Abstract: This study was performed in order to explore the antibacterial activity and mechanism of polyphenol extracts from adzuki bean seed coat against two pathogenic bacteria. High performance liquid chromatography (HPLC) was used to determine the composition of polyphenols in adzuki bean seed coat. The antibacterial effect of the polyphenol extract on Listeria ATCC19119 and Salmonella ATCC14028 was evaluated through determination of minimum inhibitory concentrations (MICs) and bacterial growth curves, and the underlying mechanism was elucidated in terms of protein and nucleic acid contents of bacterial cells, cell membrane potential, intracellular ATP concentration, extracellular alkaline phosphatase content and bacterial cell morphology. The results showed that a total of 13 phenolic compounds were found in adzuki bean seed coat. The MICs of the polyphenol extract against Listeria ATCC19119 and Salmonella ATCC14028 were 625 and 2 500 μg/mL, respectively. The polyphenol extract had a significant impact on the protein and nucleic acid contents of bacterial cells, intracellular ATP concentration, extracellular alkaline phosphatase content and bacterial cell morphology. Therefore, the results of this study provide theoretical reference of developing natural antibacterial products from food sources and comprehensively utilizing food processing by-products.

Key words: adzuki bean seed coat polyphenol; Listeria ATCC19119; Salmonella ATCC14028; antimicrobial mechanism