Fig 4. Cytoplasmic membrane depolarization of Gram-negative and Gram-positive bacteria by HICA.

Membrane potential levels of Escherichia coli O157:H7 NCTC12900 (A), Escherichia coli AGR3789 (B), Pseudomonas aeruginosa ATCC25668 (C) and Pseudomonas aeruginosa NZRM4034 (D), Bacillus cereus NZRM5 (E), Bacillus cereus M4 (F), and Staphylococcus aureus NZRM917 (G) upon addition of 4 mg/mL HICA (red line) or sterile water (untreated control, blue line) were assessed by the release of the membrane potential-sensitive dye DiSC₃(5) measured spectroscopically at 610 nm excitation and 660 nm emission wavelengths. The time point of HICA, or sterile water (as control) addition is highlighted with arrows. Data are presented as mean ± (s.d.) of DiSC₃(5) fluorescence of three replicates (n = 3).