Peptide Interaction with B. pseudomallei

The interaction of peptides with B. pseudomallei was examined using fluorescence microscopy and an assay based on the uptake of the fluorescent dye SYTOX Green (Invitrogen, USA; Matsumoto et al., 2010 (link)) with minor modifications. First, bacterial cells at about 5 × 10⁵ CFU/ml were treated with 8× MIC₉₀ peptides for 1 h at 37°C. The cells treated with 0.5% Triton X-100 and 1× PBS were included as the controls. Bacterial suspensions were then stained with 1 μM SYTOX Green and incubated for 30 min at room temperature in the dark. An aliquot of the reaction mixtures was spotted onto a glass slide for visualization at 200× magnification under the Leica DM5000B upright microscope equipped with a GFP2 filter cube (bandpass 480/40 nm). Three independent replicates were performed.