In this paper, the antimicrobial mechanisms of Amomum tsao-ko extracts against Escherichia coli (E. coli) and Salmonella typhimurium (S. typhimurium) are studied. The effects of Amomum tsao-ko extracts on the growth of E. coli and S. typhimurium are studied by measuring the minimum inhibitory concentration (MIC), the minimum bactericidal concentration (MBC) and the growth curve. The changes of microscopic morphological structure of bacterial cells are observed by scanning electron microscopy (SEM)), and the effects of the Amomum tsao-ko extracts on the cell wall permeability of E. coli and S. typhimurium are studied by measuring the alkaline phosphatase (AKP). The results show that Amomum tsao-ko extracts have obvious inhibitory effect on the growth of the tested bacteria, the MIC and MBC values of E. coli are all 0.625 mg/mL, and the MIC and MBC values of S. typhimurium are all 1.25 mg/mL. With the treatment of Amomum tsao-ko extracts for 8 h, the cell structure of E. coli and S. typhimurium is damaged and the permeability of cell wall is increased.
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