Antibacterial characteristics and mechanisms of action of Aronia melanocarpa anthocyanins against Escherichia coli

This study aimed to evaluate the antibacterial activity and mechanism of action of Aronia melanocarpa anthocyanins (AMAs) against Escherichia coli. AMAs displayed strong antibacterial activity against Escherichia coli. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of AMAs against E. coli was 0.625 mg/mL and 1.25 mg/mL, respectively. Analysis of alkaline phosphatase activity, potassium ion leakage, absorption material release at 260 nm, and change in soluble protein content revealed that AMAs could destroy the cell wall and membrane structure of E. coli. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) further confirmed the cell wall and cell membrane damage induced by AMAs. In addition, the interaction between AMAs and DNA was elucidated through agarose gel retardation and fluorescence spectroscopy. In summary, the present results indicate that AMAs kill E. coli by attacking multiple targets in the bacterial cell, which could favour the application of AMAs as natural food preservatives.