Inhibitory Effects of Hibiscus Acid on Foodborne Bacteria: A Comprehensive Analysis of the Viability, Motility, and Membrane Disruption of Enterohemorrhagic <i>Escherichia coli</i> , <i>Salmonella</i> Typhimurium, and <i>Listeria monocytogenes</i>

Hibiscus acid has antimicrobial activity against pathogenic bacteria; however, the mechanism of action against these bacteria has not been completely identified. The effect of hibiscus acid on the viability, motility, and cell membrane of multidrug-resistant enterohemorrhagic <i>Escherichia coli</i>, <i>Salmonella</i> Typhimurium, and <i>Listeria monocytogenes</i> was determined. Cell viability was determined by the pour plate technique, and motility was determined by phase contrast microscopy. Acridine orange/ethidium bromide fluorescent staining was performed using a fluorescence microscope to observe live and dead cells. Bacterial cell damage was analyzed by scanning electron microscopy. Finally, nucleotide leakage (DNA and RNA) was evaluated by measuring absorbance at 260 nm using a UV-VIS spectrophotometer. Hibiscus acid treatments (minimum inhibitory concentration [MIC], minimum bactericidal concentration [MBC], 10× minimum inhibitory concentration [10× MIC]) significantly decreased the viable cell counts of the three pathogenic bacterial strains in a time-dependent manner. Hibiscus acid at concentrations of MIC, MBC, and 10× MIC inhibited the motility of bacteria and caused lysis of the bacterial cell membrane. The damage to the membrane was greater as the concentration of hibiscus acid increased. High red fluorescence was found in the cells treated with hibiscus acid at the MIC and 10× MIC, and the release of intracellular material was observed after 2 h of treatment with the three pathogenic bacteria studied. The antimicrobial effect of hibiscus acid was due to the alteration of the membrane permeability of the three pathogenic bacteria studied. Hibiscus acid may represent an alternative to antibiotics for the treatment or prevention of infectious bacterial diseases.