of bacteria following exposure to AMPs. This chapter describes the methods of using these as bacterial dye release experiments for assessment of the antimicrobial mechanism of AMPs.