FOOD SCIENCE ›› 2019, Vol. 40 ›› Issue (5): 38-44.doi: 10.7506/spkx1002-6630-20180301-006

• Basic Research • Previous Articles     Next Articles

Sucrose Laurate Exerts Antibacterial Activity against Staphylococcus aureus by Destroying the Cell Membrane

NING Yawei1, YANG Kun1, HE Jianzhuo1, ZHANG Yan2, LI Qiang2, WANG Zhixin1, JIA Yingmin3,*   

  1. 1. College of Bioscience and Bioengineering, Hebei University of Science and Technology, Shijiazhuang 050018, China; 2. Hebei Food Inspection and Research Institute, Shijiazhuang 050000, China; 3. School of Food and Chemical Engineering, Beijing Technology and Business University, Beijing 100048, China
  • Online:2019-03-15 Published:2019-04-02

Abstract: The antibacterial activity of sucrose laurate against Staphylococcus aureus was determined, and the mechanism of cell membrane damage by sucrose laurate was investigated. The minimum inhibitory concentration (MIC) against S. aureus was determined by the two-fold dilution method, and the time-killing curve was assayed by the plate counting method. We studied the effect of sucrose laurate on the membrane potential of S. aureus was studied by fluorescence spectroscopy using DiSC3(5) as the probe, the effect on the membrane permeability by fluorescence microscopy and flow cytometry, the effect on the leakage of macromolecular substances by ultraviolet spectrophotometry, the effect on the leakage of intracellular potassium ions using the fluorescent probe PBFI, and the effect on the ultrastructure by transmission electron microscopy. The results showed that the MIC of sucrose laurate against S. aureus was 0.312 5 mg/mL. Compared with the control group, the fluorescence intensity of S. aureus with the probe DiSC3(5) increased in a concentration-dependent manner after treatment with sucrose laurate; The percentage of S. aureus stained with PI was 84.7% after the treatment of sucrose laurate at MIC for 30 min. The absorbance at 260 nm gradually increased with increasing treatment time at each concentration of sucrose laurate, but the increment was small. Sucrose laurate caused leakage of intracellular potassium ions and this effect was positively correlated with its concentration. After treatment with sucrose laurate at MIC for 1 h, the surface of bacterial cells became rough with blurred edges. Accordingly we concluded that sucrose laurate could dissipate cell membrane potential and destroy membrane permeability, leading to slight leakage of intracellular substances and consequently exerting antibacterial activity. This investigation can provide a theoretical basis for the development of versatile antibacterial products with glycolipids.

Key words: sucrose laurate, Staphylococcus aureus, cell membrane, flow cytometry, transmission electron microscopy

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